Interview: Maki Kawai
2016 Welch Award Recipient
Interviewed by Michael Trenary, 2019
TRENARY: Today is May 24, 2019 and I’m Mike Trenary, representing AVS. With me today is Maki Kawai, who won the 2016 Welch Award of AVS. Her citation read, “For elucidation of the role of vibrational dynamics in single-molecule reactions at surfaces.” We are meeting on the Wako Campus of RIKEN, where you spent many years as a researcher and administrator. You are now serving as director of the Institute for Molecular Science in Okazaki. I know you come from a family of distinguished academics. Can you tell me a little bit about your grandparents and parents?
KAWAI: I think I will talk about my grandfather. (Laugh) He was a quite famous mathematician, and he spent several years in Germany where he met Hilbert, and he became a member of Hilbert’s group. That experience led to his obtaining a prestigious position as a mathematics professor after coming back to Japan. I also heard that he served as chairperson of the ceremony of the first Fields Award, which is the most prestigious award in mathematics. This means he was a little bit older than the first people who were awarded, but he was one of the people who made this system work. I met my grandfather several times, of course, but he passed away when I was nine years old. So, my memory of my grandfather is of an old man and I do not have many memories of communicating with him as an adult, or of being advised by him.
TRENARY: I see. He was a professor at the University of Tokyo?
KAWAI: Yes.
TRENARY: And, as I recall, there’s a statue of him at the Komaba campus?
KAWAI: Yes. But, I think that was made a little bit later. What surprised me a lot is that when I had a chance to be in Boston and I had a little time and visited the Science Museum, and there is a sort of timetable for science, and especially in mathematics, and in the very beginning of this table my grandfather’s name is there. And so, I realized at that point that he was actually quite an important person in the world of mathematics.
TRENARY: And his name was Takagi, right?
KAWAI: Yes. Teiji Takagi. Takagi is my maiden name.
TRENARY: And were your parents also academics?
KAWAI: Yes. My parents were in the physics department, but they were both in crystallography. My father was a theoretician and my mother was an experimental physicist.
TRENARY: I see. As a child, were you interested in pursuing a career in science?
KAWAI: Not seriously. (Laugh) I did not think of myself as being a scientist until I became a scientist, actually. But there was no hesitation for me because there were several people surrounding me who were scholars, and so that was a natural way that I thought of doing it after finishing graduate school.
TRENARY: Did you go to a typical public high school?
KAWAI: Until junior high school I was in the normal schools, meaning that they weren’t special. The Japanese, as you may know, are very serious about getting into and pushing the children to the higher universities.
TRENARY: Right.
KAWAI: And so, if the parents are very serious about education, educating their child or children, they put them in a very famous primary school and things like that. My father had a very unique way of thinking, that for a person to be normal they should experience the average system and a variety of people. He firmly believed that his child, or children, should attend a normal public school, and that’s the way it was for me. I went to a quite famous high school, but before that I had not only high-class friends, but there were many people who were, you know, more normal.
TRENARY: You were admitted to the University of Tokyo, and I know that’s a very competitive process. Was it a fair process for women and men?
KAWAI: Yes. Completely fair. So, there was nothing to worry about. You just have to be able to get through the exam.
TRENARY: As an undergraduate, did you do any research?
KAWAI: Not until the final year. Meaning, until six months before graduation, we do not touch any specific research. So, in the last half year, we were guided to a certain lab, which happened to be Professor Kenji Tamaru’s lab, famous for catalysis research. So that was how I got into a specific type of surface science.
TRENARY: Right. As an undergraduate?
KAWAI: In the final half-year.
TRENARY: He was your Ph.D. advisor, too?
KAWAI: Exactly.
TRENARY: So, tell me a little bit about Tamaru and his research group, and what he was like as a mentor.
KAWAI: Tamaru, not only Kenji Tamaru, but his father, Setsuro Tamaru, was a famous scholar in catalysis. Setsuro Tamaru worked for Fritz Haber, in Berlin. So catalysis was sort of their family business. For example, the ammonia synthesis reaction.
It was a very interesting thing. And so Professor Tamaru led me to be in his area of science. It’s like not, say, telling us the details of something, but he suggested to me in a way that infrared spectroscopy is a very interesting tool to elucidate the molecules on surfaces. And, in his lab there were several females, or girl students, and they were all involved in this infrared business. And I did not want to do it.
TRENARY: Oh? You didn’t want to do infrared?
KAWAI: Actually, I did not know many things about surface science when I entered this lab, but I had some impression that some of the electron diffraction techniques gave, at that time, a very new knowledge about the order of surface systems. And because my father and mother were crystallographers, I was attracted to electron diffraction.
TRENARY: Oh, they were crystallographers?
KAWAI: Yes. So I sometimes had the chance to listen to what they were talking about with their friends or their colleagues, who visited my house, and then I caught some of the words like that. And so I thought it would be interesting and so I wanted to do some work like that. But Tamaru did not want me to go in that direction but into vibrational spectroscopy. After all, that was a good idea, finally. (Laugh)
TRENARY: It’s been a big part of your career.
KAWAI: Exactly. He gave me one actual catalysis system and that was NOx. It was in the mid ‘70s. It was a serious problem. The problem that he gave me was the use of ammonia for reducing NOx, and the effect of oxygen on the reaction over a vanadium pentoxide catalyst. I did my best to identify the adsorbates and how they react, etcetera. My first publication was on this. I found that two species exist in the reaction pathways, ammonium [NH4+], and nitrogen dioxide, NO2. These two were involved in the reaction path, and that detecting them was possible because I could use infrared spectroscopy and confirm the sort of species on the surfaces.
TRENARY: Great.
KAWAI: So, that was quite successful.
TRENARY: I believe you met your future husband then, when you were in graduate school?
KAWAI: Exactly.
TRENARY: Was he also in the Tamaru group?
KAWAI: Right. He was an actual supervisor for the reaction that I just talked about.
TRENARY: In your first publications, your name is listed as Maki Takagi Kawai. Some young women take their husband’s names and some do not.
KAWAI: Uhm-hmm.
TRENARY: Do you think that had any impact in your career? I mean, in terms of citations and things like that? Do you have any recommendations for young women about such things?
KAWAI: For myself, I didn’t think about it. Actually my first paper is under my maiden name, so it’s Maki Takagi. But I think for the second or third one, I just switched to my husband’s family name. I did not think so seriously about it. But now I cannot go back to my maiden name.
TRENARY: Of course.
KAWAI: So, that’s a good thing. (Laughter) Yeah. I have no serious suggestion. Whatever name you use is up to you, but you have to believe that you will be notified by the name that you publish in your paper. So, you should choose which you would like to be called.
TRENARY: After your Ph.D., I saw from your CV you did a variety of short-term things, postdocs and worked for a company for a while, and you were here at RIKEN for a while, and then back with companies.
KAWAI: Yes.
TRENARY: So, tell me about that period of your career.
KAWAI: So, nobody wanted to take me. (Laughter)
TRENARY: That’s the explanation?
KAWAI: Actually, yeah. I think there are several reasons, but at that time I was married during graduate school and I had one child, and after I finished my Ph.D. I had the second child. And so, I was a little bit busy on my family business actually. And so probably my performance was not as good as the others. Or, I don’t know what it is. But I tried quite hard to apply to many positions, but nothing was successful.
TRENARY: I see.
KAWAI: I had to go to some postdoc position, but it was not sort of a highly prestigious postdoc position, that I had to survive by sort of continuing one by one, but after all it was a quite good experience. Because, it’s not easy for young people to have the experience to be in a government institute, a university, and even the private sector, and then come back to a research position again. I had a little bit more than one-year experience in a private company, which was actually a gas company, and as you can imagine they are selling natural gas, but they have to have some certificate that they can do some technological improvement in using something else to produce natural gas, etcetera. So, that kind of strategy drove that company to push some research work. And so what I was doing was methanation, CO plus H2, to make methane, and my purpose was to help the people who were producing methane from this system. I learned quite a lot about the process itself. That was very important, because unless you’re inside this community you will never know how they think about this, and what is the cost performance of the whole system, etcetera. I think I learned quite a lot during this one year or so.
TRENARY: You also had a position at Tokyo Institute of Technology?
KAWAI: Yes. Yes. Yes. (Laugh) So, that was after three years of my starting a tenure position at RIKEN. Suddenly a call came to me that there is an open position in Tokyo Institute of Technology and so they are trying to make a new system of laboratory given by the donation from the private company. They were looking for somebody who will take care of this system, but at the time it was guaranteed for only three years. So, it was very short-term but it was a donation from a private company. I don’t know what you call these kind of donated labs? What do people call that?
TRENARY: Sometimes we call it an endowment. But, no, I don’t know that we have anything quite like that. It was a short-term donation for a professorship?
KAWAI: Yes. Not only professorship, but they gave a certain amount to make all the research. Tokyo Institute of Technology was the second university to drive that system, after University of Tokyo. But they wanted to be different from the University of Tokyo, which invited some professors from outside Japan, who are on sabbatical, so they wanted to do something else. They wanted to have somebody who is not on a kind of sabbatical, but a professor who had some different situation. Finally I think they sought a young woman. (Laugh) That would be quite attractive. That was something that made me completely switch my career. The three years of experience at Tokyo Tech was very hard, but very interesting. As I told you, I started in catalysis and I had been doing catalysis up to then, but the interest in Tokyo Tech was more materials science. It was a time when the high TC superconductors, oxide superconductors, were invented. So, I decided to switch completely from catalysis to making thin-film oxides. This is not very different from catalysis in the way that oxidation has to be done on surfaces. So, I decided to do molecular-beam epitaxy of metal oxides.
TRENARY: Right. I’ve seen on your CV that you have over ten years’ worth of publications on materials like strontium titanate, and similar materials. Some of that work was published in JVST, right?
KAWAI: Exactly.
TRENARY: You went from Tokyo Institute of Technology to chief scientist of the Surface Chemistry Laboratory here at RIKEN.
KAWAI: Yes.
TRENARY: So, they created this position for you?
KAWAI: When I was hired at RIKEN, before being a professor at Tokyo Institute of Technology, I was in a catalysis lab at RIKEN for three years. The chief scientist of this catalysis lab retired while I was at Tokyo Tech and they were looking for a new person to be his successor. I was not quite sure whether they chose me or not, but I applied and then we had a serious interview, and finally RIKEN decided to take me as a successor of the former PI of this catalysis lab. So I was asked to come back, and then I thought a little bit seriously what to do. Because of my experience in this private company, for one year or so, I decided to do something very fundamental, which would not be seriously related to applications, but more in generally encouraging fundamental science. I thought surface science, or surface chemistry, would be what I should do. So I switched from application to more fundamental problems, and so I asked to change the name of the lab from catalysis to surface chemistry.
TRENARY: That was in 1991?
KAWAI: Yes.
TRENARY: I met you in ’93, during my first trip to Japan, and at that time Jun Yoshinobu was working with you. I’m curious how you decided to hire him when all your work, at that point, was on oxide superconductors?
KAWAI: Some catalysis too. As a PI, I thought how to form the team was very important. I had some knowledge of catalysis and, of course, infrared spectroscopy, etcetera, but I thought, “I need somebody who will seriously put this catalysis part to surface science,” meaning more physics and physical chemistry. I was looking for a certain candidate for the researcher in my lab, and it reminded me of three or four years before when I was trying to hire somebody for my research associate in Tokyo Tech. I had a very nice communication with Professor Onchi of Kyoto University and at that time he told me that he had three very talented graduate school students, and one of them was Yoshinobu. But they had not yet graduated. I mean, they were finishing their Ph.D. degrees, so I would have to wait for two more years or so. As I had only a three-year contract, I could not wait two more years. (Laugh) So, I kept these names in my mind. And then, I was sort of watching how they were growing, etcetera. And finally, when the job of RIKEN’s researcher was open, Jun happened to be in RIKEN as a postdoc in Professor Aono’s lab doing some of the STM work, etcetera. Professor Aono appreciated Jun’s research very much, and so I had to beg him and ask him whether he can release Jun to my place. That’s the way I tried to attract Jun, in a realistic way, but the job itself was a completely open position, and so people had to apply at the time. Of course, if there was somebody better than Jun, I should have taken them, but Jun was very good.
TRENARY: I am quite familiar with the work that Jun did with you, a lot of infrared of CO on Ni (100), and things like that, but I know in about 2001 you started with the low-temperature STM work. I’m curious how it is you were able to obtain all the money to buy a low-temperature STM. That’s quite unusual in the U.S. to be able to raise that much money for equipment for a single PI lab.
KAWAII: I think it was not so expensive, actually. What happened was that I had to borrow some money from RIKEN. We had a reasonable-sized project. So, when we started some research with Jun, we first started the infrared reflection-absorption spectroscopy. We did that for three years or so, and Jun was just so interested in STM that he started with Aono-san before coming to my place. He pushed me very seriously that we should do some work together with this infrared. We had this not seriously low-temperature, but a little bit low-temperature STM system before that. Finally we had to think about something, that if we are sort of tracing individual molecules on surfaces, we have to seriously consider about the migration of the molecule, because all the molecules will escape from under your tip at a reasonable temperature. We knew what the potential energy surface is like, and so we could calculate what will be the temperature needed to catch the molecule, the interesting molecules, with STM. It was quite clear that we had to go down to liquid helium temperature, otherwise the molecules are so wiggling around that we cannot image them. We simply had to have low-temperature STM in order to observe individual molecules, especially at low surface coverages. By that time, Jun had already moved to the Institute for Solid State Physics, and Komeda-san joined my group. Komeda-san was the second student Professor Onchi recommended. (Laugh) And I took both of them. We had three to four thousand million yen per year project running at that time. We knew that to get this low-temperature system we have to spend about two years, two years’ of money for the thing. I have to talk a little bit about that. We asked RIKEN whether we can use the money in such a way. RIKEN is a quite large institute, so, if somebody wants to use their money in advance, somebody else will want to use their money later, and the administration office allowed flexible use of this money and
that’s the way that I succeeded to get it. But, I had to ask all my colleagues in my lab if I should use all the money for this year, so there would be no way of having other large instrumentation for two to three years. Some of them hesitated seriously. But, I have to say that this was a decision of their own. That’s the way that we got this low-temperature STM. Then, I think something was pushing me. We were quite lucky to have a chance of a nanoscience initiative in RIKEN. The nanoscience building was built, then the science building, and then the serious leading commitment of the president of RIKEN, Professor Kobayashi, and he was pushing this nanotechnology or nanoscience in those days. We had a building called “nano building,” and the next year we had something that we put into this building. It was quite, quite a large budget that we had. It was not only me, but we had to make a clean room. We had to put in an e-beam lithography system, then set up for semiconductor research, and all these things, including personnel and everything.
So, compared to these things, our low-temperature STM was a minor expense.
TRENARY: So, it was a good time, then?
KAWAI: Very – yeah. So, I asked everybody to be patient for three years, having nothing settled, and they finally agreed and finally the money came. So that was the trick.
TRENARY: I see. I remember that your first low-temperature STM was in the main building, and then you moved it over to the nano building when that was finished?
KAWAI: Yes.
TRENARY: Very soon after you got the machine you published a Science paper in 2002 on lateral hopping of CO?
KAWAI: Yes.
TRENARY: And that, I think, was the beginning of action spectroscopy? Would you say that?
KAWAI: Yes. So, the wording of “action spectroscopy” came a little bit later, because with this first Science paper we were only focusing on the CO stretch and how it goes to translational motion. We were not focusing on the whole scope of the molecules at that time. But gradually we started to realize that if you take this IETS, inelastic electron tunneling spectroscopy, it was not very easy to quantify the amount of electronic transition that is made by these systems. But we know that the reaction coordinate, if it’s excited, this is related to how the vibrational state is excited. So the action of the molecules will give us a very good quantitative measure of the phonon density of states. That kind of idea came into my mind when we were seriously discussing it with Ueba-san, who is the theory person who was always very interested in the phonon density of states, or in electron-phonon coupling. He was struggling with how to quantify the amount of excitation from IETS. Finally, he realized that if the reaction occurs, this will be a good measure. At that point we decided to have more serious research into this action versus how IET occurs. Action spectroscopy came to my mind a little bit later than this Science paper. But I think the publication containing this name was in 2004 or 2003. It was not very interesting to all my colleagues to do this action spectroscopy, so people did not want to write that down. I mean, they were more interested in inelastic tunneling, because the famous people were doing this. So, I had to write it by myself. The first paper containing action spectroscopy was in 2005, but the year before I had a chance to put this in a Royal Society paper.
TRENARY: I know that single-molecule chemistry and action spectroscopy was a big part of your work for many years here at RIKEN and, at some point, you also got a position at the University of Tokyo.
KAWAI: Yes.
TRENARY: You also became deputy director of RIKEN, and then executive director.
KAWAI: Yes.
TRENARY: You were doing all these different things. How did you balance everything?
KAWAI: It was expected that a deputy director of RIKEN would also be a PI at RIKEN.
So, a deputy director still maintains a research program. Being a PI was something that I had been doing before, so that was not so serious. The reason why I accepted becoming a professor at University of Tokyo was that I thought at some stage we need some people to be in the university. I was asked whether I was interested in, for several years, continuing, but I thought it was a little bit too hard to do two jobs together or to close my job at RIKEN. That was not my will. So, I hated it a little bit but I thought it would be the time that I should accept. And so I did that.
TRENARY: Tell us a little bit about your position now with the Institute for Molecular Science. You’re the director there? What are you trying to accomplish, and you have some goals for the Institute?
KAWAI: The Institute itself is a quite well known institute in Japan, and maybe a little bit in the world. It was established more than forty years ago. From the point of view of physical chemistry, I think, for Japan it is a very important institute because it produces many young talented scholars who go on to universities. As the director-general, I’m not allowed to do any of the research inside the institute by myself. I can encourage some people, but I do not have any lab over there. As a research scientist I commit a little bit, but my major role is to encourage the young ones and to prepare a reasonable environment for the people that are willing to do the serious science.
TRENARY: It’s the Institute of Molecular Science, so it’s mainly spectroscopy and gas phase? Or, is there any surface work?
KAWAI: There aren’t so many people doing surface work, but there are very few people doing gas phase work nowadays. Cold-atom people are there. They are looking towards this quantum computing. So, it’s more sort of applied. But, it’s quite interesting in a way that Professor Ohmori does this trapping of rubidium atoms in three dimensions.
He excites these atoms to the Rydberg states. They can tune to a higher Rydberg state or to a lower one, and if the energy goes higher, then the overlap between the neighboring atoms become stronger. His strategy is that he can tune the interaction with the neighboring atoms by tuning the laser. With the system that he invented it’s not very easy to directly utilize it for quantum computing. But, if you have dipoles nearby you can sort of switch off or tune the Rydberg state. This is probably the only isolated system that the people are doing in IMS. Some people are inventing laser systems, and IMS has a synchrotron radiation light source, which is in a quite low-energy region. So that would be very good for materials science in the way of spectroscopy. They are utilizing this to produce some of the solid-state physics, but some of them do complex molecular systems, as well. There are people who are remaking some molecules also. So, it’s sort of a complex of chemical systems. We have a little bit more than thirty principal investigators, and, as a whole, including all the administration people, we have a little bit less than three hundred people.
TRENARY: All right. So, let’s wrap up. Do you have any general advice to offer to young scientists today, and in particular to young women scientists? I know that many quite successful young women have come through your laboratory, and so do you have any advice?
KAWAI: Especially in Japan, the people think that it’s not very easy to be a professor or a PI in basic research. But there are all sorts of positions, of course. Before you give up you have to continue, and especially for the ladies. If you continue, and if you’re reasonably good, I would suggest that there is a good chance to become a PI or professor. So, there is only one message that I will give them: “Don’t give up.”
TRENARY: Don’t give up? Okay. That’s a good message. I think some of the people reading the transcript might want to know a little bit about your children and grandchildren. So, how many children and grandchildren do you have?
KAWAI: Two children, a son and a daughter. My son is an engineer, and he does microengineering, MIMS. He used to work for Tohoku University and he switched to the private sector now, Denso, which is a sort of radio company to Toyota Motor Company. He’s producing something, but I don’t know what. (Laugh) He has two children, a son and daughter, who are four and two years old. They are very cute. (Laughter)
TRENARY: Your daughter is still in Europe?
KAWAI: Actually, she came back today. (Laugh) She has been mainly in Germany for eight or nine years. Her specialty is music, western music, and voice. She’s a mezzo-soprano and trying to be a performer in the classical world.
TRENARY: Wow.
KAWAI: It’s not very easy. (Laugh) Well, she had several chances to perform in a small theater in Germany, and now she wants to switch back to Japan and try to do something here, again.
TRENARY: Very good. Well, I think that will wrap up the interview, and we will end it there.