Awards > Awardee Interviews > Interview

Interview: Paul Bagus

2016 Gaede-Langmuir Award Recipient
Interviewed by Dick Brundle, June 18, 2016

BRUNDLE: So, this is Dick Brundle, and I’m here representing the AVS, and I’m here to interview Paul Bagus. Would you hello, Paul Bagus, so that…
BAGUS: I’m delighted to be here. This is Paul Bagus, and I’m looking forward to this interview.
BRUNDLE: Okay, that’s so that our voices can be recognized by the transcriber. So, Paul Bagus is this year’s—this is 2016—Gaede-Langmuir Award winner for the AVS, which is one of their two highest awards. The citation for this award reads for “Seminal contributions to understand photo-electron spectra of solid surfaces and molecules absorbed thereon.” So, I should also make it clear that I’ve known Paul for many years. He hired me into IBM originally, and was my manager for quite a while. Then I was his manager for a while. We’ve both since long left IBM. I’m going to shut up now and ask Paul about his history. As we generally do for these, I’d like to start with your personal history. That is, the background of your family, how you grew up, and where you went to school, and things like that. 
BAGUS: Great, okay. My parents were both immigrants. My father came from somewhere in Poland/Estonia/Latvia—somewhere in that region—and my mother from the Ukraine. 
BRUNDLE: You say somewhere from there, so you don’t know?
BAGUS: I don’t know exactly where, no. I would assume no records exist, and if you remember—I don’t think you were there—maybe you were—there was an electron spectroscopy conference in Kiev in 1980-something-or-other.
BRUNDLE: Yes, I was there with you.
BAGUS: Oh, that’s right.
BRUNDLE: We traveled on the train from Moscow.
BAGUS: From Moscow, yes. At some point I thought it might be interesting to try to find a family record, and then decided to give it up. My parents met in the United States. My father was a glazier and my mother had a couple years of college education. They were both determined that I was going to go off to college and do well academically.
BRUNDLE: So, she had college education in the U.S., or before she came?
BAGUS: In the U.S. I believe—she was very young when she came, so it may well even be that her younger sisters may have been born in the U.S., but I would guess they were both born very late 19th century. In any event, they had the idea that it was important to have an academic background. At the time, in the 1940s and 1950s, having an academic background, working at universities, and in particular doing science were really highly regarded things. Everybody wanted to do that, or wanted their kids to do that. 
BRUNDLE: Highly regarded by native born Americans, not just immigrants?
BAGUS: Well, you know, it’s hard to tell because most of the people I knew were children of immigrants, or immigrants. I even remember the names of some of them, especially the ones my father played cards with. I went to high school—I went to Bronx Science, which was a specialized school for teaching young scientists. It was a fairly good school.
BRUNDLE: I think that’s where Dan Auerbach went—a previous award winner, and also an IBM former colleague.
BAGUS: I think that’s right, and also, Frank Herman, who was a former IBMer went to Bronx Science as well. I have a feeling that our friend who’s down at Sandia—Peter…
BRUNDLE: Peter Feibelman
BAGUS: Peter went to Bronx Science as well. So, quite a few people associated with the AVS have gone to Bronx Science. Then came a question of where to go for university and I interviewed with the University of Chicago. A large part of why I wanted to go to the University of Chicago was because I wanted to get away from home, as I think most young people—I was not quite 16—want to go away to a university, not live at home and go to a university. 
BRUNDLE: So, you were applying for university when you were not quite 16?
BAGUS: I started at university before my 16th birthday. 
BAGUS: There was this wonderful thing where I succeeded in skipping a few grades, and so the first year I was at university, on the 19th of November, I turned 16. 
BRUNDLE: Didn’t your companions there think you were incredibly young to be at university?
BAGUS: Yes. Well, there was another reason for the choice of Chicago, because the idea of the chancellor who set the policies at Chicago—Hutchins—was to bring people in young, so many of the students who came didn’t have high school degrees, and so I wasn’t so blatantly young. I started out in chemistry, interestingly enough, and decided that I wasn’t really suited to work in laboratory.
BRUNDLE: I will vouch for that, having run a lab in IBM where Paul would come in and randomly twiddle the knots while he was talking to me.
BAGUS: Well, there were times when I helped you, Dick. You would call me and tell me to turn the power off, or turn the power on.
BRUNDLE: Or fill up the liquid nitrogen traps.
BAGUS: And once I learned that on equipment made in the UK switches were the opposite of U.S. switches, I was able to turn the power on and off. Although, I had to call you up to check—the switch was up which meant that the power was on— then why did you want me to turn it on? In any event, after a year of freshman chemistry, I switched to physics. I worked one summer for Bob Gomer. I’m not even sure if he remembers the not extremely competent young man who was working in his lab and trying not to break things. Then I went to work for Roothaan, who was one of the pioneers in theoretical electronic structure theory— Quantum Chemistry. I discovered that I could program, I enjoyed programming, and I could make sense, or some sense of what I was doing. 
BRUNDLE: Tell us a little bit about Roothaan—what area this is you decided to work in.
BAGUS: Roothaan—I’m trying to think how much background to go into. Roothaan immigrated to the U.S. from The Netherlands. He was living in The Netherlands under the Nazi occupation; in fact, his brother was in the resistance, and when the police came to arrest his brother—when the Gestapo came to arrest is brother— his brother had the sense not to be there. The Gestapo took whoever was at his house and they arrested Roothaan. Eventually what they did was to put him to work at Phillips, computing trajectories of artillery shells, which he kind of enjoyed. He was able to work out how, with a mechanical calculator, to get 16 digits of precision. Roothaan loved computing, and loved computation. After the war, he immigrated to the U.S. and became a graduate student of Mullikan’s, who was also at Chicago. Mulliken won the Nobel Prize in the early 60s for his work on Molecular Spectroscopy. Mulliken was very good friends with Hertzberg, and he also interacted with Pauling despite the fact that Mulliken’s work was based on Molecular Orbital theory and Pauling used Valence Bond theory. In any event, there was at that time—the late 40s, the early 50s—a belief that computation could help solve—a belief among many people, not everyone—that computation could help solve problems in chemistry. There was, in 1951, a Shelter Island conference, which brought together all of the greats in the United States and Europe to discuss the future of theory in chemistry.
BRUNDLE: Okay, Shelter Island—that’s just off the coast of Maine, right? Its south of the Canadian border.
BAGUS: Yes, and if anyone is interested and they would like a copy of the Shelter Island proceedings, I just happened to have acquired one a few years ago. They are a marvelous reflection of what happened then. I also have a group picture of the people in the meeting, and Mullikan is incredibly young. Slater is very young. Roothaan is also pretty young.
BRUNDLE: For those who are not in the background—not in this kind of work—these are all famous names in quantum-chemistry or quantum-physics. 
BAGUS: Yes, fair enough. Basically, Mullikan believed that by helping to train Roothaan in chemistry, he’d bring computing to chemistry. In some measure, he did. Then, in an unusual event which probably could not happen today, after Roothaan got his Ph.D., he was offered an assistant professorship at Chicago. Normally, you don’t get an offer to be a young professor at the school where you’ve gotten your degree. He then started to get students and formed a group—a group that we thought was large then. I would say there were maybe just shy of ten people, which is not a terribly large group these days. 
BRUNDLE: So, when you joined there were 8 or 9 people already there in this group?
BAGUS: Something shy of that. I’d say 6, 7, 8. I can probably remember some of the names. This was the day before there were computer programs around that could check other programs. We had a mathematical technician—a man called Tracy Kinyon —who you gave your formulas to, and you had him check the calculation that your program made, and so he would compute integrals by hand on what was by now an electric calculator. If they agreed with the calculation that was done with the computer program, well then, great! The computer program worked. It was also a very interesting thing, because it was Mullikan who hired Tracy Kinyon, and Tracy, while being very good at using an electric calculator, was handicapped. I believe Mullikan was a forerunner of the belief that opportunities should be given to disabled people and to others who might be victims of discrimination. I am very proud of Mulliken. I thought, here’s somebody who did things because they were the right things to do. That is a bit of a diversion from the scientific efforts in Roothaan’s group. Basically, Roothaan believed in computing wave functions. He believed in Hartree-Fock calculations, which were then thought of as very good things. He believed configuration mixing—configuration interaction—to go beyond a mean field approximation. But he also believed computer programs should be beautiful. They should be as compact as possible, and they should be as fast as possible. He was certainly an excellent person to learn from how to compute. An advantage of having Mullikan around is that Mullikan had an incredibly good feeling for chemistry, and incredibly good feeling for spectroscopy. One of my favorite stories about Mullikan—someone in the early 60s had done what was, at that time, a very high level calculation, and gotten the right sign of the dipole moment of CO. We, the students and the post-docs, thought that this was a very important advance because a good Hartree-Fock calculation gives the wrong side of the dipole moment. So, we were all being a little raucous and happy that theory, once again, proved how powerful it could be. Our celebration was outside of Mulliken’s office and he came out of his office and asked us what we were so excited about. We explained that good theory corrected the error of Hartree-Fock and that it now gets the right sign of the dipole moment of CO. Mulliken explained that the important chemistry is that amount of CO is very small, especially for a polar molecule that is largely C(+)-O(-). I will paraphrase the question he asked us: “Do you really care if the small dipole moment of CO is+0 or -0?” That’s a story that I have remembered for a very long time, and I think it’s an important story, because the fact is Hartree-Fock does fairly well. It gets a small number. I believe it gets a number which is negative, minus a small amount where the experiment is plus a small amount. But it doesn’t make any difference. So, that was basically my career in Chicago. I went from Chicago, spent a year as a post-doc in Paris. It was kind of fun. It was nice to go to Paris. 
BRUNDLE: Yes, I know you’re a Francophile, and I know you speak French quite fluently with an atrocious American accent. At least it’s much better than me, since I don’t speak French at all.
BAGUS: I was at Daudel’s laboratory. Daudel was also a pioneer in the idea of theoretical quantum chemistry. I had one of my highest academic positions. I was a “Maître de conférences” which is the equivalent of an assistant or associate professor. But, I guess we both—my wife then, and I—felt it was kind of lonely in Paris, and while it was nice to be there, we decided not to stay. We went back to Chicago, and then from Chicago, I interviewed for a position at IBM Research. I was interviewed by a man called Enrico Clementi, who is also famous among theoretical chemists. One of his goals, which he achieved, was to do theoretical calculations on the properties of DNA and RNA; if you go back 40+ years, this was a very, very daunting project. Enrico’s goals and vision brought me to IBM Research in San Jose where Clementi had formed a pretty good group…
BRUNDLE: So, what year was that, when you joined IBM?
BAGUS: 1968. I remember that because we were driving across country when Bobby Kennedy was shot at the Democratic National Convention, which I think was in Los Angeles. 
BAGUS: I joined IBM in 1968, and I retired from IBM 25 years later. That must have been 1993. IBM, I think, was an absolutely great place to work. I don’t know if you feel the same way, but we had good resources, we had good people. We didn’t have too much pressure. We had some, but not too much. 
BRUNDLE: Yes. I agree, but you don’t realize how lucky you were in these things, until you look back on them. We probably complained a lot at the time. 
BAGUS: Yes, that’s right. Unfortunately, we did. But one of the things we didn’t have to do, which our academic colleagues do have to do, is get government grants, get contracts, and basically support ourselves, and to some measure, help support our institution. That is a certainly significantly time consuming effort. That’s unfortunate, both for the professors and for the students. It’s unfortunate for the professors because they’ve got to spend a significant amount of their time writing good proposals, and it’s unfortunate for the students because they don’t have as much of the time of their sponsor—of their professor—as they should. They might learn a bit faster by having more access to a professor. So, that was certainly a good thing about IBM. There were some differences. While many of us would have a post-doc most of the time, there was never the same thing as at universities, where there are four or five or six or seven, or more post-docs. I’m not sure whether our model was better or worse than a model where you have lots of people. In general, we had very good people. There was an occasional person who wasn’t so good. I think you had that experience as well as me. 
BAGUS: But by and large, they were pretty good. It was and is a real joy working with a sharp young person. That is something I definitely do miss. 
BRUNDLE: Not because there aren’t sharp young people around, I hope.
BAGUS: Not at all because there aren’t sharp young people around, but because I’m not in a position to offer them positions. 
BRUNDLE: Yeah, okay. I’m going to take a break right now, just to check that this is working okay, and we will start again in a minute. 

BRUNDLE: Okay, we’re back online here after a short break. So, Paul, you’ve gotten now as far as being at IBM, brought in by Clementi. I wasn’t there at that time, so I didn’t really know Clementi, though I did meet him later. Did you then immediately fit into whatever his program was, or were you already going in your own direction? Or, what happened there?

BAGUS: Basically, the first thing that I and the colleagues that I was working with then at IBM did was to create what we now call a software package. We called it Alchemy, and it was a complete package for doing molecular orbital calculations.

BRUNDLE: I remember that, yes. So, you were using it when I came later as well then?

BAGUS: That’s right. And I have been using Alchemy with various extensions and additions ever since; thus the period of my use of this package goes from the mid 70s to now, about 40 years. It was and is a pretty good program. Next I moved from Enrico Clementi’s department on Quantum Chemistry to join Eric Kay’s department—Eric had a department in Surface Science, and I joined that department; it was a good department in what seemed to me to be an exciting new area. It became a better department. Eric had an extremely good talent for attracting both good permanent staff, and good visiting staff. IBM, at that time, did have an excellent visitor program, especially in connection with Europe.

BRUNDLE: Particularly with Germany.

BAGUS: Yes. That was for a very direct reason. The IBM Country Organization, which in the case of Germany was IBM Germany, would pay a significant fraction of the visitor’s salary, and so we had Jürgen Behm, who worked with Dick. We had Dietrich Menzel, who worked with Dick. We had Gianfranco Pacchioni, who worked with me. We had Klaus Hermann, who also worked with me. Many of these collaborations that began there have continued on for many, many years. Michael Grunze, was another post-doc who worked with Dick who I should have thought to mention as well.

BRUNDLE: Yes. I don’t think he was officially on the program, but he did come as a visiting scientist twice, actually.

BAGUS: Wasn’t he one of Eric’s visitors?

BRUNDLE: I don’t think so. I don’t think it was part of the IBM program where they were paying. He had other funds, and he came through that. As did David King, as you remember.

BAGUS: Oh, I certainly do remember David.

BRUNDLE: As did Jim Castle.

BAGUS: I had forgotten Jim. I remember Dave very well. In fact, if you have an email address from Dave, I’d appreciate having it.

BRUNDLE: I think I can find one.

BAGUS: Good.

BRUNDLE: It’s rumored he might be here on Thursday, but I’m not sure about that—in the John Yates Symposium—but I’m not sure it’s true.

BAGUS: That’s getting a bit offline.


BAGUS: Basically, I think I was in Eric’s department for easily 15-20 years. I joined it—about 20 years, maybe a bit less. Then I had visions of grandeur that maybe I could be an administrator, so I went off to manage a project, which was designing software to build better disc-drives. That was a misadventure that didn’t last terribly long. I discovered that really what I wanted to do was do science. Then, at some point, IBM was having financial difficulties, and was asking were there people who would be willing to take an incentive and retire. So, I chose to retire from IBM, but not to retire from science.

BRUNDLE: So, let me take you back a bit. You’re in Eric’s group, and so you’re now working on absorption, and molecules on surfaces, and things related to that. Was that Eric’s suggestion that you do that, or you’re in a surface science department, so you decided to move into that area? Or, how did that come about?

BAGUS: That’s a good question. Let me back up just a little bit. My thesis was on core level ionization. That was even before XPS was a commonly used accronym. I may have been the first, or one of the first people to actually do rigorous calculations on taking a core electron out of rare gas atoms—neon, argon, and fluorine-minus, sodium-plus. That is something that I’ve continued to have an interest in ever since. Core level spectroscopy has been a part of my research all through the years. It continued, I think, when I was working developing Alchemy—yes, I know it continued then. It also continued when I was in Eric Kay’s surface science department. I suspect he may have brought up the idea that you could use a model system to describe a solid surface with just a few atoms. I thought, gee, this is a really intriguing way to use the methods of Molecular-Orbital Theory to find out about a whole new area of surfaces. So, that is what I did.

BRUNDLE: So, you started working with clusters to represent surfaces and atoms absorbed to them.

BAGUS: At first, the clusters were one atom. Then, they went to five atoms. They’ve since gone to between ten to 100+ atoms. But, one of the pieces of work I’m proudest of is one where the surface was represented simply by a point charge. What I wanted to find out was how would adsorption of anionic NO, NO minus, on a surface—it was a silver surface—be changed by being absorbed on the surface. My logic was that it was the electric field of the surface that the NO-minus was moving in, and that significantly changed its frequency.

BRUNDLE: You mean vibrational frequency?

BAGUS: Yes, vibrational frequency. I’m sorry. So, it was the NO stretch frequency that, if I remember, was significantly lower when NO was on a copper or a silver surface. A test of the idea was simply to replace the surface with the image charge of NO minus below the image plane, and yes, low and behold, the effect of the image charge was to give about the same magnitude, and the same sign of the stretching frequency change. So, in the best of cases, you can represent a surface by just a point charge. But, yeah, for…
Paul, do you want to finish this thought? It was when the battery ran out?

BRUNDLE: Okay, once more, we’re back online, after a change of battery. Okay, Paul, so now, you’ve told me a lot about IBM and the fact that you’d left in 1993, which is when I left, too. I stayed in the same physical area, and decided to work for myself as a consultant contractor, and you took a different route. So, explain to us what you did then.

BAGUS: Well, basically I thought it was going to be a piece of cake to find a job at a university, and so what I did first was spend quite a bit of time as a visiting professor in different universities in different countries. I was at Bochum, with Christoph Wöll, I was at Heidelberg with Michael Grunze for a few months, and I was in Barcelona, Spain with Francesc Illas. It wasn’t so much fun being away from home quite that much. I got an offer to come as a lecturer to Texas A&M.

BRUNDLE: You were still living in the Bay Area at this point?

BAGUS: We were still living in the Bay Area, but it was an awful lot easier commute between College Station and San Jose than between Berlin, Madrid, Barcelona, and San Jose. I stayed at A&M for, I think, three years.

BRUNDLE: Yes, I visited you there.

BAGUS: Right, that’s correct. It took me a while to get used to the idea that one of my most important responsibilities was to get funding. I wasn’t terribly good at getting funding. Around this time, I started interacting with the folks at PNNL, and also, I think around this time, I went and spent some time with Hajo Freund, when Hajo was still at Bochum—when he had the chair in physical chemistry, that then went to Christoph Wöll, and is now with Beatriz Roldan. Basically, I think Hajo and I met at that meeting in Kiev, started talking about problems in XPS. He asked me if I’d come to Bochum for two or three months and give a course, which I did. Actually, Hajo and I first met around 1980 when he was a post-doc with Ward Plummer at the University of Pennsylvania and we talked about the XPS of Ni(CO)4. But this was put aside and forgotten until we met again in Kiev.

BRUNDLE: So, Hajo Freund was the Welch award winner—he was Welch, right?

BAGUS: No, he was Gaede-Langmuir—2014.

BRUNDLE: Oh, Gaede-Langmuir in AVS two years ago.

BAGUS: Yes. He and I have been working together doing some interesting things with respect to photo emission, with respect to surfaces, and with respect to particles.

BRUNDLE: Particularly, on oxides.

BAGUS: A great deal on oxides, or on things related to objects absorbed on oxides. So, we tried to understand the difference in the binding energy shifts for small metal particles, which were of interest, of course, because they were absorbed on oxides, and came up with a novel explanation, that it was due not so much as a final state effect due to the fact that all the charge was on the surface of the particle. Of course, particles are pretty small. But it was due to the fact that the inter-atomic distance in particles is largest for small particles, and decreases for large particles, to the bulk value.

BRUNDLE: So, but now you’re still—where are you living now? Have you moved to Texas at this point?

BAGUS: Ah, okay, good. We moved to Texas, and moved to Austin. Basically, what I was doing was commuting between College Station, and San Jose, and that got to be kind of a drag.

BRUNDLE: Yeah, it’s a couple thousand miles or something, right? 1500?

BAGUS: Yeah. Plus, the drive to the airport, because there was no direct flight from College Station—it was either drive to Austin and fly American, or drive to Houston, and fly United. Connie had an opportunity to change her job from where she was working for IBM at Santa Teresa in San Jose, California to the IBM Austin computer lab.

BRUNDLE: Okay, let me stop you there, because Connie has not been mentioned yet. So, people who don’t know who Connie is…

BAGUS: Connie is a very important person.

BRUNDLE: Very important person in Paul’s life. His wife, and also collaborator, and also quantum chemist—makes all these PowerPoint slides as well. So, obviously you’re already married to her, but that happened a while back.  Tell us how that came about.

BAGUS: That’s an interesting story.

BRUNDLE: Yeah, I know.

BAGUS: You were involved in our relationship a bit before we got married, or right around when we got married. We have problems remembering exactly which year we got married. I could go on my laptop and look it up, but when people ask us, we discuss it, Connie and I. We sometimes agree. We sometimes disagree. Usually one of us is right. I think it was ‘81. Winter of ‘79, I was spending the year Clausthal, and went up to see a friend in Lund, Sweden, and Connie was there as a kind of short-term post-doc. We met there, kind of liked each other, saw a bit more of each other. I took her out to see San Jose, and then we got married. We got married one week before or after her birthday. So, our anniversary is either the 10th or the 17th, and her birthday is either the 17th or the 10th.

BRUNDLE: Okay, there actually was an intermediate step there, because, I remember, you’re in Sweden, and Eric comes in and says, “Paul has had a very serious accident in Sweden.” Motor-car accident. In fact, you were in a coma for a week?

BAGUS: A few days, easily.

BRUNDLE: Yes, we were all very worried about that. But, you recovered out of that, and you came back and Connie was with you, and you were married a bit later than that.


BRUNDLE: So, Connie kept her own name. This is Connie Nelin (spelling?). She
worked for IBM—pretty senior mid-level manager, or senior manager, I would say?

BAGUS: She became a distinguished engineer, which is the lowest executive level in IBM.

BRUNDLE: In the computing facility, not research, right?

BAGUS: Correct.

BRUNDLE: She flew all over the place. Is she a native Texan?

BAGUS: No. Where was she born? Illinois.

BRUNDLE: It doesn’t matter. She lived in Texas.

BAGUS: She came to Texas to attend the university. She got her degree at UT.

BRUNDLE: Okay, so she’s at home in that area. So, now you want to move there, too, because it’s easier for you, so you, much to the surprise of the people who knew you in the San Francisco Bay Area, you pack up and leave, and high-tail it down to Austin, where you’ve lived ever since.

BAGUS: Right.

BRUNDLE: Except that you’re still a globe-trotter and spend lots of time in various other places.

BAGUS: Well, interestingly, I think we moved in the summer of 2001, and we were taking a vacation to Australia, and while we were in the air, 9/11 happened. Happily, we were far enough out. They didn’t call us back. Although, when we returned, one of the things we did is we had gone to a winery just outside of Sydney, and had half a dozen bottles of wine, which we didn’t trust to pack in our suitcases and check, so we carried them on. That was before you were limited to three ounces. But, yeah, Connie’s background is in theoretical chemistry, much as mine is. The man that she worked for, who is Al Matson, may or may not have been at the Shelter Island conference. I think he was. So, she’s got a pretty good background in theoretical chemistry as well. We’ve got lots of joint publications, and there are, as Dick has pointed out, an awful lot of things that she can do better than I can do. She’s much more organized than I am. When I scribble numbers down on pieces of paper and misplace them, she has them in spreadsheets. She can tell me what it is we did not only last week, but last year. That is a real virtue, because it means that instead of having either to spend a lot of time searching for things, or to have to redo things we knew we did. So, it is great working with her. We do have lots of joint publications.

BRUNDLE: So, you both moved down to Texas, and this is quite a long time ago now, and you’ve been there ever since, but you do have an affiliation now with another university in Texas.

BAGUS: Yes, with the University of North Texas, where I have great people to work with who’ve got some reasonable surface science, although more in the area of graphene films, which I’ve not gotten involved in. We’ve got a good theory group.

BRUNDLE: And you have lots of computational access there? Or do you get that from somewhere else?

BAGUS: Somewhere else. Okay, two ways. We do have reasonably good super-computer, or reasonably good massively parallel system at UNT, within, in fact, the chemistry department, but it’s very heavily subscribed. You put work in, and you wait until it comes out. I have two dedicated work stations that my grant from DOE gave me the money to buy. And I have access to the massive super-computers at PNNL.

BRUNDLE: That’s right. You do actually have collaboration with people at PNNL, as well. How did that come about?

BAGUS: I’m trying to remember. There was someone I met at either at a meeting or an NSF panel. Oh, it was an NSF panel, and he said, gee, it sounds like what you’re doing is interesting. Why don’t you come out and give a talk at PNNL. I think I talked about photo emission. Can’t swear to it because it was a while back. (Note added in proof: The topic of my talk was the XPS of MnO modelled with an Mn2+ cation.) People in the geo-chemistry group were interested in this because they wanted to understand oxides better. They want to understand oxides, not for their catalytic behavior, but for their contaminate behavior, and for the nasty things that happen as a consequence of their presence.

BRUNDLE: Yes, that’s Don Bear and his team, and others.

BAGUS: Right. It’s a significant…

BRUNDLE: - have to stop the pollution ever reaching Columbia River, is the simplified objective, I guess.

BAGUS: Yes, or make sure it stays in suitable containment tanks, many of them at the Hanford site that’s just outside of PNNL?

BRUNDLE: Well, I thought that is part of PNNL, right?

BAGUS: No, PNNL is a separate institution from the national lab. Sorry, PNNL is the national lab. The other lab, Hanford, is a basically nuclear site. PNNL is not entirely a nuclear site. PNNL has got lots of things.

BRUNDLE: Yes, it was the old military site, originally. Probably enough said.

BAGUS: A relevant point is that they bury nuclear waste at Hanford.

BRUNDLE: Or let it leak into the ground.

BAGUS: Well, they do their utmost best to see that it doesn’t leak into the ground.

BRUNDLE: Another thing I remember you did, that you haven’t mentioned. Somewhere along this line after leaving IBM, you actually spent two years, I think, at NSF, as a program director.

BAGUS: One year at NSF as a program director, yes.

BRUNDLE: So, that’s in the Washington area.

BAGUS: Actually my position as a Rotator in Physical Chemistry group of the NSF Chemistry Division was for a year or two position. The person who had it before me is an old friend of ours, an old post-doc of yours—Jeremy Broughton. He went and recommended me for the job, and I was tired of going and spending time in Europe, so I took the job for a year, and I had this vision that I was going to have input that would help change the world, and change the direction of science. What I learned was that no, my job wasn’t to change the direction of science. My job was to get competent peer-reviews of proposals, and appropriately interpret what the reviewers said.

BRUNDLE: So that the NSF did not waste this money.

BAGUS: So the NSF used this money in the best possible way. While it was fun to live in Washington, while there are great shops—Kramer’s is an excellent bookstore—I was just as happy to come back home.

BRUNDLE: I’m not sure how much you knew, but I tried—well, I thought about following you there and also getting a year’s position. They offered me one, and I dilly-dallied and wanted them to make some concessions to me in terms of working as an independent consultant as well, and they wouldn’t make those. In the end, I decided, okay, I’ll come and work anyway, and the guy said too bad, we’ve given it to somebody else, now. But, yes, it would have been interesting for a year.

BAGUS: It’s interesting for a year. I think it takes a different kind of person to make a career out of it.

BRUNDLE: Yes, very definitely, but for a year it’s fine. You learn a lot about politics and how the world works, I would think.

BAGUS: You certainly learn something about politics. You learn, in some sense, what your place is in the world. When the National Science Board meets, you can attend the meetings, but they’re at a big table, and you’re at the back of the room, sitting in a small chair.

BRUNDLE: One of the junior staffers.

BAGUS: Yeah. It certainly is interesting to see how the NSF works. At one point, it did give me some useful contact, but it’s been quite a few years, and I don’t think that any of the people I once knew there are still left.

BRUNDLE: Okay, well, let’s bring you up to speed now. You’re giving your award lecture tomorrow. The title of that is what?

BAGUS: The title of that is Multiplets and More, which I kind of liked as an interesting title, especially on the subject of multiplets that I don’t believe gets the attention it deserves; understanding multiplets is essential in order to be able to understand electronic spectroscopies.

BRUNDLE: That’s to do with XPS?

BAGUS: That’s to do with XPS and XAS.

BRUNDLE: Is that specifically on things like the Lanthanides, and the Actinides?

BAGUS: And 3d transition metals. It’s a combination. I have something in it about Cerium. I have something in it about Uranium. I have a lot in it about Titanium and Iron.

BRUNDLE: You’re really stretching into the really complicated elements, at least, for photo emission, the spectra are very complicated. Makes your job very complicated, as a theorist, to understand them. But that is what you’re doing currently, at work?

BAGUS: What I’m trying to do, and having some success, but not complete success, is to be able to reasonably, accurately predict both the multiplets, and the shake structure for a heavy metal oxide, and for a light metal oxide, too. For Fe2O3, and FeO as well.

BRUNDLE: I’ll just make the comment in passing that this is important theoretically, and to understand chemistry, but it’s also very important in a simple sense. If you want to do quantitative analysis, you have to know about all these things, too. So, you know which peaks you have to include in your intensities to get quantitative analysis.

BAGUS: And which regions of the spectra you should look at. One of my holy grails is that I think people should look more at the lower core levels, rather than the deeper core levels, because the lower core levels have a more pronounced multiplet splitting, which I think more clearly identifies the oxidation states.

BRUNDLE: So, they contain more information that is useful.

BAGUS: They contain information that is easier to dig out. But I’m not sure I’m right. And that’s something where you’re probably in a better position to know what the difficulties are in looking at the 3p of say ferric oxides, or ferrous oxides than I am. I know people do look at them.

BRUNDLE: I don’t think there’s much difficulty. I just think in the analytical world, people have not done that much because these are not the most intense peak.

BAGUS: That’s right. Signals are weaker.

BRUNDLE: But we can certainly start looking at them if that’s the better thing to do.

BAGUS: Well, we’ll see how convincing I am in my talk tomorrow. I think there is good reason to believe that it might be worth looking at them. I think another fascinating topic, which has been too much neglected, is vibrational broadening of XPS lines. I was surprised and pleasd that you remembered it when we talked about it during your talk at the QSA, Quantitative Surface Analysis, meeting this past Sunday. My impression is that most people seem to think that if they get a better resolution of their photons, and if they do better resolution for their analyzer, they can get as good a resolution as is possible to get. That’s just not true, because you are going to get vibrational excitations, and that’s in nature.

BRUNDLE: My awareness of that, of course, comes from my original background working in UPS, where you not only know they’re there, but you actually—since you have so much higher resolution for gas molecules—we actually, a lot of what we did was interpreting vibrational frequencies, and the meaning of the Frank-Condon factors, etc. So, I had a familiarity with it before. But, yes, you’re right. And we got a lot of questions from people in the audience afterwards—asking about line widths, and what was meant by this, and so it is something I think that has not been taken notice of much amongst the analysis community.

BAGUS: And I think even among the community of people who try to get basic understandings of the spectra. It isn’t thought about that much, and it should be.

BRUNDLE: Okay, so we’re pretty much up to date at this point, I think. I realize there’s maybe a couple of things I never even asked right at the beginning. We normally ask, when were you born? When were you born, Paul?

BAGUS: I was born on the 19th of November, so 11 days from now, in 1937, which means I’ll be 80 years old next year.

BRUNDLE: And I believe there’s going to be a celebration for that.

BAGUS: Yes, there’s going to be a day’s meeting at the Fritz Haber that Hajo Freund is organizing in Berlin, and the thing that I’m looking forward to is when we go out for that meeting, my daughter will come along with us to Berlin. This will be the first time in probably thirty years that she will be in Berlin. I think she’ll enjoy both seeing her father being feted for his 80th birthday, and seeing Berlin.

BRUNDLE: Yes. Okay, and to end, something we usually ask in these interviews, and you heard it last year because you sat in when we interviewed Hajo Freund. We’ve heard your history and how you got into things. What piece of advice do you give young students today for their careers with all the changes you’ve seen and what’s happened over the years?

BAGUS: I’m going to make this a suggestion for people when they’re doing theory, or when they’re thinking about theory, or when they’re looking at someone else’s calculations. Don’t look so much at the numbers. Look for consistencies. Look for significant changes between one material and another. Don’t worry whether the shift is 1.23 or 1.35 EV. It probably isn’t going to matter that much.

BRUNDLE: Yeah, that’s very much a chemist’s approach, where its relative sizes of things that matter. Not detailed numbers.

BAGUS: And that’s what’s important. For the theorists I would also say that an awful lot of good theoretical work is lost because people insist on clothing it in complex equations, which nobody can follow. The complex equations have two uses. First, they prevent anyone from following it. That’s not a use. And second, they may well hide the fact that you made a mistake. It’s better to put the detailed arithmetic, the detailed mathematical formulations in an appendix, and try to keep the main stream of the paper on what’s important. What are the important concepts?

BRUNDLE: Yes, well, as an experimentalist who has worked with you in the past—we do have joint publications—yes, I always appreciated that you didn’t try and explain all the details of the equations. What you did was get the sense of what it meant over to me as an experimentalist, and then I could come back to you and give you the sense of what the experiment meant to you. That’s a very good way of collaborating, I think.

BAGUS: Oh, I agree. It is a delight to collaborate with an experimentalist who understands the principles behind the things that are being measured. It’s the same thing with an experiment. People look for incredibly high precision in measurements, in a measurement that has a narrower full-width at half-maximum—a more precise measurement of the intensity, a smaller background is supposed to be better. It may not be. Same advice to experimentalists as to theorists. Don’t get lost in the trees of the numbers. Look at what you’re doing.

BRUNDLE: Anything else you’d like to say before we finish?

BAGUS: I’d like to say I appreciate the interview. I appreciate the chance to get some of this philosophy off my chest.

BRUNDLE: Interesting interview this time. First, it took me a long time to get the recorder to work, to find out how it worked, and then halfway through the battery failed, so we stopped. I hope we can patch all these pieces together, but I think we’ll be able to do that. So, thank you Paul, and have a very happy birthday next November—your 80th.

BAGUS: Oh, thank you. It would be great.

BRUNDLE: Thank you.