Oral History Transcript — Dr. Esther Conwell
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Interview with Dr. Esther Conwell
Esther Conwell; January 22, 2007
ABSTRACT: Discusses her early education and family background, education, first job, expermental work, work at Columbia University, study at the University of Chicago, PhD research, teaching at Brooklyn College, Bell Laboratory, Subrahmanyan Chandrasekhar, DNA, Charles Duke, Art Epstein, GTE, Rochester Univeristy, J. R. Schrieffer, William Shockley, Sylvania Electric Products, Inc., Victor Weisskopf and the Xerox Corporation.
Ashrafi:Today is January 22, 2007. This is Babak Ashrafi in the office of Professor Esther Conwell at the University of Rochester. Esther, you were born in New York. May I ask when?
Ashrafi:1922. And your parents, what did they do?
Conwell:My father was a portrait photographer and my mother was a housewife.
Conwell:Oh, yes. I have two younger sisters.
Ashrafi:Was there someone in your family in science or engineering?
Conwell:Probably not, but I can’t say I know much about my background beyond paternal grandparents. My parents were immigrants, and my father did bring over his father and mother and siblings. My mother’s parents, I never met them ever.
Ashrafi:Where were they from?
Conwell:She was from Austria, and he was from I guess it was Russia, then.
Ashrafi:So you went to school, was it in Brooklyn?
Ashrafi:What was the science or math education like, in say, high school years.
Conwell:Well, I went to a good high school, and I took biology and physics. I didn't take any chemistry. And they were rough. Biology in those days was primitive. I mean it practically consisted of classification. I remember the biology teacher as being very old. We joked about her being cracked.
Conwell:Cracked—not all there. The physics was probably good. I don’t remember much about it.
Ashrafi:Were there mostly boys, or were there girls in those classes, as well?
Conwell:Well, I suppose it was a majority of boys, but I don’t remember being so distinctive as a female as I was in college. And when I became a physics major, I was frequently the only woman in the class, or maybe there was one other.
Ashrafi:But was there an early mentor before you got to college?
Ashrafi:Were there particular things that excited your interest in science?
Conwell:It must have been natural, because I don’t remember any early mentor. In college, I started out taking chemistry, and I really enjoyed the first year of chemistry. I registered for an advanced course, and I went to the first day of that course, which was a lab, and the instructor spent an hour talking about lab technique. At the end of the class, I didn't even talk to the instructor. I went to the Registrar. At the Registrar I asked to drop the course, and I knew then that I was going to be a Physics major. I was taking the second half of the introductory course in physics, so there was nothing I could do that would help me along the way but take another math course, which I needed. But I don’t remember anyone at that stage mentoring me or suggesting that I major in one thing or another. It was all personal preference.
Ashrafi:If we step back a bit, was it obvious for you along that you would go to college? Was there any discussion?
Conwell:I guess not. My parents were immigrants and didn't know what was available or what the future might hold. I remember my father, who was hit psychologically by the Depression. It wasn’t so bad, financially, for my family. I don’t remember being at a lack for anything. He impressed on his three daughters that in order to have a future, to be able to get married, we had to have jobs and be able to earn money, and he would prefer that we be professionals.
Ashrafi:In order to get married?
Conwell:Yes. That we would have to be—well, I think the way he put it, he had a comic way of exaggerating, and the way he put it was that we would have to be able to support a husband before we could be sure to get married.
Ashrafi:So did you share this impression at the time?
Conwell:Oh, I believed anything like that he said.
Ashrafi:So when you chose physics as a major, was there some employment consideration? Did you think about, “What would this lead to?”
Conwell:Oh, yes. My idea was to be a high school physics teacher, because that was all that I had ever seen.
Ashrafi:And so you had physics in high school, you dropped chemistry right away in Brooklyn College, and you entered in ’38. Could that be right? You graduated in ’42.
Ashrafi:And you took math and physics courses.
Ashrafi:So can you tell me what the Brooklyn College math and physics education was like?
Conwell:Oh, it was very good. People really couldn’t do research there because the teaching load was very heavy. But in the Depression days and before the war, those were good jobs. They paid well at the city universities. Well, Brooklyn College wasn't part of the city universities, but those were good jobs. They paid well, and we had good teachers. One of the outstanding teachers was Melba Phillips. She happened to be on leave on the years that I might have taken a course with her. But there were others of her caliber who made some effort to do research, but with the teaching load that was there, impossible.
Ashrafi:And you said that you were often the only female or one of two females in the physics classes. Was that difficult? Were there some issues associated with being the only woman in the classes?
Conwell:It didn't bother me. I didn't mind getting some extra attention.
Ashrafi:Did you get extra attention in a way that helped or hindered your studies?
Conwell:I don’t remember it as having been bad or helpful.
Ashrafi:Were all of the other instructors, other than Melba Phillips, male?
Ashrafi:What kind of classes and what kind of topics were covered? I assume you had classical up to relativity.
Conwell:Oh, yes. And the standard E&M, and Mechanics, Modern Physics of some kind, and it was a pretty standard undergraduate curriculum for that time.
Ashrafi:Modern Physics, including some Atomic Physics?
Ashrafi:Okay. Was there a particular mentor that you remember?
Conwell:Well, I did develop a particular mentor there, Professor Kurrelmeyer. He was married to a physics professor at Columbia. He certainly had a big effect. I didn't know about graduate schools, really, and at that stage, I was even more convinced that I was going to, my career was going to be teaching physics in high school. I actually took a couple of education courses preparatory for that. But the courses had so little content and so little interest that after a couple of them, I said, “If I starve, I’m not taking any more of these.” But it was he who suggested that I apply to graduate school. And he even took us to an APS meeting down at Princeton. I guess it was a year before I graduated, and he was most helpful.
Ashrafi:Who was “us”? Was it a group of you students?
Conwell:Yes, a group of us, the advanced students.
Ashrafi:Did you work together in groups of other students, or did most people work alone?
Conwell:I worked alone, in perhaps an unfortunate tradition, but that’s how I developed as a physicist, and I mostly worked with a couple of other people and usually a post-doc, for instance.
Ashrafi:Are there other important events or people at Brooklyn College that we should be sure to talk about?
Conwell:Two people, really. I could confuse it with what happened when I came back there as a teacher, not so many years later. But a Professor Mais gave a lot of the courses that I took, as well as Professor Kurrelmeyer. He was a very good teacher, and he was also helpful to me and wrote letters for me.
Ashrafi:So then you went to Rochester?
Conwell:Yes. I applied for fellowships and got two offers: one was in Minnesota and one from Rochester. I was only 19 when I graduated and my parents were very concerned about letting me go so far away from home alone. Since Rochester was closer to home, I accepted the offer at Rochester. But the War was already on when I got there, and many people had already left for MIT or Los Alamos. After I’d been there, I guess a little less than a year, the professor that I might work with was Weisskopf.
Ashrafi:Mm-hmm [yes]. He was already there when you arrived?
Conwell:He was, oh yes. Yeah, this was his first position in this country. And my graduate career here was soon to come to an end, I mean everybody was going to leave. The Navy and Marines came in to take these B-12 courses, which I taught for a very short time.
Ashrafi:I’m sorry, B-12?
Conwell:What it was, they sent them back to school, I’m not sure why, once they were drafted, before they sent them on to wherever they were going in the Army or Marines. I particularly remember the Marines. They may not have been as stupid as they seemed, but they seemed to make a point of acting stupid.
But anyway, it was realized that I would never be able to go straight on and get a Ph.D. there as would have been expected. So they decided to have me do a Master’s thesis. Weisskopf had contact with the people at Purdue, and they were just starting to work on semi-conductors. Germanium at that time; silicon came a little later. And he went down to Purdue for a weekend and came back with a thesis subject for me, which was this impurity scattering. I think that was early Spring, maybe March or something, and he was slated to leave for Los Alamos in June or something like that.
Ashrafi:What year was this?
Conwell:1943. ’43, because I’d just been there a little over a year. And I really was in quite a stew, figuring I had three months to do original research, and I’d never had any experience or anything for research before that. But he suggested a way of going about this problem, and I did the work. The day before he left, I handed him a write-up, tied with pink ribbon, and that was the last I ever heard of him or from him, until I saw him at MIT, about 30 years later. I guess he was busy at Los Alamos.
I was in contact with the people at Purdue who had given him the problem. That was Professor Lank Horowitz, actually, the Chairman of the Department, and Professor Vivian Johnson. They had sent along data, the resistivity versus temperature over the whole range of temperatures. I guess they had sorted out the mobility, having measured the Hall effect, but I don’t remember now. And so that was the data that I was supposed to fit. After a few months, although we didn't know the impurity concentration, but with that as an arbitrary number I could more or less fit the low temperature data, I could fit the temperature dependance which is the outstanding thing about the data. This was considered war work. And Vivian Johnson wrote to me and asked would I send her my thesis, which I was writing up. I was rather reluctant, but they sent me a special appeal from Seymour Benzer, who had been one of my classmates at Brooklyn College, who was there as a graduate student. He later on became very famous in biology, very good. So I sent them my thesis, and they sent back a letter saying that it fitted their overall data very well. They had the part of the story that I didn't, and she said that to finish the thesis and really make a comparison, with experiment, I would need to include the contribution of the lattice vibrations. She recommended that I get this from the article by Bethe in Annalen der Physik. Of course I didn't read German, or I speak any German.
Well, by that time, I was finished with Rochester and had moved back home to New York. So I read the article, and over some time I was able to complete the thesis. When I submitted it officially to the University of Rochester, I guess they were told by Purdue that it had become classified—it couldn’t be published because this was war work. And it was not declassified until after the war was over.
By that time—Well let me go back briefly, because this is of interest. After my first semester at Rochester, I wanted to go back to New York for the summer. My boyfriend, ultimately to be my husband, was there. And I took a summer job at Western Electric, which was the manufacturing arm of the Bell system. It had a plant in New York. They were kicked out of New York, subsequently, because of an explosion. So on the strength of the graduate work that I had had, they hired me as an assistant engineer. And I was in the Quality Control Department. After I had been there a couple of weeks, my boss said we had to go see his boss. So we went up to see his boss, and he informed me that there was no such payroll classification for women as “Assistant Engineer,” and I would have to be, quote, “an Engineer’s Assistant.” And it’s obvious what that did to my salary. But you could hardly—well, no one could complain to them. There was no legislation at that time. The department I was in, this Quality Control Department, had all kinds of people at all levels of degrees. And so there were people with or without graduate work doing the same jobs, which amounted to reading the blueprints of vacuum tubes, and if you saw that the engineers weren’t following the blueprints, remind them of that. I mean that was the kind of work that it was.
Ashrafi:Let me step back a couple of steps. Can you tell me about your coursework when you first arrived at Rochester? Let me get the chronology right. So you came to Rochester…
Conwell:In January 1942 when I graduated from Brooklyn College. They had two graduations a year.
Ashrafi:Okay. And then you came to Rochester?
Ashrafi:And then you stayed. After one semester, you went back for the summer and you worked as an assistant engineer, and then engineer’s assistant.
Conwell:At Western Electric.
Ashrafi:And in the Fall, you came back to Rochester?
Ashrafi:So what was the coursework at Rochester?
Conwell:Well, I remember a course in thermodynamics with Marshak. Bob Marshak. I don’t know if you should put this…
Ashrafi:You can edit it later.
Conwell:Oh, well. He was busy working on whatever research he was working on, and couldn’t be bothered with us. There must have been, I don’t know, eight graduate students in the class, and he had us take turns giving the lectures and he sat in the back and worked on his theory. So I never learned any thermodynamics.
Ashrafi:Is that right?
Conwell:Yes. And there were, well, a course, in Mechanics, and I guess, electromagnetic theory. I think it was standard, there was no such thing as solid-state physics then, so I never had any of that. I think it was the standard stuff, the usual curriculum. And I was a member of the cyclotron crew briefly. They had one of the first cyclotrons in the country, pretty small, but at the time it was a big deal, and they made radioactive isotopes for the hospital and what not, and did some research with it. I remember the head of it was named Dessauer, a nice guy. And when I came to work there, he handed me some rags and things and said, “You’re a woman. You clean the cyclotron.” But I really didn’t take it badly, because it was said with a smile and he didn’t mean to be insulting me, I don’t think. I took it as a joke. But I wasn't cut out for experimental physics anyway.
Ashrafi:How did you know that?
Conwell:Well, this cyclotron experience wasn’t great, really. I mean, shortly afterwards, the people who had built the cyclotron were all gone, and it had been put together with chewing gum, sealing wax, and the vacuum wasn’t good. Leaks were painted over with something called Glyptal. So a lot of time you were hunting for leaks. And then one time it wasn’t working and it was something in the electronics, and we couldn’t find a reliable circuit diagram. They had penciled in some additions to the circuits and what not. Not a good experience and I didn't feel competent to deal with it. I suppose it did a lot to turn me off. I guess I enjoyed the theory more.
Ashrafi:What about quantum mechanics, or scattering…
Conwell:Oh. I certainly took quantum mechanics with Weisskopf and that was a very good course. He was a wonderful teacher.
Ashrafi:Would you happen to have notes of any of the Rochester classes?
Ashrafi:Do you know if any exist?
Conwell:I don’t think so. In my travels since, I surely discarded those a long time ago.
Ashrafi:How was the atmosphere? So you were again probably the only woman student.
Conwell:We had one other. We shared an office. And she was a quite different kind. I think she was suited to be an engineer, really. I don’t think she went on in physics, even, after the first semester we were here.
Ashrafi:And did everyone take you seriously as a potential physicist?
Conwell:Well, I wonder whether Weisskopf did, for instance. He laid out this calculation. Well, as I told you, he never got in touch with me about the thesis that I gave him. And Marshak certainly didn’t. When I met Weisskopf at MIT, many, many years later, he said, “Well, you were my first woman Ph.D. student,” acting as though he was proud of me then. And when I was inducted into the National Academy, he was there, and he kissed me. But of course, it wasn’t a Ph.D. thesis. It was a Master’s thesis, and it did go on to be famous because it was a first. And I guess, oddly, I got more mileage out of it because I was a woman.
Ashrafi:How do you mean?
Conwell:Well, I mean when Shockley wrote his book, he featured it primarily as Conwell-Weisskopf formula theorem, and it was referred to in all of the papers at the time, and some years later, even.
Ashrafi:When the folks at Purdue requested your thesis, why were you reluctant to send it?
Conwell:Well, I thought they might publish it as their own, and I had done the work.
Ashrafi:Was it published?
Conwell:Ultimately. After Rochester I worked briefly in New York at Columbia, at the project there. I suppose I could have gone to Los Alamos, but I didn't have enough physics to be really useful there. And so I took this job at Columbia, which was deadly. I mean, they had me sitting and looking at a spot on the galvanometer to decide how well they had separated U235 from U238 in particular samples.
Ashrafi:So you were saying that you took a job in Columbia looking at a spot on a galvanometer to see how well uranium was separated.
Conwell:Well, I’m not sure they even told me that that’s what I was doing, but that’s what I was doing. Then I discovered that there was still some graduate work going on at the University of Chicago, and I applied there and was accepted. I left for Chicago. They were short of people to teach undergraduates, and so they gave me the responsibility of teaching elementary physics, the whole course, including the lecture demonstrations, which were a source of grief to me particularly, because for some of them, for example conservation of momentum experiments, you had to pull back a spring, and I wasn’t strong enough to do this, and that struck the boys as very funny, because I was the only woman around. The first semester I registered for three graduate courses, and I took on full time teaching this elementary physics, lectures, and presentations, and labs. And that was tough.
Ashrafi:Can I ask you to make sure I get the chronology straight, you went back to Western Electric the first summer in Rochester, and that was the summer of ’42.
Ashrafi:And then you went back to Rochester, and in the Spring of ’43 was when Weisskopf suggested this problem to you.
Conwell:That’s right. And I left in the summer of ’43 to come back to New York.
Ashrafi:And then you stayed in New York; you didn't go back to Rochester. Is that right?
Conwell:No, I never went back to Rochester.
Ashrafi:Did you finish your Master’s in New York and send it back?
Conwell:Oh, well, the Master’s wasn’t really awarded for a couple of years, but I finished my thesis, I suppose some time in ’43 or early ’44, because I got to Chicago in ’44 and Fred Seitz was here.
Ashrafi:And here being?
Conwell:I’m sorry, it was at Chicago. I showed him what I had done, because I knew he was, well, he was already the solid-state physics guru of, and he said it looked all right. But the people at Purdue were said to be quite satisfied with it. Well, late ’44—or no, it must have been ’45, I was at Chicago, and one day, the bulletin of the American Physical Society came and I looked at it and I found my name in there, which was a surprise, as I hadn’t sent anything in. It turns out that the work had been declassified, because the war was over and Lark Horovitz and Johnson had sent in two abstracts; one under their names with the comparison with experiment, and one under Conwell and Weisskopf with the theory of the impurity scattering.
Ashrafi:They sent it in without saying anything to you?
Conwell:Well, that is true, they didn't say anything to me. And I had never met Lark Horovitz. But years later, or I don’t know, one year later he said, that they had made me an offer as a graduate student at Purdue, but that isn’t true. Maybe he thought he had really, or maybe he had wanted to, I don’t know. But after seeing the abstract I didn't get in touch with them. I went to New York, which was home after all, and went to the Physical Society meeting, and then met Lark Horovitz the first day there. He apologized. He said, “Oh, we couldn’t find your address and your telephone number.” He said they tried. And I gave my paper. I understand that Bell Labs was out in force to hear that paper, and Shockley and Bardeen were there. I was very nervous—my knees were knocking. And then, of course, we could publish the paper and Weisskopf approved my write up, and it was published.
Ashrafi:So let’s talk about Chicago now. Can you tell me about the instruction there?
Conwell:Well, I had already taken most of the courses that you should take. The system they had then for getting your Ph.D. was that you had to offer 15 courses and be ready to be examined in them, in addition to the original research or thesis. So I didn't take many courses. I took Fermi’s class on nuclear physics, and I really enjoyed that and did well in it. And I guess they felt guilty for having given me all of freshman physics a few years before, so I got a job grading, I got paid for grading papers in Fermi’s electromagnetic theory class. I sat in on his class and that was an easy job, because I could pick out Yang’s paper, or Chamberlain’s paper. I mean, there must have been half a dozen future Nobel Prize winners in that class, and I graded the papers. But I didn’t stay long on campus. The faculty weren’t back yet too much. I had taken a course in cosmic ray physics with Marcel Schein, and I think Shine was worried that I would want to work with him, so I think it was he who arranged that I work with Chandrasekhar, the astrophysicist, at Yerke’s. So that was where I went for my Ph.D. thesis. And he was a wonderful man, of course.
Ashrafi:Mm-hmm [yes]. So Schein tried to move you off campus so he wouldn’t have to take you on the physics team?
Conwell:Yeah, I think that’s true, but he never as much as said that. I think we can edit this later, but he wasn’t a great man. When I came back from my Ph.D. orals, he was on the committee. Zachariesen, who I had taken mechanics with at Chicago, and Chandra, and Allison, the nuclear physicist—it was a very distinguished committee. Mulliken for atomic physics. I think we had one more. And Schein had a couple of—I mean everybody had a chance to ask me a couple of questions, and Schein asked me a question and I answered. And he thereupon enlarged on my answer, or maybe said I hadn’t said it all, and spent around five minutes at this Ph.D. oral, explaining what he thought I should have given as the answer. And at the end of that, I said I thought that my answer was equivalent to what he had said. He let it go at that. I think he was really anti-woman, or he would not have done that. But he did not cover himself with glory in that exchange. It’s a moment that I have treasured.
Ashrafi:Were there other women graduate students at Chicago?
Conwell:Oh, yeah. Not many. There was Leona Marshall, who worked with Fermi. And that should have been the start of a brilliant career for her, but somehow she disappeared, not long after working with Fermi. But I don’t think they were many others. The integrated time I spent on campus, I don’t think was a year, because I went up to Williams Bay to work with Chandra. And I didn't stay there too long, either. I guess I was back on campus briefly after that. But by that time I was married, and we decided that we would live in New York, so I left Chicago.
Ashrafi:What year were you married?
Ashrafi:So that’s right at the beginning of your Chicago career.
Conwell:No. I got there in ’44, didn't I?
Ashrafi:Oh, I see. The Master’s from Rochester was awarded after you arrived at Chicago.
Conwell:Yes. I mean they waited for the thesis to be declassified.
Ashrafi:So what was your work with Chandrasekhar?
Conwell:Well, it was work in atomic physics. Somebody had measured an absorption edge in the sun’s spectrum, and he had discovered that it fits the absorption by negative ions of hydrogen. And that was quite unusual for the time. People didn't really believe in H-minus, and you can see why they might not. Oh, I’m assuming you have a physics background.
Ashrafi:Yes. But whatever you put in the interview, the more you put in the interview, the better.
Conwell:Okay. He had the calculation that he had done for the energy levels of H-minus, which was based on a variational calculation. So he had arbitrary parameters in there. And he wanted me to take a different approach to finding the wave function for H-minus, and he thought that he could identify another absorption edge in the sun’s spectrum as O-minus, and he wanted me to do calculations of what the energy levels would be for O-minus. I did some calculations for both of those, and I was briefly back on campus and they gave me a human computer to do some of the calculations, but it was really pretty hopeless. I mean these were problems that really required a computer and a lot more physics than even had been developed at the time. So my Ph.D. thesis was not a very big contribution. But Chandra, I think was impressed by the fact that I worked mostly on my own and the astronomy, or astrophysics students seemed to prefer his holding their hands a little longer through the thesis. Anyway, he passed it and I got my Ph.D. and I wasn’t about to question.
Ashrafi:So tell me about the human computer.
Conwell:Oh [chuckles]. He was a nice guy, but not fully there. But he could do numbers, and so he did a lot of the routine calculations that a computer would do now very rapidly.
Ashrafi:Was he a student, or was this his profession?
Conwell:It was his job. You wouldn’t call him a professional. He really—I mean his IQ must have been below a hundred.
Ashrafi:So now, was your Chicago Ph.D. awarded right away?
Ashrafi:Okay, and this was ’48?
Conwell:Yes. Well, it wasn’t right away. I mean I left Chicago with a partly finished thesis, and not having had a few of the courses I was going to offer in my fifteen. We had decided to live in New York and I went back to Brooklyn College as an instructor. I mentioned the teaching. It was a 16-hour teaching load—which everybody had; I mean it wasn’t only me—which included a few lab courses, but it could include new courses and preparations. So it was that, I came back in ’47?
Ashrafi:I have you from ’46 to ’51 being an instructor at Brooklyn College.
Conwell:Oh, then I came back in ’46. So I was there for, well, I went back to take my final orals in maybe it was the end of ’47, and the Ph.D. was awarded in, the ceremony was in ’48. I remember that from the…
Ashrafi:Did you take more courses when you were in New York?
Conwell:No, I didn't take more courses. I just read and studied as much as I could, and it was a tough year and a half there. I remember that after I passed my orals, I was teaching and I went on with the teaching, as I had to, but I couldn’t seem to do anything else. I could hardly make the beds consistently at home. I was really tired for a couple of months.
Ashrafi:So did it seem to be that that would be your career, teaching at Brooklyn College?
Conwell:It did. It did.
Ashrafi:Were there other Ph.D.s there?
Conwell:Oh, there were. Well, I think you had to have a Ph.D. to be a full-time instructor. So some of the people had lower level jobs and were teaching, but most of them were—more than half of the department was really good. I mean, Kurrelmeyer and Mais were still there, and Bill Rarita had come back from or Los Alamos or wherever during the war. But it was kind of split. I mean there were some not too competent people, but nobody was ever fired in those days; you had tenure. And Melba Phillips was back. So it was a very good department, but everybody had these huge teaching loads and there was hardly any chance to do research. I made an effort. I would start a project in the summer, work during the summer, and I couldn’t get back to it, really, until the next summer. And by the time I got back, I spent most of my time trying to remember what I’d done the year before, and I got nowhere.
Well, I did have a piece of luck. An older woman, Mrs. Tabley who had been on a year’s leave the last year I was there because of illness, decided she was well and was coming back again, and they suddenly did not have a teaching line for me. They managed to get me tenure but no job [chuckles], tenure and a leave of absence in 1951. And Professor Kurrelmeyer arranged for me to spend a year at Bell Labs, actually working with Shockley. I did a couple of useful papers while I was there, but I never really got into things there.
Ashrafi:This is Murray Hill?
Conwell:Murray Hill, yeah. It was obviously a wonderful place. Now Bardeen was just about gone by then, and they gave me his office in the corner. But it didn't rub off.
Ashrafi:So can you just describe the life for me there? You were there for a year?
Conwell:Yes. Well, there, I really felt very conspicuous as a woman.
Ashrafi:Is that right?
Ashrafi:So at this point, in your responses so far, it seemed like it wasn’t really an issue that you were a woman, except for the fellow in Chicago who had you moved off campus.
Conwell:Yes. Well, even at Rochester, somebody made the remark that I was only taken on as a Ph.D. student because I was a woman and not draftable. But otherwise, I didn't feel any particular discrimination. But at Bell Labs, I mean there was only one other woman on the technical staff. And people are very class conscious there. There was a big difference between members of the technical staff and the support staff. I mean there were different dining rooms, it was just very conspicuous who you were eating with, and I really felt singled out.
Ashrafi:Can you describe that hierarchy to me? So you’re describing a bit of the social structure of Bell Labs. What was that like?
Conwell:Well, I can’t say I really felt a part of that, so I don’t think I can describe much more than saying that there was a big class difference between the members of the technical staff and the support staff.
Ashrafi:How did one know where in the hierarchy you fit? How did you know you didn't fit in?
Conwell:I mean, I was just so obviously different from everybody else. And, well, there was another reason. I had come in to work for Shockley, and so I didn't get exposure much to other people in the lab. Perhaps I should have made it my business to—uh, I didn't feel very secure or confident there.
Ashrafi:How was it working with Shockley?
Conwell:He was generally nice to me. Yes, he was generally nice to me, although he obviously didn't make any great effort to get along with some of the other people, like Walter Brattain, for instance. Poor Brattain was not nearly as sophisticated as some of the others, and good in the experiments that he did, but wouldn’t make any real effort to interpret any of his data. When he found an effect with his point contact he went to Bardeen to work on the interpretation and suggest further experiments. And Brattain would try to stand up to Shockley, and it was just pathetic. Shockley would just wipe the floor with him. Shockley is a very, very bright man, who definitely—well he went off the deep end in sociological things.
Ashrafi:Was there any manifestation of that, at this stage?
Conwell:Yes. Yes. He already was talking about eugenics.
Ashrafi:Just to be clear, we’re talking about ’51 and ’52.
Conwell:The year I was at Bell Labs, yes. I was only there for a year… And he came up with the idea, which I guess he tried to follow, go further with later on, he was going to improve the population by giving out 2 tickets to each woman at birth, and these tickets could be sold or traded. He figured that the poorer people would sell them or give them to, I don’t know, wealthy or more useful people and that he would improve the population this way. He was really talking about that idea, even at that time.
Ashrafi:So what did you work on at Bell Labs?
Conwell:Well, I came in with a background in semiconductors, having done the impurity scattering which is what I assume made me at all attractive to them. So the first assignment that I had was to read a paper he had just written on hot electrons, which is a memorable paper, and I must say it’s guided my career on hot electrons, because I worked on them for years afterwards, after I left Bell Labs, and it was a good subject. I was working on transport problems. One of the nice things I got to do, subsequently useful in my career, had to do with special issue on transistors of the Pioc. IEEE. Shockley was asked to write two articles, one on the basic materials and one more on transistor operation, I guess, and he didn't want to be bothered to write the article on basic materials, so he asked me to do it. And that article was really many people’s introduction to semiconductors. I think many people who wrote books thereafter just plain picked from that article. Anyway, having had a year of research, real research, I did not want to go back to Brooklyn College at the end of the year. So Shockley helped me find another job. He was always nice to me. And that job was at Sylvania.
Ashrafi:So let me ask you a few more things about Bell Labs. Were you hired specifically for a one-year term?
Ashrafi:And all the work that you did was specifically assigned to you by Shockley?
Ashrafi:Okay. So then after the time was up, he found you a job at Sylvania. Okay. Do you know how that came about?
Conwell:Well, it was the days not long after the invention of the transistor and a marvelous time for research, because many companies felt that if they hired a few physicists and got them to working in this area, they too would have transistors or the equivalent invention. And I guess Sylvania felt that way, too.
Ashrafi:I forgot one question. Were you funded in any special way at Bell Labs, do you know? Was it just Bell Labs research saying that Shockley had to hire an assistant, or?
Conwell:I never thought of that money there. It must have been that way, but it was in Shockley’s budget.
Ashrafi:Sorry. Now to Sylvania.
Conwell:Yes. They did not have good people there, for the most part. I mean there were a few, mostly chemists, I guess. They did better in chemistry than they did in physics. They didn't even have many Ph.D.s in physics.
Ashrafi:Okay. So you went to Sylvania, and you said they were stronger in chemistry than in physics. So what job specifically did you go to?
Conwell:Well, my job was to do research in semiconductors. I mean, they were willing to support this kind of research not directly related to their product, because as I said, they were hoping that by hiring a few physicists and turning them loose in this area, they would end up with great inventions.
Ashrafi:So this is in New York?
Conwell:Yes. It was in Queens, actually.
Ashrafi:And can you tell me how the research was organized in the group you were in? Who was in charge?
Conwell:Oh, they had a boss, yes. A nice guy, Rudy Hutter. He had been a professor at Brooklyn Polytech. And within this area, they let me choose my projects. Subsequently, they thought they might want to get more serious about maybe making transistors, and they set up an operation in the Boston area, Sylvania, and hired a lot of people. And we used to have joint meetings with them and give talks on what we were doing. But that died after a few years. They weren’t getting anywhere. They hadn’t hired very good people. Everybody was trying to hire people in this area. IBM made out pretty well, because they had a lot of money.
Ashrafi:So how was this research funded? Do you know?
Conwell:Corporate, yeah. The corporate budget allowed some money for the research labs.
Ashrafi:And was the goal to publish? Was the goal to put out internal reports?
Conwell:Well, the only goal—yeah, publishing was encouraged, which was good. And I guess they would have welcomed invention proposals, of which I got a couple. But mostly the people in charge that didn't know enough to discriminate between what was good or bad, or useful or not useful, so people just did as they chose.
Ashrafi:So you were free to do what you liked?
Conwell:I had to stay within that semiconductor area, which I wasn’t inclined to leave anyway.
Ashrafi:Oh. And was there much communication about developing products about broad directions at all, or were you completely free?
Conwell:Well, this lab that they started in Waltham was really supposed to be thinking about products, but I think it didn't last very long. Sylvania had been making vacuum tubes as well as fluorescent lights, and there was a tradition that people who had been in the vacuum tube business did not do well going into the transistor business. And this is really quite understandable because you had to worry about things for transistors that you just didn't have to worry about in vacuum tubes. For example, a clean room, and the quality of the surfaces and the quality of the single crystals—I mean nobody ever worried about whether an electrode in a vacuum tube was a single crystal or whatever. So there wasn’t enough sympathy for thinking about these problems, and that’s why a place like Sylvania was never going to get anywhere in this business.
Ashrafi:So how was it, being a female on the staff of Sylvania?
Conwell:Well, I think I was treated as well as anyone else. They made me an Area Manager after a while, and they actually offered me a big management responsibility after some years, which I very wisely refused to take, I guess for one thing, because I wasn’t impressed with the workers, what the people in the area were doing, for the most part or the management. Some of them were very good, but not too many. I felt that if I ever had to leave, my own research and my own skills would be what I would have to sell, and I was right about that.
Ashrafi:Mm-hmm [yes]. Now were you completely independent, or did you have a mentor? Because you were still fairly young, at this point.
Conwell:Oh, no mentor. I mean I was working with some experimental people to test the theories I came up with…
Conwell:At Sylvania, yes. And I was working with the younger, theoretical people, having them do calculations. No. I felt sufficiently confident of myself and sufficiently superior to many of the people there that I didn't have to worry about that.
Ashrafi:How about your contacts with academia? So let’s break it up. You were there for 20 years before you went to the École Normale. And then for part of that time…
Conwell:Twenty years before I went to the École Normale?
Ashrafi:I’m sorry, no. I misread. I’m sorry.
Conwell:It was 20 years, total.
Ashrafi:Yes. Okay, so you were there for 20 years, and as part of it you were a researcher and then a manager.
Conwell:Well, a manager.
Ashrafi:Uh-huh [yes]. So when did you become a manager?
Conwell:It probably says that in my vitae. Well, it says here, manager of electronic materials program, 1961 to 1962. Then they called it the physics department, manager of physics department, ’63 to ’72.
Ashrafi:So let’s talk about the time before you took on management. Was all that time working basically alone?
Conwell:Well, as I told you, I was working with some experimentalists, and I had theoretical people working with me on calculations that I wanted.
Ashrafi:And what were your relations with academic physicists at that time?
Conwell:Actually what we were doing was pretty much academic. At conferences I would be treated like one of the academic people, except I have to say, looking back, I did not get my share of invited papers, and that was due to being a woman. Looking back on it, I would say that. I felt many times that I should have gotten an invited paper, but I didn't. But I also didn't know how to work the machinery. As a woman, I was not properly socialized.
Ashrafi:Can you explain that?
Conwell:Well, I mean you have to know how to get invited papers for other people, or yourself. For instance, you have to know how to treat and be treated by other people in the physics community, and I was pretty innocent about that for a very long time.
Ashrafi:Was there a time when you learned this?
Conwell:Well, I must have been accumulating it slowly over the years.
Ashrafi:But you think male physicists in the community did it more quickly?
Conwell:Not all of them, but some of them certainly did. No, not all of them. I mean, as a woman, and you see this in all of the studies, we’re not given a reason to have the same kind of self-confidence that some of the men do, as an example, the way I sneaked through graduate school, essentially, including working with somebody off campus, although a Nobel Prize winner to be sure. And getting my Ph.D. on what turned out to be the old system, at Chicago, because they changed the system in Chicago after the war. When they got Yang, Chamberlain and Steinberg and so on after the war, they changed the system, and they made the requirements for the Ph.D. quite difficult, which they could get away with for a number of years, but I think they loosened them again when those guys moved on and they couldn’t keep up that level.
Ashrafi:Did you ever have to ask for funding before you became a manager? Did you have to argue for your position, or convince someone that your work was worthy of support?
Conwell:To some extent, yes.
Ashrafi:How was that done?
Conwell:Well, as an area manager, I dealt with the levels of management not too far above me, and I could talk to them.
Ashrafi:So you became an area manager in ’61 or so, ’60 or ’61?
Conwell:’61, it says.
Ashrafi:’61. So what were you managing? Wait, I’m sorry. I’m getting ahead of myself. Were there things we left out before the ’61 period in Sylvania, that we should talk about?
Conwell:Well, one nice thing, there was one engineer at Sylvania who I guess took a liking to me, and he got me into being a fellow of the American Physical Society at a relatively young age. Another thing is that Sylvania was bought by General Telephone, GTE. This was an example of a male corporation taking over a female corporation.
Ashrafi:What does that mean?
Conwell:GTE had male characteristics, being more active, aggressive, and so on. And Sylvania was passive, and the analogy [chuckles] is pretty obvious.
Ashrafi:When did this happen?
Conwell:It must have been roughly halfway or less through the time I was there.
Ashrafi:And this was when you were an individual researcher, or a manager? Do you remember?
Conwell:Probably I was already an area manager. Let me see if I can get any clue here. It didn't make that much of a day-by-day difference, but the difference it made immediately, and well this is private history and not necessarily my history—is that of interest to you?
Conwell:Okay. GTE was a telephone company which had grown considerably, fast in the tradition of other telephone companies, but it’s quite small compared to the Bell system. But they got to the point where they felt big enough to play with the big boys, and so they decided to have research labs. And they bought Sylvania to acquire, apparently mostly to acquire, the research lab. And then they hired some general to tell them what to do about research. And this general apparently wanted to live in California, so he suggested that they start a new lab right behind Stanford at Palo Alto. They put a lot of money into building a gorgeous new lab, and they hired some people, and not long after this was started, they realized that they couldn’t support two labs. And it ended up that Stanford got those buildings. So you could see that they knew nothing about research, not that Sylvania knew so much. But Sylvania had some tradition of research, at least in the lighting part of the company. So we then got a new head of the labs. People would say about him that he was one who played football without a helmet. He looked like a football player, and he had played football. I guess he acted like a football player. He came from a background of government type research in California, and it was his idea that when you finished a project, you swept out the people on that project and hired a new bunch for the next project. So it took some effort to get him from sweeping out some of our best physicists early in his tenure there.
Ashrafi:Did the processes by which you took research directions or the topics that you did pick change in the transition from Sylvania to GTE?
Conwell:Well, not really, because GTE could hardly be hands-on running the labs, because they just didn't know anything, and nobody there knew anything about what was going on. They just felt apparently that a research lab was an important thing for an up and coming corporation.
Ashrafi:So the relationship between research and development which under Sylvania, as I understand what you’re telling me was none, there was no new relationship under GTE either. So you’re shaking your head no.
Conwell:I think the new labs in Waltham were probably, oh, I can’t remember whether they were started with GTE or not. But that was the real effort to do some applications and make some devices, but it did not thrive.
Ashrafi:What about your notebooks and your papers? Did the company make any claim on them?
Conwell:Well, if you have an invention proposal, yes. But otherwise, no.
Ashrafi:And so they made no effort at preserving research documents?
Conwell:Right, no effort.
Conwell:No. It was entirely up to you to save or not save your own papers.
Ashrafi:And no one came in to tell you whether or not you could publish something, whether it was going to be proprietary or a trade secret, or anything like that?
Conwell:They did have someone who cleared things for publication.
Ashrafi:Oh, they did.
Conwell:Yes. Yes. But that didn’t affect my work, because I was never close enough to a device that they would stop publication.
Ashrafi:Do you have a sense of whether or not it affected anybody else’s work in your lab?
Conwell:There may have been some people whose work was affected by it, but I don’t know first-hand how that turned out.
Ashrafi:When you became an area manager, how did your work change? What were your responsibilities as an area manager?
Conwell:Well, I felt a responsibility to see that the people in the group were doing respectable research, and I was actually collaborating with a couple of them, really finding out what they were doing. From the experimentalists I got things that I could do calculations on. So I kept aware of the work, but it was a small group.
Ashrafi:Was quality an issue?
Conwell:Well, personally, it was. But there was nobody but me judging the quality of the work of my crew.
Ashrafi:So what would you do? Would you tell someone that his work isn’t good enough, or how did you proceed?
Conwell:It didn't come to that. I mean, I knew the people that I had and they were okay.
Ashrafi:I’m trying to understand. So far it seems to me that there wasn’t much structure in determining research directions, picking priorities, and I’m trying to understand if that’s accurate, you say.
Ashrafi:And if that changed at all in your twenty years at Sylvania-GTE.
Conwell:Not in my group, not where I was. I think it’s true of most of my life in industry. Maybe they had faith in me or maybe they didn't want to bother with me, or didn't care or think about what I was doing, but that’s been true of most of my life in industry.
Ashrafi:I also have the impression that funding was never an issue.
Conwell:Well, I mean, I’m a theoretician anyway, and I never asked for any equipment. So I was always, as far as research was concerned, cheap for them.
Ashrafi:How about any hiring of researchers? Did you have post-docs?
Conwell:Not back at GTE. I acquired post-docs at Xerox, but that was later on.
Ashrafi:How about the hiring of staff? Were you involved in hiring staff and having to argue for a position?
Conwell:Well, we didn't expect to be able to expand. I didn't. We weren’t encouraged to expand. I certainly— I mentioned the fact that the manager at GTE was ready to sweep people out. Well, I made a big thing of keeping the staff that we had at that stage, and was successful.
Ashrafi:I take it you felt more comfortable at Sylvania and GTE than you did at Bell Labs.
Conwell:Oh, very much so, yes.
Ashrafi:Were you still the only woman around?
Conwell:No. There was—well, I mean most who did research were still not women, but there were a couple more around. But I didn't think much about the disadvantages of being a woman there.
Ashrafi:Do you have children?
Conwell:I have one son.
Ashrafi:When was he born?
Ashrafi:’56, so that’s while you were at Sylvania.
Conwell:Yes. So we moved from Brooklyn to Bayside, which is where the labs were, bought a house there and we lived there until he was 17, which was his last year in high school. And then we moved because the labs imploded, and I had no more job there.
Ashrafi:Let me ask you about when he was born. Was Sylvania sufficiently unstructured that it wasn’t a problem to take time off?
Conwell:They really didn't know what to do with me, and in fact, I told them that I was planning to take three months off full time and come back part-time for a few months, and then full time. And they actually terminated my employment and re-hired me, which I think meant that it ultimately killed a lot of pension money.
Ashrafi:Is that right?
Conwell:Yeah, because it happened to be just a few months’ difference before I was eligible for a full pension and I didn't get that. But I must say, by the time I left, I didn't want anything from them anymore.
Ashrafi:Okay, so let’s step back now. So you were there for twenty years, but in 62 you go to Paris for a year.
Ashrafi:Can you tell me how that came about? Well, is there anything else in the first ten years we should talk about before we talk about Paris?
Conwell:I don’t think so. I met people and talked to people, published and so on, and they invited me to spend a year at the Ecole Normale Superieure in Paris. It was just before my son’s sixth birthday. His birthday is in September. And my husband was a writer then, those times, and so he was a portable husband, and we took off for Paris for a year. And I certainly enjoyed the year in Paris. I had to continue some work on a government contract that we had while we were there, but otherwise I was free to do whatever, and I taught a course one semester. My French isn’t too bad. I got the French medal in high school, but my spoken French is not as good as my written French. So I gave the first lecture in French, and I found that I could only think about the French, but not the physics, so I gave that up. They encouraged me to do it in English because the students had to go to the international conferences which were in English already. It was not much of a year, physics wise. That particular part of the Ecole Normale at that time was under Pierre Aigrain, who was well known in the physics community. A very bright guy. He had lots of good ideas, but he never was going to work any of them. He was also a politician. He was in the government. And, as someone else said, that particular part of the Ecole Normale was not an institute. It was a hotel for physicists, which is how it worked out for me. So I spent a lot of the year writing a book, which was a worthwhile enterprise, and in publishing some papers. I had one graduate student to collaborate with. Otherwise, no collaboration.
Ashrafi:So then you went back.
Conwell:I went back to…
Ashrafi:Okay. So you finished your year in Paris, you went back to GTE, and you had a different title, which was Manager of Physics Department.
Conwell:Yeah, but the responsibilities weren’t very different.
Ashrafi:So now we’re in your second period of time at GTE, from ’63 to ’72. And so what shall we talk about in this period? Did the structure change? Did the research change? Did the social arrangements change?
Conwell:Well, I’ve already summed it up; what I already said describes that period. The subject of my research changed. When we’re in there, I’ll have to look at the publication record to figure it out. So I’m looking for ’63 to ’72?
Conwell:Well, I’m still working on hot electrons for part of that time. I did something with ultrasonic waves and acoustics. Oh, yes, and then there was the Gunn effect, where hot electron people migrated to in that period, which I worked on for some years. And by ’72, people had started working on optical wave guides and such things, so I was working on that. I guess we’ll talk more about the research later.
Ashrafi:Sure, or we can do it as you like.
Conwell:Well, I think it’s easier to do that separately.
Ashrafi:Okay. So were you still working mostly alone? Did the number or nature of your collaborations change?
Conwell:Well, I think what I described before still applies. I’m still working with some of the experimental people and some of the theoretical people.
Ashrafi:How about the nature of your relationships with academic physicists? Did that change at all in these twenty years, or were you still basically considered academic physicist by others?
Conwell:I think that describes it, that I was still considered basically an academic physicist.
Ashrafi:Okay. So we could go on and talk about MIT, or we could…
Conwell:Oh, well, no. Let me, tell you about how that world ended. I guess GTE finally realized it wasn’t getting much out of these research labs, and they decided to give up their site in Bayside. The city had been moving out in that direction. Bayside had been a home for Hollywood actors and movies, somewhere along in the 1900s, and included the remains of estates like the Barrymore estate and so on. But the city was finally moving out that far. And the real estate that the lab was sitting on had become quite expensive. We used to joke about it, saying that when it got expensive enough, they would give up these research labs in Bayside. And whether it actually happened that way or not, I don’t know. They suddenly decided to cut the labs off. I had been at a conference on integrated optics in Las Vegas, and came home one Thursday night to be greeted by my husband with the news that the labs were moving. They decided to move up to Waltham, where GTE had a building. They announced the move on Monday of that week while I was away, and they announced who would be in charge of organizing the move in the different groups, and I was not in charge of any of that. To be in charge of the area I was in, they had picked a man who I had hired maybe a year before, from IBM, which impressed the local management because it was sort of man bites dog kind of thing, to be able to get somebody from IBM to come to Sylvania-GTE.
So I figured I was looking for a job, and I started out looking. Nobody said anything. I mean it was supposed to be a move, but in the move, they were going to select the people who would move with the labs, and I didn't see myself selected because I wasn’t part of organizing the move. And after a couple of weeks, the head of the labs, who I said had played football without a helmet, called me in and said of course they would want me to come up to Waltham as a consultant for him. I should give him as much time as I could spare. He understood, he said, that I couldn’t just move up to Waltham because I was married. He never asked me if I could move to Waltham. I think he was happy to get rid of me, because I had bucked him on the business of not firing everybody at the end of a project, and I had spoken up on other things, too. I think I just wasn’t popular. So I didn't say anything, but kept on looking for a job.
Well, you don’t manufacture a job quickly, but I wrote to, among other people, Millie Dresselhaus, and Millie saved me. She quickly arranged for a temporary chair at MIT, the one that she later occupied. I think it was for six months, not a year. And I went on working on integrated optics there and gave a lecture on it for the faculty, but kept on looking for a job. MIT was a good address to look for a job from.
Ashrafi:So this was from the beginning, a temporary position at MIT?
Conwell:Yes. It was intended for six months. She was very good to get it for me for the six months, because if I hadn’t gotten that, if I had really become unemployed, I don’t know whether I would have been able to work my way back in. In that period, I was interviewed by Xerox. I was interviewed first in the Palo Alto branch (PARC) but I think somebody there didn't like me, perhaps because I would be treading on his turf; he suggested the Rochester lab was the place for me, so I interviewed at the Rochester lab also and was hired. The time at Xerox was a very pleasant part of my work life. It started out as a particularly wonderful company to work for. It was when they were flush with money saying that our employees are first-class, they would send people to conferences with first-class reservations on airplanes, things like that. I think I was slightly after that time, but they had been doing that. I didn't go first-class, but I got to go to conferences, and there was the understanding that what we were doing was basic research although they wanted it to be in an area that was more or less relevant to their business. So I dropped integrated optics and I finished my last paper on that subject there. There was a new experimental effort started on glassy one-dimensional organic metals, and so I went into that.
Ashrafi:And this effort was started at Xerox?
Conwell:Well, at Xerox there was Art Epstein, who had really been one of the first people to work in that area. His Ph.D. thesis at the University of Pennsylvania was done on one of these quasi one-dimensional organics, and he worked with Schrieffer and Heiger. [Break]
Ashrafi:Now we’re back from lunch, and there were several things. First, is that you go by two names.
Ashrafi:One is Esther Conwell; the second is Esther Rothberg, which is your married name.
Conwell:Well, I sign my checks Esther Conwell Rothberg.
Ashrafi:Oh, I see, three names.
Conwell:Yes, and after I left Xerox, where I had been Esther Conwell for many years, I had to change my name to a hyphenated name, Esther Conwell-Rothberg, because checks and Social Security identified me as Esther Rothberg. I guess that’s where the difficulty started.
Ashrafi:And your son is Ellis Rothberg?
Ashrafi:Lewis, who is also faculty at Rochester in physics and chemistry. Okay.
Conwell:And chemical engineering.
Ashrafi:Well, very good.
Conwell:Well, he’s very good.
Ashrafi:Another issue you brought up during lunch was that you felt that women had been treated better in industry than in academia.
Conwell:Yes. Well. One thing I can say is I’d really never gotten a real offer from a University, including this one. When we get to that, I had been associated with a science and technology center. Should we get to that now? I mean, that’s well past 1972.
Ashrafi:But I wonder if you can share what you mean in general about women being treated better in industry, and for women physicists, are there any general observations that you can make at this point?
Conwell:Well, they just don’t seem to make any big distinctions. I mean, women are particularly, I guess talented women seem to be getting more what they deserve in industry. They’re promoted. People like Cherry Murray could be a Vice President at Bell Labs. It’s well documented in academia that the women are hired less as assistant professors, promoted more slowly, paid less, get less labspace, and everybody knows that. But these things don’t seem to happen in industry. Maybe they’re getting these very talented women, particularly in industry. I don’t know why, but you seem to get more of what you deserve. Now, I’m talking about the Ph.D. level now, the professional levels. I have been, in the past, a member of committees in the government, or associated with the government on Women in Industry and Women in Physics and so on, and we had a conference on women in industry. Well, the subtitle was, “Why so few?” And some industries or some companies really do not treat women at all well. I mean they really get a much worse deal than the men, and that might be true in engineering companies. It might be more likely to be true in engineering companies. But in the really professional company, they seem to be—maybe there’s more fear of government looking for discrimination, and maybe they feel that women have more of a backup that way. But they are much more likely to get what they deserve, what they have earned. I don’t think I could elaborate further on this.
Ashrafi:The third thing you mentioned that sounded interesting, was that you think there’s a physicist personality, and that you have it.
Conwell:Yes. I think so. I think my son has it, too.
Ashrafi:What does he have? How does that manifest itself?
Conwell:Well, I guess it’s easier to talk about him than about me. My son has a dry sense of humor and the jokes are liable—I mean not telling actual jokes, but the witticisms—are liable to be typical physics ones rather than general. You’re putting me on the spot, because I’m a physics person. I haven’t tried to rationalize it, but “I know it when I see it,” the old expression.
Ashrafi:Yes. Is there something else that you mentioned during lunch that we should get on tape?
Conwell:On the subject of women in academia, I would say I have never gotten a reasonable offer of a job from a university, and I’ve had a good reputation for some time. I’m a member of both academies, for instance. So that says something; that I spent my life in industry.
Ashrafi:So shall we go back to the story?
Ashrafi:Now how did you find, oh, you interviewed both at Palo Alto Xerox, and at Rochester Xerox, and…?
Conwell:And ended up here, in the Rochester Xerox.
Ashrafi:And you were telling me about some work about Schrieffer and his collaborators.
Conwell:Oh, yes. The field that I went into after a few months at Xerox, was glassy one-dimensional organic conductors. Schrieffer was one of the people who had an original interest in this. One of the things that started people in it was the Peierls transition, which is a metal-insulator transition that occurs in many of these one-dimensional materials, so that they are semi-conductors at low temperatures and metallic above. I guess this is something that theorists are always interested in. The poster child of the field for quite a number of years here was polyacetylene, which is just a series of carbons and hydrogens. Each polyacetylene chain is such a series. The paper that I referred to by Su Schrieffer and Heiger, was on the physics of this material and the kind of state it would support for an excess electron or a hole. These states are extended. If you put an electron on a polyacetylene chain it’s extended over a number of sites, and is a kind of polaron. It is a, I say it’s a large polaron because it’s extended over a number of sites. There are small polarons, which are polarons by virtue of polarizing the lattice around them in the usual way. Those were worked on for years, in the alkali Lalides, for instance. In polyacetylene the electron digs itself a potential hole by distorting the chain that it’s on over a number of sites, and that’s what a polaron is, in that case. When it came to DNA, my first idea was that if you put an electron on a DNA—well, the DNA has an outer helix, and inside there is a series of bases along the axis of the helix—and the extra electron, or hole, would sit on the bases. And my first idea was, “Well, it will be just like an electron on polyacetylene, one of these conducting polymers; it will dig itself a hole, an energy hole or a bound state by distorting the spacing of the bases around it. We wrote a few papers on that idea, but finally realized, and this has been substantiated by more calculations and by experiments, that there isn’t a distortion around the hole or electron in DNA. The polaron results from the hole or electron polarizing the water. The DNA chain is floating in water and ions, and there’s a lot to polarize there. The excess charge can dig itself quite a deep hole by polarizing the surroundings. So that’s what we’ve been working on more recently.
To go back to conducting polymers, they started out as a physics interest. They’re all chains and you don’t usually have single crystals. You might, with great effort achieve one. But then somebody discovered quite by accident, serendipity, that these things radiated a lot of light when they were properly stimulated, which could be by an electric field or fluorescence or luminescence. And since then, a lot of people are in that business, figuring that this going to be another way of getting TV on the wall. The conducting polymers have advantages because they don’t have to be single crystals and they’re flexible, like Saran Wrap. So there’s a lot of work on that now. I was there at Xerox when this optical discovery was made, so I was working on optical properties with these materials also, and what happens when they’re excited by light, excimers and things like that.
Ashrafi:So now that we’re talking about Xerox now and you have your GTE-Sylvania experience, how does the relationship between research and development at Xerox differ?
Conwell:Ah, yes. This is another thing I want to tell you. When I first joined Xerox, as I told you, it was flush with money. The copier, the 914, the first big copier, had made a tremendous hit. They didn't know what to do with their money, there was so much coming in. So they felt they could afford basic research, and they really started out funding basic research. They did not insist on a connection with any product. And in Palo Alto, they started PARC, which can legitimately be said to have invented a lot of the computer as we see it now.
That was their basic research. The basic research in the Rochester lab was more associated with xerography. There’s a lot of physics to do there to understand how it works and transport is an important part of it. When you make your latent image with light on the surface of the photoconductor, you have to have transport to get that image to be registered elsewhere. So that was an important subject for research. Xerography started out using selenium, but they have since used other materials, so there was a lot of materials research that you could do there. Even something that wasn’t directly related to a product in a particular Xerox machine could be of general relevance to Xerox.
Ashrafi:How did the scientists in your group who might be doing various kinds of physics research, how did they come to know it would be good research for Xerox’s business? How was that communicated, or was it?
Conwell:Pretty directly. Well, I mean people were taught about invention proposals, IPs and writing in notebooks, and things like that.
Ashrafi:What were they taught?
Conwell:Well, they were given a notebook in which to write.
Ashrafi:What happened to that notebook after they were done with it?
Conwell:I guess it belonged to the company.
Ashrafi:Did they have some system for retrieving them from scientists and storing them and referencing them in the future?
Conwell:I don’t know if that was so important. The important thing was to make sure that you applied for patents when it was appropriate to do so. So the procedure was, if you thought you had an idea that would lead to a device or an improvement in a Xerox machine of some kind, you wrote up what you call an “IP”, an invention proposal, and there was a committee delegated to look at these and decide which of them were worth pursuing, whether they needed more work or whether they could be immediately used to apply for a patent. And so you found out quickly and what you needed and what was necessary to apply for a patent. And as I say, even I have a few patents. So I learned about that.
Ashrafi:This is Tape 3 of the interview with Esther Conwell on January 22nd, 2007. You were saying that at Xerox there were different parts of the lab, and they were treated differently.
Conwell:There were some parts that worked directly on the machines and were, as they put it, “putting out fires” all the time. Say, if some particular part wasn’t functioning well, on a lot of machines, then they went after that, not necessarily in any deep or basic way. But there was another group which had the responsibility of digging more deeply, to find out what caused these failures. People went back and forth from one group to another, to some extent, in the spectrum of capabilities and interests.
Ashrafi:So there were three parts to the lab? You said there was “blue sky,” one “putting out fires,” and one “thinking more deeply about.”
Conwell:Oh, yeah, they had different managers.
Ashrafi:So can you tell me what the structure of the lab was?
Conwell:[chuckles]. I have to admit to having been indifferent to organizations and hierarchies and whatnots, all my life. I suppose I said that I—well, I duly place no value on management [chuckles].
Ashrafi:So for your group, how were research priorities decided on? Was it really an individual choice?
Conwell:When I started there, it was completely individual choice. As the years went by, money got scarcer, and there weren’t as many people. By the time I left, I was actually asked to think about conduction in carbon, you know, a mess of carbon. That I do remember. I mean, they were asking me to do something a lot more practical than they had been, but there was good, basic physics involved in it, too, and it was an interesting problem to think about. There had been a couple of reorganizations along the way where each time there were fewer and fewer research people left, fewer Blue Sky people left, because the company profits just didn't continue to grow. When I joined the company, they were giving options to people at my level, and the stock was 170. And I remember my son, who was a rotten teenager then, 17, 18, saying, “That’s the end of that stock,” meaning that once I joined the company, the stock was going to go down. And that was absolutely prophetic. It just went all the way down to where it’s been, I don’t know, 15 or 16. I think it’s up to 16 now, having been 14 for years. I never got to exercise that option. They did subsequently give me options at better prices, but I didn't get rich on options.
Ashrafi:So your experience in the, let’s see, you were there from ’81 to ’90, roughly, and I’m sorry—no, from ’72.
Conwell:Oh, no. I was there from ’72 to ’98.
Ashrafi:Oh, to ’98. Okay. And your experience there was that it was reorganized to tie research more closely to development.
Conwell:Ultimately. It was a long time before that happened, but ultimately—Well I remember Charlie Duke saying to me—Charlie Duke was my boss a lot of the time there, a great boss. He did a lot for me. He got me a post-doc—uh, I remember him saying that there was going to be another reorganization, and that I was likely to end up in a business organization where I wouldn’t know what to do and they wouldn’t know what to do with me. So it was time to leave, and I left. Of course, by then I was well over 70. There was no compulsory retirement.
Ashrafi:What about your relationship with the academic physicists? How were these physicists…
Conwell:Well, again, there was no distinction drawn. And even at the stage where I was asked to do research on conduction in carbon, these were not single crystals, I mean, polycrystalline carbon. If I had found something fundamental, I could have gone to a meeting, talked about it, published it, like anyone from a university. So there was still no basic distinction, and this was true, even of people who were working fairly close to what went on in the Xerox machine. A lot of them, had to be more careful about getting clearance to give papers outside or publish their results, but a lot of the time, they got it.
Ashrafi:Okay. What was it like being a woman at Xerox?
Conwell:Oh. That didn't seem to be a disadvantage. It really didn't. In fact, they were very good about women. I mean that was one of the companies who were good about maternity leave and letting people come back after a leave of absence. They were notable for being good about women. A number of companies were cited that way; when I was in one of these committees and we had a symposium on women in industry. It’s interesting that people were not sure about IBM being good to women, but Xerox came through well. And Corning had very good credentials—I mean they really took affirmative action to heart. They had compulsory classes which the men had to attend, as well as the women. One thing they did was have actors come in and show how the women were being discriminated against in subtle ways. Corning had a lot of good measures. I gave a number of talks on them, and I believe I have the slides somewhere.
Ashrafi:They’re on the web. One of your talks is on the web, with the transcript and the slides. In fact, I printed it out.
Conwell:I never went to that website that I told you to go to [chuckles].
Ashrafi:It’s, “Esther Conwell, Woman Physicists in Industry, the Five Slides.”
Ashrafi:Did I write down the URL? No, but I found it in Google. Let’s see. So how should we break up? This is a long period, now. Were you always in this one position at Xerox? Were you promoted to different positions?
Conwell:Oh, yes. I was promoted. I never had any administrative responsibilities there, which was okay with me. Well, I shouldn’t say that. I really did. I was manager of what was called, “The Electro-Optics” program, ’75 to ’77. It was not a long-lived program. They weren’t really interested in putting resources into it. But I was promoted. Eventually I became a research fellow, which was the highest non-management type rank and a privileged position.
Ashrafi:Did your role in setting research priorities for the lab change, or shall we always think of it as basically individual until the end, when they started asking you to do just specific problems?
Conwell:I, to some extent, collaborated with Art Epstein in his work, and I wrote, well, I had review articles covering many other people’s work. But those were published in, you know, Springer books, ect . I was basically an individual contributor. We were not encouraged to go for government money. That’s probably changed. Charlie (Duke) insisted that Xerox should support us in the style to which we had become accustomed, and they did in my case. I mean, like they were probably nicer to me than to the average, because of being a member of the Academies, which they appreciated. They felt that it was good for the reputation of the laboratories, good for hiring new people. think it was basically an individual contributor stuff.
Ashrafi:Did you get government money when you were at Sylvania-GTE?
Conwell:Yes, we did have some. I remember, well I mentioned that I was doing some work on a government contract when I was in Paris, still. I had a contract on microwaves.
Ashrafi:This is NSF, or?
Conwell:Yes. It was NSF. I think it was part of the engineering directorate at NSF.
Ashrafi:And then I wrote down, I think you became an Adjunct at Rochester, in ’90?
Ashrafi:You also mentioned a post-doc.
Conwell:Yes. I had a series of good post-docs, which Xerox recorded as members of the technical staff and with salaries commensurate with their experience, but they worked with me, predominately, and there was some good work coming out of that. A couple of them went on to accept jobs at Xerox doing much more applied work, ultimately, and they made good employees. Xerox still has them, making good use of them. One of them is now a professor at UT-Dallas, a very good physicist. One was a woman, she was supported by NSF. By that time, the University of Rochester invited Kodak and Xerox, to join them in a science and technology center, and actually got one that lasted ten years. It was called the Center for Photo-induced Change Transfer. I didn't appreciate it enough at the time. It started in the chemistry department, and they didn't really have many physics people in there. What impressed NSF was this blending of work of the University and Xerox and Kodak. They thought that this was going to lead to products being generated in the Center that Xerox and Kodak could manufacture. But ultimately they were disappointed, because it was not a realistic goal. By then, the companies, Xerox and Kodak, were so much less profitable that they could not afford to really launch a big, new product or big, new research area to make a new product, if we came up with such a thing. So it was mostly academic research for the ten years, and I somehow was in at the beginning of the Center and played an active role, ending up on the Executive Board, an associate director of the Center. And since it was still associated with the chemistry department, I had an office in the chemistry department. The center had space assigned to it. They built new space for it on the second floor of Hutchison Hall. When I left Xerox, it was natural to come here. The Center was still on at that stage, and at that stage I still had post-docs, but they were being supported by the NSF center.
Ashrafi:Mm-hmm [yes]. What was it that you didn't appreciate sufficiently at the time?
Conwell:Well, I haven’t been able to get any money on my own. I can’t say that I’ve tried very hard. I wrote two or three proposals, and that was all. But I was pretty soured by the fact that I sent in a proposal on transport in DNA, and the first time I made a mistake in sending it to the biology section of NSF. Well, they did actually, in some sense, share it with the solid state area, but when it was rejected, they said, “This is not biology.” And NSF talks about being interdisciplinary, but it’s baloney, as far as I was concerned. We put in a couple of other proposals, interdisciplinary, on the biophysics, DNA, and transport, but no money. So I don’t have any graduate students. In fact, the chemistry department wouldn’t even let me have any graduate students. The physics department would.
As it happens, somehow I’ve been able to get papers out, anyway, not as many as I would have if I had a post-doc. Two years ago, it was brought to my attention that the Dreyfus Foundation, which likes to support chemists—they support assistant professors and all sorts of chemical activity—was going to support a mentor for undergraduate research in chemistry. The chemistry department urged me to put in a proposal, so I did get $10,000 a year for two years. The money was to go to the undergraduates, not me. They got paid for the time they put in. I had three undergraduates, an average of three for the two years, and those kids did the calculations for the papers. We had one paper published, with one of these kids, J. Phys. Chem, and we just sent a paper in to JACS with two of those kids doing the calculations. The calculations were not trivial. They were solving the Schrodinger equation, for a case where the chargeon the DNA was interacting with water, and determining the resulting transport. First we found the wave functions, which depend on the sequence of bases, adenime, thymine, quinine and cytosine; One of our papers was about the eloquence dependence.
Ashrafi:What should we say more about Xerox? That’s from ’72 to ’98. Is there anything else we should say before we move on to your leaving Xerox for Rochester?
Conwell:Well, the one thing that you might say is that I felt a new freedom in leaving there. I would never have gotten away with working on DNA at Xerox. But once I was here, I could do anything. Somehow, there had begun to be experiments on transport of excess electrons or holes in DNA. And after the first experiments, Jackie Barton at Caltech interpreted them by saying that DNA is a great conductor, and so people flocked into the area in large numbers. It turns out that DNA is not a great conductor. But there is conduction. However, a lot of people didn't find any conduction. If you measure a long DNA, it’s an insulator. But if you can get a shorter piece and do the experiments properly, you will get conduction. With some sequences, it’s not too bad. But it was a hot area for a while, and I enjoyed it. Now it’s cooled off a lot. The problem is difficult, very difficult to do experiments. But there are still some experiments, and there are still calculations important to do. I’m still enjoying it.
Ashrafi:So you left Xerox because of Charlie Duke’s suggestion that it was time to leave.
Conwell:It was time to leave. Charlie is gone now, too.
Ashrafi:I’m interviewing him tomorrow.
Conwell:I thought he had already done it for this series.
Ashrafi:There’s a question set interview, but not this kind of long biographical interview.
Ashrafi:Yes. So you were already Adjunct at Rochester.
Conwell:I wasn’t Adjunct, because that title is reserved for someone who has a job elsewhere.
Ashrafi:And so you came, and are associated with the chemistry department.
Ashrafi:And now, you’re associated also with the physics department. Is that right?
Conwell:Yes, but I end up, doing my own work. I occasionally give a seminar. The head of the physics department, which is much more forward-looking, I think, than the chemistry department, did ask if I was interested in teaching a course in bio-physics, and I may do that yet, but that would be in the physics department. I’m thinking about it.
Ashrafi:So how did it come to be that in 2003, after you’d been at the chemistry department for five years already, you were appointed to the physics department, as well?
Conwell:Appointed to the physics?
Ashrafi:Yes, you have a dual appointment?
Conwell:Yes. I have a dual appointment.
Ashrafi:Yes. How did that come about?
Conwell:Well, the physics department, under this chairman, decided to be inclusive, and bring in physicists who were sprinkled throughout various departments. So they brought them in a few at a time. That’s how, Lewis my son (who is a professor in the chemistry department) became a member of the physics department, then I.—It was their decision, totally. I mean I would have felt more at home in a physics department to begin with, but since I was already on the executive board, and the Center was still running, and I was coming here anyway for the Center, and I had the post-doc here, the chemistry department was the natural place to go
Ashrafi:What else should we talk about?
Conwell:Well, we haven’t talked about my research.
Conwell:I have enjoyed working with these undergraduates much more than I expected to.
Ashrafi:Now you’re talking about the Dreyfus Foundation program.
Conwell:Yes, there, mentoring undergraduates. A couple of these kids have been very eager, and research has been a magic word. They work very hard on some aspects, particularly the numerical work. The reward of their names on the papers has really motivated them.
Ashrafi:Yeah, I can imagine.
Conwell:The money does not amount to much. Still it paid for a couple of students in the REU Research for Undergraduates.
Ashrafi:Now, REU, does that refer specifically to NSF?
Conwell:I think so. I think that’s where the money comes from.
Ashrafi:So Dreyfus is a separate thing?
Conwell:Oh, that’s a separate foundation, yes. I paid Dreyfus money to the NSF for these students’ housing and meals, and whatnot during the summer. NSF is willing to support them. It makes some sense. I mean, if you’re worried about whether anybody is going to go into physics or chemistry anymore, this is one way of hooking them.
Ashrafi:You’re saying that there’s a problem with getting people to go into physics or chemistry?
Conwell:Well, I think there is, and there are certainly fewer in physics and chemistry. I don’t have the proper statistics.
Ashrafi:Shall we talk about your research?
Conwell:Okay. You have the full list of references. You will find that these references are organized; I separated out invited review and survey articles first, and then the papers in journals with peer review.
Ashrafi:So we’ll attach your CV and list of publications to the interview.
Conwell:The first full paper is in 1948.
Ashrafi:This is with Chandrasekhar?
Conwell:Yeah. And this Theory of Impurity Scattering is with Weisskopf. And then there’s a series of papers on hot electrons. I think I told you that—well, I don’t know whether Shockley started it, but he did some of the early work on hot electrons. There’s important work in it, on the changes in transport when the average energy of the electrons is higher than thermal energy as a result of applying a high enough electric field to heat up the electrons. I don’t know if you’re familiar with this kind of thing.
Ashrafi:Not in detail, no.
Conwell:Oh. This effect obviously could be very important in transport, because when the electrons are moving faster, you get more collisions or fewer collisions per unit time, depending on what the scattering mechanism is, and obviously it has an important effect on how fast the electrons get to where we want them to go. But we did a lot of other things; we looked at how other properties were affected. Shockley hadn’t, in this early work, considered the optical modes of vibration properly. He had considered the vibrations that scatter the electrons as being only the ones like acoustic waves with long wave lengths. But there are two atoms in a unit cell in germanium and silicon, and the vibrations of these atoms, relative to each other, repeated from one unit cell to the next, called “Optical modes have a very important effect in scattering electrons. I was one of the first people who incorporated that into the theory.
And then the high frequency conductivity, AC conductivity and the dielectric constant are affected by having hot electrons, because when they move faster there is a shorter or longer time between collisions and that effects how they can respond to a high frequency electric field. It also affects their contributions to the dielectric constant, which is a matter of their falling behind the electric field and contributing to the displacement current. So we were after effects like that.
Some of the early papers are the basic papers on the electric properties of germanium, which included a little of the scattering, and how the carrier concentration varied with temperature. Recombination of excess carriers has an important effect. It is important how long they last after you create them by exciting the sample with light. And if you are in a high electric field, they recombine faster or slower, depending on what the detailed processes are. So we did calculations of the recombination rate as a function of field collaborating with an experimentalist who make measurements of the recombination rate.
Ashrafi:This is all at Sylvania, now?
Conwell:Yes. When you don’t excite the electrons, you have a distribution of phonon lattice vibrations of acoustic modes and optical modes that interact with the electrons. In the higher electric field, if you’re going to ultimately come to some kind of steady state, the electrons have to be able to get rid of the energy you’re feeding into them with the field, and they do that by emitting phonons. Thus in making hot elections, you disturb the phonon distribution and this in turn affects the electron distribution, you disturb the phonon distribution. We did a number of papers on that.
Then there was gallium arsenide. Gallium arsenide, is like germanium or silicon in that, on average, there are four electrons in the outermost shell. When you make a material consisting of gallium and arsenic you’re mixing something with three outermost electrons with something having five outermost electrons. And so in some respects, they act like germanium or silicon with the four outermost electrons. One of the things that people found in gallium arsenide was the Gunn effect oscillations when you apply a DC field. Usually when you increase the voltage, on a material, including gallium arsenide, the current increases. But in the case of gallium arsenide you get to some point where a further increase in voltage causes a current decrease, or negative differential conductivity, and that’s an interesting phenomenon. That gives rise to oscillations, and lots of other effects. So I spent some time on this, a few papers and a review paper.
Ashrafi:This is when, now?
Conwell:It’s still at the GTE-Sylvania. This is still semiconductors. Then around that time, people started working on optical rays and wave guides.
Ashrafi:This is before you went to Xerox, or…?
Conwell:Well, I ended up still doing some of that when I went to Xerox, but mostly it was before.
Ashrafi:Did you want to finish your tea before we started talking again?
Conwell:No. It was too hot to drink, anyway. There are a lot of papers, here.
Ashrafi:We’ve got 200 or so, now.
Conwell:Yes, but just the ones that were for here. I’m scanning a lot of them. Yes. So you can get light waves traveling in quite different ways if you have an inhomogeneous medium in which you have regions of high dielectric constant and low dielectric constant. Such media can act as guides, wave guides for the light waves, light with low index regions being reflected by the high index regions. There is a lot of theoretical work that can be done here, and I ended up calculating a three-dimensional optical wave guide. And that was, as I said before, what I was working on at MIT and the Xerox. Bloembergen was working in that area. He was one of the people that started this. And he had done such experiments.
Yeah, one of the things that I did, was to study the consequences of not having a perfect arrangement of the atoms. It is important to not have a perfect arrangement if you want good conductivity in germanium and silicon. You have to put in impurities. If you put a arsenic into the place of a germanium or a silicon atom, it has an extra electron, outside closed shells. And that last electron in a medium of high dielectric constant is loosely bound to the core and easily detached, and that’s where you get carriers from, the carriers that you need in the semiconductors. And of course, when they leave the core behind, it’s positively charged, and that gives you the impurity scattering, which is what I cut my teeth on.
By this time, I’m at Xerox. And our favorite one-dimensional, quasi-one-dimensional conductor was abbreviated, TTF-TCNQ, which is tetrathiafulralene tetracyanoquinodimethane. You didn't really have to understand all the details of the structure. Art Epstein was measuring electrical conductivity of these things. Now these things were metals at high temperature and semiconductors at low temperatures, that would be correct, due to a distortion in the lattice. Do you know what a Brillouin zone is?
Conwell:Oh, okay. Well, the Peierls distortion made the two atoms in a unit cell move together. When you change the spacing, you change the Brillouin zone and thus you change the filling of the Brillouin zone. And where you had a half-filled band, a gap opens up at the half-filled band energy and you now have a semiconductor. With one filled band and a vacant band. I did a lot of calculations for this type of material. Art Epstein was measuring conductivity. He had calculated thermoelectric power.
Oh, yes. I got into a big controversy about the temperature dependence of the conduction at temperatures above the Peierls transition in these quasi-one-dimensional materials. They can be made into good crystals, so you could talk about optical modes and acoustic mode. I was fighting with some Israelis, and I think we provided the conference entertainment for a few conferences, arguing about the origin of the temperature T dependence. The conductivity was found to decrease as T-squared with increasing temperature, instead of T as it would in an ordinary metal. And these guys were insisting that for some reason, the electron was interacting with two phonons at a time. A one phonon interaction would give you the T dependence, and the two phonon interaction would give you a T-squared. It was many years ago, 1980, we were having these fights. Well, I guess almost 30 years.
So this was what I was working on. But finally we established that they were not right about the two phonons. I collaborated with a very nice Dutchman, who had made some relevant measurements and I did some theory that confirmed that the two-phonon idea was wrong. So I won one. It turned out that some of these underwent the Peierls transition, ending up sort of like gallium arsenide at low temperatures, below the Peierls transition temperature. This meant they had a very high mobility, a small gap but a high mobility. You know what I mean by “mobility.”
Ashrafi:You mean, for the charge.
Conwell:For the charges, yes. It’s the drift velocity a change develops for unit electric fields. It’s like how mobile they are, how well they move. And so at low temperatures, they got a high enough mobility so that you could apply a high enough electric field to raise the average temperature of the electrons above that of the lattice, which is set by the room temperature mostly. In ordinary conduction, it’s not too high a field. You do have to raise the temperature of the lattice slightly, so that it emits more phonons than it absorbs in order to get a steady state. But in gallium arsenide, even to some extent if you go to very high fields in silicon, and then in some of these quasi one-dimensional organic crystals, you’ve got very high mobility. So I worked on the theory of what would happen at high fields in the quasi one-dimensional organic crystals. I don't think anybody ever really did the experiments.
There’s a lot of stuff in here [looking through papers].
Ashrafi:Okay, there were a very basic tools that you applied. One was the Conwell-Weisskopf scattering type work that you did, and some of the ones that you described were more scatterings studies.
Conwell:Yes. Well, there’s huge detail to the scattering because there were so many things that can be different, even if you don’t have hot electrons. In different temperature ranges, different scattering mechanisms can be dominant. In semiconductors impurity scattering is dominant, of course, at low temperatures. As you go up in temperature, acoustic mode scattering gets important, because those phonons can have quite small emergies. So the electrons, even in a low field, can absorb and emit them easily. And then at still higher temperatures, optical phonons, which have larger energy because they’re opposed vibrations of the two atoms in the unit cell, become important.
So there are lots of different regions. Then there are differences in the scatterings when they’re random, just because the randomness. A lot of people will be measuring and calculating conduction forever as new materials come up and different phenomena, or different phonons become important, or different randomness becomes important. It’s a bottomless well.
Have you seen the page I’ve got? The years are numbered. Gee, somebody goofed in not numbering pages. There are also differences in transport when you don’t have a nice, localized electron, but the wave function is spread out, and it can be spread out in different ways. I mentioned polarons. That’s a fairly universal kind of thing. But in the polymers there’s an entity called solitons. They are discussed in that paper by Su Schieffer and Heiger that I refered to. They do involve a lattice distortion, but it’s not simply continuous, the soliton is compared to a domain wall.
Ashrafi:Are there one or two particular things that you want to mention, rather than going through the entire list?
Conwell:Well, I mentioned impurity band conduction. Yes. When you have, say, arsenic in germanium or silicon, and you get the electrons coming off, the fifth electron on the arsenic coming off at high temperature, there are changes in the band structure that result because these electrons can have a lower energy than where the band was, where the bottom of the conduction band was. And at low enough temperature, they will go into the levels where they feel the charges, the impurities more, and therefore have a lower energy. And in fact, you can imagine, people calculate a tail on the density of states. Instead of just ending at the band edge, there are these states of lower energy, and an electron that happens to be in a region where there are a lot of impurities around is going to have a very low energy. And you can get conduction in those levels also, which will be different from the conduction in the usual band levels, because the wave function is quite irregular. So that’s called impurity band conduction, and I did some of the early work on that, of some importance.
I’d like to mention our latest work on DNA. In the paper I referred to earlier we simplified the calculations by assuming that DNA had only one chain of bases inside the double helix. In the next paper we improved the model to accommodate two chains of bases inside the double helix, as in DNA inside our bodies. The most important feature of our calculations is that the wave function of the extra electron or hole was assumed to be spread out over a number of bases rather than localized on a single base. I think most chemists still believe that the wave functions are limited to one base, and it will take time—more experiments and theoretical work—to convince them otherwise, which I believe will eventually happen. Well, I guess not too many people continue into their 80s. I remember seeing Pauling at an Academy meeting when he was in his early 90s. And he sounded, you know, like a young man. He was really on top of it all, mixing in the debate and whatnot. But he died a few years later. I think people should be encouraged if they want to continue working in such old age. I can’t work at the pace that I used to. I can’t put in that many hours a week. I’m probably down to a 40-hour week, which would not buy you very much as a usual working physicist. I’m sure you know that. But it’s still enjoyable, and I think I’m still doing useful work. The work gets lots of references, even though not everybody is willing to believe in polarons in DNA. I think I will win this fight, but it may take some years. People aren’t doing the experiments fast enough.
I imagine that it gets harder and harder to get support in your old age, I mean to get grants in your old age. I have to believe that some of the reason why I didn't get funded was they figured, “Well, there is no future there.” So that makes it tough. But I guess I will rely on undergraduates in the future, because if you get a bright undergraduate, it could be better than some of the graduate students.
I think that’s about it.
And this last paper, we improved the model so that we had the two chains—there are two chains at stake, duplexed. So the first paper we had calculated that they were one chain at the center of the helix, and the wave functions, the polaron is spread out along the one chain. And most of the chemists still believe that the way functions is limited to one base, that it cannot spread out, that it’s not de-localized, and it is hard to sway them in this new idea.