Awardee Interviews | Donald Baer - 2009 Albert Nerken Award - Interview

Donald Baer

2009 Albert Nerken Award - Interview

Interviewed by Paul Holloway, November 12, 2009


HOLLOWAY: Good afternoon. My name is Paul Holloway. I'm a member of the AVS History Committee. Today is November 12, 2009. We're at the 56th International Symposium of the AVS in San Jose, California. I have the pleasure today of interviewing Dr. Don Baer of Pacific Northwest National Labs. Don is the 2009 Albert Nerken Award winner, and his citation reads: "For seminal contributions towards advancing the application of surface-sensitive techniques to understand environmentally important materials and interfacial processes." So Don, congratulations for receiving the Nerken Award and thank you for the interview.

BAER: Thank you, Paul.

HOLLOWAY: Could we get started by you giving us your date and place of birth?

BAER: I was born in Warren, Ohio 62 years ago, since this is my birthday on November 12, 1947.

HOLLOWAY: Well congratulations and happy birthday!

BAER: Thank you.

HOLLOWAY: Could you give us some information about your educational background, starting as early as you would like?

BAER: Well, I went to high school in Ohio and then went to Carnegie Mellon University not too far away in Pittsburgh where I majored in physics. After that, I went to Cornell University where I majored in experimental physics, and I was in an electron transport laboratory doing low temperature physics, and I got interested in surfaces because we were looking at electron transport in very small crystals that had a size effect. So I was interested in how electrons interacted with the surface from the inside rather than the outside. That got me interested in the importance of surfaces and properties of materials.

HOLLOWAY: So who was your mentor then?

BAER: My thesis advisor was someone by the name of Ray Bowers, who was a physicist who had helped discover the helicon wave, electron waves in metals, and a fellow graduate student was someone by the name of Ken Wagner, whose father I didn't know at the time was Chuck Wagner, who had done all sorts of great things for ESCA and had been a winner of the Nerken prize in the '80s. 

HOLLOWAY: That's a marvelous connection there! So did you work closely with Ken Wagner then?

BAER: I was the student that came after him and worked on some of his leftover projects and used some of the equipment that he had made. He was still finishing his research when I joined the group and he stayed a while as a postdoc. I had met his father when he came to visit with no idea what he really did or that he would soon become someone I knew when I moved to Pacific Northwest Laboratory (now Pacific Northwest National Laboratory).

HOLLOWAY: So did they have XPS capability yet at Cornell?

BAER: Prof. Thor Rhodin was there and he was doing surface studies, but to my knowledge there was no XPS capability at that time. However, I did take an unofficial course in surface science from him. I went from Cornell to do a post-doc in low temperature physics with Prof. Ralph Simmons at the University of Illinois at Champaign/Urbana, and after a post-doc there for two years, I got hired at then Pacific Northwest Laboratory to look at plasma-wall interactions for tokamak reactors.

HOLLOWAY: Is that right? So you got started in the plasma area, then.

BAER: And we were really interested in how things would come out of the plasma and interact with the wall which would then have sputtering or chemistry that would introduce contaminants to the plasma that would then contaminate the plasma and quench the fusion reaction.

HOLLOWAY: Now the place that I associate the tokamak with is Princeton. Did you interact with Princeton at that time?

BAER: The group that I was working with at Pacific Northwest Lab at that point was interacting with all of the major plasma tokamak type reactor facilities: General Atomics and Oak Ridge National Laboratory all had tokamak projects at that time.. The Princeton lab was actually being constructed and I visited Princeton (and a young researcher by the name of Fred Dylla who became an AVS president) soon after I arrived at PNL. My initial effort at PNL was to design some way of testing the plasma wall interactions at tokamaks around the world. However, part way through the design effort, there was a change in policy and the US Department of Energy decided that our laboratory wouldn't have a major fusion effort and so we would either have to move to a different laboratory or do something else. So that transition caused me to move from thinking about plasma wall interactions to other types of surface studies.

HOLLOWAY: Did you use surface analytical techniques to characterize the plasma wall interactions?

BAER: We did. We looked at stuff that came out of the plasma, we looked at deposits on the surface, and we did lots of surface studies to understand the nature of that deposit.

HOLLOWAY: Now you had a surface effects emphasis at Cornell, so that served you in good stead when you went to PNNL or Pacific Northwest Labs?

BAER: Well, that introduced me to the importance of surface phenomena, and that got me started down the surface track and that's why they hired me, because I was interested in materials and surfaces.

HOLLOWAY: So what happened? What did you go into after you finished with the plasma interactions and that effort was abruptly ended?

BAER: Yes it was abruptly ended. We started looking around for other projects. There were important surface concerns related to corrosion studies, and that started my first project at that laboratory dealing with basic energy science and corrosion-related research. The first effort was high temperature corrosion and understanding the effect of grain size, including some nearly nano-size grains. We were studying the corrosion behavior of large and small grain material even before the term nanoscience was widely considered. It's been sort of interesting that the papers that I wrote at that time are now being increasingly cited after a hiatus of not appearing in the literature for a while.

HOLLOWAY: Well, that's always comforting. What comes around goes around apparently.

BAER: It's nice to know something that I wrote 30 years ago is still being looked at and referenced.

HOLLOWAY: Still germane. What year did you actually join PNNL?

BAER: I moved to the lab in 1976 as a post-doc. I became an official staff member in early 1977.

HOLLOWAY: And how long did the tokamak effort last?

BAER: Well, that was an interesting process. They hired me as a permanent staff member so that I could travel at the beginning of March, 1977, and we lost our tokamak funding at the end of March, 1977.

HOLLOWAY: [Laughs] I'm sure there were a few sweat droplets on your brow for a while.

BAER: Well, there was, and we spent the summer being encouraged to consider moving to one of the major plasma physics tokamak reactor laboratories, and as a group, Dave Styris, M. Tom Thomas, and I decided not to move.

HOLLOWAY: Wow, you were in good company. [Yes.] Tell me about the high temperature corrosion and oxidation effort. You have certainly contributed dramatically in the literature and in your efforts in that area. How did you get interested in that area?

BAER: Well, at least the early stages of corrosion involve surface processes. My thesis involved surface interactions, but I was at that point concerned about what happened from the inside. Now I was concerned about the outside and how surfaces affected materials. So we were using at that point a fairly, new high resolution Auger to look at the differences of corrosion in different areas, and to begin to understand what the surface reactions were and how they changed at different locations on the sample. So we were characterizing what reactions occurred over grain boundaries and what occurred over grains, and were concerned about the supply of chromium to the surface and how that affected passivation.

HOLLOWAY: Now you were not looking at single crystal ultra pure samples. 

BAER: No, these were real engineering materials, 304L stainless steel.

HOLLOWAY: Looking at real engineering materials has been sort of a characteristic of your career. Is that true or is that not true?

BAER: Well, it has spanned between some relatively fundamental studies to some work on applied materials, although at times I thought that people that did truly fundamental work looked at what I considered fundamental and considered that applied. But I span between real engineering materials and model materials.

HOLLOWAY: Yes. So you were using high resolution Auger and others were using XPS at that time as well?

BAER: Initially we did not have XPS. XPS came a little later, about the time when vitrification for nuclear waste storage became important and it was very difficult to use Auger to look at some of the waste glass studies.

HOLLOWAY: What sort of a time frame did XPS come, what year approximately?

BAER: Well, when I arrived, the Auger was there. I think we got to using XPS in the early '80s.

HOLLOWAY: So what about SIMS and some of the other surface analytical techniques?

BAER: We quickly got SIMS because we could look at some of the trace elements and the combination of XPS and SIMS was important to do for the profiles of the glass and glass leaching layers that we were interested in at the time. That was not primarily my work; that was somebody by the name of Larry Peterson who came as a new staff member not too long after I did.

HOLLOWAY: Do you remember the people that influenced you most or most dramatically when you first arrived at Pacific Northwest Labs?

BAER: I mentioned already Tom Thomas. He's a long time, in fact 40-year, AVS member. He's the one that introduced me to the AVS. One of the aspects of that was interesting is that although I had done surface studies, I had not used surface tools as a graduate student. As I said, we were scattering from the inside and putting coatings and doing things like that on surfaces, and so I ended up with a job where I had to learn quickly the ins and outs of surface tools and what they did and didn't do. I quickly learned that I needed more quantification than I could trust to get in other ways. So Tom encouraged me to become involved both with the AVS and with the relatively new ASTM E42 committee on surface analysis. And E42 was really interesting because at that point, people were identifying all the ways that you could mess up doing surface analysis, and learning how you could mess up taught me how to do it right. So that was a very important community for me because people were very open in sharing not only what worked but what didn't work, and that allowed us to learn to do things in the proper way, and for our work, we needed precise quantitative data.

HOLLOWAY: So then in the neighborhood of '76 when you joined PNNL, how long was it after that that you became active in ASTM and AVS?

BAER: I'm not sure exactly, but I think it was within two or three years. So it was right around 1980, just before or just after.

HOLLOWAY: So you were working on corrosion and oxidation. Was it more oxidation than corrosion?

BAER: Initially it started as high temperature oxidation, and not too long after that we got involved with other groups around the lab that were interested and had concern about how surfaces affect their properties. I started working with a physical metallurgist by the name of Russ Jones, who started leading a project on stress corrosion cracking. That was an interesting project because we needed to understand how the composition of grain boundaries influenced the cracking of materials. That was in a corrosive environment, and so we started looking at passive film formation, and how that related to the grain boundary composition. So we were using Auger spectroscopy and fracturing materials in the spectrometer to get grain boundary compositions. Once we learned what was present and what amounts of material caused cracking, we started a modeling part of the program to understand the electrochemical behavior and the dissolution rates of these materials. We made model materials that had the same composition for grain boundaries and looked at their corrosion properties.

HOLLOWAY: So did you ever do any corrosion studies and dissolution studies in the spectrometer itself?

BAER: Well, what we created was a liquid corrosion cell that was attached to the spectrometer. So we prepared a sample in the vacuum system, by removing any oxide layer, so that it had the surface composition characteristic of a grain boundary. We moved it through a small bit of ultra high vacuum plumbing to an electrochemical cell. We then did our corrosion experiment, and then moved it back into the system without exposure to air, and analyzed what films had formed in solution and what elements either remained on the surface or were removed.

HOLLOWAY: So what sort of analytical techniques did you have on the chamber that you would do your analysis in- XPS, Auger, and SIMS?

BAER: By that time, we had the system that had all three techniques. XPS was probably the most valuable for us in looking at the corrosion films because that gave us some sense of the chemistry and some quantitative ability to determine what was there. SIMS was informative, but obviously in that circumstance very hard to quantify, and Auger we had to worry too much about damage of the layer.

HOLLOWAY: In your address after receiving the award last night, you mentioned the fact that you owe a debt of gratitude to Jim Castle. Can you tell us about that?

BAER: Well, in approximately 1984, I had been at the laboratory for eight years. I concluded I needed to do something either to move to a different laboratory or show something that would show signs of life and get experience outside the laboratory. So I inquired in several places about the possibility of a sabbatical, and Jim offered me the chance to go work with him for approximately two-thirds of a year. So I got to go, and he was one of the leading experts in applying surface tools to corrosion. So I spent eight months working in Jim's laboratory with several of his students, and that gave me experience with a more sophisticated use of XPS than we'd done in the lab. He had a monochromatic system and at that point we did not. And with one of his students we did some fundamental studies on the nature of charging and how to do charge referencing. I have an interesting paper that has come out of that with Jim and a student by the name of Mike Edgell, now obviously a Ph.D., a well-established professional who worked with Evans for a number of years. Also we were looking at welding and the breakdown of films during braising and welding. The braising work involved Auger; the other studies were with XPS. So I got to do something very different than my PNNL research. 

HOLLOWAY: Where was Jim at the time?

BAER: At the University of Surrey in Gilford.

HOLLOWAY: So you learned the English language then, huh?

BAER: A frequent comment was that if the word is pronounced the same, we (UK and US) spell it differently. 

HOLLOWAY: [Laughs] So early in your career you were working on metallic corrosion and oxidation. Did your career evolve beyond that?

BAER: Well, after several years of doing corrosion and oxidation, the challenge, as you know, in surface business is instrumentation, and the laboratory was starting a new facility which eventually became called the Environmental Molecular Sciences Laboratory (EMSL) where we started asking different questions. What are the important environmental questions and how should they be studied? Environmental issues are of major concern to society, and we immediately observed that it's really oxides and minerals, at least oxidized forms of things are what are stable in the environment. So we concluded that if we were to make an impact on environmental science, we had to try to advance the understanding of oxides and minerals towards the level that was then available for metals and semiconductors. So we made that transition which required learning new things and developing tools specifically tuned to looking at those classes of materials.

HOLLOWAY: So were the people you worked with in EMSL the same as the people you'd work with in the corrosion and oxidation area?

BAER: No, there had to be a transition. The laboratory director at that time set up a rule that indicated that only very few people could move from other parts of the lab to the new focus on fundamental science in the EMSL, and I was one of two or three people that were allowed to make the transition. We had to hire a whole bunch of new people. It was very interesting. We hired people that were interested in that type of science, wanted to have an impact, and also wanted to work with users.

HOLLOWAY: Who were some of the leaders at EMSL when that was first born?

BAER: Well, Tom Thomas was the lead of development very early on in part of the capabilities, and Mike Knotek, who has long-time associations with the AVS, was at one point the director. At that point it was called the Molecular Science Research Center (MSRC). He was the director for a while. Charlie Duke, who is a past president of the AVS, came for a year to be a deputy lab director and head of the MSRC. So we had a large number of associations of people with links to the AVS. And in having advisors come in, there were other people that were important to the AVS. Victor Henrich (Yale) came in and talked about oxide surfaces. John Yates came in and was an advisor to the setup of the facility. There are some others that I'm not thinking of at the moment, but there were a number of senior surface scientists who advised us because of the importance of surfaces in our plans for what became the EMSL.

At the start of EMSL we also hired many new staff members who became important members of the AVS, many who became AVS Fellows including Mike Henderson, Scott Chambers, Chuck Peden, and Bruce Kay.

HOLLOWAY: Right. So your career path evolved into studies then of mineral and oxide surfaces. Did you emphasize any particular type of surfaces?

BAER: We started looking at the structure of oxides. Titanium oxide in some sense is the platinum of the oxide world. It's stable in all sorts of conditions. It has interesting photochemistry, importance in catalysis, and it is stable in the environment. So we started doing a lot of work on that, which has really expanded and continued and still goes on at PNNL and at EMSL. We also started looking at other minerals, and I ended up in a program that was looking at a calcium carbonate, and because we wanted to look at things in solution, we at that point could use atomic force microscopy to look at dissolution and growth properties of the material and not be in vacuum. One of the things that has become sort of a continuous aspect of my research is it involves in situ studies where we're doing electric chemistry early on and then we did AFM in solution and linking that to the best external ex situ studies that we could do.

HOLLOWAY: That's a remarkable correlation, but a difficult one to try to establish. In your opinion, how successful has that been?

BAER: In some areas, it worked very well; in other areas, there are still challenges. But usually if there's not a direct mapping, there is some type of linking between what you have in solution and what you have in vacuum and you have to work hard to understand that linkage, and apply as much chemical knowledge as you can so that you know what might be a problem and what's nonsense and what tells you consistent stories.

HOLLOWAY: So your focus on minerals was aimed at general contamination of the ground soils? PNNL has a specialty in terms of radioactive contamination. Is there an emphasis there?

BAER: Well, I had not been directly involved in work associated with actinides except in a couple of short-term cases. We looked at glass leaching that had plutonium and neptunium in the glass and were able to do Rutherford back scattering spectroscopy on the glass, and looking at how these things had been removed from the glass. It was a real adventure to do the leaching studies in a radiochemical lab and be able to get them out into an accelerator, but I have not done that much actinide work. But we had looked at how contaminants would interact with materials in the environment. So when the calcite dissolution studies progressed, we added different types of transition metals to see how that would affect both the dissolution and what types of phases would grow on their surfaces. So it was related to the contaminant transport, but mostly not dealing with the actual materials.

HOLLOWAY: So is there correlation with groundwater cleanup or other activities like that?

BAER: Well, my part has been fairly fundamental. But I'll jump to the next stage of my research involving nanoparticle reactions in ground water, where iron nanoparticles can interact with various contaminants. It could be uranium, it could be technetium, it could be carbon tetrachloride. The iron would be oxidized, the contaminants reduced, and that often puts contaminants in a safe, stable form. So we have looked at the interaction of iron nanoparticles with carbon tetrachloride, and now are looking at the interaction of small mineral particles, not necessarily the iron metal-core oxide-shell nanoparticles, and how they interact with uranium and technetium (both of these can be contaminants around some of the waste tanks at Hanford site). So we're beginning to do additional studies sort of circling around again, I guess, to look at some of these nuclear waste legacy issues so that we understand how these types of contaminants interact with phases that are actually in the ground.

HOLLOWAY: Well, that's not only a problem associated with your part of the country, it's universal across the country, and TiO2 photochemistry is quite commonly used to address those issues. Have you worked in that area?

BAER: We started doing that. We now have probably five other researchers in the lab doing titanium work of various different types. One of the approaches that I philosophically apply to my research is that when an area starts getting really busy I look for some other area that's not quite so busy and that's where I put my attention.

HOLLOWAY: Right. That's a good philosophy, actually. So what sort of time frame have you been working on nanoparticles?

BAER: Probably seven or eight years.

HOLLOWAY: So you were nano before it became popular.

BAER: Well, before it became really popular, somebody asked me (and this is how we got into it) "how you would make microtechnology smarter?" My answer was to put smart responsive nano-components into the micro-technology. So we started at that point trying to grow nanosized features on components of micro technology, and that was done on internal laboratory money, and that got me started in nanotechnology as it was growing. The Department of Energy came out with an initiative to have proposals in the nanotechnology area, and as a laboratory, we decided that nanotechnology related to groundwater, which was a strong area at the lab in groundwater contamination, could benefit from nanotechnology. The calcite work, which is geochemistry and my previous corrosion work actually come together in the nanoparticle studies we have now been doing for the past several years. If you're putting something in the ground and it's an active metal, it is going to corrode. When in the ground, geochemical processes and transport will also take place. Because of that background I was asked to lead a project that involved iron nanoparticles and contaminant removal from groundwater.

HOLLOWAY: That is very interesting. You've won a number of awards at the laboratory. Could you give us some information on some of those awards?

BAER: Well, two awards that I think I prize the most are for support of science education and mentoring. The Fitzner Eberhardt Award is for contributions to science education. My education contributions included teaching courses at the branch campus of Washington State University, which is in the town with the laboratory, which is Richland, Washington. I have also taught courses on nano science at the laboratory associated with both Washington State University and the University of Washington, and we probably had 20 summer students working with me over the years. 

HOLLOWAY: That's a remarkable number students. By the time they go back and contact and discuss with their friends, that's a lot of outreach.

BAER: One of the fun students is somebody by the name of Kristin Steffens. She worked with me on an NSF program. We had (and still have) an intern program for high school seniors where they work a half a day in the lab. So she worked with me for a year on a program that I had looking at the impact of sulfur on stress cracking, and she then went to Whitworth University, still working at the lab part-time with me and Larry Peterson, who I mentioned earlier. She then went to Stanford University, got her Ph.D., moved to NIST as a post-doc and is now a staff member at NIST and an AVS member and she's beginning to do XPS. So there's been this long follow-through on my association of students coming back. It's certainly lots of fun to end up at a meeting and find students that you've worked with in some cases for a very long time circling back and coming up to say hello and how much they appreciate the interactions that we've had over the years.

HOLLOWAY: That's what you call a beautiful tale.

BAER: That's right. I guess I should also mention, to answer the above question, there's also a Chet Cooper Mentor Award, which I received for mentoring staff members. I consider it a part of the satisfaction and even a responsibility of my position to help staff members learn how to work in the lab and teach them how to do the type of research that we can do in a national laboratory that is a little different than what you can sometimes do in universities.

HOLLOWAY: Now coming back to the nanoparticles, you made a point in your presentation that you think that the surface analysis techniques are underutilized in characterizing nanoparticles. Could you elaborate on that?

BAER: Certainly. One of the common statements about nanoparticles is that they have high surface area, but a lot of the early work focused on the small size and the different physics. In many cases, people either deliberately or by accident have coatings on nanoparticles, and often these are not really characterized. So the real structure of the nanoparticle, whether something segregated to the surface or whether there is contamination is apparently ignored by too much of the research community. This becomes really critical when you're looking at health and safety issues, which people are beginning to think about increasingly. If you're worried about how a nanoparticle interacts with the body, you'd better know what that nanoparticle surface is because it really interacts through the surface. So there has been a lot of focus on the size and shape of nano-objects. They may have important internal properties, but all the interactions of nanoparticles with the outside world occur through their surface. So if we don't characterize that surface properly and understand it, then we will not understand those effects.

HOLLOWAY: Do you think that the current state of understanding in XPS, Auger, SIMS etc., are sufficient to understand how to use them appropriately for characterizing nanoparticles?

BAER: Well, I think we understand enough to do a better job than is often being done now. I think we will learn a lot more so that we can do an even better job in the future.

HOLLOWAY: We covered a lot of ground, so do you have anything else you'd like to add to the interview, Don?

BAER: Well, I think that I've seen a lot of change in the technology related to characterizing surface, and it's still changing very rapidly. So I'm really excited to see what new things are going to come up. There are a lot of very creative people, a lot of interesting things going on. So I think it should be an exciting time.

HOLLOWAY: Very good. Well, unless you have something else to add, let me congratulate you again on the Albert Nerken Award 2009 and say it was well deserved.

BAER: Well, thank you very much.

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