00:00:00 All right, let me divert for a moment from chemical lasers to talk about rapid

00:00:14 scan infrared spectroscopy because this was crucial to our moving into the

00:00:18 chemical laser field. I had an extremely talented graduate student named Kenneth

00:00:23 Herr who became interested, along with me, in the possibility of doing

00:00:30 spectroscopy in the infrared on the millionth of a second timescale,

00:00:34 microsecond timescale. Nobody had ever been able to run a spectrum before in

00:00:39 less than a millisecond, thousandth of a second, so that represented three orders

00:00:44 of magnitude speedup. We had some ideas on how we might do it using germanium

00:00:49 detectors, and we got hold of one, and Ken built the apparatus around that tiny

00:00:57 chip of germanium, and pretty soon we were able to get infrared spectra on the

00:01:04 microsecond timescale. So that's what I called rapid scan spectroscopy, and it

00:01:09 came about because of this very talented guy, Kenneth Herr. At that time, I began

00:01:17 to realize that maybe this gave us an avenue toward chemical lasers, and I

00:01:23 asked another very talented student, Jerry Casper, to look into the possibility

00:01:27 of using these rapid scan techniques as a means of hunting for the chemical

00:01:33 laser behavior, and that turned out to be the second unique thing that we did that

00:01:43 caused us to be the first to discover the chemical laser. First, we looked in

00:01:49 the infrared, and second, we looked on the millionth of a second timescale, and the

00:01:55 first instance of chemical lasing that we saw was the so-called iodine atom

00:01:59 laser, and Jerry was bright enough and had an open mind to recognize it when we

00:02:09 weren't expecting it, and once he had recognized it, then we were able to go

00:02:15 back to earlier studies that we'd made with the hydrogen-chlorine explosion as a

00:02:20 likely source of chemical laser action and get it to work too. So there we had

00:02:25 our first two chemical lasers.

00:02:29 Okay. Who else was working in this area in the mid-60s?

00:02:34 Well, I mentioned the list of laboratories and people who were involved.

00:02:41 This was all very interestingly culminated at the end of 1964 by a conference down

00:02:47 in San Diego that was put together by Kurt Schuller, who was big in chemiluminescence,

00:02:55 and he attracted some 25 or so papers written by people from all of these big

00:03:03 labs, Bell and IBM and so on, and it was just about the time the meeting was about

00:03:09 to take place that we had our first success with the iodine laser, and with a

00:03:15 very apologetic tone, I phoned Kurt and asked him whether he would be willing to

00:03:19 let Jerry Casper come down at last-minute notice and talk about our work to put

00:03:25 alongside what other people were doing and what other successes they had. It

00:03:30 turned out that ours was the only successful laser there and continued to

00:03:36 be for some years. The reason was that the natural thing for people to do was to

00:03:42 look at bright flames, chemiluminescent reactions that emit light, and now in

00:03:47 retrospect one can see that that's probably not the right place, the best

00:03:51 place to look, and we weren't looking there. We were looking out in the infrared.

00:03:57 What were some of the other major results of your group's continuing efforts in this area?

00:04:01 Well, I got a very talented and able postdoctoral student, Karl Kompa, who came

00:04:13 from Germany, and we started trying to expand from the lasers we had, and in

00:04:22 particular to get away from the explosion type lasers, because one very

00:04:26 quickly loses control of an explosion. We wanted something that gave us more

00:04:30 control, and Karl was able to come up with the hydrogen fluoride laser, which

00:04:36 was our number three laser, and from that things just went swimmingly, and we knew

00:04:43 what to do, how to do it, and we came up with elimination lasers and

00:04:48 recombination-elimination lasers, a variety of types of infrared lasers with

00:04:54 people like Mario Molina. I don't know if you recognize the name, but Molina went

00:05:01 on after his graduate study to UC Irvine, where he and Sherry Rowland were the

00:05:08 first to propose that the chlorofluoromethanes might be interrupting

00:05:12 the ozone layer, but he was very instrumental in helping develop some of

00:05:19 the techniques with which we studied chemical lasers.

00:05:23 To come back to the IR techniques for gas phase, you developed this lightweight IR

00:05:35 spectrometer for the Mariner 6 and 7 missions to Mars in the late 1960s.

00:05:42 Right.

00:05:43 Can you talk about that?

00:05:44 Yeah, that had an interesting origin.

00:05:47 Why don't you start with a sentence, maybe, referring to the Mariner mission so that my question can be cut out.

00:05:57 We've been talking about the rapid scan technique and chemical lasers. That brings to mind the development of the

00:06:05 Mariner spectrometer, with which we attempted to learn about the atmosphere

00:06:11 of Mars, the search for life on Mars. The beginnings of this project were of rather

00:06:18 interesting flavor. While I was in the Navy at the Office of Naval Research, my

00:06:24 immediate boss was a chemist, again, who had been relabeled a nuclear physicist by the

00:06:31 Navy. His name was Ernest Liddell, and Ernest had, as a chemist, done some of the

00:06:39 very early infrared spectroscopy. At the time, I had no idea I was going to end up

00:06:43 working in infrared spectroscopy. Now, many years later, Ernest had moved from the Office

00:06:53 of Naval Research over to NASA. On some sort of an official visit, he came out to Berkeley.

00:07:00 I asked him to come to the lab and see my rapid scan spectrometer. As he left, he said,

00:07:07 Look, if you can take an infrared spectrum in a millionth of a second, you ought to be able to tell us how to take an

00:07:13 infrared spectrum of the atmosphere of Mars. I thought that was an interesting thought, but wasn't quite sure how to do it.

00:07:22 A couple of weeks later, I was on a plane coming back from Washington, D.C., and I decided to spend the ride back

00:07:30 trying to figure out how I would do it. I came up with a rather novel infrared spectrometer of a type that was not yet in use,

00:07:41 not discovered, in which instead of using a dispersive element like a prism or a grating, we attempted to use an

00:07:49 interference filter that was, as I used to call it, wedged, so that as you move this interference filter in front of the

00:07:56 detector, you change the range of the infrared light that struck the detector. This simplified the spectrometer very, very much,

00:08:05 making it compatible with the idea that there would be only 25 pounds associated with the whole infrared spectrometer.

00:08:12 Taking infrared spectra under conditions no one had ever taken in a laboratory with no such restrictions whatsoever.

00:08:20 We, of course, were doing what Liddell had suggested, taking advantage of this germanium detector, which we had access to.

00:08:28 And, sure enough, it turned out that... Is that too much noise in the background there?

00:08:34 Okay, cut.

00:08:39 Of course, we were following the suggestion of Ernst Liddell, making use of this extremely sensitive germanium detector,

00:08:48 which was not in common use, but we had to couple with that some rather, well, certainly novel and unprecedented techniques for space exploration,

00:09:00 which was to carry along the capability of cooling this detector to essentially liquid helium temperatures, which had never been done before.

00:09:11 And we did this with a high-pressure gas system that turned out to work just fine, but which the Jet Propulsion Lab was dreadfully afraid of,

00:09:22 because they were afraid that these bottles of 5,000 pound per square inch gas would blow up on the way and wreck the whole spacecraft.

00:09:31 In any event, the experiment turned out to work beautifully.

00:09:35 The spectrometer had about a 10-inch F1 lens to look at the planet, and it was a flyby.

00:09:45 We went by at about 10,000 miles nearest approach and took continuous spectra every 10 seconds through the infrared,

00:09:55 looking at the light emitted from the surface of the planet, which was tantamount to using as a heat source in the spectrometer a piece of ice,

00:10:05 because that was the surface temperature.

00:10:09 The experiment was able to give us a very good reading on what was in the atmosphere of Mars and what was not in the atmosphere of Mars.

00:10:19 We saw the ice cap was solid CO2.

00:10:25 We saw high clouds that might be likened to our cirrus clouds, which are ice clouds, except they were dry ice clouds.

00:10:35 And we put upper limits on lots of things that might have been there, like SO2 from volcanoes and methane from life and so on.

00:10:46 We were able to put upper limits on these, which then showed that it's a very inert planet.

00:10:53 It's interesting how, during this interview, you always talk about we and not I.

00:10:58 Chemistry is a very collaborative work.

00:11:01 Yes, it's collaborative in what I consider to be the best possible way,

00:11:05 in that it's collaborative between the research director and one or at most two other individuals, generally one.

00:11:14 Most of my papers that have been published have had two co-authors, myself and a graduate student or a postdoctoral student.

00:11:22 The upshot of this is that it's very highly personalized, but definitely collaborative.

00:11:28 And I think the best possible kind of beginning for a science career for a young person.

00:11:34 Why?

00:11:36 Well, because I think that it optimizes the opportunity to nurture the creativity of the young person,

00:11:45 while benefiting from the experience and hopefully wisdom of the research director.

00:11:54 And I want to contrast that with the modern trend, which is to very large groups,

00:11:59 where oftentimes there will be five to ten co-authors on a paper,

00:12:03 and each individual has a tiny role in it, and nobody has complete responsibility for the experiment.

00:12:11 And that goes with very expensive equipment, as one finds in big science.

00:12:16 But in our case, I was in a situation in which I could ask the student,

00:12:22 what do you think we should do next?

00:12:23 And if it wasn't too far out, say, well, why don't you try it?

00:12:27 And let the student make mistakes and find his own way.

00:12:31 Let me come back to NASA for a moment.

00:12:34 Do you want to discuss a bit your connections with NASA

00:12:37 and the process by which you and your co-workers designed, built, operated, and interpreted the data from the Mariner missions?

00:12:45 In our work on the Mariner spectrometer, we were building a state-of-the-art spectrometer.

00:12:53 There was no such thing.

00:12:55 And so we insisted that we had to build it ourselves.

00:12:58 And what that meant, build it ourselves, was that we would build it,

00:13:04 have it machined and built in the chemistry department machine shop.

00:13:11 Jet Propulsion Lab felt uncomfortable with that.

00:13:14 They didn't know what a marvelous machine shop we had.

00:13:17 And to be assembled by Ken Herr himself and all of this to be done at Berkeley

00:13:24 at a time when the only thing anybody knew about Berkeley was that we were having tear gas down in the plaza.

00:13:30 And so once again, it made Jet Propulsion Lab very nervous.

00:13:36 My people were all typical Berkeley students.

00:13:39 What's a typical Berkeley student?

00:13:42 Well, you know, extremely informal, and let's say the mirror image opposite of the organization man.

00:13:52 That tended to be the image of the person that one ran into at Jet Propulsion Lab.

00:13:58 And they operated with many meetings, regular meetings.

00:14:03 Once a week, we'd have to fly down there and get to the Los Angeles airport

00:14:07 and pick up a Jet Propulsion Lab helicopter and fly out to be at a 9 o'clock meeting.

00:14:13 And, you know, all those committees, committees, committees.

00:14:18 And we didn't function very well that way.

00:14:22 And we were a tough nut for Jet Propulsion Lab to swallow.

00:14:26 But to their credit, they managed to do so, managed to give us the latitude we needed

00:14:33 while still trying to maintain their quality control.

00:14:36 And it worked out, in my view, very well.

00:14:41 It didn't work out well from the Jet Propulsion Lab and NASA view in this sense

00:14:46 that we still thought like our research activities were like those that we were used to conducting.

00:14:56 That is to say, we designed the experiment, we did the experiment, collected the data.

00:15:00 We should interpret the data.

00:15:02 And the pattern they preferred was that someone would decide on an experiment,

00:15:07 farm it out to some instrument company to build the experiment,

00:15:11 and when the data came in, a team of people would look at it.

00:15:15 And we didn't go for that.

00:15:17 We were more or less close-mouthed about our interpretations.

00:15:23 And they felt uncomfortable with us.

00:15:26 So we never got another flight.

00:15:30 Let's now talk a little bit about the ChemStudy Project.

00:15:33 It's had a lasting effect on American secondary science education.

00:15:38 How did it come about? How was the text written?

00:15:44 Turning to the ChemStudy Project, which of course was a high school educational project

00:15:51 to develop curricular materials,

00:15:54 in the wake of the Sputnik, in the first instance,

00:15:58 and the physicists' development of what was called the PSSC course in physics

00:16:04 to upgrade science education so that we wouldn't fall further behind the Russians in space effort.

00:16:13 I had been teaching freshman chem, so I had a very great interest

00:16:17 in the chemistry preparation of the students coming into the class.

00:16:21 I felt very, very discouraged about the high school education they were getting.

00:16:26 It was literally no better, no more improved, no more modern

00:16:30 than the high school chemistry course I had had decades earlier.

00:16:34 But that one must have been pretty good to get you going.

00:16:37 Well, it certainly served as, gave me an impetus to get involved somehow.

00:16:45 I was also serving on an advisory committee of a high school teacher

00:16:49 who had decided he was the person to lead such a project.

00:16:53 I just felt that he wasn't up to it.

00:16:55 He didn't have the depth of understanding to bring it into a modern chemistry world.

00:17:02 Well, about that time, the director of the ChemStudy Project was selected, Arthur Campbell,

00:17:09 who was a former Berkeley person now teaching at Harvey Mudd College down in Claremont, California.

00:17:16 And he and Glenn Seaborg, who was the head of the advisory committee,

00:17:21 decided that I was a candidate for editing the book and being in charge of writing it.

00:17:28 They arranged a luncheon at the faculty club one day,

00:17:32 which Arthur Campbell, Glenn Seaborg, who was then chancellor,

00:17:36 and the dean of the College of Chemistry were the other three people there.

00:17:40 They asked me whether I would do it, what were the conditions,

00:17:43 and I named off the conditions, and every time I named a condition,

00:17:47 one of the people was there to say, you got it.

00:17:50 And so by the time it was over, I had no basis for not accepting it.

00:17:55 What were some of your conditions?

00:17:57 Well, one of the conditions was that I would be relieved from teaching for a year

00:18:01 so that I'd have that time free to work on the book

00:18:05 without interfering or interrupting my graduate research career and activities.

00:18:10 I still had a big graduate group, and I wanted to keep that going.

00:18:13 That was the main one.

00:18:15 And the second one was that I wanted to, oh, incidentally,

00:18:20 be relieved of committee work, faculty committee work.

00:18:24 But the most important one was that I wanted to have a clear understanding

00:18:29 that if I was the editor of this book with 20 co-authors,

00:18:33 that I would have the last word on the inevitable disputes.

00:18:37 And Art Campbell was the person who could give me that assurance,

00:18:40 and he stood by it throughout.

00:18:43 So the text was written by 20 people?

00:18:48 Yeah.

00:18:49 What happened next was that we were doing this on a breakneck schedule.

00:18:54 This was in the spring that we made this agreement.

00:18:58 We selected the co-authors who were ten of the leading

00:19:04 lower-division chemistry teachers at the top universities

00:19:09 and ten of the best high school teachers we could get

00:19:13 from the point of view of contributing as authors.

00:19:16 We brought them together for six weeks down at Harvey Mudd College in Claremont,

00:19:20 and we all lived in residence there in a dormitory

00:19:23 and worked very, very intensively, you know, like 14 hours a day

00:19:28 on that book for six weeks.

00:19:31 All this time, of course, we were continually

00:19:34 trying to rationalize different points of view.

00:19:37 Every one of these college people had, generally speaking,

00:19:42 more age and as much experience as I had

00:19:45 and felt I could do this job myself, what do we need Pimendale for?

00:19:50 And so it was a lot of diplomacy involved,

00:19:53 but Art was a great help in this.

00:19:56 In any event, I ended up with draft chapters of the entire book

00:20:02 at the end of six weeks and a commitment that we'd have a book

00:20:05 in the hands of 40 classroom teachers at the beginning of the fall semester.

00:20:11 So I brought it back and worked alone with one of the high school teachers up here

00:20:17 for the next six weeks, trying to bring it into a unified, coherent textbook.

00:20:24 As it turned out, we got a third of the textbook ready

00:20:27 for the beginning of the semester,

00:20:29 and the other two-thirds came along at the appropriate time.

00:20:33 We didn't miss a deadline, and no classroom was ever without a textbook,

00:20:38 but it was a real tour de force.

00:20:41 Then for the next two years, we ran teacher institutes,

00:20:45 which we tried to show teachers what we had in mind.

00:20:50 They were teaching at the same time, using the materials,

00:20:55 and used that as a basis for two successive revisions in the next two years.