Sciences : histoire orale

STENSGAARD Ivan, 2001-03-08

Sophie Jourdin — 2011-11-11T21:40:34Z

Ivan Stensgaard received a PhD in physics from the University of Aarhus, Denmark, in 1977. He subsequently spent two years at Bell Labs in Murray Hill, New Jersey. From 1979 to 1998 he was Associate Professor at the Institute of Physics and Astronomy of the University of Aarhus. From then on, he has been a Research Professor at the Center for Atomic-Scale Materials Physics (CAMP).

From the 1970s onwards, Stensgaard has investigated surfaces. His primary tool before the advent of the Scanning Tunneling Microscope was ion scattering. His first publication investigated radiation damage in reactor materials, and soon he moved on to investigate other surfaces, such as platinum, tungsten, and silicon. He used both backscattering and channeling of ions to infer the reconstructions of crystal surfaces. Most of his research employed ions in the MeV range, but he has also worked with low and high energies.

Because of his extensive knowledge of surface structures and the tools used to gain knowledge about them, he was in a good position to judge the efficacy of the scanning tunneling microscope when it came upon the scene in the mid-1980s. In collaboration with Flemming Besenbacher and Erik Lægsgaard, he built up a research project (CAMP) that relies extensively upon this new tool.

In our interview, Stensgaard outlines the history of CAMP and describes some of the many uses to which the STM can be put.

IVAN STENGSAARD (IS) : In the early the days, the way I recall it at least, in the STM field, most people worked on semiconductors, where the advantage is that the corrugation revealed by the STM is generally much larger than on metal surfaces. That means that the demands on the equipment are much more modest. So it was easier to enter the field of semiconductors - and of course also the technological implications were thought to be greater in that field. But when we entered the field, which must have been around 1987, there were few groups working on metal surfaces. So although the STM was really recognized as an excellent tool, there had been some delay in really using this as a common tool in studying metal surfaces.

ARNE HESSENBRUCH (AH) : But during the period of '82-'87 you would have known about the STM ?

IS : Yes.

AH : And it was something that you perhaps watched ? You watched the development of this instrumentation and you were critical to see whether it would prove its mettle for you to begin to use it ?

IS : Yes. Well we were not, as I recall it, completely convinced that it would add a lot to the insight into metal surfaces. But as soon as we did enter the field ourselves, placed the instrument in vacuum and seen the results, we were immediately convinced. I'd say from then on it has been fantastic : it has been quite easy to achieve good results with just about any topic of investigation. One saw new phenomena almost regardless of what one studied—new and completely unanticipated phenomena.

AH : So you're saying "we" now, this is presumably the CAMP group. When did that gel ? Was that in '87 ?

IS : Yes, I do mean the CAMP group. But we began collaborating earlier. Historically, I think it was like this : I returned from the US and received this grant for building up an ion scattering facility for studying surfaces [referring to an earlier mention that is not on the tape – this part of the interview will be repeated in the near future]. Some years later, Flemming Besenbacher and I worked together on ion scattering from surfaces. We looked at small molecules, and specialized on the examination of hydrogen on metal surfaces. Then in the 80's, probably around '85 or so, we began to discuss in more detail this question of building a scanning tunneling microscope. Flemming took the initiative in those days and contacted Erik Lægsgaard. Erik was really the key person in building the STM here. And from when he started until he had a table-top version, giving atomic resolution on graphite, lasted only a few months. Of course it took longer to make an instrument fitting into a vacuum system, and so on.

AH : Did you make it locally ?

IS : Yes, everything here has always been homemade.

AH : You've never bought instruments from the outside ?

IS : No. We tend to claim here that our instrument is better than what we can buy. It may sound like boasting, but I think our results help prove the contention. The fact that we can work with extremely rudimentary vibration isolation, proves that we have an highly stable instrument.

AH : So what were the characteristics of the design – the Aarhus design ?

IS : Well, there are two basic ingredients in the construction : one is the scanner tube scanning the tip across the surfaces, and I think that was copied simply from the Binnig and Rohrer design.

AH : The empty cylinder.

IS : Yes. So, the larger problem was how to approach this scanner tube tip to the surface in a controlled way so that you would come close enough to draw a tunnel current without actually colliding. To begin with we had many ideas about some mechanical way of doing it with micrometer screws, but soon we focused upon piezoelectric materials. And I think, again, that it was Erik's idea to make an inchworm. This is a really strange story. We had a very small inchworm made : only a few millimeters in diameter - maybe 10-12 mm long. It worked well and a company called DME in Copenhagen wanted to commercialize our setup. During the discussions and negotiations with them, they found out that the inchworm principle was already known, and what was worse, it was already patented. That was a something of a setback - not for our in-house microscopes but for the efforts to commercialize it. The commercially available inchworms were much bigger and not nearly as elegant as ours. But the principle was patented, and the patent had a few years left before expiration.

AH : Oh, so the patented inchworm was not intended for the STM ?

IS : No. The patent was about 10-15 years old and had been developed for something else. Whether it was developed for one of the topografiners and what they were called, the instruments used prior to STMs, I don't know. We can check the patent.

AH : Well, the topografiner was invented at the National Bureau Standards now NIST and I don't think they would have taken a patent.

IS : We could check it.

AH : So you designed the inchworm in '87, just when you were making your first STM ?

IS : Yes.

AH : But your first STM did not have an inchworm.

IS : Yes, it was a mechanical approach.

AH : Where did you get all the information for making an STM ? Did you look at the publications of Binnig and Rohrer, did you go and see them ? Did you go to the IBM labs ?

IS : No, the way I recall it, we had no personal contact. I think everything was done just using the publications.

AH : And it wasn't particularly difficult ?

IS : Not if you had a clever man like Erik. The short time required to make the first STM also indicates that it was fairly easy. Of course in retrospect many aspects of building an STM seem easy, because we know just how piezos work and what to pay attention to. The game nowadays is really to make them as compact as possible, to make them work even with vibrations in the surroundings and so on.

AH : Yes, you were saying you had very elementary vibration damping. This is another characteristic of this design ?

IS : Yes. Exactly. When you visit other STM labs, you're frequently told that they have to work at night when there is no traffic. They have all kinds of vibration damping, entire vacuum systems hanging in rubber — springs from the ceiling or something like that. They have the microscope damped with magnetic or eddy current damping. And people had to stay quiet and not move about in the room and so on. That remained characteristic until at least ten years ago. By contrast, from the beginning we hung our microscope on three or four springs, or viton-o rings, which are really rubber springs. That's all ; we have no further vibration damping. And people can even touch the UHV chamber without interfering with the tunneling. So that has been the main characteristics of the instrument here : its ability to scan fast and under adverse conditions.

AH : Fast and robust. You have told us about the robustness, could you tell us about the speed ?

IS : Fast scanning is interesting also because it has opened up new opportunities compared to other microscopes. There are more fast-scanning microscopes today but to begin with we scanned faster than most others. We scanned at the rate of one second per image, where many others spent one minute per image. This gives you the opportunity to follow dynamic processes on surfaces by sequentially recording images and then replaying the images at a faster rate - in the form of a movie. That gives you a very vivid impression of what happens on the surface. You might object that a movie yields no new information, but it turns out to be a very good means of attracting attention to dynamic processes. Such phenomena miss easily when just examining static pictures. The eye is well-suited to spotting change, so that even when there is a lot to keep track of, say 20 to 40 entities on a surface, your eye will immediately pick it up a movement of any one entity. So this question of scanning fast and taking movies, is not just a question of presenting results in a nice way, it also gives you a better insight into what is going on.

AH : But you weren't capable of making movies off the bat in 1987 were you ? How long did you need to scan in 1987, roughly ?

IS : I don't recall it really. I think we could record images in seconds, but the problem was probably rather that saving and replaying images requires a lot of data storage, and in those days the hard disks were not very big. It was slow process simply to get an image from the hard disk onto the screen.

AH : Was your ability to scan quickly a desideratum in 1987 ?

IS : Early on we probably didn't focus on the time you spent recording. It probably didn't matter whether it was 1 or 20 seconds or so. But I see now [checking on the computer] that taking movies and things like that, must have started in the late 80's. Because we have publications at least from '91 where we have included, not movies because that wasn't possible, but results based on these techniques.

AH : And what sort of thing did you image ? Metal surfaces with adsorbed atoms ?

IS : Yes, of course the standard sample in those days (as it still is for testing an STM in air) was graphite. Of course we used that as the test that our STM was working properly. Having done that we moved rather swiftly in the surface science direction again. We examined some gold-plated plastics, simply to investigate the micro-roughness. The purpose was to test the coating of large mirrors of an x-ray telescope to be used in a satellite. We also investigated some biological samples. But we were really implementing the STM in a vacuum.

AH : You say you were immediately convinced, when you saw the images, that this was a useful tool. It was seeing the images that convinced you almost instantly ?

IS : Yes

AH : Why ? There are many problems with the imaging process of course, with the noise and the interpreting just what the tunneling current actually is referring to. On metals this is less of a problem than semiconductors. Was that a help to you ?

IS : Yes, to some extent it was. Let me just mention the first system we examined, to maybe make references to that. Once we got the microscope into a vacuum we continued our work on small molecules on a metal surface. The first system we examined was one I had investigated earlier using ion scattering. We had absorbed oxygen on a particular copper surface, a copper (110) surface. And it was known what happened to the oxygen, how the surface reconstructed. What was not known was how the process took place, and that was revealed immediately almost with the STM, because we could look upon the surface while the reconstruction took place, and we could make a movie and watch the process.

AH : That must have been exciting.

IS : Yes, and then I was at least totally convinced at that time that here was an amazing tool.

AH : So the problems that there might be with interpretation were really secondary to you, you said that even with all those problems, "it's still exactly what I need ?"

IS : Yes, you said that in the case of semiconductors it is more difficult to relate the STM-produced image to the surface corrugation. That is correct of course, but you could say that we had a similar problem on our hands with oxygen on a copper surface : were we imaging the copper or the oxygen ? And it turned out that we were usually imaging the copper. This posed the question : why not the oxygen ? And why is it sometimes just the other way around, that we image the oxygen and not the copper. So scanning on metals was not completely free of problems, at least not when you have the adsorbates on them. But if you image one clean surface with only one element present, then the interpretation is straightforward.

AH : What I'm trying to understand is that when you use a completely new tool, you cannot know whether it works.

IS : I think the problems of instrumentation were so insignificant compared to the insight gained, that we were absolutely convinced of the amazing utility of the instrument. That's the way I recall it, really. There was a trend in those days—probably through the 90's—from static to dynamic problems. Other methods, such as low-energy electron diffraction, high-energy ion scattering, x-ray diffraction, are better suited for static problems. You can induce a reaction on the surface, and then you can take your tool and find out how the surface has changed. But with the STM you had a tool with which to see the transformation from one state to the next. Later on, you could even follow single atoms moving on the surface. That was really amazing, and almost impossible with other techniques. Field ion microscopy has been able to do it in some cases.

AH : Before the STM, you were using tools like ion-scattering, but it was not the tool that defined your research. Now it looks like the STM defines the group.

IS : I don't really think that's correct. No matter what you investigate,
you have to take both things into account. You have to find an interesting problem amenable to investigation with your background, its relevance and so on. Then you have to consider the available techniques. You have to find a topic amenable to the techniques available to you. I think that also describes what we did with the STM. It is a question of resources. The microscope does not define the activities ; a natural development has rather taken place. I mentioned before that we first investigated small molecules on surfaces, and we have continued to do that. Our research has now diversified but it is still to a large extent coupled to chemical reactions and the like. We have studied surfaces in greater detail – also clean surfaces although clean surfaces are less interesting for STM research because one can get the information by other means. But when you grow metal on metal for example, what happens ? How do these atoms of one metal, influence the properties of a surface of another metal. How does the surface restructure ? And, to come back to my initial point, how do the chemical properties change ? What happens if we now adsorb oxygen, what happens if we carry out a chemical reaction, let's say oxygen and CO reacting on the surface. In all these cases there has been a connection to the initial questions.

AH : Have you expanded the number of chemical reactions you worked with ?

IS : Over the years we have worked with a number of chemical reactions, but in the last few years we have focused more on catalysis. We have for many years collaborated with Haldor Topsøe AS, one of the leading companies in the catalytic world. We have collaborated on a number of issues, in once case a new catalyst was developed on the basis of our results. We proved scientifically that the catalytic conversion works. Whether that catalyst in the end will be commercially available now depends on other considerations, such as the cost of producing a catalyst, its lifetime and so on.

AH : But you discovered new catalysts with the STM, is that what you're saying ?

IS : We discovered a system that turned out to have possibilities in catalysis. We could talk in more detail about that, but it's a story in itself.

AH : Okay. What can you do now with the STM that you couldn't do in 1990 ?

IS : There has been constant improvement in speed : the rate at which you record and replay images. And new designs have made the microscope usable under new conditions. It now works over a large range of temperatures and pressures. To begin with experiments could only be carried out at room temperature, whereas we now can work from 20K or so and up to maybe 150ºC (500K). This increase in the temperature range is important for the investigation of dynamic processes because the rate at which they proceed is governed by temperature. And if you wish to study a certain reaction or a certain diffusion property, you have to have the events happen at a rate you can follow. That means that you shouldn't have too many events per second, preferably no more than one event every few seconds. And you can normally do that by adjusting the temperature.
We can also work at many different pressures now. Early on we had to work either at atmospheric (ambient) pressure or else in a very high vacuum. We have recently become able to work in the full range of pressures from ultra high vacuum to atmospheric pressures and could in principle make the system work at even higher pressures, if it weren't for some windows unable to withstand atmospheric pressure. And that again is advantageous for catalytic research, since all catalytic processes run at high pressure and high temperature. In the surface science community there has always been arguments that their field would help improve catalysts and understand catalytic reactions. That is to some extent true, but there has also been a lingering skepticism whether the processes taking place at atmospheric pressure remain the processes governing chemical reactions while raising the pressure from 10-10 Torr to atmospheric pressure. So that has been an important result : that at least in the one case that we have done so far, the system behaves identically at high pressure and in an ultrahigh vacuum, it's exactly the same things that govern the processes.

AH : What do you have to change in the STM to make it amenable to the range of pressure and temperature ?

IS : Actually not much was changed ; it's basically the same setup. The only major change is that it is located in a minor vessel ; it's in a minor chamber with a smaller volume, which is the volume that is brought up to high pressure. The suspension system has changed also, but the basic STM is the same. The suspension system is still based on a few springs, and looks differently, but the system as such is really the same. And of course minor things like gold coating surfaces to avoid reactions of those, but the heart of the microscope is completely unchanged.

AH : Why didn't you do these things 10 years ago ?

IS : I think in the field of ultrahigh vacuum there have been so many extremely interesting topics that there simply hasn't been the capacity to look in other directions. We should bear in mind that when CAMP was established in '93, much more funding became available than before. And the group grew much bigger. And although to begin with we also focused very much on processes at low to high vacuum, then at least during the second period of CAMP (from 1998 onwards) we have been able to diversify. High pressure is simply a natural development out of our original research. When I refer to new fields, I mean investigating organic molecules and other biology-related issues. So our research program has really developed quite naturally.

AH : So you started CAMP in 1993 - you, Besenbacher and Lægsgaard.

IS : The history of CAMP is more complicated – it is related to changes in the funding of Danish research. A large insurance company, Statens Livsforsikringsanstalt, was sold and a fund, Grundforskningsfonden, was set up with the money from there : 1 or 2 billion Danish kroners. Interest from the capital there was to be spent on basic research in all fields. In those days the interest rate was high and leading to a fair amount of interest each year. They requested and received many proposals for research centers. I don't recall exactly but it was a very large number. And in the end they funded 23 centers in all kinds of science : medicine, humanities – Søren Kierkegaard. We got a center too, a collaboration between our group here at Aarhus and Jens Nørskov's group at the Danish Technical University at Lyngby. The group there focused mainly on theory, and Nørskov was the director of the center, as he still is technically. The reason the two groups joined in this project was that we had had a prior collaboration within another program called FTU, research for technological development. In addition Flemming had collaborated with Jens Nørskov on another topic. So we knew each other. A proposal was made based on the joint resources of these two groups and after some external referring procedures it was eventually funded.

AH : And the project was focused on the STM ?

IS : I think the scope was broader : the interaction between small molecules and surfaces, to some extent chemical reactions. Our tool of investigation was STM but the center as such was not a STM center, it was a center doing research in a specific field. And our tool of research was the STM.

AH : You mentioned that you had contacts with Topsøe and other companies. Have you had contact with chemists, people in chemistry departments ?

IS : We have, but not much.

AH : Are they not interested in this ?

IS : I think they are in many cases, but we work in surface physics, as it is called in Danish. The English term, "surface science", is more neutral. Of course what we do is to some extent surface chemistry. But our background is just physics. You could say that a center like this might just as well have been placed at an institute of chemistry. It just so happens that we had this collaboration, and that we had not had the opportunity to interact much with chemists.

AH : So it's not the barriers between physics and chemistry that are particularly high, it just hasn't happened ?

IS : It just hasn't happened. It might have worked out differently, had we had a common institute instead of a separate physics and chemistry institute. Some of the activities going on here might as well have been placed in the institute of chemistry and vice versa. Nowadays it's not that natural to have this division into two institutes.

AH : How far is it from here to chemistry ?

IS : It's just across the parking lot, 100 meters. We're even connected underground to them, although it takes a specific key.

AH : But you don't go to each other's seminars ?

IS : Very infrequently.

AH : This does seem surprising and in need of an explanation. No ?

IS : I think much of what we're doing is of interest to chemistry as such, but our institute is comparatively small. Chemistry and physics are amazingly broad fields and our small institute is only able to cover certain areas. It has just so happened that we work in a field without a natural counterpart in the institute of chemistry. There are no ill feelings on the other side of the parking lot ; it's not based on that.

AH : And what about chemists in general out there in the world ? Do you get resonances ? Where do you publish, for instance ?

IS : We publish in papers with as high an impact as possible. We have published very large number of Physical Review Letters during the period of CAMP, on very few occasions in Nature and Science also. But that is not that easy, and sometimes you feel it is more difficult being European than if you had been American, but that's another story. We publish of course also in other journals ; some material will go to Surface Science. Surface Science does not have that high an impact, but it is obviously a very natural journal for people working in surface science. In my opinion the quality is rather mixed, but these are the main journals that we choose. We do not publish much in European journals, or journals that are particularly European such as European Journal of Physics and European Physics Letters.

AH : For any particular reason ?

IS : Simply because impact and visibility are low.

AH : When you say that in Physical Review Letters the visibility is high, is it not limited to the physics community ? Isn't your work broader ?

IS : It's probably correct, but we have colleagues in other places working in chemistry departments. And some of them will also publish in Physical Review Letters. I think it is recognized as some natural place for good work, also. But we have also published in Chemical Physics Letters, there are also a number of publications there, but they're not quite as prestigious as Physical Review Letters.

AH : Are you under pressure to produce results of commercial interest and if so, does this conflict with your own interest in pure science ?

IS : I don't' think so. I don't think we are under much pressure in CAMP to produce results of direct relevance to industry. I do think that we in CAMP all see an extra benefit or satisfaction in producing something of relevance to the "real world” and not just to pure science.

AH : So when you get around to renewing CAMP for another five years, the grant-giving bodies will not look to commercial applications ?

IS : It won't come to that. The funding will stop after ten years. It's the general policy that centers such as ours may reapply only once, so that they run for a maximum of two periods. After two periods, they ought to find alternative funding and in some way become a more integral part of the institute. What will happen in two to two and a half years from now, I don't know.

AH : You are not worried ?

IS : Not terribly, I think some kind of funding will come. I think that the government has set aside some funding for integrating centers into their host institutions.

AH : The reason I'm asking these things, is that Jens E. T. Andersen at the DTU was telling me about tremendous pressures. The DTU has now a patent office, and renewal of academic contracts is subject to results in terms of patents rather than scientific publications.

IS : The emphasis on patents has definitely increased here also, but in my opinion it has not yet become a pressure. There is a greater emphasis on it, and some of that emphasis originates from the government. A new law was introduced in Denmark. Up until maybe a year ago, you had the rights to exploit your own inventions, even as an employee and civil servant. That has now changed so that when you develop anything patentable or otherwise exploitable, you have to first contact the university. Your invention will be assessed. The university decides whether it wants to patent your invention and exploit it. If it declines, then you are free to do it yourself. So you could say that maybe the timing is a little bit strange, because on the one hand you remove some carrots from the researcher and on the other hand you apply the stick to encourage work resulting in patents. I think the general political perspective is that a fair amount of knowledge of interest to industries is generated at the universities, but no good forum for the transferal of that knowledge exists. Maybe the thinking was that having the knowledge documented in patents would facilitate the transferal.

AH : Is it possible to pinpoint advances made in the field of catalysis over the last ten years related to the possibilities of the STM ?

IS : I think this story about developing a catalyst from scratch based on pure research is rare, almost unique. There are no more than one or two other examples. Normally catalysis has been a highly empirical field. Developments have mostly been trial and error - of course guided by different kinds of knowledge. But in the end it came down to trying something, modifying it, changing the stoichiometry or the ratios, optimizing and so on. The understanding of the catalyst emerged gradually out of this process. By contrast, ours is a clear case of going directly from scientific insight into the working of a catalyst to its development.

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« Entretien avec Ivan Stensgaard », par Arne Hessenbruch, 8 mars 2001 Sciences : histoire orale, https://sho.spip.espci.fr/spip.php?article131.

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Entretien avec Ivan Stensgaard, par Arne Hessenbruch, 8 mars 2001

Lieu : CAMP Aarhus : The Scanning Tunneling Microscopy Group, Aarhus University, Denmark.

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Transcription : Arne Hessenbruch

Edition en ligne : Sophie Jourdin

JORGENSEN Jans Friis, 2001-03-06

Sophie Jourdin — 2011-11-03T14:01:46Z

Jan Friis Jørgensen is the main developer of the Scanning Probe Image Processor or SPIP™, a computer program that processes the output from scanning probe microscopes. This program is currently the only one of its kind in the world, and sales figures are rising steeply. SPIP™ includes the visualization of image files and various other features such as auto-correlation and Fourier transforms. Add-on modules include calibration and roughness analysis.
An electrical engineer with an industrial PhD in scanning probe microscopy, Friis Jørgensen participated in the early developments of the scanning tunneling microscope in Denmark. Erik Lægsgaard built the first one in 1987 in collaboration with colleagues at the University of Aarhus (Flemming Besenbacher and Ivan Steensgaard). Towards the end of 1987, Danish Micro Engineering (DME) turned to the production of SPMs. Friis Jørgensen joined that company between 1989 and 1990. He then worked on an industrial PhD at IBM Denmark, and also spent 4 months at IBM Zurich. From 1993 to 1998 he worked at the Danish Institute of Fundamental Metrology (DFM), interrupted by a year at the National Institute of Science and Technology , just outside Washington, DC. In 1998 he founded a company called Image Metrology to market the program, honed on his experience in the previous decade. The company is located on the campus of the Danish Technical University, in the same building as DFM. In May 2001, the company acquired an additional location close by.
Since 1999, the company has participated in the European Network on the Calibration of Scanning Probe Microscopes, sponsored by the EU Commission. The purpose of this network is to establish a basis for the application of SPMs to metrology on the nanoscale.

ARNE HESSENBRUCH (AH) : Did you study physics ?

Jan Friis JORGENSEN (JFJ) : No, not at all, I am not a physicist. Many people think that I am, but actually I was educated in electrical engineering, got a master degree with a special within biomedical engineering. And I think I've worked around seven years within different fields of medical engineering, oral visuality and also all the sound diagnostics that we've took care. When I started in a small Danish company called DME, which is still existing, and producing STM, SPM, microscopes.

AH : When was this ?

JFJ : I think it was back in 89. I worked there for almost two years and in the beginning I was not meant to work on the STM, but they were behind schedule, so I was assigned to the project and I got stuck. I stayed there for almost two years.

AH : And you had never heard the STM before joining the company ?

JFJ : Not really.

AH : After joining and learning about the STM, what did it mean to you ? Was it an exciting instrument ?

JFJ : Sure, very exciting, it was new. It was very new that people could visualize atoms, achieve atomic resolution, so it was of course attractive to work with. But as a software engineer, you are a little bit of an outsider because all the good people were physicists. It was physicists who had invented the microscope ; nevertheless I recognised several problems in the microscope : even with very fine resolution there was much distortion in the images. Already at that time many people had tried to correct it - of course in hardware which is also the best way to do it if you can - but there are still many problems that could not be solved this way. So I thought why not ? But there was no time for such work in that company, there was not enough resources, and there were many other things to do. I got a chance to work on it only upon leaving the company in November 1990, when I started on an industrial Ph.D being hired by IBM Denmark and collaborating with the Danish Institute of Fundamental Metrology and the Danish Technical University, the Image Processing Department. I finished in 1993. I could almost define the project as I wanted. I had already had seven years of experience working in private companies. But now I had to study again, and of course that was hard but it was also good to know about all the problems which I wanted to solve. It was a kind of a niche, because, as I have said before, most people at that time were physicist working on it, and so they had different approaches for solving the problems, and I used my small capabilities to solve that.

AH : Could you elaborate on the problems ? The tip and sample overlap, is that the kind distortion we are talking about ?

JFJ : Well, that was the one distortion people had been very focused on : how well the tunneling process worked when scanning over the atoms and several people produced very good theories on how to understand these mechanisms, but when you were scanning over a hundred nanometers or more it didn't really matter. There were other sources of error in the equipment itself : the hysteresis of the scanner and of different kinds of noise in the operations. These were actually the main problems and I guess within science it was given too little attention. Of course it was more exciting to look at atoms.

AH : Was it a case of low and high status research ?

JFJ : I don't know, it might have been. Anyway I think I found a niche ; I solved some hysteresis problems in new ways that nobody had considered before. And it is a part of our living today.

AH : Are there more distortions ?

JFJ : You mentioned the tip-sample which is of course a problem. It is understandable that to measure something very small, the probe should be at least as small to get a good image.

AH : That's not an issue you can address with your tools, is it ?

JFJ : I can not address it today. At that time, when I made my Ph.D, I addressed the problem but I did not solve it, because I didn't have the time for it, but other people solved it in meanwhile - I mean as best as you can. With software you can do a little, but you can't make everything perfect. Nonetheless software helps you a lot. First of all, you need an understanding of the shape of the tip. Some tips are simply too poor to use for imaging but others are acceptable. With these I can use software for correction and reconstruction, and this can lead to more accurate measurements.

AH : Were you alone in your field ?

JFJ : There have been more papers on tip characterization and on understanding the tunnelling mechanism, while there have been few on hysteresis.

AH : But in your niche were you completely alone, or were there other people working on it, say around 1990, when you were doing your Ph.D.?

JFJ : There were a few working on metrology, but not with these automated image processing tools. I think at that time it was quite unique. There was nothing out there to copy, so I had to invent the tools myself.

AH : How did the opportunity to do an industrial Ph.D. come about ?

JFJ : There was an ad in Ingeniøren, a Danish periodical for engineers.

AH : Whose advert ?

JFJ : IBM Denmark and the Danish Institute of Fundamental Metrology.

AH : Was Kim Carneiro behind this ?

JFJ : Yes. I found it natural to also connect the Technical University to the project. So I ended up with three partners.

AH : The Ph.D topic was to write software to deal with the distortions in the machine itself, the noise coming from within ?

JFJ : Yes. Maybe there was also another approach, because there had been people before doing some software by making certain algorithms and demonstrating that it could work from the very beginning. I tried to enable others to use this and I built the house bigger and bigger. It's the still the same building but we have taken it from Unix to normal PCs to really reach many people. I also stayed also a couple of months at IBM in Rueschlikon where the STM and AFM was invented.

AH : When did you go there ?

JFJ : It must have been 91 or 92 - I don't remember exactly.

AH : Were they interested in your project ?

JFJ : Sure, sure.

AH : Did they also recognize it as a niche ?

JFJ : Yes, but there was also skepticism. Some said : "well, people have been making software before, but when they leave the software gets lost because nobody knows how to use it and continue to work on it."

AH : This is a general problem of software, right ? That it has to be made user friendily and to become independent of its maker.

JFJ : Yes. It's hard to get enough attention within a scientific institute I think, because their focus is on something else ; there are barriers. At the beginning only physicists worked with the STM and nanotechnology. Now there are physicists, chemists, biochemists, biologists - a lot of people who previously did not communicate. They need to learn from each other now. And you can not build an STM without using a lot of different sciences. One of which is of course software. But at that time, people were happy simply to see an image on the screen after pushing a few buttons.

AH : So the demand for your software has developed with the increasing expectations of what you could do with a STM ?

JFJ : Maybe, I think at the time nobody believed you could start a company based on image processing for scanning probe microscopy.

AH : Because the market for SPM was very small ?

JFJ : Very small, but when I finished in 93 I considered commercializing and I discussed it. Nobody believed in it.

AH : Now it is feasible to run this as a business because the market is large enough ?

JFJ : SPM is of course a niche but from a software engineer's point of view it's simply image processing. There's no shortage of images requiring treatment such as scanning electron microscope images and optical microscope images. We now have enough expertise to address the other markets too, so we kind of expand from the nanometer range of SPM to many other things around us.

AH : I would've expected the noise and distortion in other instruments to have been completely different so that you would not be able to draw on your expertise with SPMs.

JFJ : Many of our tools can be applied to other images. Some distortions are indeed peculiar to SPM images, but there are also some generalities. For instance, satellite images are scanned line by line the same way an STM image is, and this line by line scanning can give the same kind of distortions and artifacts in each type of image.

AH : I see ; that is indeed very general. As a physics student I scanned photographs of the solar surface using an optical photometer and of course it scanned in just this way. Interesting ! When you started your Ph.D., did you already think in terms of such generality ?

JFJ : Sure ! You have to. I mean I didn't go into the field to just to be an SPM person. I wanted to learn something which I could use widely. Of course the SPM is interesting in itself, but image processing is also interesting in itself.

AH : All right ; in 1993 you finished your Ph.D. What were your options then ? Could you have gone to IBM ?

JFJ : Probably yes ; I didn't really try. I didn't because I really wanted to stay in the field of STM. I think there was still a lot of work to do so I continued at DFM.

AH : What about the big STM companies like Digital Instruments and Park, could you have gone to them, were they interested ?

JFJ : At that time, I didn't have much contact with them, and they do not pay much attention to single individuals. You really have to scream loudly to get their attention. Of course they know me now ; I have visiting several such companies. I visited Digital Instruments back in the autumn of 99, and I gave my talk twice. The second one was in an R&D meeting and that brought me a lot of attention. There is potential for some cooperation with them. Actually we have a non-disclosure agreement with them to solve their instruments' hysteresis problem. But they act slowly.

AH : What was attractive about DFM for you after the Ph.D ?

JFJ : That I could continue the work on image processing within the same field, SPM. Also, while working on SPM, I looked for a post-doc position. I finally found one at the [U.S.] National Institute of Science and Technology, which had relations with DFM, because both are metrological institutions. At NIST they also worked with SPM and I could do some image processing there. So, it was a very attractive position for me.

AH : Did they have a big outfit for STM problems at NIST ?

JFJ : Not that big, but they were working on what I would call a high risk project : a "molecular measure machine". The idea was to measure several milimeters across while keeping atomic resolution. At least atomic resolution it is very hard to measure even 100 nanometers across. In addition, they not only wanted atomic resolution but also to use interferometers and things like that in order to make all the accurate measurements. Of course, the more equipment you add, the heavier the construction and much can go wrong. So, it was a high risk project. I actually think it is still running. Obviously they have learned a lot by working on these complicated projects and I contributed a little software.

AH : How long were you at NIST ?

JFJ : One year. I came back and worked at DFM for almost two years.

AH : And you started your own company. Thinking about intellectual property, how have you managed this ? For example, write software at NIST, they presumably get the rights ? How does this work ?

JFJ : Well, I carried most of my software with me, so it was mostly a matter of porting it to run on their Sun machines. The difficulties centered on being able to read and handle their special file formats. So, I wouldn't claim that I made an invention while at NIST.

AH : The experience at NIST rather taught you something about generalizing your software to be used on various other systems.

JFJ : Yes.

AH : Presumably that is a continuous story now that you put it on Windows, as you mentioned.

JFJ : Yes, we jumped from Unix to Windows. The market for Unix was not that big even then and it is not really growing.

AH : So what did you learn from the NIST experience ? What did you take home ?

JFJ : Well, a lot of connections. Very often, the best you get is getting to know people and to discuss problems with them. I recognized some new problems within SPM I hadn't known about before, which of course leads to new ideas for solutions.

AH : For example ?

JFJ : We are getting deep into the way you scan. Scanning with a tip, you might have some friction making the tip bend. When scanning from left to right it bends one way, and when scanning from right to left it bends the other way. At the time most people thought that it was only in the AFM that you have these problems. Probably the most important thing I learnt was from their instrument that was more accurate than any I had ever seen before which enabled us to track very small residual errors. This showed me that the problem just mentioned is more general. We needed algorithms to improve the accuracy in order to measure at the sub-pixel level. Some of the algorithms which we have developed more recently for metrological systems are based on my experience at NIST.

AH : Let me make sure I understand. How would you know about the friction ? From a systematic difference in the scanning this way and scanning that way.

JFJ : Yes, you can see systematic dissimilarities between left to right and right to left.

AH : But that would only work if you stay in one line and just go to and fro, right ?

JFJ : You could do that but you can also take every second line. Usually, if you make an image, it's only from left to right. They were scanning one line left to right and then the second line back the other way, and you can address all kinds of different hysteresis problems. And if the lines are not aligned then you need to analyze how much the odd lines shifted compare to the even lines. That's very technical.

AH : But this would work only for a homogeneous surface, wouldn't it ? You know, if you have a very inhomogeneous surface where every line is different, you can't really tell what is the error and what is a sample, right ?

JFJ : Yes and no. The best thing is of course if you have something like a test structure on a homogeneous surface, but the closer the scan lines are together, the higher is the correlation, so by image processing and correlation techniques, you can actually correct for them. For instance, you can take every second line and make a cross relation and from that see that the line in between had been shifted, maybe just by 0.5 pixel.

AH : I see - and this shift is likely due to the bending of the tip scanning the sample surface ?

JFJ : You can hysteresis in more ways. You can have it in the piezo itself and indeed in other mechanical parts.

AH : And so what you have to do is to identify all the various kinds of hystereses and adjust ?

JFJ : All the non-linearities.

AH : Okay, let's get back to the chronology. The STM project continued at DFM after your post-doc ?

JFJ : Yes, I got a permanent position which included other tasks. I became head of the consultancy section. So, I was able to continue my image processing work, but only part time.

AH : Consultancy for whom ?

JFJ : Everybody who wanted to buy our services. So, of course, one service I wanted to sell was image processing.

AH : Any image processing ?

JFJ : Yes, but we particularly wanted to sell our SPM expertise. People who come to DFM to get some images of a surface and a report. We had a few jobs, and the number of these jobs have increased.

AH : I am curious about the volume of this demand over time, if you have a sense of it. You started in 95 ; presumably there were very few few companies in 95 asking for such services ? Actually, was it companies that came for your services or government bodies ?

JFJ : No, it was university research institutes. They are still the majority but more and more high-tech companies are now using SPMs.

AH : Do you have a sense of how many SPMs there were in Denmark in 1995 ?

JFJ : I think we arranged our first user meeting in 93 or 94. We were only 20 or so ; in 96 maybe 50 people attended our user meeting.

AH : And each person corresponds to one instrument ?

JFJ : No, no, it's hard to say, because each one of those people may have had five, six, seven, eight instruments, or even more. But still there weren't that many in Denmark and there aren't even today.

AH : Can you put a number on it ?

JFJ : No, it's hard for me to put a number on it. I know for certain that DFM has four which I use. One is shared with DTI, the Microelectronic Center and the physical department here have one. I am not actually sure whether it is in working order, but they will eventually build a new one.

AH : They will build a new one ? They don't buy off the shelf ?

JFJ : They build it or buy from the Aarhus group.

AH : The DFM services are for people who come with their data right ? They don't come with an STM, so that, say, you would build the software into their software package.

JFJ : No, we never did that. Of course there are many ways you can use USB expertise. But the kind of job I had was like the one where I simply received some images from a company in America and had to give some feedback on distortions and such things. So, they can bring images that I analyze. Other customers came with surfaces to be measured and analyzed. We SPM-recalled and analyzed.

AH : Working here at the DFM, did you use your software in real time, adjusting while the SPM scanned ? In other words, did you build the software into the SPM ? Or did you measure the data first, and then run the software on the data set ?

JFJ : I never got to build the software into SPM. Before I left for NIST, we had started a project at DME with the intention of integrating our hysteresis algorithms into their software but we never finished. I forget why, but it also had to do with my going to America.

AH : How much of the starting your own company was your own desire to do it and how much was the current pressures in academia ?

JFJ : There was no pressure

AH : None at all ?

JFJ : No, no. You have to fight for what you want.

AH : You wanted to start your own company ?

JFJ : Sure ! And nobody pushed, not at all.

AH : In that case, the market issue we broached briefly before must have been very important. The number of SPMs in existence must be a crucial one for you. But we talked only about the number of SPMs in Denmark, and obviously you want to sell globally.

JFJ : Oh yes. Denmark is very small market. We could almost exist without it.

AH : What precisely are you selling ? The service of unscrambling data or the software ? I have noticed that you do offer free downloads on your website. What's the business rationale for doing that ?

JFJ : Well, we are not doing any conventional marketing, so this is a actually crucial part of the marketing. People can go by themselves and find the product and try it and if they are happy, they might want to buy the full package.

AH : Okay, it's a test, it's a demo.

JFJ : It's a demo. It's very easy to give them the full version, we can just email them a key and they can implement it in ten minutes.

AH : Do you have any sense of how many people download this program ?

JFJ : Yes, around 2000 different people.

AH : 2000 downloaded demos ?

JFJ : Yes. We are preparing a release and once we have it, we will send an email out to to everyone who has downloaded in the past and then I will be able to update on our numbers. It has been a long time since I checked but I think it will be around two thousands.

AH : Presumably the idea is to sell new versions and upgrades ?

JFJ : We are working very gently with this. When they buy, they get one year of free upgrades. It's part of the deal that whenever we have improvements for the modules they bought we send them without further cost for the next year. This is big selling point because we are upgrading very fast. We don't want our customers to have an obsolete product.

AH : So this a long term business plan ? I mean, small businesses don't usually make a profit in the first year, and one couldn't expect that of you either ?

JFJ : That's true

AH : Are you in profit yet ?

JFJ : Yes, right now we are.

AH : Wow, that's great !

JFJ : We had some positive surprises in February [2001]. So, it's quite a good development ; it keeps us busy.

AH : How many people are you ?

JFJ : Only three. I have had a permanent employee for one year now and we have also been using some students who have since left. No we have three permanent people.

AH : And you are all software people ?

JFJ : Yes.

AH : No marketing people ?

JFJ : No, not yet.

AH : So that will happen ?

JFJ : Yes. It has always been part of our business plan. But the timing is not right now.

AH : How do you work out the business structure with the not-for profit institutions that you collaborate with ?

JFJ : It's not a problem. That's why we are here. It's definitely an advantage. It's most important for us to have somebody around us using the software heavily in their work.

AH : They can tell you about the troubleshooting ?

JFJ : Yes, but not only errors, also new ideas and feedback on what they need. That is very important to us and we encourage all of our customers to give us feedback. New ideas are often built into free upgrades.

AH : What's in it for the Danish Technical University to have you here ?

JFJ : I do not know. Of course, we are paying rent here and we can contribute to their visibility, showing that they are helping new companies. Actually, we are talking about the Danish Institute for Fundamental Metrology which is not a part of DTU. It's like DTI, a self-owned technological service institute ; most of their income stems from project money from the government. We have a license agreement with them. They get 5% of everything we sell and they are a part owner.

AH : Are they under pressure to show their relevance for Danish industry ? Is that what you meant by visibility ?

JFJ : Sure, if you can show that a successful company was spun off an academic or government institute the latter would have an easier time getting money later on.

AH : What competition have you got in this field of unscrambling SPM images ?

JFJ : I think we are probably the only company making software exclusively. There are some other companies selling software to go with hardware, the latter being their main business.

AH : Such as Thermo Microscopes, and Digital Instruments ?

JFJ : Thermo Microscopes are only selling software to their own customers, I think. There is a small Spanish company coming up with some software right now. So, I have to consider whether they are a competitor or not. When I started I expected my major competitor to come from the United States. Don Chernov has a company called Advanced. He had something and it was very expensive - it was still in the DOS world. I think it has changed since then and in this respect I don't really regard them as competitors. So right now we are sitting pretty and have only a few competitors. And for those people who really want accurate and serious measurements, the competition is very small.

AH : So you are not worried about people downloading and doing some reverse engineering and so on ?

JFJ : One should of course always pay attention to such issues.

AH : Thank you very much !

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Pour citer l'entretien :

« Entretien avec Jan Friis Jørgensen », par Arne Hessenbruch, 6 mars 2001, Sciences : histoire orale, https://sho.spip.espci.fr/spip.php?article119.

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Entretien avec Jan Friis Jørgensen, par Arne Hessenbruch, 6 mars 2001

Support : non communiqué

Transcription : Arne Hessenbruch

Edition en ligne : Sophie Jourdin

ARRIBART Hervé, 2001-02-19, 05-29, 02-20

Sophie Jourdin — 2011-06-16T07:31:17Z

Hervé Arribart is the Scientific Director of Saint-Gobain Recherche, an international company of French origin with an emphasis on glass manufacture. He took his PhD from the Ecole Polytechnique in Paris in the mid-1970s and subsequently researched ionic transport using nuclear magnetic resonance. In the late 1970s he worked with Jean Rouxel's group at the University of Nantes. In 1981 he joined the company Elf to work in research and development. In 1985 he moved to Saint-Gobain, where at first a large portion of his research was closely related to the practical problems of production. In 1990 he started a laboratory (a joint venture of Saint-Gobain and the CNRS) on the basic science of glass surfaces, using a diverse set of tools and especially the Atomic Force Microscope. In 1999 he moved to the more managerial position of Scientific Director. Hervé is also on the staff of this project.

2001-02-19 :

HERVE ARRIBART (HA) : I studied at the École Polytechnique in Paris. The selection to the school is done mainly on mathematics. But during my studies I learnt to appreciate physics in particular. I decided to pursue research in solid-state physics. It was a good place to study physics. While in my last year as an undergraduate I did a Diplome d'Étude Approfondie in parallel (an intermediary between an M.Sc. and a PhD typically done for a year before starting one's PhD studies). In Orsay, near the École Polytechnique, there is a very famous place in solid state physics, a lab started by Jacques Friedel - a great name in solid-state physics. I followed this course and afterwards I did the PhD at the École Polytechnique in the field of condensed matter physics. In principle I ought to have started with a topic distant from materials science. I extracted spin-polarized electrons from semiconductors. This was in 1974.

ARNE HESSENBRUCH (AH) : How did one extract spin-polarized electrons in 1974 ?

HA : It is true of all solids, but in semiconductors it is especially interesting that when light falls upon a surface there is a coupling between the spin of photons (in classical physics : the polarization of light) and the spin of electrons. Electrons in the upper layer absorb light photons depending upon the spin. If by some technique you can extract electrons from the conduction band of the semiconductor, you can find ways to select electrons of specific spins. This was quite important at the time because at big-science institutions such as LEP [Large Electron Positron collider] or SLAC [Stanford Linear Accelerator Center], there was a need for spin-polarized electrons. And of course you then needed solid-state physics to do it. But the man who in principle was my supervisor decided to do something else. His name is Claude Weisbuch, and he is now a good friend of mine. For a few years he was the scientific director of the French Department of Defense. He is still working in solid-state physics, in the optics of semiconductors. But he decided to do something else and Bernard Sapoval, another professor at the lab, proposed that I work on new materials. At that time there was little contact between solid-state physics and solid-state chemistry. The idea was to link up with chemists. This is why very early on in my career I had contact with chemists. We worked with Parisian solid state chemists on a new material. We found a new way to draw single crystals of an already existing material. It was very nice because we could examine transport and NMR phenomena. And the material, a copper vanadium sulfide exhibited astonishing properties : a large spread of conductivity that one can measure in a standard experiment. We suspected that this was due to mixed conduction properties. Mixed conductivity refers to conductivity by both electrons and ions. The experiment appeared to verify our a priori suspicion. This gave me the possibility to present a model for mixed conduction in this material and to understand the influence of ion transport and electron transport. I also used NMR in order to understand which ions moved. It turned out that the copper ions moved. So, this was the subject of my first thesis. At the time, in France, there were two theses. The first one was called "thèse de troisième cycle". The second was the "Docteur es sciences". This degree does not exist any longer. The thesis that is done now is shorter.

I decided to continue to work with chemists. I decided to combine NMR and transport measurements. I changed my collaborators, turning to two different groups. In my PhD there had been two chapters on NMR. But I wanted to study proton transport. I had two reasons. One was that protons give a strong NMR signal. The second reason was that two reasons had been given for proton transport. In one, protons move in individual jumps. In the other the proton is a part of a more complex molecule such as the ammonium ion (NH4+) or hydroxonium (H30+). In the former case we can see the transport phenomenon as a result of molecule rotation and proton jump. The molecule would turn and the proton jumps to the neighboring molecule, which again turns and so on. This was called the rotation-jump model. The second model was for the whole complex ion to jump. This was called the vehicle model because the whole molecule acts as a vehicle. So I worked with one group of chemists in Nantes, at the Institut de Matériaux de l'Université de Nantes. It had just been created by Jean Rouxel, a chemist. With them I worked on a substance called antimony acid - a solid. I was able to show using NMR that transport occurred in this case with rotation-jump. Protons used H30+ as a complex rotator. I was also able to show that the jump was due to quantum mechanics within a certain temperature range. It was not the usual ion transport of classical mechanics.

AH : A tunneling effect ?

HA : Yes, this is one aspect of protons, because protons are very light ions allowing for this quantum effect. The other material I studied was ammonium beta alumina. This was the standard beta aluminium in which the sodium had been ion exchanged with ammonium. This material was very interesting from the perspective of NMR. All kinds of ionic motion took place at different temperatures. At the lowest temperatures, that of liquid helium (1-4K), there was rotational quantum motion. As the temperature increases the motion becomes classical.

AH : If I may make a comparison with Stanley Whittingham here. You were working on some of the same materials, you were using some of the same tools (NMR), but you were asking very different questions, right ?

HA : Yes, that is true. I was not at all involved in the application. For two reasons : French chemists were interested in materials and did not look to the application. And chemists were between me and the application, so I had no contact with attitudes such as Whittingham's. I was very happy working on the solid-state physics problems.

AH : And we are talking about the late 1970s now ?

HA : Yes, I began the proton transport research, I think, in 1976.

AH : And it went on for how long ?

HA : For five or six years.

AH : And you lived in Nantes ?

HA : No, I remained in Paris while collaborating with the Nantes group.

AH : Were you employed in Nantes ?

HA : No, not at all. At the beginning I was employed at the Ecole Polytechnique as a research assistant, and then I was hired by the CNRS - in 1977.

AH : So, the CNRS paid your salary, you were able to do basically whatever you wanted, and you collaborated with Jean Rouxel and coworkers because you found it interesting ?

HA : Yes. It was a chance to work with an outstanding chemist. French chemists were really very good. The problem, as we just said, was that there was little interest in application.

AH : What did you do next ?

HA : After my PhD thesis, I found it interesting to go to industry.

AH : I imagine that there were many advantages and disadvantages to leaving academia for industry. For instance, where was status greater, what paid better, where were working conditions better ?

HA : First of all, it was rare, even more so than today, for CNRS people, or people within the public system, to go to industry. I cannot give you a clear answer about my motivation - it was not even clear to myself at the time. I did get a higher salary in industry. I also had personal reasons for leaving Paris and going to the Elf company. I went to an Elf research lab in the Southwest of France, in a very nice place in the Pyrénées. I had small children at the time and it was much better for them to grow up in the countryside and in a very nice climate. I was also curious. So the decision involved many elements. And anyway, it was not irreversible. The CNRS allowed me to take a three-year leave after which I could have gone back. With regard to the working conditions : I was of course less free than I had been at the CNRS, but I found it more stimulating because there were a lot of different problems on the horizon, arriving almost every day. We could easily get the necessary equipment at the CNRS and at Elf, so there were no differences there.

AH : The restrictions at Elf had to do with what you were allowed to study ?

HA : Yes.

AH : What did Elf want you to do ?

HA : In principle I was hired to work on solid-state sensors. Because it was not in the direct line of my previous work I proposed that I work on solid-state sensors and ion conduction. We developed a family of sensors named ISFETs (Ion Sensitive Field Effect Transistors). It was a new kind of transistor at the time but now it is very common. You control the electrode using field effects, opening and closing the circuit between the two other electrodes. This is the way the transistor works. My idea - not an original one - was to replace this way of controlling the electrode, the gate, to replace it with a membrane, selective to such and such an ion. If you put the device in a solution containing the ion for which you have designed the system, the membrane will be charged. This charge will change the state of the solid-state transistor. It worked all right for protons. We could use the device to measure pH and afterwards we just had to change the nature of the membrane, choosing a different solid electrolyte, such as calcium fluoride.

AH : Your toolkit remained the same and you still used NMR ?

HA : Not NMR, but yes. You need large samples in order to do NMR. So it was mainly electrochemistry and surface analysis. This was between 1982 and 1985. But as I told you, in industry new projects can arrive almost every day. I had developed some skills in electronics using instrumentation at the École Polytechnique. Elf applied for a patent for a medical analysis system, a small instrument to be sold to private practitioners, as opposed to hospitals. This had nothing to do with solid-state ionics. But the people working on this project needed someone who knew about electronics, and so I got progressively more involved. After one or two years it had become my main project. This worked very well. I was very proud to design an electronic system that required no manual setting. It was set in the factory forever. This was a critical issue, because we thought that doctors could not be expected to deal with electronics - and I am sure that we were right in this. So there was nothing to check or calibrate - the system was self-calibrating. So it worked very well, and after only two or three years Elf built a plant and people were hired. But in 1984 and 1985 there were big changes in chemistry. And there was a great redistribution of all chemical industries. And Elf, that had been an oil company, in this period expanded to become also a chemical company. As a result a lot of the more diversified lines of business lost in importance. Many projects like ours were discontinued. But because we were already quite advanced we found a way to keep going. In fact it was Dupont de Nemours that found that our system was complimentary to some of theirs. The result was that Elf shipped the patent and everything else to Dupont. For a few months I considered following the project to Dupont and to the United States. In the end I decided against. I still wanted to work in solid-state physics and not to work completely in the instrument making business. But for one or two years I continued as a consultant.

2000-05-29 :

HA : For both personal and professional reasons, I decided to stay in Paris, and then Saint-Gobain offered me a position, working in a new research field : polymer adhesion on glass and other materials. It was a new topic for me too. At the time adhesion was not even considered a science. It was before Pierre-Gilles de Gennes's Nobel Prize in polymer adhesion [1991]. It was rather considered an art. Even though I had no background in the field I was interested. What interested me in the Saint-Gobain proposal was that real breakthroughs were to be expected in the science of adhesion when two materials are brought into contact. In fact this was my first real industrial experience. Of course CNRS had not been an industrial experience at all, and even at Elf I was always in the research lab. As I explained, my work at Elf had nothing to do with the industrial activities. I never visited factories. At Saint-Gobain I had to do this, at least in the beginning.

AH : Did you not say that your development of the medical analysis system resulted in the setting up of a plant ?

HA : Yes. I did participate in the design of the plan, in order to make it efficient. But I had no role in the plant itself after construction. It was also a small plant for high-tech activity.

AH : You had nothing to do with the fabrication side of it, situated in the plant – merely the R&D before the plant became functional ?

HA : Yes, exactly. Saint-Gobain of course has many plants all over France and Europe, and even the United States. But at that time, the company was still franco-français [French through and through] in its general spirit and culture, despite the many factories in other countries. There were only French directors and the system was based on the French system of education. There is a hierarchy from the École Polytechnique through the École des Mines and the École Centrale to lesser schools, and you carry the status of your school within you for the rest of your life. I remember that I strongly felt the weight of tradition when I first joined the company. It is true that winds of change were already blowing then, but they were barely noticeable and needed a couple of years before really expressing themselves. But eventually the company changed its culture, and now the company considers itself an international one. I think a deep change has taken place during my 15 years with the company.

So, anyway, this was the first time I gained experience of the industrial aspect of research. My first task was to examine and synthesize different kinds of adhesion in Saint-Gobain's products and processes. I decided to simultaneously pursue fundamental reflection and a practical approach, helping the factories improve their processes. This was a very instructive experience. I learnt many things although I am not sure that I helped the factories all that much. I certainly learnt for myself that I preferred to stay within R&D and not to progress into production. On the fundamental side, I developed a network of contacts in public labs in France and the US. This became useful later on. After three years in the field, and having created a small research lab, I decided to gain some distance from the practical aspect of my work. It was also obvious to me that fundamental research was required first. Progressively the idea came to me to propose the creation a special laboratory dedicated to the basic aspects of polymer adhesion - and of course also to related issues such as the surface science of glass. But I knew that Saint-Gobain was not ready to have a laboratory for basic science by itself, so my idea was to set up a lab jointly with the CNRS. This was in 1988. From the administrative point of view this was feasible : a number of such joint ventures already existed, an example of which is Rhône-Poulenc. Of course I had to convince both Saint-Gobain and the CNRS of the utility of the project which was not straightforward. Although I managed to convince Saint-Gobain in a manner of hours, CNRS needed more prompting.

AH : Would you explain the nature of Saint-Gobain's research before your proposed laboratory ?

HA : It was a quite common kind of R&D geared towards problem solving. Helping the development of new products and solving problems within production.

AH : So the research agenda was driven by questions arising out of production ?

HA : Yes, and my idea was to get a more fundamental understanding of the questions which would enable us to help with such questions in a much better way.

Figure 1. Saint-Gobain Recherche, Paris

At Saint-Gobain I had to sell the idea primarily to the Vice-President of R&D. He took the decision just before retiring. The CNRS process was more complex. It has a democratic organization where decisions are taken by committees. The members consist of both elected researchers and individuals named by the Ministry of Research. They are divided up into different scientific sections. So here I had to convince a diverse group of people, and not just one person, as at Saint-Gobain. As I mentioned, I had developed a network of relationships in the fields of adhesion and surface science and now this turned out to be useful. I knew that many people approved of my research agenda. My project was accepted without much fanfare, but it still took a while because of the administrational hoops that a proposal has to jump through within the CNRS. They meet only twice a year, and every decision has to be validated by the CNRS directors and so on. It took maybe 12 months. The laboratory started on January 1, 1990. But there was only a building and neither instruments nor people.

Figure 2. Joint lab : Saint-Gobain Recherche & CNRS

The three yellow arrows point to the units of the joint lab within the Saint-Gobain Recherche building.

In the meantime I conferred with scientists in many other labs trying to recruit people. Of course the CNRS could not order people to go, so I had to entice scientists away. I estimated that I needed three scientists from the CNRS in addition to three scientists from Saint-Gobain. Two of the latter had already worked with me, and they followed me to the new project. A further researcher came from somewhere else – it was a young Chinese woman. We also had two or three technicians and some PhD students. Altogether, it took a year or so to gather everyone together. We also had to buy instruments and the process of getting the laboratory shipshape lasted altogether something like 2 years. We began to actually do some research in late 1990. And from then on the activities progressed rapidly. In two to three years we reached a plateau of 20 people, a level that had been stipulated by the CNRS. A third of the people had come from the CNRS, a third from Saint-Gobain, with PhD students constituting the last third.

AH : Where did they come from ?

HA : The latter were doing industrial PhDs (Contrat à Durée Déterminée) with Saint-Gobain, and their salary came jointly from the French Ministry of Research and from Saint-Gobain. Of the entire staff, about half each came from chemistry and physics. It was crucial that we develop knowledge and expertise in both these fields. Later we also developed an interest in mechanical problems.

Figure 3. The SPM from Park Scientif Instrument

AH : What was the instrumentation ?

HA : There was a conjunction of the beginning of our lab with the very early days of scanning probe microscopy. This new kind of instrumentation offered a very exciting opportunity. There was a risk in this. We purchased the first Atomic Force Microscope (AFM) ever in France. We bought it from Park Scientific Instruments. Later we built the first AFM for UHV purposes. There were many people then who thought the instrument had no future, so it was a risk to invest time and money in it.

AH : Why did people think it had no future ?

HA : The objection was that it was not clear that atomic resolution could actually be achieved with the AFM. It was not until 1993 that Binnig showed true atomic resolution.

AH : Well, yes, but before he had claimed to achieve atomic resolution. In 1993 he only claimed that so far he had been mistaken and only in 1993 did he achieve true resolution. Is that not right ?

HA : Yes. But in 1993 the community was convinced. The reason I did not hesitate was that atomic resolution was not actually the big issue for our purposes. Even a resolution of 1 nanometer amounted to a great deal. Much could be done with such a resolution in the field of adhesion, and also in fracture mechanics and surface chemistry.

AH : I have the impression that since 1995 or so many people argue that atomic resolution is not really that important, and that in the early 1990s it was still considered the holy grail. So you were unusual in that you had this attitude so early ?

HA : You are right that atomic resolution had a special ring to it in those days.

AH : Did you emphasize the issue of atomic resolution in your application to the CNRS ?

HA : I am not sure. Even today, nobody has achieved atomic resolution in glass. So it would have been a hard sell, also then. The same goes for polymers. And those two were our substances under investigation.
There is a difference between STM and AFM. They obey two different logics. The STM has remained a tool of basic research, in surface science. The AFM, even early on (and this would be interesting to discuss with Calvin Quate or Gerd Binnig), there was a hope that it could be useful, for example in other fields of science, such as mine, or in technology, such as process control, microelectronics, semiconductors, and so on. Generally speaking, in early phases there are always many people who think that a novelty will never become common. We have to remember that in 1987 or 1988 solid probe microscopes were still big and unwieldy instruments. Of course miniaturization had set in by 1990, but it was a novelty. Only very few people were convinced that the AFM would become so common. Calvin Quate is one of the few. The STM has revolutionized basic research on metals and semiconductors. There was a reaction against it, because surface science was done using diffraction techniques working in reciprocal space. Surface scientists were formed in this mode of research. They resisted the change, feeling that newcomers would enter their field without the kind of abstraction that had hitherto been key to access to the field. Working in ordinary space was too easy ! Of course it has not actually become easy because the instrument has brought its own problems, and there are still people working with diffraction and in reciprocal space. The two complement each other.

AH : So this is the background against which your decision has to be seen. You went out on a limb.

HA : Yes. The beginning of my lab coincided with the first commercial scanning probe microscopes (SPMs). We had to grasp the opportunity.

AH : How did you know about the AFM ? Was it a very visible instrument at the time ?

HA : No. I knew about it from publications, but in order to actually see an instrument, I had to travel to California - although I guess I could have seen one at IBM Zurich. There was an STM at Marseille, because two physicists there (Salvan and Humbert) had worked at IBM Zurich, and they had brought one back with them. But they had no experience with the AFM. So I went to the US and visited the very few labs with AFM, both academic labs and the start-up companies of PSI [Park Scientific Instruments] and DI [Digital Instruments]. At Stanford University I met Calvin Quate and at UC Santa Barbara I met Paul Hansma.

AH : Was there a relationship between Paul Hansma and DI ?

HA : I don't remember. But at any rate it was not as close as the one between Quate and Park. I think Park was a former student of Quate's.

AH : So you purchased an AFM from Park. What about the other kinds of instrumentation you purchased for your lab ?

HA : Yes, we had to get other instruments, partly because it took a long time for the AFM to arrive. I had to go to the US to compare the DI and the Park instruments, and I discussed it with the physicists and chemists in our lab before ordering, and then we had to wait for the delivery – maybe 4 months or so. We got a 40% discount, because we were the first French customers, and they hoped that we would open the French market for them. I had very good discussions with Quate, and I think he trusted me to be a good advertisement for him in France. I think we paid 400,000 French Francs, so that the catalogue price was in the order of 800,000 French Francs [approximately US$100,000].

We bought also an infra-red spectrometer, in order to study molecular grafting on oxides. This we used as a complement to the AFM. And as I said in a previous part of the interview, our approach was to combine the traditional surface science (very clean surfaces) with “true surfaces” interacting with the environment. The infra-red spectrometer, XPS (X-ray Photoelectron Spectroscopy), and LEED (Low-Energy Electron Diffraction) were good tools for the traditional surface science approach working in UHV Ultra-High Vacuum). And also HR-EELS (High-Resolution Electron Energy Loss Spectroscopy). Our choice was risky, but it turned out to be correct. Our decision to build bridges between the two approaches was taken in 1992 or 1993. Quite early on in our project we built a surface force apparatus (SFA). It is not at all an AFM – there is no concept of high resolution, but it is similar in that you can get a direct measurement of the force interacting between two objects only a few Ångstroms apart. The idea is to make the measurement quantitative in order to study whether the interaction is due to van der Waals or electrostatic forces. In fact this project took six years – not for technical reasons but simply because we had to get the right people.

AH : Each instrument had its strengths and weaknesses in terms of resolution and the scale of the surface analyzed. And each instrument required special skills. The AFM, for example, requires quite some expertise to disentangle signal from instrumental artifacts, right ?

HA : Yes, artefacts were a real concern at the beginning, when we all had very limited experience. We had to pay much attention in order to ascertain the results.

AH : Can you explain how one separates signal from artefact ?

HA : There are different kinds of artefact. One that now seems quite natural but was hard to understand then is the tip effect. If the surface under examination has sharper topographic features than the tip, then the tip will be imaged rather than the surface. We had trouble with this kind of artefact. In fact, when studying tin oxide deposits on some substrate we got very nice images that we at first interpreted as small crystals having the similar orientation. We were very excited to find a growth mechanism of specific orientations on isotropic surfaces such as glass. I decided to present this result at a small meeting in Davos, Switzerland. The topic there was in fact “The AFM for Technological Applications”. Famous scientists attended, including Calvin Quate, Jim Gimzewski, and Heinrich Rohrer. There were only some 10 people there, because this was very early, maybe 1991. The night before my presentation, I began to wonder that the result was really too beautiful to be true. I telephoned my lab and asked people there to turn the sample by some angle and do the experiment again. That way, the features should have changed if they belonged to the surface. But they did not, and so we knew that the features belonged to the tip. So I did not present that particular slide in my talk.

AH : So rotating the sample by some degree is one way of identifying artefacts.

HA : Yes, that will eliminate this kind of artefact, the tip effect. There are also adhesion artefacts, some of which have been solved in the meantime thanks to new recording techniques such as the tapping mode.

AH : Digital Instruments has a patent for the tapping mode, right ?

HA : Yes.

AH : So the Park instrument that you bought did not have the tapping mode ?

HA : No it did not. The tapping mode did not become available until 1993 or so. Later on, Park Scientific Instruments did do something similar, but they may not call it tapping mode. The DI patent covers the name. And in the straightforward contact mode many artefacts were possible ; for example when looking at soft materials and polymers surface scratches easily occur. If you do that you image the substrate only. One way to identify this effect is to scan again with a smaller tip-surface interaction. In some cases you will find miniature small squares where the surface had been damaged in the course of the first scan. Some artefacts are very common, others are quite specific and harder to identify.

AH : In what you have explained, the identification of artefacts is internal to the instrument itself. It is not that you can go and compare the results of an AFM scan with those from a different instrument ?

HA : You can change the tip, and you should identify artefacts unless you are very unlucky to get the same tip. Everybody understood that the AFM has great potential not just as an imaging instrument but also to measure adhesion, hardness and so on.

AH : Using force-distance curves ?

HA : Yes, force-distance curves. This turned out to be very useful for us. For instance in order to understand the electrostatic interaction between oxide and a silicon nitride tip under water. This was original work. For example, in polymer adhesion we checked if it stayed on the substrate and what scratching would do. Of course such ideas were floating around at the time.

AH : Were you important to the subsequent spread of the AFM in France ?

HA : Yes, people came to our lab. Another lab, at the Institut Curie, that got an AFM at almost the same time. For a while we were a small community but then gradually we grew larger and larger. Yes, we were the pioneers. It was exciting.

2001-02-20 :

HA : I went with one of my sons who was 11 years old at the time to see Park Scientific Instruments. There were no more than 10 people working there, in fact I think it was more like three. It was very small and familial. We discussed and had tea. I enjoyed discussing with these people. It was nothing like an established company.

AH : What did it look like ? Did they work out of a garage ?

HA : Something like between a home and a garage. It was a small house. Even Digital Instruments started out like this. Already in those days DI, and especially Virgil Elings, was much more commercially aggressive, but they were very small too at the time.

AH : Did you stay in touch with some of these guys ?

HA : I stayed in touch with Calvin Quate for five or six years, until 1996. After that I lost the contact but he will probably remember me because we had many discussions. It was curious to see his impact upon materials science. In fact it was very difficult for him to get the first paper on the AFM accepted in Physical Review Letters. Some of it was considered just a pure mechanical profilometer. It had good resolution but it was not really anything new. His project now is very interesting from what I can tell reading his articles in the scientific journals. And he really is a very nice person. Maybe the last time I saw him is when I invited him to give a talk at Saint-Gobain Recherche.

AH : So you stayed in touch with him in the early 1990s, while you were developing your own AFM. I guess the use of the AFM changed the project from what you had originally envisaged ? Did you continue using all the other tools or did you focus exclusively on the AFM ?

HA : We used the other tools.

AH : What did you buy for your laboratory ?

HA : Infrared spectrometer, XPS, HR-EELS (High Resolution Electron Energy Loss Spectrometer), LEED. Quite quickly we had three AFMs. I wanted to develop a PSTM working in the infrared but unfortunately that particular project died because the physicist we had working on it left.

AH : What journals show the history of these instruments best ?

HA : In the beginning it was mainly in the general physics journals such as Applied Physics, Applied Physics Letters, Physical Review Letters, Surface Science. Now there are specialized journals. A journal like Journal of Scientific Instruments is not so important in this respect. Langmuir is also important for soft matter.

AH : Do any of these journals have review articles ?

HA : I am almost sure that all of them do.

AH : We were talking about the various instruments you had in your lab. How did you apply them to your research project ?

HA : The idea was to have two parallel approaches. We were mainly interested in adhesion, molecular grafting and so on. One approach is the classical view of surface science, the ideal surface approach. The other is the REAL surface approach, taking the environment as a part of the system.

AH : Not working in Ultra-High Vacuum (UHV) ?

HA : Yes. But we were trying to make the two approaches meet.

AH : So when you started working with the AFM in UHV, the point was to simplify the experiment ?

HA : Yes.

Figure 4. UHV Chamber et AFM in UHV Chamber

If a probe were to be introduced directly into the UHV chamber, it would take days of pumping to achieve UHV. Instead, it is first introduced into an antechamber, whereupon a vacuum is produced there. Only then can walls be opened without reducing the UHV too much. By pushing the rods labelled 1 and 2, the sample is transported in successive stages into the central chamber. Several instruments are attached to the chamber, including an XPS. On the right, an AFM can be discerned in the UHV chamber.

AH : How did the various instruments complement each other ?

HA : The spectrometers provided structural information. They give a chemical signature. One point of interest was silver on magnesium oxide. In order to have a simple model of glass we chose to study this problem within pure single crystal. We had the probe in situ in the same UHV chamber where we had the instruments to add the deposition techniques. In the case of silver it was just thermal evaporation. We wanted in situ real-time studies of the atoms arriving upon the substrate, the oxide surface. There were two models in this problem. One was that the atoms remain isolated or form small islands, so that the growth process is two-dimensional, so that you first get a perfect monolayer before a second layer is started upon. The other is that growth is three-dimensional with occasional collapses into flatness. To study this it is of course useful both to look directly and to use diffraction techniques. But in order to understand the process you need to grasp the interaction between the silver and the oxide. And only spectroscopic techniques will help here. We always tried to look at a problem from two differing points of view – in this case geometrical and chemical.

AH : You make it sound easy. You just use one tool and you get the topography, and then you use another and you get the chemical composition.

HA : Well of course it is not at all easy. It was very difficult because for instance, the STM works very well when you have a smooth surface but when you have corrugation it becomes much more difficult, because this corrugation interferes with the instrument. In spectroscopy you integrate over the size of the beam which is much larger than the surface scanned by the AFM. So you have to do many different experiments to see what effect the temperature has and so on. You also have to model the interaction. This was a little known problem. What is the mechanism of very small silver clusters on magnesium oxide with other silver clusters in the neighborhood ? It was a new problem. So it took time to understand the system.

AH : What is the measure of success ? It was partly CNRS, so you were under pressure to publish ?

HA : Yes.

AH : And since it was partly Saint-Gobain you had to get patents ?

HA : We had to do both. It was an interesting exercise in communication. In my position as head of the lab, I could not use the same words, the same way of presenting things when addressing different audiences. From time to time it was necessary to gather the scientific and the industrial people together under one roof.

AH : And what language did you speak then ?

HA : Fortunately everyone was happy with this lab, so it was not quite so difficult. The conditions were good. Nonetheless your question is quite correct. It was interesting.

AH : How did you convince Saint-Gobain that this would have a pay-off ? And how did you negotiate long- and short-term goals ?

HA : The short term was a problem. It was not straightforward to plan a new product for the company. The pay-off was very diffuse and difficult to identify. One way of motivating the directors was the argument that we trained very good PhD researchers for Saint-Gobain. And this was not expensive for Saint-Gobain, because they shared all the expenses with CNRS. Up until now this has not been a problem.

AH : Stanley Whittingham told me that in the last 15 years or so there has been a tremendous shift in company planning towards the short term in industry. Partly this was due to the MBA education and the fanning out of this new generation of business administrators into all nooks and crannies of industry. As a result the long-term disappeared, because everything had to fit into the financial year so that you have something to show to your shareholders.

HA : It is true that this has taken hold in industry. We had the good fortune that it was not very developed in Saint-Gobain. But also, the time required for the development of new glass materials just is acknowledged to be greater than that in electronics or informatics. When we start new projects, we are simply not able to show a product six months later. So we are less exposed than people in other fields, but the general development that you alluded to certainly has taken place. Maybe our situation will also change in the future. We may be excessive.

AH : Has the accountancy changed for you ? Did you have to write annual reports ? And has it changed over the last ten years ?

HA : In general ?

AH : Well, for the CNRS I can sort of imagine it. In academia you would specify the number of publications that you have produced and that is the measure. End of story. And that is very simple accountancy. But if you account to a company, keeping in mind the increasing influence of MBAs : did you have to account for your expenses in ever greater detail ?

HA : I do not think there has been such a change in the last decade.

AH : And do you write annual reports ?

HA : Bi-annual. But I am not in this lab anymore ; I left two years ago.

AH : Okay, so during the 1990s up until two years ago you wrote biannual reports to the company and in that period the structure of the reports did not change.

HA : That is correct.

AH : Did you have to specify just how much money you spent ?

HA : Yes, but also there, no change took place. And I always reported to the same person within Saint-Gobain. He was basically content with what we did, so it was never critical. It is true, it might have changed with a different person in charge.

AH : So, how did the instrumentation change throughout the 1990s ? The AFM became commercially available to an ever greater extent, you were able to buy many more things off the shelf. Is that true also of all the other instruments ?

HA : Yes, there are different aspects to your question. We used to build many instruments ourselves, and this was of great use for training. And this has changed. A reason the French PhD has been shortened is that equipment is being bought and not made in-house. That is a general trend. Science is changing as a result, because using a commercial instrument is not the same. When you develop an instrument yourself you know exactly how to get the result. In the specific case of AFM/STM : probably the AFM has been developed much more than the STM. In the STM the major breakthrough was with the driver and that was quite early. I think it was possible to purchase an STM driver already by 1992. Variable temperature was a little more difficult, but it was certainly available by 1994. Different ways of scanning and acquiring information were developed. Otherwise the evolution was purely technical : cheaper, and more diverse (such as an STM expressly for electrochemical research). By contrast the AFM has developed rapidly. Tapping mode and other modes where you measure not only the distance but also hardness, conductivity, adhesion, chemistry. It has become possible to map all these parameters. This explains why more and more people use the AFM.

AH : It has also become cheaper, right ?

HA : Yes.

AH : It has certainly become more user-friendly, adaptable to different circumstances.

HA : Yes. For the STM : there have very beautiful studies made of the coupling between tunneling and modulation. You might modulate the tunneling current with light for instance. You can even leverage the spin of the tunneling electrons. So you can do beautiful physics. But this contributes little to the democratization of the technique.

AH : I have the sense that Calvin Quate, by contrast, is working hard to increase throughput.

HA : Yes, that is right. There can be two reasons for doing that. To make the investigated part of the surface larger – of use in the semiconductor industry. And to shorten the time required for a scan. He is trying to use the system technologically.

AH : Okay. Two years ago you left your lab. Your own lab. Why ?

HA : I wanted to try something new and I was lucky to find someone who was well capable of taking over and for whom I have a lot of respect. He is from a different background. So now it is a different group. I became the Scientific Director of Saint-Gobain Recherche. There are two parts to the job ; one is to be the scientific manager, the other is to establish contacts in the outside world, and to promote innovations within the company, for instance with the marketing people.

AH : You were promoted ?

HA : Yes.

AH : And you have become slightly removed from lab work ?

HA : Yes, completely, I am now involved in organizational work.

AH : In fact, our project resembles your job in the sense that we stand back and look at the scientific research and try to gain a perspective ?

HA : Yes, you could say that.

Fin de l'enregistrement

Pour citer l'entretien :

« Entretien avec Hervé Arribart », par Arne Hessenbruch, 19 février, 29 mai et 20 février 2001, Sciences : histoire orale, /spip.php ?article47.

Pour citer l'entretien :

« Entretien avec Hervé Arribart », par Arne Hessenbruch, 19 février, 29 mai et 20 février 2001, Sciences : histoire orale, https://sho.spip.espci.fr/spip.php?article47.

Lieu : dans le salon (les 19 février et 29 mai 2001) et dans la petite salle de réunion (le 20 février 2001) du Dibner Institute, Etats-Unis.

Support : enregistrement sur cassette.

Transcription : Arne Hessenbruch.

Édition en ligne : Sophie Jourdin, Sacha Loeve.

ENDO Morinobu, 2002-08-26

Sacha Loeve — 2011-06-07T20:19:40Z

Morinobu Endo, né en 1946, est Professeur à la Faculté d'Ingénierie de l'Université de Shinshu à Nagano (Japon). Après un Master's degree à l'Université de Shinshu, et une Thèse en ingénierie à l'Université de Nagoya, il intègre l'université de Shinshu comme chercheur, Professeur associé puis Professeur en 1990. Il y fonde un laboratoire au sein du Department of electrical and electronic engineering. Ses recherches sont dédiées au carbone sous ses diverses formes ; elles vont du fondamental (propriétés physico-chimiques du carbone dans ses multiples formes allotropiques : graphite, nanotubes, carbone nanoporeux) à l'appliqué (fibres de carbone, composés d'insertion au graphite pour batteries et condensateurs). Morinobu Endo est notamment un pionnier des nanotubes de carbone (caractérisés en 1974 lors d'un travail effectué en collaboration avec Agnès Oberlin en France à la Faculté des sciences de l'Université d'Orléans). Ainsi en 1991, date généralement retenue pour la découverte des NTCs par Sumio Iijima, Morinobu Endo avait déjà développé et breveté un processus de fabrication donnant lieu à des usages industriels des NTCs comme composés d'insertion dans des accumulateurs lithium-ion (batteries d'usage courant pour l'électronique portable). Morinobu Endo a co-dirigé des initiatives pour la coopération université/industrie au sein de la Japan society for the promotion of science (JSPS). Depuis 2004, il préside la TANSO (Japan society of carbon). Membre du comité de rédaction de la revue Carbon, il est auteur d'une trentaine de livres sur la science du carbone et de plus de deux cent articles. Ses recherches lui ont valu de nombreuses distinctions : Carbon society of Japan Award, (1995) ; Charles E. Pettinos Award (American carbon society, 2001) ; Lee Hsun lecture series Award (Institute of metal research of China, 2002) ; ShinMai Award (Shinmai Bunka foundation, Japon, 2003) ; Ishikawa Award (Ishikawa carbon science and technology promotion foundation, 2003) ; Medal of achievement in carbon science and technology pour la découverte et la synthèse des nanotubes en 1974 (American carbon society, 2004) ; The Minister of education, culture, sports, science and technology prize for contribution to intellectual Cluster (Japon, 2005) ; Honorary citizen of Suzaka-city (2006) ; Small Times magazine best of small tech lifetime achievement Award (2006) ; JPA lectureship Award (2007).

BERNADETTE BENSAUDE-VINCENT (BBV) : In which discipline did you take your degree, and your PhD ?

MORINOBU ENDO (ME) : I started 30 years ago. I graduated from Shinshu University in 1971. Then took a Master in Electronics. I spent one year in a company, Statch. Then I came in this university in 1972 as a Research Associate.

BBV : So you spent your entire career in this University. How and when did you come into carbon science ?

ME : I became interested in carbon as a research assistant. At that time, carbon was considered as a dirty, dusty science, in comparison with the more attractive semiconductor science. But I found it promising.

BBV : Were there people already working on carbon here in the early 1970s ?

ME : Yes my professor Tsumeo Koyama was working on carbon. He was aged already but he asked me to incorporate here.

BBV : Why did you find carbon so promising ?

ME : I read a few pioneering papers by S. Mrozowski and by M. S. Dresselhaus. This encouraged me. At that time, there was an activity in carbon fibers based on Polyacrylonitrile (PAN) for aerospace industry. Industrial companies were most active in this field, especially Toray. There was a concern for new methods for preparing this promising material because PAN-based fibers were high-cost fibers. Professor Koyama asked me to prepare carbon fiber from vapor. This is a carbon fiber directly grown from the decomposition of hydrocarbons such as benzene. Vapor Grown Carbon Fibers (VGCFs) were totally different from the commercial PAN fibers. PAN Fibers are continuous while VGCFs are shorter. They have a unique structure. In the early 1970s I was able to prepare the fiber without understanding the mechanism at work, or what elements were essential.

BBV : So you had the technique but no knowledge of its structure and properties.

ME : Fortunately I had a chance to work in France with Madame Agnès Oberlin at the CNRS in Orléans.

BBV : How did you come in contact with her ?

ME : When I was a Research Associate in this university, I wrote a paper in Japanese showing that very beautiful carbon fibers can be grown by gas pyrolysis. A nice Japanese professor who was a good friend of hers, introduced my work to her. He invited her in Japan as a visiting professor and she asked to meet with me. I traveled to France with my fiber in 1974 and I worked in her laboratory for one year. In Orléans they had an electron microscope in 1973. I found that there were small opaque particles at the tip of the fibre (figure 1). In order to use the electron microscope it was necessary to use very thin fibers. For that it was convenient to stop the growth process at an early stage. I thus found that the fiber had an hollow core and later in the growth process the diameter of the fiber increased. Here on this picture you can see the particle. I found with Agnès Oberlin that this particle was iron. This result was published in France in 1976 in a paper entitled “Filamentous Growth of Carbon Through Benzene Compounds” (Journal of Crystal Growth 32 (1976) 335). In this paper we argued that VGCF had a “hollow core” which is the strongest part of the fiber. It never breaks when the fiber breaks. Sometimes you have cross-linkings of the fibers. Here just at the center of the fiber you can see the single wall nanotube (figure 2).

Figure 1. “Hollow core” in a vapor grown carbon fiber, 1976

Courtesy of Morinobu Endo.

Figure 2. Cross-linked single-wall nanotubes, 1976

Courtesy of Morinobu Endo.

BBV : Nanotubes ? You did not name it as such in 1976 ?

ME : We called it “hollow core” or “central tube”. Here you can see the fine particles at the tip (figure 3). By using bright- and dark-field image I found that they were Fe3C. This is the chemical product after cooling. At the end of the growth the particles should be iron. I suggested a growth model : the fiber first forms over this fine particles of iron then grow in the radial directions.

Figure 3. “Central tube” in the core of a vapor grown carbon fiber, 1976

According to Dr. Endo, this “central tube” is a double-layered carbon nanotube. Courtesy of Morinobu Endo.

BBV : Where this iron came from ?

ME : We were able to understand where it came from. We used a special sand-paper as a substrate. Without this sand-paper, no fiber. With this sand-paper that we used in France, we got beautiful fibers. We analyzed the electron barriers and we found that it was Fe2O3. Iron oxide coming from the sand-paper proved to be very important as a catalyst to generate the carbon fiber.

BBV : So you understood the mechanism when you came back to Japan ?

ME : I came back in 1975. I clearly described how the fiber grows, including the seeding methods, in a paper published in 1988, “Grow Carbon Fibers in the Vapor Phase” (American Chemical Society - ChemTech 18 (1988) 568-576). In a way this fiber grows in two steps : 1) this very thin fiber, the hollow core ; 2) the secondary process is the thickening of the fiber.

BBV : Do you mean that it took you about 10 years to understand the process ?

ME : No in 1988 it was already established. It is a review paper. So we put the small particle on a substrate (we used a ferrocene). Then we can grow that fiber as you can see on the screen (figure 4). As a result we got this very nice fiber. From an academic point of view, it was a full success because I was able to grow the fiber, to reproduce the product (there were many observations of such fibers but nobody could reproduce them). I clarified the growth mechanism – that the small iron particle acted as a catalyst for the decomposition of hydrocarbon, that the thin hollow tube grew then thickens to a carbon fiber. As a result we got a fiber with a diameter similar to that of the PAN fibers prepared by Toray.

Figure 4. Endo's vapor grown carbon fibers

Courtesy of Morinobu Endo.

BBV : Did you collaborate with industry in these years ?

ME : Yes we had collaborations. Showa Denko tried to develop this VGCF. But its productivity was very low. Because we put a substrate the growth rate was too slow. We tried to reduce the cost by using a continuous process. But in the same period the cost of the PAN fibers was drastically reduced so that we could not compete. Our VGCF are just beautiful fibers.

There had to be a breakthrough.

BBV : What kind of breakthrough ?

ME : I developed another method. This is the Endo-Japanese patent. I introduced the catalytic particles, which are derived from organic-metallic compounds such as ferrocene, into the reactor, in the three dimensions. The main difference is that there is no substrate. Here in this region, the particle reacts with the hydrocarbon and makes the hollow tube (figure 5). On the hollow tube then the deposition takes place. The process is in hysteresis. As a result we can get another type of fiber. It is totally different. This one is very competitve and commercialized.

I should add that at the early stage of the growth of the fiber, this is a carbon nanotube grown by a catalytic process. So it is now possible to grow carbon nanotubes by this method.

Figure 5. The Endo-Japanese patent, 1987

Courtesy of Morinobu Endo.

BBV : So you have already answered my next question : “How did you move from carbon fibers to carbon nanotubes ?” In fact, you prepared carbon nanotubes before this name came into use.

ME : We used to say “hollow core”. I get a little bit irritated about how the story is told. Here are my laboratory notebooks written in France (1974-75). Agnès Oberlin signed them. You can see a two-layered carbon nanotube. This is the TEM (Transmission Electron Microscope) photograph. I envisaged the possibility of very thin carbon nanotubes. Here you can read “mince cylindres” (thin cylinders). We had found the possibility of very tiny tubular structures.

BBV : Why did Mrs Oberlin signed this notebook in 2002 ? Was there a priority controversy ?

ME : Because I visited her in France last June. And because people said you should get the evidence that you had observed such nanotubes in 1975.

BBV : So nanotube was not discovered in 1991 by S. Iijima in his paper in Nature as people usually say..

ME : People say that Iijima clarified the structure of nanotubes. But Endo observed them in 1974. This is a recent understanding. I clarified the growth mechanism and the mass-production of a thick fiber out of a very thin cylinder.

BBV : The irony is that I came in touch with you through MIT thanks to Millie Dresselhaus and not through your French connection although I live in France.

ME : Mrs Oberlin lives near Montpellier in a mountainous area. She is now 75 year old. She gave me many evidences that I observed nanotubes in 1975.

BBV : Do you also know Bernier in Montpellier ?

ME : I know him but I am not as friendly with him as with Mrs Oberlin. He is a newcomer in science while I have been in carbon science for 30 years.

In my process the carbon nanotube is essential to grow the fiber but we can easily extrude the carbon nanotube. Now we can easily expand the technology to make carbon nanotubes. Several companies such as Showa Denko manufacture carbon nanotubes based on my method. Recently in order to make electronic circuit with carbon nanotubes people used this catalytic process. They put the small particle of iron on the electrode and expose this substrate to hydrocarbon to grow the nanotube. Here is a nanotube paper I am not too happy with ; they don't cite my old paper. Many people are not fair. They only take into account recent science and never go back to older papers…

Anyway this catalytic process is now applied in the mass-production of carbon nanotubes, whether they have single wall or double wall. To me it is very important to produce carbon nanotube and use them for practical applications. So coming back to your question about the date of discovery of nanotubes : in 1975 there was no practical use of carbon nanotubes. The interest was in carbon fibers. So we designed a process to get a thicker fiber.

BBV : When did the interest shift from fibers to nanotubes ?

ME : Carbon nanotubes quickly developed after the discovery of C60 in 1985. But they still have no practical application because they are still high cost. For carbon fibers, by contrast, we already had the technology, the know how to produce them. However my nanotubes are already commercialized for Lithium ion batteries since the late 1980s (figure 6). It is useful to provide safe small-size batteries for mobiles and camcorders. For safety reasons it is better to use only Li+ instead of metallic lithium. For this, we need to intercalate carbon at the anode. Almost most of the Lithium ion batteries manufactured in this country use my fiber in the anode. It is the only material that can work in this application. There is no alternative, no substitutional material. Only my product. So finally what the Japanese companies produce is based on my carbon nanotube.

Figure 6. Mass-producing and commercializing Multi-wall carbon nanotubes since 1988

Courtesy of Morinobu Endo.

BBV : Which Japanese companies manufacture the Li-ion batteries with your patent ?

EM : Many companies (Sony, etc). But, now this is not my patent. It is the company who manufactures my fiber who owns the patent. Only the production system is my patent. And I am happy with that. Even French companies like Alcatel who have a battery division need to use my fiber. Recently we got the allowance to export this material abroad. The Ministry of Industry (MITI) gave us permission to export this material. Now Alcatel and a number of American companies can use my material.

BBV : Do you mean that a Japanese company cannot export one its products without permission from the Ministry of Industry ?

ME : It is only for strategic materials with potential military applications because it is a strategic material for military uses (although I don't know which one). In such cases we are under the control of ICOCOM. Anywhere we can get such allowance.

BBV : Coming back to the earlier period of carbon science, what was your reaction and the reaction of your colleagues in 1985 to Curl's, Smalley's and Kroto's paper on the fullerene structure ?

ME : I felt very nice because it was familiar to me. I was very excited with that kind of nanosize particles.

BBV : After this publication did you get more funds to start research programs on nanotechnologies ?

ME : There was an impulse to work on nanotechnology. And the government gave us substantial funds. 95% of the research budget went to nanotechnologies.

BBV : If you get such substantial funds from government do you also have support from industrial companies ?

ME : Most of my research is supported by industrial companies. Only a small part of the basic science is supported by MITI. For carbon nanotubes we work in close collaboration with industrial companies. We have a very nice cooperation. We are always aware of pratical purposes. So in my research science and applications are closely intertwinned. It is our policy.

BBV : But industrial companies have their own research laboratories ?

ME : Yes, we collaborate with them. Presently I have about 100 collaborators who run joint projects with me. More exactly, I should say 50 researchers who come to join me. It becomes big science when you want to reach the commercial applications because you have to do all kinds of tests : safetyness, production cost, optimizing the size, the diameter of the fiber, its packing...It requires a lot of time and a lot of money. The PAN-fiber, for instance, was designed in 1965 and Toray spent more than 20 years of R&D before the commercialization of PAN fibers in the early 1990s. For the batteries we took 7 years.

BBV : Do you have a kind of division of labor with Research conducted in academic laboratories and development in industrial laboratories ?

ME : We have a lot of feedback. For any specific material we need a lot of time and money. Carbon fibers still need a lot of additional technology for commercial mass-production.

BBV : So your financial resources come both from industry and from government ?

ME : Fortunately we get a lot of money from industry because I contributed a lot to industrial applications. We also get money from the Ministry of education for scientific development. I am acting as a bridge between science and industry, and also as an interprter for tax-payers. We do a lot of coordination with social demand, between university and industry and also of education for industry. We are very busy.

BBV : In your career is there a close connection between teaching and research ? In particular how important was the book on carbon that you co-authored with Stan Mrozowski and Millie Dresselhaus ?

ME I have been deeply encouraged by Millie Dresselhaus. Our book was not intended as a textbook. Rather it was a review book. When it was published in 1996 most of the people were rather interested in fullerenes. This book triggered the interest in nanotubes. The publisher Pergamon is very active in carbon science.

BBV : As historians of science and technology, we learn a lot from success but failures are even more illuminating for us. Would you tell mes about a case of failure in your career or in your field ?

ME : I don't remember any project of mine which failed. I spend a lot of time selecting my research projects. It is important because lot of Japanese companies trust me. I have no right to fail. Every problem has a solution. In a sense the tiny cylinder of the nanotube is a miracle. How can we control particles at the nanosize !

Carbon is an old but new material. Professor Kroto who got the Nobel Prize in 1986 said in his Nobel address : the 21st century will be the century of carbon. I believe that. Carbon is a key material. Carbon fibers and carbon nanotubes are vital in three respects : for energy, fuel cells in particular ; for information technology (mobiles and computers) ; for environment, especially for the purification of air and water. The question of water is crucial : 2 million of people die every year from impure water and 20 million are sick from impure water.

BBV : How can you use carbon for the purification of water ?

ME : It is possible. We can use activated carbon to take off bacteria. Developing countries need clean water at a reasonable cost. So carbon is and will be in the future a key material. My own research is focussed on carbon nanotubes, their action, their preparation, growth mechanism, control of the structure and applications. We study batteries, new devices for energy storage in new cars, devices for water purification for the developing countries.

BBV : You mean that in one laboratory you can afford to conduct all these projects altogether ?

ME : Yes, as they are all related to carbon. Carbon and its properties are important everywhere. I'll show you a very nice table. Carbon is not the most abundant on the earth like silicon. It is only 0.04% of the material resources. But carbon is localized, concentrated in some places so that it is easily accessible and easy to extract.

BBV : How many people are working in your laboratory ?

ME : I have 25 people including students and post-doc. We have ten research projects. They come from materials science, electronics or electrical engineering, physics and two post-doc chemists.

BBV : Do you have financial constraints for the purchase of laboratory equipment ?

ME : We have few constraints to buy instruments. For instance, we have got a very sophisticated Transmission electron microscope, all computerized (figure 7). It is a unique model made by a Japanese instrument maker. It has three functions : EDX (Energy-dispersive X-ray spectroscopy), EELS (Electron energy loss spectroscopy), and Mapping.

Figure 7. Endo's Lab TEM

BBV : Did you acquire it with industrial funds or state money ?

ME : It was state money. We also have various analytic instruments for carbon materials such as STM (scanning tunnelling microscope), TGA (thermal gravimetric analysis), FE-SEM (Field emission scanning electron microscope), Thermal conductivity analyser, Raman, XRD (X-ray diffraction), pore distribution analyser, etc.

BBV : Do you have a lot of routine reporting to your sponsors ?

ME : We have obligations towards the university. The annual report mentions how much money I get from the Ministry of Education. But how much support I get from industry this is included in the global amount of subsidies provided to the university. The annual report does not mention openly how much Endo gets from industry. I think I am one of the most funded.

BBV : Publishing or patenting ? What is the priority ? Which one is the most important for the credit and reputation of a laboratory in materials research in this country ?

ME : It is now the Japanese policy that patenting and publishing should run parallel. For me publication is more important. But as part of the national community I should keep a balance between publications and patents. The Ministry of Education recognizes and rewards patents.

BBV : Do you file patents in your own name ?

ME : It depends. If the research project was financed with state money as a national project, then the patent is a state patent. If the patent comes out of a project financed by industry or by the university then it is your individual patent.

BBV : Who gets the royalties ? you or the university ?

ME : We have a judge who decides. If we invent a product with funds from the unviersity, most of the time it belongs to ourselves.

BBV : The patent on vapor deposition carbon fiber belongs to yourself ?

ME : Yes it is my patent.

BBV : Do you have international collaborations : in which countries ? How much do they matter ?

ME : With Millie Dresselhaus, it is a private collaboration. I also have collaborations with Sussex University (U.K.) and with Mexico. In France I have friends but no more collaborations.

BBV : Did you notice differences in the research styles of various countries ?

ME : I cannot see any difference in research styles. The Japanese style is very much americanized. Or rather, our style is between the French and the American styles.

BBV : What is the French style ? And how would you characterize the American style ?

ME : American style is top-down with the state at the top. French style is rather bottom-up. In Japan it is half-half. I feel rather close to the French style but for patenting we are more like the USA. In France it is difficult to file a patent.

BBV : You have spent 30 years on one single material, carbon. But do you think that the materials generic perspective with its basic notion of structure, properties, performances and process, is useful for your research ?

ME : I think that I have a very general concept of carbon. I generalized the concept from structures to properties. Process is very important to get up with the structure in the case of carbon. Carbon science developed by studying its structures but now processing is important. You get different structures with different processes.

BBV : What aspect is the more important for you ?

ME : I am neither a specialist in processing, nor a specialist of structures. I am a carbon scientist.

BBV : What is the place of materials science in general and carbon science in particular in Japan ?

ME : Unfortunately carbon is a minor field. Semiconductor is the major field. In the minor field of carbon I should say I am number 1 or number 2.

BBV : Does carbon science attract students ?

ME : Yes many students come to work with me, because we have advanced equipment and there are job opportunities in this country : in car companies or electric companies.

BBV : Where do you locate the leading centers in the field of carbon science ?

ME : The major countries are Japan, USA, France and Germany. Then come India, then China, England and Canada.

BBV : Do you see Japan as the leader ?

No. Japan, USA, France and Germany are at the front. It depends on the field. Certainly Japan produces 70% of the carbon fibers by the aerospace applications in the USA.

BBV : Where do you locate the strengths and weaknesses of Japan ?

ME : The human network is too strong. More open competition like in the USA would be necessary. In France the system is too centralized, too concentrated.

Fin de l'enregistrement

Pour citer l'entretien :

« Entretien avec Morinobu Endo », par Bernadette Bensaude-Vincent, 26 août 2002, Sciences : histoire orale, /spip.php ?article8.

Pour citer l'entretien :

« Entretien avec Morinobu Endo », par Bernadette Bensaude-Vincent, 26 août 2002, Sciences : histoire orale, https://sho.spip.espci.fr/spip.php?article8.

Lieu : bureau de Moronibu Endo, Endo lab, Université de Shinshu, Department of electrical and electronic engineering, Wakasoko, Nagano-shi 380-8553, Japon.

Support : enregistrement sur cassette.

Transcription : Bernadette Bensaude-Vincent.

Édition en ligne : Sacha Loeve.

ANDERSEN Jens E.T., 2001-03-06

2009-12-21T23:53:02Z

Jens E. T. Andersen est chercheur au Département de Chimie de la Technical University of Denmark à Lyngby. Dès 1992, il utilise une technique inaugurée par Dieter Kolb et Richard Nichols un an auparavant : le microscope à effet tunnel en milieu liquide, appelé également « STM in situ » ou « microscopie électrochimique à balayage » (SECM pour Scanning ElectroChemical Microscopy). À partir de 1995, Jens E. T. Andersen a étendu la gamme de ses usages du STM in situ de l'électrochimie à la biologie, en imageant des protéines adsorbées sur des surfaces. Il a organisé trois conférences sur la technique du STM in situ en 1994, 1996 et 2000.


Autorisation de diffusion

ARNE HESSENBRUCH (AH) : Could you give us an overview of your academic career ?

JENS E.T. ANDERSEN (JA) : I studied chemistry and physics. I majored in chemistry and got a bachelor's degree in physics at the University of Copenhagen in 1987. I did the Danish equivalent of the PhD for three years in surface science at Preben Juul Møller's laboratory at the University of Copenhagen, doing metal on insulator surfaces. I finished in 1991, after which I got a post-doc at the University of Cambridge, with Dr. Richard Lambert - he is now a professor at the Chemical laboratory. I worked for a year and a half on a catalytic effect denoted as NEMCA, Non-Faradic Electrochemical Modification of Catalytic Activity (figure 1). We wanted to investigate this effect, invented by a Greek scientist in the late 80's, and we wished to check this under UHV conditions. Then I saw this advertisement for a Danish position to implement a technique called in situ STM. Not just STM, but in situ STM, or electrochemical STM. You see in 1990, as far as I recall, or 1991, Prof. Kolb (University of Ulm) and Richard Nichols (University of Liverpool) found that you were able to operate an STM while the atoms were submerged in a conducting liquid, in an electrolyte, like water. This was a sensation. We used LEED (Low Energy Electron Diffraction) imaging to study electronic details of electronic diffraction, but it was very difficult, especially because we needed UHV conditions. It seemed absolutely sensational that one could image something like that under ambient conditions in air in a liquid, just by electrochemical control of the STM tip. That was brilliant, and this really aroused some interest in me. I took this position. I applied with Per Møller at the Institute of manufacturing and engineering here at the Danish Technical University in 1992 to get the job and I was successful. We continued for two years developing the instrument together with DME. So the purpose with this project...

Figure 1. Non-faradic electrochemical modification of catalytic activity (NEMCA) Principle.

AH : So when you started out with surface science, did you know about STM in the late 80s. It was not of very great interest ?

JA : Well it was interesting as such, because we all speculated : is this technique really able to image atoms. What is it that we really see in the images ? Are these blobs really atoms ? But I think in the mid 80's it became evident that you could image a silicon 7x7 reconstruction, and this convinced me that this was some kind of atomic resolution. So it was all a technique that was developing.

AH : So you even knew about the STM in the early 80's. You'd heard about Binnig and Rohrer and you kept an eye on it, but you were not convinced. The blobs had to be...

JA : Had to be something to do with metal conduction bands and the band structure of metals. Semiconductor structures, and maybe more subtle to interpret. But with the silicon 7 x 7 reconstruction it seemed sort of convincing.

AH : And was this common in surface science, or maybe even in chemistry ?

JA : I think it's more or less a part of the education that you keep an eye on some of the new techniques. You see, the question always arises : what is an atom in reality ? At that time Transmission Electron Microscopy was the prominent technique of atomic studies. But it has become less prominent in the light of STM, because the latter is fairly easy to use and also less expensive. But then again one asks, is it really atoms ? At that time lots of people were speculating and still there is not a convincing theory describing all the details of the tunneling experiments.

AH : I presume that by the time Binnig and Rohrer had gotten the Nobel prize in 1986, then there was no doubt that these blobs were atomic resolution. Everyone agreed about this. But there was still not commercial STM's on the market, you couldn't have used STM's yourself.

JA : I'm not really sure, the Nanoscope, was that in 1980 ?

AH : Late 80's. Digital Instruments was only founded after the Nobel prize.

JA : But when they received the Nobel prize I presume they invented Atomic Force Microscopy in the same year ?

AH : 1986, right. But you would have had to build one yourself, and Joergen Garnaes over there [across the road] in the early 90's he was building his own. And he could only buy one off the shelf in 1992, and there was no longer a point in building one.

JA : In 1991 DME was putting the instrument on the market, but I think Digital Instruments, they were much earlier. I think Besenbacher, who was the Danish pioneer, built his own instruments in the early 80's, mid 80's. He's recognized as a real scientist of developing STM also to convince scientists that this is really a technique of the future. I think he made a really impressive contribution there. So I think he did that in the mid-80's, he must have because I started out doing surface science in 1987, and he was well known in the field at that time. [Actually, Besenbacher, Lægsgaard, and Stensgaard built their first STM in 1987.]

AH : So in your own work in 1987, what tools did you use, what characterizing tools did you use ?

JA : I used the most common tools, low energy electron diffraction and electron spectroscopy, Auger electron spectroscopy, electron deposition for building up atomic layers, and high resolution EELS (Electron Energy Loss Spectroscopy).

AH : The whole palette ?

JA : Not x-rays. X-rays is a common surface technique of elemental analysis, but we analyzed by AES (Auger Electron Spectroscopy). I think I was also one of the only ones in Denmark doing high-resolution ELS and analyzing surface optical phonons on insulators. This is a fairly difficult technique, and Preben Juul Møller, I think, was the only one who had the instrument at the time. And together with 2 Chinese guys we made it work properly. So we got some interesting surface optical phonon studies of metallic insulator surfaces. The interface of insulators and metals.

AH : Would you describe how that works ? The instrument, and what you had to do to get it work.

JA : The difficulty is, that it is a very narrow electron beam of low energy and you have to focus it delicately - it's a very delicate focusing problem. You have to optimize with an electrometer where you measure all the currents at the equipment and then you try to focus into the detector, which is a fairly difficult process, and the manufacturer couldn't really tell you how to do it. Just told us optimize, use optimizing procedures. And we were three people, working on this for three months, and then we made it work by a systematic optimizing approach. You can never do anything by trial and error. Optimizing by statistical methods, experimental planning basically. We used the instrument for a fortnight each, and we did as well as we could, a sort of competitive method of achieving the best signals, and suddenly we got the same signals as the manufacture's best signal. But I think it's quite a struggle, and too much of a struggle in comparison to the information you get out of it. But it was fun trying to make this very delicate instrument working. This is interesting for low energy electron studies, when you can do spectroscopy of something like phonons, that's quite interesting I think. And one of the Chinese guys, Guo Qinlin he's now a professor in China with a group of 30 people, and the other one, Dr. Wu Mingcheng, he went to the States and was employed in Texas A&M, College Station and he is still living there. So he did quite a good job and produced very exciting results, it was really good experimentally, brilliant. But then the technique you can study surface optical phonons, and overtones of these optical phonons, it can give you an idea about the electronic structure of the surface of insulators.

AH : So, is this a common thread for you to use new techniques try to stay abreast in most recent technology and use them to find out about surfaces ?

JA : In the sense that they can give us new information inside of how Nature is working, then it's interesting. Some new techniques emerged, I think, that are not that much of a help to something that we know already. When it's complementary, they can be the sort you need to advance only slightly. Some of the really new exciting technologies can do something that was not possible before, such as the in situ STM, where you can study atoms in an electrolyte medium.

AH : And you started using the in situ STM when you got here in 1994 ?

JA : 1992.

AH : But you had an interlude in Cambridge, and you didn't work on the STM in Cambridge. What tools did you use then ?

JA : Mainly mass spectrometry and Auger. I think we may have used electron energy loss spectrometry. Oh yes, we also used thermal desorption spectrometry together with the mass spectrometer to study molecules desorbing off a surface. This was quite an interesting project and we had a close collaboration with the Greek group who invented this technique.

AH : In Athens ?

JA : It may have been the University of Athens. Constantinos Vayenas was the head of the group. And Ioannis Yentakakis was our collaborator at the time. He went to Cambridge and we started this phenomenon under UHV conditions. We succeeded and I was happy to see what was going on, and we went as far as we could interpreting their method. They have brilliant articles in many famous journals where they show how this effect was working. When we got it running under UHV conditions it was not a significant effect, we could not be convinced that this was as brilliant, as they told us it should have been. To this day, a lot of work is going on to study what exactly this NEMCA effect is. So we didn't really finish the project completely because I left for another position, but I got enough information as to decide not to build a career on it. It was something really exciting, a new science and a new idea, a new and novel effect you can study in detail and resolve all the chemical mechanisms. But I think it was fairly simple. It was an increase in oxygen production by the material that was used for the electrochemistry - it was sort of solid state electrochemistry. And a zirconium dioxide ionic conductor where you can pass oxygen ions through a material by electrochemical potential differences. You can also desorb oxygen off the surface, and of course if you got an oxygen consuming process at the surface you will consume the oxygen produced by the material. And in my mind it was all coming from the material, but my colleagues were not quite convinced, so we disagreed a little.

AH : So you agreed to disagree in the end.

JA : Yes.

AH : How did you get to work in Cambridge in this period ?

JA : Well I had been working with Dr. Preben Juul Møller at University of Copenhagen in surface science and it was sort of a natural continuation of the career. You have to apply for vacant positions abroad, and I was maybe overdoing it a little applying for a position at Cambridge. Richard Lambert knew Preben Juul Møller very well. He was familiar with his work on insulators. So I had been working on insulators and metallic surfaces contacts for 3 years and I knew what it was about. And I think also very quickly, within half a year, we constructed the necessary UHV improvements to study this NEMCA effect together with Ian Harkness, a scottish PhD student who made a brilliant job of constructing this electrochemical cell for UHV conditions. It's not trivial to make this sort of system, but we did it within half a year. And then we got a whole year of studying the NEMCA effect which worked quite well. But of course I was extremely surprised and happy that I could get this post-doc position at Cambridge.

AH : The laboratory life at Cambridge is very similar to that of the University of Copenhagen ?

JA : Yes.

AH : Same kinds of equipment same level of funding ?

JA : The funding is better at Cambridge. More students available for the studies, but equipment is similar. The level of science is also basically similar, teaching is probably a little better at Cambridge. I haven't followed the graduate courses, but to my knowledge some of the people there were really brilliant. The young PhD students were really brilliant scientists.

AH : Were you a member of a college ?

JA : No, I was not affiliated through the colleges. I did try to become a member of some of the colleges, but as a post-doc you are not supposed to interfere with college life.

AH : So the people you talked to were people in your field, in your lab.

JA : Yes it was a highly professional and competitive working environment and I think a very good time.

AH : Was it also a lot of fun ?

JA : Well, it was hard work – I am not sure about fun. I had my family with our daughter aged six months. Also my wife was not too happy, it was one of the reasons why we left a little early. We were supposed to stay for 2 years, we left after 1.5 years. My wife also wanted to go back because it was tough when I was working from 9am until late in the evening. She didn't really have anything to do apart from taking care of our daughter. And she has a Masters in music and rhetoric and wanted to use her education. It was a little too boring for her, I think. But for me it was excellent.

AH : And so you went back to the in situ STM ?

JA : Yes, I started with the STM when I arrived back in Denmark. I had never worked with the STM before.

AH : But you had kept an eye on STM all the while.

JA : Oh yes, as a surface scientist you always look out for interesting techniques that are competitive to what you have in your field. And when I saw this atomic resolution in an electrolyte, I couldn't believe it, because you can't imagine the struggles you have to go through to make a metallic surface clean under UHV conditions. And once it's clean you have only approximately half an hour to make all your studies because it adsorbs all the gases even under UHV conditions. Approximately one hour you can keep your surface clean under UHV conditions. By contrast, with the arrival of the STM you suddenly were able to study atoms under brilliant conditions (ambient conditions) with a low cost instrument and you can even deposit atoms electrochemically. You can study the metallic overlayer at atomic resolution while it is being constructed atom by atom. I just couldn't believe my own eyes. My colleagues and the PhD students had a good laugh and they said : “So, you're going into in situ STM submerged surfaces. Well, you will need a diving suit.” I assured them that “No, no, no, it's atomic resolution.” They didn't believe me. We discussed the article and I have to say that even Richard Lambert was really surprised that this was possible.

AH : So you were one of the people that convinced others that this was possible, that this was real.

JA : Well it seemed real. If there is a paper in Physical Review Letters my attitude is always to take it seriously ? And you can study also the references in the particular paper by Richard Nichols. You can see in the references that they had been struggling with various modifications of STM to get this result. So it seemed very convincing to me.

AH : But if someone like Lambert was critical, he must have had a good reason. And you say that...

JA : It's so difficult to get a clean metallic surface and it's so highly reactive towards gases in the background and it will destroy the clean surface in a matter of minutes and then suddenly you can have water on top of the metal adsorbing to the metallic surface and you can still observe your atoms. At first nobody really understood, and they said okay it was an aqueous monolayer or something like that, we observed under liquid conditions. Of course this is not what Nichols told us - It's really metallic atoms deposited electrochemically, you can see atom by atom building up. No doubt !

AH : So Richard Lambert didn't develop a new STM really, he just used it ?

JA : Well he did acquire an STM for UHV studies at a later stage. Maybe he got it while I was there, but he was convinced that this was a technique he also had to consider for catalytic studies.

AH : But he didn't build his own STM. You take an STM off the shelf and use it for new studies.

JA : But it wasn't much off the shelf for UHV conditions. I think there was one Swiss company building UHV equipment for the STM.

AH : So a UHV chamber with an STM inside as a package ?

JA : Yes.

AH : And the job here was advertised for in situ STM you said ?

JA : It was advertised in a Danish union journal. Magisterbladet, I think. Or maybe it was in Ingeniøren.

AH : So the people here, they must have trusted the new technique also.

JA : Well you see, Danish Micro-Engineering produced the instrument already before I arrived. I think they sold 10 or 20 air STM equipments around Europe. So they wished to develop the STM. They considered this to be a minor problem and they employed me to do the job. As a matter of fact, Per Møller who advertised this position wasn't really familiar with science as such, but the purpose of implementing this technique was to use it for bulk electrochemical studies. So he would more easily be able to study corrosion processes under the real conditions in an electrolyte. He also wanted to use the instrument to automate electrochemical deposition. You know, he is an expert in plating. So we would like to optimize plating processes, let's say pulse plating and things like that. We wanted to study such things with the instrument. He also wanted to build small metallic machinery, something like submarines swimming about in your veins, depositing medicals at the right spots.

AH : Nanomachines ?

JA : Nanomachines. Within 10 months we got the desired atomic resolution and we finished development of the instrument. I'm saying we because Carl-Erik Foverskov, an instrument maker at the institute, he made the design for a bi-potentiostat. Actually, I must mention that I visited Richard Nichols. I think that without his help we would have taken much longer.

AH : Where was Richard Nichols ?

JA : Richard Nicols was employed at Schering, in Berlin. Schering is a pharmaceutical company, and they were taken over by a French company, Atotech. He stayed in Berlin for a number of years doing in situ STM. But he helped me out with some of the problems. I visited him in Berlin and he participated in our conferences. He was invited to help us out, and he also delivered some of the gold samples that were necessary to obtain atomic resolution. So he was very helpful. Within 10 months, we improved the DME instrument, got atomic resolution, and it was ready for distribution, ready for sale. They needed maybe six more months before they were ready to sell the instrument.

AH : What was the connection between the Danish Technical University and the DME in your job ? You said there was a DME that started the job how did they influence the DTU ?

JA : The connection was Per Møller, the center leader. He was head of the Center for advanced electroplating at the DTU. In Denmark, such a center must be a collaboration between DTU and a company. I think there must be something like 3 institutions involved. I don't know which was the third, but I think it's Danish Plating Industry, something like that. So it was a joint venture. I think we succeeded. But I remember that Møller wasn't too happy about the outcome, because he wasn't really interested in the scientific achievements. And we even made this instrument work for pulse plating, varying electrochemical potentials up and down very quickly. This influences the instrument, so you lose the imaging, but we could maintain the imaging while doing pulse plating.

AH : What did you do next ?

JA : Then I was employed with Professor Ulstrup, who's a bioinorganics scientist. I never expected to be involved in bio-something. But then suddenly I found myself in the imaging of proteins. I still don't know what a protein is. [Laughter] Today I do know a little about this field. We started a joint venture with Per Møller, and we applied for the [Danish] National Technical Science Foundation and got a three-year project. We were supposed to image proteins, and yet we uncertain about what we saw in the STM images (figure 2). But we knew some other group in Europe was grappling with proteins because if you can image proteins, you can image the molecule of life. That's really a big thing. It took quite a while but we succeeded.

Figure 2. In situ STM image of azurin adsorbed on gold(111).

From Esben P. Friis, Jens E. T. Andersen, Yu. I. Kharkats, A. M. Kuznetsov, R. J. Nichols, J.-D. Zhang, and Jens Ulstrup, 1999, « An approach to long-range electron transfer mechanisms in metalloproteins : In situ scanning tunneling microscopy with submolecular resolution », Proceedings of the National Academy of Sciences of the United States of America, vol. 96, n° 4, pp. 1379-1384 (figure 7). Quoting the paper : « individual molecules and a submolecular central feature of brighter contrast are clearly visible ». Copyright © 1999, The National Academy of Sciences.

AH : Which groups ?

JA : Professor Kolb in Ulm. Well, he is working not on proteins as such. Dr. Davis at Oxford and his group. Prof Allen Hill, also Oxford. They are the prime investigators in Europe I think. They have come up with some of the best results, including the imaging of proteins. So we've been working in parallel towards the same goal and we arrived there sort of simultaneously.

AH : And when did you succeed ?

JA : 1996 I think.

AH : Were in touch with Hansma ?

JA : Not as such, but I asked him for some preprints, and he sent me some piles of preprints and said "I'm happy you're working in this important field." He encouraged us very much and we invited him to our conference last year in 2000, but he was not able to attend. But he's done very good work and I think encouraged us to continue what we were doing.

AH : So these workshops. How did they start. Who took the initiative ?

JA : That's professor Ulstrup. 100%. He took all the initiative. When he saw this instrument and that we were able to image proteins he became very excited because he's a theoretician doing electrochemistry on metalloproteins. He has developed protein electrochemistry together with Allen Hill but from a more theoretical point of view. And then he's got me and the group to do the experiments. This way he could develop his theory. He took the initiative and then we've got lists of Danish companies and foundations who supported the first workshop. It's no problem to obtain funding for this purpose, I think. We even got funding from the Danish National Research Foundation. You know the Carlsberg Foundation in Copenhagen, they've got a house of science, the Royal Danish Academy of Science and Letters. And they supported us so we could use the premises of their Foundation. There was I think 60 people attending the workshop, in 1994.

AH : Was it a conference on STM in general ?

JA : No it was on in situ STM, electrochemical STM, also called scanning electrochemical microscopy. Allen Bard at the University of Texas, Austin, invented a similar method, and he denoted it as SECM - scanning electrochemical microscopy. So there are various denotations of this technique. We say in situ because we image while it's occuring.

AH : What sort of people came in 1994 ? What fields did they come from ?

JA : Well we invited people to display their results in STM in general and we did get some contributions that were not really in situ. It's definitely not under water, it is not in an electrolyte. We accepted more or less a wide range of contributions because there were overlaps also with in situ in many fields : solid state depositions by vacuum evaporation can also be considered as in situ, and can be made as comparison to some of our in situ experiments. But the purpose was to promote in situ STM. We still believe that in situ STM is superior to regular STM. The availability, information, methods, and scientific results you can obtain are more varied, there are many things you can do. So we would like to promote this technique and of course you can also image proteins in air, but we would like to image molecules in their own environment, which is electrolyte environments. And I've also considered to image viruses and things like that. At the present stage we have imaged proteins satisfactorily, and we have been promoting in situ STM also in the year 2000 to make people understand that this is really something worthwhile.

AH : Have you had a conference every year since 1994 ?

JA : No, only in 1994, 1996, and 2000.

AH : Were the people who came in 1996 all in situ STM people ?

JA : Almost yes.

JA : It was absolutely the most important groups in Europe represented at this congress and some invited speakers from the States also present. I think there were a couple of students from Japan, but no speakers from there.

AH : How many people came in '96 ?

JA : There was around 60 people – same as in 1994.

AH : And in 2000 ?

JA : The same

AH : Any change in composition of attendees in 2000 ?

JA : No, the same groups were represented. The focus was more bio-oriented in 2000 because now the issue was protein superstructures. Bio-inorganic imaging, that was the purpose, so there were some new groups.

AH : Is that because you are now more involved in the bio-side, or because the field in general has moved towards bio.

JA : I don't think the field in general has moved towards bio. The prime investigations are still made in superstructures and under-potential deposition, which is mono-layer studies, because in situ STM is the only technique where you can obtain atomic resolution. Subatomic resolution can be obtained even with other techniques than in situ STM. Some groups may consider imaging of proteins as subatomic. It's not really atomic resolution. Superatomic I'd say, not really at a higher resolution but at a lower resolution than atomic resolution. And they don't consider this very interesting because you get some difficulties in STM theory : how does it work when you see a protein ? People are a little anxious that they may be studying artifacts rather than real molecules.

AH : Yes of course.

JA : There are a number of artifacts in STM, it's known for artifacts.

AH : Can we back up a little ? I have difficulties imagining just how you would scan something like a protein where you don't have a surface, right ? You have something more unwieldy - how does it work ?

JA : It's a little surprising when you try to study large features with STM because the tunneling distance is some 10 Ångstroms, and a protein is at least 40 Ångstroms in diameter. Obviously, the tunneling current itself ought to deform the protein completely. And something like the deformation of a protein is observed : it's flattened considerably. The measured thickness of a protein is approximately 20 Ångstroms so it's probably flattened while in scanning. But it needs to be immobilized at a surface, otherwise you cannot get the image.

AH : How do you do that ?

JA : We choose specific enzymes and proteins where you have a sulfide bridge to a gold surface. If you react sulfides or thiols with gold you form a covalent bond that is relatively strong. Sulfides react readily with gold surfaces, and our problem in the first instance was to show that we were able to image proteins that were immobilized properly and the question was : Is one sulfide bridge from the protein to the gold surface sufficient linkage for imaging ? And it turned out it was adequate. There was just one molecular bond to the gold surface from the protein, through this sulfide bridge.

AH : Thank you !

Fin de l'enregistrement.

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Pour citer l'entretien :

« Entretien avec Jens E.T. Andersen », par Arne Hessenbruch, 6 mars 2001, Sciences : histoire orale, https://sho.spip.espci.fr/spip.php?article4.

Lieu : Danish Technical University, Lyngby, Danemark.

Support : enregistrement cassette.

Transcription : Arne Hessenbruch.

Édition en ligne : Sacha Loeve

GAUTHIER Sébastien, 2006-11-16

2009-12-15T15:58:16Z

Sébastien Gauthier, né en 1956, est physicien, directeur de recherche CNRS. Il soutient sa thèse en 1981 à l'Université de Paris Diderot. Elle porte sur une étude quantitative de la spectroscopie tunnel. Il travaille ensuite au Groupe de physique des solides de Paris Jussieu (Universités Paris 6 et 7 - CNRS). Il contribue à y développer la microscopie à effet tunnel pour l'étude des surfaces cristallines. Puis il intégre l'équipe « STM, AFM, NFOM, nanomanipulation, surface » du Groupe Nanosciences (GNS), coordonné par Christian Joachim au Centre d'élaboration des matériaux et d'études structurales (CEMES). Ses recherches au CEMES concernent l'instrumentation associée à la microscopie en champ proche, les nanosciences et l'électronique moléculaire.


Autorisation de diffusion

SACHA LOEVE (SL) : Pourriez-vous nous dire où vous avez été formé au STM ?

SÉBASTIEN GAUTHIER (SG) : Où j'ai été formé ? Et bien... nulle part ! Quand on a démarré, on partait de pas grand-chose. Je suis allé à Zürich, là où a été construit le premier STM. J'ai vu Rohrer, qui m'a reçu. Il m'a expliqué un certain nombre de trucs. Il m'a donné une photo de son appareil, et avec ça, je me suis débrouillé ! J'avais des questions à lui poser, et il m'a expliqué. Il m'a montré un certain nombre de choses, voilà... et puis j'en ai fabriqué un.

XAVIER GUCHET (XG) : Et le STM que vous aviez fabriqué, il était différent de celui de Rorher ?

SG : Oui, un peu différent. Je suis quand même parti de ce qu'il m'avait montré, après, ça a évolué de manière assez différente.

XG : Et il y avait beaucoup de physiciens qui, comme vous, s'intéressaient déjà à cet époque à cet instrument, qui en fabriquaient ou essayaient d'en fabriquer ?

SG : Oui, enfin, en France, il y avait quatre ou cinq groupes qui s'y sont mis à la même époque.

XG : Il y avait beaucoup d'échanges entre les groupes ?

SG : Au début, oui. On était tous dans le même bateau.

XG : Peut-on dire qu'à cette époque, une petite communauté STM s'était constituée ?

SG : Oui, je pense. Il y avait cinq labos qui avaient démarré simultanément, avec pas mal d'échanges.

XG : Et aujourd'hui ?

SG : Aujourd'hui, le problème, c'est que le STM sert à tellement de choses différentes que ce sont des communautés différentes. Même si il y a des recouvrements, les thématiques sont très variées. Et l'instrument en lui-même ne suffit pas à souder les gens... C'est vrai que je connais personnellement beaucoup de gens qui font du STM sur des sujets très différents, c'est sûr ; mais je n'ai pas forcément d'interactions avec eux sur le plan scientifique, même si j'en ai sur le plan technique. Sur le plan technique oui, un peu, mais pas sur le plan scientifique.

XG : D'après ce qu'on avait cru comprendre, le STM, c'est quand même un instrument manipulé par des physiciens, pensé par des physiciens, mais qui commence à se diffuser dans des communautés qui ne sont pas celles des physiciens, mais des chimistes, des biologistes, d'autres communautés qui commencent à l'utiliser. Est-ce que c'est quelque chose que vous constatez ?

SG : Oui, mais c'est le cas depuis le début. En particulier, il y a eu les biologistes, beaucoup de biologistes... Disons que le STM a suscité pas mal d'espoir pour certaines recherches en biologie ; et donc, il y a des labos de biologie qui se sont équipés dès le début... et il faut bien dire que ça n'a pas été un franc succès. Parce que cet instrument, il n'est pas comme un microscope optique : je veux dire que faire des images avec, ce n'est pas tout à fait simple ; interpréter des images, ça n'est pas simple non plus, alors bon... je ne veux pas dire que le STM, c'est l'exclusivité des physiciens, mais que ce n'est pas un appareil que l'on peut utiliser en routine de façon habituelle. Enfin après, tout dépend ce que l'on veut faire avec, mais souvent, il y a beaucoup d'artefacts. Maintenant, les gens sont spécialisés. Il y a des gens qui travaillent pour les biologistes, mais en général ce sont des physiciens qui sont allés vers la biologie quand les biologistes sont allés vers la physique. Ce sont des physiciens, mais qui ont une espèce de double compétence. Ce ne sont pas des appareils que l'on peut utiliser comme ça. Ce n'est pas routinisé.

XG : Et ces biologistes qui se sont équipés : ils ont acheté des STMs, ou ils ont fait venir des physiciens dans leur labos ?

SG : Il y eu les deux. Certains ont seulement acheté des appareils ; et il y a des physiciens qui sont venus dans la biologie avec l'instrument.

SL : Ce qui implique, pour les recherches en biologie, qu'ils n'utilisent pas le STM en ultravide ?

SG : Oui, en pratique pour les biologistes, la plupart du temps c'est même en milieu liquide qu'ils font tourner le STM.

SL : Alors ces labos de bio qui se sont équipés en STM, vous disiez que ce n'était pas un franc succès. Bref, comment vous voyez ces travaux ?

SG : Alors en effet, il y a des labos qui ont acheté un STM. Ils ont constaté qu'ils n'y arrivaient pas et ils ont laissé tomber. Il y a des labos qui se sont dit « il faut que j'y arrive » : ils se sont mis à fond là-dessus et il y a des cas où ça marche, justement, en milieu liquide. Il y a des physiciens qui sont allés vers la biologie parce que ça les intéressait. Il y a eu un peu tous les cas de figure. Mais ça demande une compétence... oui, une compétence de physicien que les biologistes peuvent acquérir, bien sûr, mais néanmoins, le biologiste, il faut bien dire qu'il n'est plus tout à fait exclusivement biologiste quand il commence à travailler avec cet outil. Inversement, il y a eu des physiciens qui ont voulu s'intéresser à des problèmes de biologie et qui sont tombés complètement à côté. Ils qui ont fait des choses qui, finalement, n'avaient aucun intérêt du point de vue de la biologie. Il obtenaient peut-être des belles images au niveau de la physique sur des objets biologiques, mais bon, c'était limité.

XG : Vous avez un exemple de ce cas de figure ?

SG : Je n'ai pas tellement d'exemple très précis là-dessus mais je sais qu'il y a eu pas mal de scepticisme chez les biologistes quand à ce qu'apportaient ces travaux. Ceci dit, ce n'est pas dû au STM, c'est un peu général... il faut dire que la façon dont les physiciens abordent les problèmes des biologistes se fait par une approche de physicien et non pas de biologiste... et il y a des biologistes qui trouvent que cela n'a pas d'intérêt.

XG : Est-ce que vous continuez à essayer de perfectionner le STM ?

SG : Oui. Tout le temps oui. C'est quelque chose de permanent. Perfectionner, modifier, adapter l'instrument à de nouvelles choses.

SL : Quelle est la proportion, au CEMES, entre les instruments qui sont achetés tout faits, ceux qui sont construits « maison », et ceux qui sont moitié commercial, moitié construits ?

SG : Oh, la tendance est clairement à acheter, maintenant.

SL : Et ça a changé beaucoup de choses ?

SG : Oui. Enfin pour ce qui concerne la microscopie en champ proche, oui, ça a été un changement. Mais ceci dit, il y a encore des gens qui fabriquent, ce n'est pas exclu. Mais il y a eu pas mal de changements à ce niveau là, oui.

SL : Pour quelle raison fabrique-t-on et pour quelle raison achète-t-on un STM ?

SG : Et bien au début, on fabriquait parce il n'existait pas d'appareil standard. On ne pouvait pas acheter un STM. Maintenant, on achète parce que finalement, développer coûte aussi cher que d'acheter parce que cela prend beaucoup de temps pour des résultats qui sont parfois meilleurs d'ailleurs... enfin cela dépend... c'est pour cela qu'on trouve des labos où on en fabrique encore et d'autres où on achète. Pour nous, en ce qui concerne les choses récentes, on a plutôt acheté.

SL : Qu'est-ce qui fait que l'on peut avoir un meilleur résultat quand on a un microscope qui est construit ?

SG : Pour un microscope à effet tunnel, ce qui est important c'est la stabilité. La température à laquelle on travaille est aussi très importante. Après, il y a beaucoup de choses autour. C'est rare que l'on fasse que du STM. Il y a plein d'autres techniques, un ensemble de choses disposées autour (figure 1) et qui varie d'une expérience à l'autre. Par exemple, il faut transférer l'échantillon. C'est toujours une opération un peu compliquée, plus ou moins facile ou difficile. Enfin, il y a toutes sortes de commodités annexes qui sont importantes dans l'utilisation quotidienne. Il y a des appareils beaucoup plus lourds à utiliser que d'autres. Cet aspect est important aussi.

Figure 1. Le STM et ses dispositifs périphériques.

XG : Vous voulez dire que le STM est devenu un instrument parmi d'autres ?

SG : Non pas tout à fait. Pour nous, c'est l'instrument central, en général, dans les manips' que l'on fait. Ce qu'il va y avoir autour, au niveau instrumentation, dépend un peu du type de physique qu'on fait avec le STM. Par exemple, le problème avec les molécules, c'est que le dépôt est important. Il faut donc pouvoir déposer les molécules sur les surfaces comme on aimerait qu'elles le fassent, ce qui n'est pas toujours très simple. Il faut donc aménager des dispositifs pour le faire.

SL : On peut vouloir faire des choses très différentes avec le STM. On comprend bien que les possibilités sont très larges. Mais encore faut-il que les instruments le permettent. Les instruments commerciaux ont-ils toujours toute cette variété de fonctionnalités ?

SG : Si, et ils l'ont mêmes plutôt davantage que les instruments construits, mais il y a des cas où, si on développe un instrument pour une utilisation spécifique, il sera peut-être plus simple et peut-être plus performant pour cette application-là que l'instrument commercial, qui lui peut tout faire, mais... un peu moins bien. C'est souvent le cas de figure. Et puis aussi, l'intérêt d'un appareil qu'on a fait soi-même, c'est que c'est quand même plus facile à réparer qu'un appareil commercial. Et les budgets de maintenance il ne sont pas négligeables. C'est aussi à prendre en compte.

XG : Oui d'accord, évidement, un appareil qui a été fabriqué par vous il...

SG : il est plus réparable mais pas forcément plus simple... Enfin au moins, on ne dépend pas d'un service après-vente !

SL : Une fois qu'on l'a monté on sait comment le démonter...

SG : Oui.

SL : Et vous qui avez construit ce type de microscope, est-ce que vous vous occupiez aussi du soft, de l'électronique ?

SG : Ah oui, c'est pareil pour les softs. Au début, on faisait les softs du STM, maintenant, on les fait beaucoup moins.

SL : Et les logiciels développés par le labo, ESQC et STM Virtuel ?

SG : Le logiciel ESQC c'est un logiciel de calcul d'image, l'autre, de simulation. Mais ce n'est pas le logiciel qui pilote l'appareil. ESQC c'est du calcul d'image, le STM Virtuel c'est un peu différent. Il utilise l' ESQC mais c'est une sorte de superstructure qu'il y a autour.

SL : D'accord. Mais pour le traitement des images, j'imagine qu'il y a eu des standards, des normes à adopter dans la conception de l'électronique, pour stabiliser les images ?

SG : Des standards ? non. Et c'est pour ça qu'il y a tellement de types de microscopes, de microscopes à effet tunnel. Il n'y a pas une proportion très standardisée, non je ne pense pas.

XG : D'accord c'est-à-dire que le STM qui est utilisé ici, ça ne va pas forcément être le même que chez le voisin ?

SG : oui, sauf que celui qu'on utilise maintenant est commercial, donc il y a un standard qui est imposé par l'entreprise qui le fabrique. Sinon, pour les appareils fabriqués il n'y a pas forcément de standard.

XG : Et l'offre commerciale, elle est très importante pour ces outils là, ou alors est-ce qu'il y a très peu de modèles, finalement, à choisir ?

SG : Par exemple, pour ce qui est du STM en ultravide, des fabricants sérieux, il y en a peut-être cinq sur la planète. Entre cinq et dix, mais je dirais plutôt cinq que dix. Chacun propose deux ou trois modèles différents. Vous voyez donc que ce n'est pas gigantesque.

XG : Et la différence des images obtenues, peut-elle être très importante d'un modèle à l'autre ?

SG : Non. Parce que la qualité des images dépend quand même beaucoup du savoir-faire de la personne qui manipule ce truc là ; ça dépend des échantillons ; de la préparation de la surface ; ça dépend de tellement de choses qui ne sont pas liées à l'instrument qu'on a beaucoup de mal à isoler la contribution de l'instrument dans le résultat.

XG : Et ça représente un changement par rapport au tout début de cette aventure ?

SG : Au début, il y avait effectivement des choses pas très fiables... mais bon il y a encore des bons et des mauvais instruments, c'est clair ; mais ça dépend de ce qu'on veut voir. Pour un certain type d'expérience, c'est clair qu'il faut avoir l'instrument adapté. A partir de ce moment là, les différences sont davantage liées au savoir-faire des gens qu'il y a autour que des instruments, très souvent. Bon, il y a aussi des instruments qui marchent bien mais qui sont beaucoup plus lourds à utiliser. Ce qui fait que les gens seront un peu moins productifs avec ce type-là d'instrument. Mais sinon, en termes de résultat, c'est difficile de montrer ce qui marche le mieux. C'est difficile à montrer. Il y a des groupes qui ont une grosse tradition de STM et d'autres qui l'ont moins, et c'est à ce niveau là qu'on voit la différence, c'est pas tellement au niveau de l'instrument lui-même.

XG : Vous, avec le recul, vous préférez travailler avec un instrument que vous avez acheté, ou que vous avez fabriqué, ou alors cela vous est indifférent ?

SG : Dans l'absolu, je préférerais travailler avec un instrument que j'ai fabriqué. Après, en pratique, si l'instrument marche bien, alors je n'ai pas de position de principe... Peut-être avec un exemple... tiens, le problème avec l'instrument que j'ai maintenant c'est que le soft il ne fait pas tout ce que je voudrais qu'il fasse. Et aller mettre le nez dans le soft actuellement c'est impossible parce qu'on n'a pas les sources. Alors là, on est complètement dépendant des gens qui vendent le logiciel. Et donc, qu'est-ce qu'on peut faire ? Soit on refait un logiciel complet, soit on est coincé. Mais si on a pas les sources c'est vraiment... Alors que sur un instrument fabriqué, moyennant le temps... si on suppose qu'on a le temps de développer le logiciel, on a toujours la possibilité de le faire, alors que là, par principe, on ne peut pas le faire.

SL : Vous ne pouvez pas faire appel au constructeur ?

SG : Pour les constructeurs, si il y a vingt groupes différents qui demandent la même chose, ils le feront. Si il y a un groupe qui demande quelque chose, il ne le feront pas. C'est la logique commerciale. Ils ne vont pas faire quelque chose comme ça à l'échelle d'un groupe. Ou alors, ils vont faire payer le service tellement cher que ce ne sera pas intéressant.

XG : Et quand vous dites « je ne peux pas faire ce que je veux avec le soft », cela va évidemment influer, j'imagine, sur les rapports que vous avez avec les chimistes qui synthétisent les molécules que vous manipulez et les autres physiciens qui aident à la conception ?

SG : Oh... un petit peu... certainement...un petit peu oui...

XG : Vous pouvez être plus précis ?

SG : Oui, par exemple, cette histoire de molécules qu'on peut déplacer avec la pointe du STM, il se trouve que c'est pas facile à faire. C'est compliqué quoi, on ne peut pas tout faire. Donc, si on a une idée de projet où il faut absolument manipuler une molécule de manière sophistiquée, on va avoir tendance à dire « non on peut pas le faire » ; l'idée, on va l'écarter tout de suite, on va se censurer là-dessus. On va plutôt essayer de faire des choses qu'on sait faire. Et donc l'instrument, ce qu'on sait faire avec lui, ça conditionne les choses. Ceci dit, comme il y a beaucoup de choses à faire, ce n'est pas une limitation majeure pour l'instant. Le jour où on aura une idée de projet où on considérera qu'il faut absolument faire une manip' compliquée, alors soit on trouvera un moyen de la faire, soit on sera effectivement coincé.

XG : Là, il n'y aura pas d'autre solution que de racheter un autre appareil ?

SG : Oui ou, enfin, de refaire un logiciel ou de faire... une astuce. Ou alors, d'aller voir le fabricant pour essayer de le convaincre... et il faut avoir les moyens. C'est sur ces limitations que cela se joue.

XG : Vous connaissez des collègues qui continuent de fabriquer eux-mêmes leurs instruments ?

SG : Oui. J'en connais même un certain nombre. Je connais quelqu'un à Paris, Dimitri Roditchev. Il travaille à l'INSP [Institut des NanoSciences de Paris] à Paris, mon ancien laboratoire. Lui, il continue en partie à construire. Il y a des choses qu'il achète et des choses qu'il fait... c'est un peu l'école russe.

XG : Donc cette logique, celle d'abandonner la fabrication des instruments et de se mettre à acheter, elle n'est pas inexorable, finalement ?

SG : Elle n'est pas inexorable en effet, mais après, tout dépend des moyens qu'on a sur le plan technique. Pour faire du développement, il faut des gens, il faut des mécaniciens et, éventuellement, des électroniciens. Il faut tout ce monde-là, et cela prend du temps. Donc soit on a du temps, soit on a de l'argent, et si on a les deux, alors c'est parfait. Mais nous, ici, on a plutôt de l'argent mais pas beaucoup de bras, et donc ça dicte forcément une logique : celle d'acheter de l'appareil commercial. Si on a avait moins d'argent et plus de bras, peut-être qu'on construirait encore. Et puis les appareils commerciaux ont fait beaucoup de progrès aussi. Ça dépend un peu de tout ça.

XG : Est-ce que vous pensez qu'il est envisageable, si jamais vous bloquez un jour sur des limites liées au soft, d'envoyer les molécules, pour les faire traiter par des instruments fabriqués qui, eux, n'auraient pas cette limitation ?

SG : Bien sûr. Ça on le fait, oui. Parce qu'on est dans des réseaux européens, avec un certain nombre de gens qui font du STM. Et en fait, la répartition du travail se fait souvent sur ces bases-là. On peut très bien faire une molécule ici, faire une partie du travail dessus, et puis l'envoyer pour que ce soit repris par un autre groupe qui lui, peut très bien faire autre chose. C'est assez courant en fait.

SL : Et vous utilisez beaucoup l'AFM, également, au CEMES ?

SG : Globalement l'AFM est beaucoup plus utilisé que le STM, mais pas pour ce qu'on fait nous, parce qu'on travaille dans l'ultravide. Le problème avec l'AFM, c'est que sa résolution n'est pas au niveau du STM. Voir des molécules isolées, comme on le fait nous, c'est quelque chose qui n'est pas du tout routinier, et donc pour l'instant, il se trouve qu'on fait de l'AFM, mais que dans le contexte « molécule unique » c'est encore quelque chose qui n'est pas très... disons qu'à ce moment-là, imager la molécule à l'AFM est une fin en soi, alors que ce n'est plus le cas en STM. En STM, imager la molécule, c'est la première étape. En général, on veut aller beaucoup plus loin ensuite. En AFM, si on arrive à imager une molécule, on est déjà assez content. On essaiera peut-être de passer au-delà mais disons que ce qui, avec le STM, ne nous satisferait pas est suffisant en AFM pour l'instant. La résolution n'est pas du même niveau.

XG : Les chercheurs en matériaux utilisent davantage l'AFM ?

SG : Oh et bien l'AFM, c'est un instrument qui sert à tellement de choses... il sert au gens qui font des polymères, il sert à des biologistes...

XG : Je voulais dire dans le cadre du CEMES...

SG : Au CEMES, oui. L'AFM sert un peu au gens qui font du matériau, pour caractériser en surface la rugosité, la texture et des choses de ce genre. Mais là, c'est utilisé plutôt comme un appareil de routine parmi toute une palette de techniques. Il n'est pas du tout central pour eux comme le STM l'est pour nous.

SL : Et du microscope optique en champ proche, où la pointe est, si je comprend bien, une fibre optique ?

SG : La pointe est une fibre optique qui vient capter les photons près de la surface et qui utilise cela comme information pour faire de l'imagerie.

XG : Et c'est un appareil acheté ?

SG : Non, fabriqué.

XG : C'est vous qui l'avez fabriqué ?

SG : Non, c'est quelqu'un qui s'appelle Renaud Péchou. il a fabriqué ça il y a un petit moment.

SL : Il y a beaucoup de types de microscopes en champ proche aujourd'hui, non ? C'est tellement diversifié, spécifié...

SG : Ah oui, aujourd'hui, c'est tout un catalogue. Selon le type de sonde qu'on utilise, il y a vraiment pas mal de choses différentes.

SL : Elle s'est diffusée relativement vite quand même, la microscopie en champ proche ? Si on la compare par exemple avec la spectroscopie, on a l'impression que ça a pris très vite.

SG : Oui ça a pris assez vite. L'AFM c'est 1986, le STM c'est 1982. Après, je ne sais pas trop à quoi il faut comparer. Mais oui, ça a été vite. Surtout l'AFM, je dirais. L'AFM est beaucoup plus utilisé que le STM maintenant mais surtout en air, et comme appareil plutôt accessoire... il est dans un coin du labo, l'AFM, et puis, on y passe un échantillon de temps en temps.

XG : J'aimerais savoir une chose : être surpris par ce que fait la molécule que vous manipulez, par rapport à ce qui était prévu, ça arrive souvent ?

SG : Cela arrive souvent oui.

XG : Vous avez un exemple en tête ?

SG : Je n'ai pas d'exemple très précis. Je sais qu'il y a certaines molécules, comme celles qu'a fait André Gourdon et qui s'appellent les « landers », qui ont été développées pour une application bien précise, et qui se sont retrouvées servir à une multitude d'autres choses.

SL : Et il y a le cas des roues de la brouette non ? C'était des dimères, et puis on a aussi trouvé des trimères et d'autres fragments ?

SG : Oui, les brouettes, c'est un projet où pour l'instant, le gros problème, c'est déjà de mettre la molécule à peu près intacte sur la surface , ce qui n'est pas évident. Disons que elle n'a pas fait quelque chose de très inattendu, pour l'instant, cette molécule. Bon, c'est un projet ambitieux qui requiert pas mal d'étapes... pour l'instant, disons qu'il n'y a pas eu beaucoup de choses inattendues.

XG : Qu'est-ce qui a motivé, en 1997, votre arrivée au laboratoire. Pourquoi avait-on besoin, à ce moment là, d'un spécialiste du STM ?

SG : Et bien parce qu'au laboratoire, ici, il y a avait les chimistes de synthèse qui étaient déjà là, et il y avait la partie théorique où il y avait du calcul d'image. Mais il n'y avait pas de partie expérimentale STM. Il y avait un trou.

XG : Avant 97, il n'y avait pas de STM du tout au CEMES ?

SG : Non, pas dans la partie qui s'appelle GNS, ou « électronique moléculaire ».

SL : C'est quand Christian Joachim a commencé à vouloir faire de la molécule unique que sont arrivés les STMs ?

SG : Pour la chronologie, je ne sais plus très bien à vrai dire. Oui, disons que c'est à peu près à cette époque-là. Christian [Joachim] et André Gourdon étaient déjà ici. Ils travaillaient déjà avec le labo d'IBM à Zürich par exemple... donc il y avait visiblement un trou ici, parce qu'en effet, pourquoi aller faire à Zürich ce qu'on pouvait faire ici ? Et c'est comme cela que je suis venu. Effectivement, il était déjà question de molécule unique, oui.

XG : Vous êtes combien, vous, les physiciens, à vous occuper des instruments, type STM, AFM ?

SG : Pour la partie électronique on est deux CNRS, un prof et trois thésards.

XG : Et concrètement, les thésards, c'est quoi leur travail ici ? Ils contribuent à améliorer les instruments ?

SG : Non, leur travail, c'est de faire des manips', de faire fonctionner les instruments, éventuellement de les modifier si il y a besoin oui, de les modifier pour quelque chose, d'interpréter les résultats, d'essayer de faire des calculs ; leur travail, c'est tout le spectre : de la clef de douze à l'ordinateur. C'est assez varié.

Fin de l'enregistrement.

Pour citer l'entretien :

« Entretien avec Sébastien Gauthier », par Xavier Guchet et Sacha Loeve, 16 novembre 2006, Sciences : histoire orale, /spip.php ?article2.

Pour citer l'entretien :

« Entretien avec Sébastien Gauthier », par Xavier Guchet et Sacha Loeve, 16 novembre 2006, Sciences : histoire orale, https://sho.spip.espci.fr/spip.php?article2.

Lieu : bureau de Sébastien Gauthier, CEMES, Toulouse, France.

Support : enregistrement numérique.

Transcription et édition en ligne : Sacha Loeve.