00:00:00 You began to study physics at a time that was really remarkable in the history of 20th

00:00:09 century science. I wonder if you could tell us about the state of spectroscopy when you

00:00:12 began studying at Darmstadt in 1924.

00:00:17 Well the state of spectroscopy of course really, or spectroscopy generally started by Kirchhoff

00:00:24 and Bunsen back in 1860 or thereabouts. But it was at the time when I started, it was

00:00:34 just the time when it became clear what are molecular spectra and what are atomic spectra.

00:00:41 That is one knew long ago the difference between line spectra and band spectra, but one didn't

00:00:47 really or wasn't really sure that line spectra are atomic spectra and band spectra are molecular

00:00:55 spectra. When I started that had already been established. But then of course the long development

00:01:02 started with distinguishing electronic transitions and vibrational transitions, rotational transitions.

00:01:11 This was the time for example when I think it was Hetner in Berlin who first got the

00:01:18 rotation spectrum of, or was it in Frankfurt, the rotation spectrum of HCL I believe.

00:01:26 Oh you mean the pure rotation spectrum?

00:01:27 Pure rotation spectrum.

00:01:28 Wasn't that Czerny?

00:01:29 Czerny, I'm sorry.

00:01:30 Yeah, Czerny.

00:01:31 Yes, Czerny.

00:01:32 Yes.

00:01:33 Yes.

00:01:34 And...

00:01:35 It was a pretty good spectrum too.

00:01:36 Yes, yes he did. And I think I have a picture of one of his lines in my book.

00:01:43 You probably have. I've certainly used that spectrum.

00:01:46 Anyway, that was the time when I started. And then of course very soon after, while

00:01:52 I was still a graduate student, or maybe not even a graduate student, Schrodinger's paper

00:01:58 appeared in the literature. I saw it in the library of the physics department in Darmstadt.

00:02:05 And I saw the title, and having learned all about Bohr's theory and all that, and there

00:02:13 was the expression, the energy, atomic energy as an eigenvalue problem. What was the exact

00:02:25 title? Well, it doesn't matter. Anyway, it was so striking to me that I immediately started

00:02:31 to read this paper. And that was in the Annal der Physik. And pretty soon I told other people

00:02:41 about it, and I was asked to give a seminar talk in our physics globium on the subject

00:02:48 of Schrodinger's first and second paper. And I was really very pleased. You see, I had

00:02:54 the big advantage that just at that time I was taking a course in partial differential

00:03:00 equations. And that's the A and O of Schrodinger's theory, you see. So I was all familiar with

00:03:07 the concept of an eigenvalue. I remember now the title of Schrodinger's paper, the quantization

00:03:16 as an eigenvalue problem. That was the title of his paper, in German, of course. And pretty

00:03:22 soon, about a year later, even before I had my Ph.D., Schrodinger was giving a lecture

00:03:27 in Freiburg, south of Darmstadt, you know. And my professor, Professor Rao, sent me down

00:03:34 there to listen to Schrodinger. And I did. And it was very impressive. And I had a chance

00:03:40 to meet him very briefly. But he was a very, very fine lecturer. He had a delightful Austrian

00:03:48 accent in his...

00:03:49 Schrodinger was a good lecturer.

00:03:51 Oh, he was very good. He was very good. Charming. Charming person, yes.

00:03:55 It must have been an exciting experience for a young physicist.

00:03:58 It was. It was. And of course, at the same time, of course, there was also the development

00:04:05 of Heisenberg's version of quantum mechanics. And so these were really very exciting years,

00:04:12 1925, 26, 27.

00:04:16 How did you begin to apply these new insights in your own work?

00:04:20 Well, that came perhaps, well, shall we say, a year or two later, when I went after my

00:04:28 Ph.D., which wasn't really a Ph.D., but a Doctor of Engineering, because it was a technical

00:04:34 university. But it began when I had a post-doctorate here in Göttingen. And just that year, 1928,

00:04:44 was really an incredibly important year in the development of the quantum theory of molecules.

00:04:53 There was this famous paper by Wigner and Wittmer on the correlation between atomic

00:05:01 and molecular states. There were the papers by Mulliken, by Hund, and I have a long list

00:05:10 of them. And it's really incredible. It was a really important year for the development.

00:05:15 So I learned all those things. And yes, there was Heitler in London, of course, just a year

00:05:21 earlier, the first application of quantum theory to the formation of a molecule, the

00:05:28 H2 molecule. Of course, the H2 molecule has been with me ever since.

00:05:34 You still don't understand it completely.

00:05:35 I still don't understand it completely. But we have actually just quite recently completed

00:05:42 a paper in which we have the comparison between the theoretical value for the ionization potential

00:05:49 of H2 with the experimental value. And you would hardly believe it. It's down to one

00:05:56 in a million, the agreement between theory and experiment.

00:06:02 I'm not sure I would believe it from some people, Dr. Hertzberg, but if you say so,

00:06:07 it's probably true.

00:06:11 Well, who were some of the other people you worked with at Göttingen when you went there?

00:06:15 Heitler was one of them.

00:06:16 Heitler was one of them. I published two papers with Heitler. One turned out to be nonsense

00:06:21 and the other was very important, but people at the time didn't seem to recognize it much.

00:06:26 Well, it was a brand new field.

00:06:29 Yes, yes.

00:06:30 It really was.

00:06:31 But then there was, of course, James Frank, and there was Herta Spooner in the lab, there

00:06:36 was Oldenburg, and there were several other people. And then there were a considerable

00:06:46 number of guests. There was one who was especially important, or two that were especially important

00:06:54 for me. One was Scheibe, Günter Scheibe from Erlangen. He spent six months in Frank's

00:07:02 laboratory. And then there was, what was the other one now? Anyway, Scheibe, oh yes, the

00:07:15 other one was, you know, the English, L.J. Leonard-Jones.

00:07:27 Oh, Leonard-Jones?

00:07:28 Leonard-Jones. He spent three or four months in Göttingen just at that time.

00:07:32 Did he? I didn't know that.

00:07:33 And we had many discussions. I had a slight idea about chemical bond at the time. Bonding

00:07:42 and anti-bonding electrons, I think the expression I formulated in some way. And I had many discussions

00:07:52 with Leonard-Jones on this subject. And he then offered me a second postdoctoral position

00:08:03 in Bristol. And that was a very lucky break for me, because in that way I learned English

00:08:10 properly, because I spent a whole year in the English language. But while I might go

00:08:16 on briefly about the history, when I came to England, within three days there was the

00:08:24 meeting, the famous meeting of the Faraday Society on molecular structure, which was

00:08:29 actually organized by Leonard-Jones and one of his colleagues. And the people who were

00:08:34 there, for example, Raman, Richardson, and many others. And the first lecturer was O.W.

00:08:45 Richardson, who was the man with the thermoelectric effect, I mean, the emission of electrons

00:08:52 from...

00:08:53 Yeah, the Richardson effect, as a matter of fact, yes.

00:08:56 The Richardson, yes. But he was the worst possible lecturer. He mumbled, and I couldn't

00:09:02 understand a word. I thought, gosh, I thought I knew English, but I don't understand English.

00:09:09 But the second lecturer was Raman, and he was fantastic.

00:09:12 Was he a good lecturer?

00:09:14 Oh, he was fantastic. And he had just discovered the Raman effect. This was in 29. The Raman

00:09:20 effect was discovered in 28. And that was a very, very interesting meeting. Many other

00:09:28 people were there. Mecca was there, and many other people. Mulligan was not there, but

00:09:33 he sent a paper in to the meeting. But also, one person who was there, and I never knew

00:09:41 it, was C.P. Snow.

00:09:42 Really?

00:09:43 Yes. He was then a spectroscopist.

00:09:45 I was going to say, at that time, he was a physicist, wasn't he?

00:09:48 Yes, he was a spectroscopist. He read a spectroscopy paper, and I have no recollection of it. And

00:09:57 I've read many of his novels later on.

00:09:59 Yes, yes. Maybe they were better than his spectroscopy paper was.

00:10:03 Well, I looked at some of the spectroscopies much later, and I didn't find them all that

00:10:08 well written. But mind you, I like his novels.

00:10:12 Oh, yes.

00:10:13 Yeah. Now, do you recall the reaction to Raman's talk at that meeting?

00:10:18 Oh, I think it was very, very good. The contrast between Richardson and Raman.

00:10:23 Yeah, that would help.

00:10:24 In the presentation, he had enthusiasm. You could understand every word that he said.

00:10:30 And you didn't know, what did he mean now? And all this kind of thing. He was really

00:10:35 good.

00:10:36 You know, within just a few years, the new quantum mechanics, the kind of work you've

00:10:41 been talking about over the last few minutes, really did transform the way in which molecular

00:10:47 spectra were understood, as well as a lot of other things.

00:10:50 Yes, certainly.

00:10:51 What were some of the results that people were discussing in 1929, when you went to

00:10:54 Bristol?

00:10:57 Well, of course, Mulligan's papers and Hund's papers were basic in molecular orbital theory.

00:11:04 I always emphasized the fact that the concept of molecular orbitals is all clearly there

00:11:09 in Hund's papers. Mulligan invented the name.

00:11:13 Of molecular orbitals.

00:11:15 Of molecular orbitals.

00:11:16 Along with some other names that we were talking about.

00:11:19 He invented many other names, yes. But this was the name that he invented. And the strange

00:11:26 thing is, in German, you cannot really form that kind of expression. I mean, they do use

00:11:34 it now.

00:11:35 They use orbital.

00:11:36 But at that time, Hund couldn't have invented that word. At any rate, Mulligan went much

00:11:42 further and developed molecular orbital theory.

00:11:46 It took a long time for that to be of any real use to chemists, though.

00:11:51 Yes, yes.

00:11:52 I mean, the Heitler-London theory, and of course, particularly with Linus Pauling's

00:11:58 development, and others, too. But it was much more amenable to the chemist's peculiar way

00:12:04 of thinking.

00:12:05 Yes, that is right. That is right. But in the long run, I have the impression that molecular

00:12:12 orbital theory has won out over Pauling, Slater, Heitler.

00:12:17 Well, I've always felt it was inherently sounder, somehow, than the Heitler-London electron

00:12:24 pairing approach. But you don't get a chemical bond out of it. There's no chemical bond in

00:12:30 molecular orbitals. You have to kind of force it in.

00:12:34 You force it in. That's one of the things I did, actually, in this paper that I mentioned

00:12:38 a moment ago, that I tried to define which orbitals are bonding and which are anti-bonding

00:12:45 and which are non-bonding.

00:12:47 Yes. Well, Mulliken picked up that idea.

00:12:49 He did.

00:12:50 Yeah.

00:12:51 So did Hund.

00:12:52 But, you know, you have to count the number of bonding electrons and the number of anti-bondings

00:12:57 and subtract them. It's as bad as figuring out how many games the Twins are ahead or

00:13:03 behind Oakland, or behind, I'm afraid.

00:13:06 And it's just not a good way to think about chemical bonds. It's a great way for spectra,

00:13:15 isn't it?

00:13:16 It's a great way for spectra.

00:13:17 For electronic spectra.

00:13:18 For electronic spectra, it's the only way.

00:13:22 I want to move on in a minute to Stanford, when Dr. Crawford was beginning to learn chemistry

00:13:27 while you were already busy at Bristol, or actually after you had gone back to Darmstadt.

00:13:32 One other person I wanted to ask you about was Peter Debye.

00:13:35 Oh, yeah.

00:13:36 I was intrigued to learn that you were involved in some of his workshops in 1931 in Leipzig

00:13:41 on molecular structure.

00:13:42 Yes.

00:13:43 Could you tell us a little about him and about that environment?

00:13:46 Well, he was one of the people who was another one of these fantastically good lecturers.

00:13:52 Best one, second best lecturer I've ever heard, actually.

00:13:55 Yes, yes.

00:13:56 First one is not a chemistry physicist.

00:13:58 Same here.

00:13:59 Yeah.

00:14:00 But he certainly was an extremely good lecturer.

00:14:02 And he was a good organizer.

00:14:03 And he had organized these Leipziger Woche.

00:14:07 They were called, that is, a week of intense work on one particular subject.

00:14:14 And this one was on molecular structure.

00:14:17 And I was invited as one of the speakers.

00:14:19 And I did talk about this sort of thing that I mentioned earlier.

00:14:23 But there were other people there.

00:14:25 I mean, Platschek was there, and Teller was there, and very, very many very competent people.

00:14:36 And it was really a very fascinating occasion to learn to know these people.

00:14:43 Heisenberg was there.

00:14:46 That's quite a group.

00:14:48 It was quite a group.

00:14:50 I later met Debye on a number of occasions, including at Cornell University.

00:14:55 And, of course, he was really a great physicist and chemist.

00:15:02 And a very nice gentleman.

00:15:04 Yes.

00:15:05 A wonderful person.

00:15:07 Did that Leipziger Woche lead to your collaboration with Edward Teller?

00:15:12 Or did that come about in other ways?

00:15:14 Yes, I think it was.

00:15:17 It must have been at that time.

00:15:19 Because, yes, that was in 31.

00:15:22 Yes, that's correct.

00:15:23 Yes.

00:15:24 And that's where I first met Teller.

00:15:27 And then we got together.

00:15:28 He was interested in polyatomic molecules, and in particular symmetry properties.

00:15:35 Symmetry properties of energy levels in polyatomic molecules.

00:15:39 He knew all about degenerate vibrations, degenerate electronic states,

00:15:43 and the interaction between them and all that.

00:15:46 And he induced me to join him in this paper that is still being quoted

00:15:55 on electronic transitions in polyatomic molecules,

00:16:02 particularly with regard to the application of the Franck-Condon principle

00:16:06 in polyatomic molecules.

00:16:08 But I must say that the ideas all came from Teller.

00:16:13 And I was a sort of midwife who got them out of him and to write it down.

00:16:18 I'm sure you wrote the paper.

00:16:20 I wrote the paper.

00:16:21 As far as I know, Teller has never written a paper in his life.

00:16:24 That is correct.

00:16:25 That is correct.

00:16:26 But it was a remarkable experience.

00:16:28 Because certainly at that time, and I suppose even now,

00:16:32 Teller has an extraordinarily clever mind.

00:16:35 There's no question.

00:16:37 It's too bad he isn't doing spectroscopy anymore.

00:16:39 He did some wonderful spectroscopy.

00:16:42 There's an interesting side remark, and that is that Teller,

00:16:47 there were two newspaper people who wrote Teller's biography,

00:16:53 and he gave them all the access to all his papers and everything.

00:16:57 And it's quite interesting reading.

00:16:59 At the very end, these two newspapers, you ask Teller,

00:17:03 now what work of yours gave you the most pleasure?

00:17:09 And without a moment's hesitation, he said,

00:17:11 my work in molecular spectroscopy.

00:17:14 Well, he did enjoy it.

00:17:15 Oh, he did?

00:17:16 Yes.

00:17:17 Oh, he did?

00:17:18 No question.

00:17:19 He knew everything about it.

00:17:20 And when he gave lectures on it, he was just sparkling.

00:17:23 He was having as much fun as we do, just bubbling.

00:17:29 Well, just a couple of years after this is when you began to encounter

00:17:33 quantum mechanics and molecular spectroscopy

00:17:35 when you were studying at Stanford.

00:17:37 Well, I was a graduate student at Stanford,

00:17:39 34 to 37 when I got a post-doc and went to work with Bright-Wilson.

00:17:46 But you see, I had some of the same,

00:17:50 very specifically I had some of the same timely good fortune

00:17:54 that Dr. Harrisburg was speaking about

00:17:57 in that Wigner had done his group theory book

00:18:02 on atomic energy levels and atomic spectra,

00:18:06 and Bright-Wilson had the wit to perceive that

00:18:10 that would also enable group theory

00:18:14 to be applied to molecular vibrations,

00:18:18 and that made it possible really to analyze the vibrational spectra

00:18:24 in infrared and Raman, or electronic spectra too,

00:18:27 for that matter, of complicated molecules.

00:18:30 I mean, not C3 and H2 fascinating as they are,

00:18:34 H3 even fascinating as all those are,

00:18:37 but you know, benzene, anthracene.

00:18:40 I've even seen a normal coordinate treatment of RNA,

00:18:45 which is a pretty good-sized molecule.

00:18:47 Yeah, it's a pretty good normal coordinate treatment.

00:18:49 I've seen that.

00:18:50 So I came along there, you see, and this was new,

00:18:53 and I remember I did my thesis, my PhD thesis,

00:18:58 with Paul Cross at Stanford on H2S,

00:19:02 the rotational spectrum of H2S and the structure of H2S,

00:19:06 and I had some time in the summer

00:19:09 before I went to post-doc with Bright-Wilson,

00:19:13 and Paul Cross said to me,

00:19:15 well, I've taught you all that I know about rotational analysis

00:19:20 and taught you how to do rotational analysis.

00:19:22 Now it's time for you to return the compliment.

00:19:24 Why don't you learn group theory and teach me group theory?

00:19:28 So for the early part of the summer of 37,

00:19:33 why there wasn't any book on, well, it was Wigner, of course,

00:19:36 which is a beautifully written book, incidentally,

00:19:39 but so I read Wigner,

00:19:43 and there was a paper by Jenny Rosenthal and George Murphy,

00:19:48 and I read Rosenthal and Murphy,

00:19:51 and I taught myself group theory

00:19:54 and taught Paul Cross group theory.

00:19:56 We really kind of worked together on that, you see,

00:19:59 and then I went to work with Bright-Wilson,

00:20:03 who had just focused his entire new laboratory at Harvard

00:20:07 on infrared and Raman spectra

00:20:11 and the unraveling of the vibrational assignments,

00:20:15 and I got there, and Bill Avery and Harold Gershinowitz

00:20:19 had just finished building the spectrometer there,

00:20:24 and I had a very wonderful two years,

00:20:29 and that was my introduction to molecular spectra.

00:20:33 Well, not quite.

00:20:35 I had, as a graduate student, I'd followed some of that.

00:20:38 In fact, I was chuckling.

00:20:41 You were talking about going to meetings

00:20:43 and what a thrill it was for a young fellow

00:20:46 to see these great people.

00:20:48 Well, I went to a meeting at, I was telling you about it,

00:20:52 at Princeton in the Christmas New Year's vacation of 1937,

00:21:01 January 1937,

00:21:03 on molecular structure and molecular spectra,

00:21:09 and I had a card of introduction

00:21:12 to Bright-Wilson and David Dennison,

00:21:16 both of whom were working on centrifugal distortion,

00:21:20 which I was also working on for my thesis, you see.

00:21:23 So I found these two fellows together, you see,

00:21:27 and they said, oh, how nice, you know,

00:21:30 aren't you working, I think Paul Cross said

00:21:32 you were working on centrifugal distortion.

00:21:34 We were just going to go find a quiet place

00:21:36 and talk about that and argue some about it.

00:21:39 Why don't you join us?

00:21:41 So I went along, you know, young fellow,

00:21:44 somewhat abashed and very shy, as I've always been,

00:21:48 and I just grew up in the next half hour, you see,

00:21:53 because to my astonishment I could understand

00:21:56 these distinguished people, you see,

00:21:59 and fully appreciated their arguments,

00:22:02 and within about 15 minutes they said something

00:22:05 I thought was wrong,

00:22:07 and then there were three of us talking, you see,

00:22:10 and it was just wonderful.

00:22:12 So I said something about Mullock,

00:22:14 and you and I were laughing about it.

00:22:17 You see, I didn't have a card of introduction to you,

00:22:21 and anyway, you weren't much good to an infrared aiming

00:22:24 spectroscopist at that time.

00:22:26 Were you at this meeting also?

00:22:28 Oh, yes, very much so, and so was Mullock.

00:22:31 But let's see, 37, when did you do Hertzberg and Teller?

00:22:36 Oh, that was 1934.

00:22:38 That was, yeah, a bit earlier.

00:22:41 So you, yeah, yeah.

00:22:43 But that was really focused on electronics.

00:22:46 It always was, yes.

00:22:48 Anyway, Mullock had a paper on nomenclature

00:22:53 and some useful concepts,

00:22:55 and in particular I remember that was the occasion

00:22:58 when he invented the name vibronic wave functions

00:23:02 and ro-vibronic wave functions.

00:23:04 I hated that expression.

00:23:05 You did indeed.

00:23:07 In the discussion period, you know,

00:23:10 Dr. Hertzberg got up and said a few nice things about it.

00:23:14 It was really quite a good paper.

00:23:16 There were some basic ideas as well as nomenclature, of course.

00:23:19 And Dr. Hertzberg expressed some concern

00:23:22 about more nomenclature overlaying spectroscopy,

00:23:26 and it was confusing to the students already and so forth,

00:23:29 and he wasn't sure this was a good thing.

00:23:31 Mullock was just a little bit miffed,

00:23:34 and he said,

00:23:35 Well, I find them very useful and very helpful to me.

00:23:38 They help me to think about these things.

00:23:41 And Dr. Hertzberg said,

00:23:43 Well, I guess some people don't think exactly the same way.

00:23:48 And Mullock then said,

00:23:49 Well, I guess some people don't think.

00:23:51 And whoever was the chairman said,

00:23:52 I think we'd better get on to the next paper, you see.

00:23:55 I was just in heaven, you see.

00:23:59 Here were these distinguished people

00:24:01 whose papers I had read and understood some of them

00:24:05 and misunderstood some of them, especially Mullock's.

00:24:07 His papers were terrible.

00:24:10 And it turned out to be normal human beings

00:24:12 just like the rest of us, you see.

00:24:14 It was very encouraging.

00:24:17 So I was lucky,

00:24:18 and then I've been in molecular spectroscopy ever since.

00:24:22 That's an important experience.

00:24:23 It's part of what turns a student into a scientist,

00:24:26 those kinds of experiences.

00:24:28 The other thing, of course,

00:24:30 one of my colleagues, I think it was an organic chemist,

00:24:33 Lee Smith, who said it the best way,

00:24:35 he said there are two absolutely essential components

00:24:39 of a graduate student's doctoral training.

00:24:44 One is absolute failure,

00:24:47 the awful moment when nothing is working

00:24:51 and he just doesn't see how anything is going to come out of this.

00:24:56 And he said the other, of course, is success,

00:24:59 whether in that particular study or some other.

00:25:04 And it's very true, I think.

00:25:07 Well, a moment ago you mentioned

00:25:09 that when you got to Harvard in Bright-Wilson's lab,

00:25:11 a couple of your colleagues had just finished building an instrument.

00:25:16 I thought we might talk a little bit about the way in which

00:25:19 this was a do-it-yourself business in the 1930s.

00:25:22 Yes, it was.

00:25:24 Very much so.

00:25:26 Yes, I built, when I got out to Minnesota,

00:25:31 well, I inherited, George Glockner had been there

00:25:34 and he had moved to Iowa

00:25:36 and I was hired to sort of take his place.

00:25:40 And he had a Steinheil spectrometer that he used for Raman spectra.

00:25:45 Oh, yes. We had a Steinheil in Darmstadt, too.

00:25:47 Beautiful instrument.

00:25:48 Yes.

00:25:49 Yeah, quartz prisms and glass prisms.

00:25:52 Oh, yes, both.

00:25:53 Put in one, two, or three prisms.

00:25:55 Oh, yes. Great instrument.

00:25:57 And I knew it was there, of course.

00:25:59 I had met Glockner before.

00:26:02 One of the things I included in my correspondence

00:26:04 was a gentle hope that when Dr. Glockner left

00:26:09 that that wonderful Steinheil would remain at Minnesota

00:26:12 because I could certainly use it

00:26:14 because I wanted to take some Raman spectra, too.

00:26:16 And George Glockner always referred to me

00:26:18 as that scoundrel who stole my Steinheil

00:26:21 because he had intended taking it with him to Iowa, of course.

00:26:24 But the first thing I got onto

00:26:26 was building an infrared spectrometer.

00:26:29 And, yes, I built several.

00:26:33 And you certainly have built instruments.

00:26:36 I can't claim to have built any infrared spectrometer,

00:26:39 but I've built several ultraviolet grating spectrometers

00:26:42 and this sort of thing.

00:26:43 Vacuum spectroscopy.

00:26:45 It started in Darmstadt, actually,

00:26:49 where I built my first instruments.

00:26:51 And we had a very, very good shop,

00:26:54 a very good foreman of the shop

00:26:56 who did all the details of the instrument.

00:27:00 And that helped a great deal.

00:27:02 It was another piece of these pieces of luck that...

00:27:05 But it's still true, I think,

00:27:07 that if you're doing something that's fairly new,

00:27:10 you have to build your own instruments.

00:27:12 I mean, just after the war,

00:27:15 a lot of people were building

00:27:17 so-called fast scanning infrared spectrometers.

00:27:20 I built one that we were very proud of.

00:27:23 As a matter of fact, we had a lab tie,

00:27:25 and I'm wearing a Minnesota lab tie,

00:27:27 and that's an infrared spectrum.

00:27:29 It shows CO and CO2.

00:27:31 And it only took 15 seconds,

00:27:34 a quarter of a minute,

00:27:36 to scan 400 or 500 wave numbers.

00:27:38 Nowadays they do it, of course, in picoseconds,

00:27:41 but it was an achievement.

00:27:43 And if you wanted a fast scanning spectrometer,

00:27:46 as I did and Sutherland did

00:27:49 and Thompson...

00:27:51 Thompson at Oxford did,

00:27:53 you had to build it yourself.

00:27:55 And even in the...

00:27:57 It was in the late 60s, I guess,

00:28:01 I wanted to measure intensities

00:28:04 in the infrared of absorption

00:28:08 on liquids.

00:28:11 And, of course, with liquids,

00:28:13 you need the refractive index

00:28:15 as well as the absorption index.

00:28:17 The real and complex...

00:28:19 Real and imaginary parts

00:28:21 of the complex refractive index.

00:28:23 So we designed and built

00:28:25 an instrument

00:28:27 to measure

00:28:29 the optical constants.

00:28:31 The refractive index,

00:28:33 real and imaginary parts

00:28:35 in the infrared.

00:28:37 And we had to build it ourselves,

00:28:39 design it ourselves.

00:28:41 Tony Gilbey was post-docting with me

00:28:43 and he built it.

00:28:45 And this, of course,

00:28:47 just after the war,

00:28:49 happened as a result

00:28:51 of the usefulness

00:28:53 of infrared demonstrated

00:28:55 in the petroleum analyses

00:28:57 during the war

00:28:59 and in the determination

00:29:01 of the structure of penicillin.

00:29:07 But commercially available

00:29:10 infrared instruments

00:29:12 began to appear.

00:29:14 And Perkin Elmer

00:29:16 were the first ones

00:29:18 to come along.

00:29:20 And you see,

00:29:22 they were very shortly

00:29:24 nice one-switch

00:29:26 instruments that an organic chemist

00:29:28 could operate.

00:29:30 I remember Van Zandt-Williams of Perkin Elmer

00:29:32 saying that his charge

00:29:34 to the fellow who designed

00:29:36 the infracord

00:29:38 was, I want only two switches.

00:29:41 One is the power switch,

00:29:43 it should say on or off,

00:29:45 and the other should say

00:29:47 start, stop.

00:29:49 None of these controls,

00:29:51 you see.

00:29:53 But you see,

00:29:55 before that time, there were only three

00:29:57 labs in the country

00:29:59 that were properly set up

00:30:01 to apply infrared

00:30:03 to chemical problems,

00:30:05 organic structures.

00:30:07 They were all built by physicists.

00:30:09 One was Bolling-Barnes

00:30:11 at American Cyanamid.

00:30:13 One was Bob Bratton's

00:30:15 at Shell Chemical,

00:30:17 at Shell Development out on the west coast.

00:30:19 And one was Norman Wright's,

00:30:21 Dow Chemical in Midland, Michigan.

00:30:23 And all those guys were physicists

00:30:25 who had perceived

00:30:27 Koblentz's work

00:30:29 about the turn

00:30:31 of the century.

00:30:33 No, I guess that's not right.

00:30:35 That infrared

00:30:37 did show these characteristic frequencies

00:30:39 and that they could

00:30:41 be useful for chemical characterization.

00:30:43 But no organic

00:30:45 chemist could use this, you see,

00:30:47 unless he had a friend who was

00:30:49 a physicist or a spectroscopist

00:30:51 or interested

00:30:53 in infrared.

00:30:55 And now, of course,

00:30:57 gee, every organic

00:30:59 chemist has one and his students know how to

00:31:01 use it probably better than the professor does.

00:31:03 And that was the big revolution.

00:31:05 And that was a part of

00:31:07 the whole instrumentation

00:31:09 revolution that

00:31:11 Arnold Beckman, I guess, really started

00:31:13 it with his...

00:31:15 Remember the DU spectrometer

00:31:17 that

00:31:19 Howard Carey

00:31:21 designed and developed

00:31:23 for Beckman. He was working

00:31:25 for Beckman Instruments at that time.

00:31:27 And before that, of course,

00:31:29 Beckman was the guy who really made

00:31:31 the pH meter

00:31:33 a simple, useful thing

00:31:35 like a glass electrode, you see.

00:31:37 And that got it into the laboratory.

00:31:39 And, of course,

00:31:41 that plus the spectrometers

00:31:43 and on and on. It's revolutionized

00:31:45 chemistry, revolutionized

00:31:47 the biological laboratories, revolutionized

00:31:49 medicine. And that's

00:31:51 the real instrument development

00:31:53 since

00:31:55 you started working and I

00:31:57 followed you ten years later.

00:31:59 And now, of course, we have this new

00:32:01 development of Fourier transform spectroscopy.

00:32:03 That made a great deal

00:32:05 of difference. It made a great deal of difference

00:32:07 because you get as an output, both

00:32:09 from the point of view of high resolution

00:32:11 and low resolution, you get

00:32:13 directly the output on a piece of paper.

00:32:15 You don't have to

00:32:17 worry about

00:32:19 conversion,

00:32:21 converting millimeters into centimeter minus one

00:32:23 or whatever.

00:32:25 All of those things.

00:32:27 But you see, that was made possible by an

00:32:29 instrument development also.

00:32:31 Namely, the computer.

00:32:33 Because as long as you had to

00:32:35 crank out those

00:32:37 integrations against

00:32:39 the cosine functions, you know,

00:32:41 on a Marchant or

00:32:43 a Frieden.

00:32:45 Goodness, we had a Frieden.

00:32:47 Those were hand-cranked calculators.

00:32:49 Well, the Marchant was.

00:32:51 Bumpity, bumpity, bumpity, bumpity, remember?

00:32:53 But

00:32:55 you couldn't do a Fourier

00:32:57 transform.

00:32:59 So it was the computer

00:33:01 and John Tukey's

00:33:03 algorithm, the fast Fourier transform

00:33:05 algorithm that made those

00:33:07 nice gadgets that we both

00:33:09 fully appreciate

00:33:11 possible.

00:33:13 When I, several years

00:33:15 ago, I interviewed Arnold Beckman and

00:33:17 one of the things we talked about was how

00:33:19 the entire development of the scientific

00:33:21 instrument industry after the war

00:33:23 can be characterized by saying that

00:33:25 manufacturers and engineers and scientists

00:33:27 who worked on those instruments were designing

00:33:29 the skills into the machine

00:33:31 so that you could have a machine that would have an on-off switch

00:33:33 and a start-stop switch.

00:33:35 Could we just go back for...

00:33:37 There's a bad side to it, too, of course.

00:33:39 That is, those instruments tend to get frozen

00:33:41 at the level

00:33:43 of development which their

00:33:45 instrument-making

00:33:47 designers

00:33:49 had at the time.

00:33:51 I'm not talking about the mechanical

00:33:53 or electronic tools.

00:33:55 I'm talking about the

00:33:57 chemical sophistication.

00:33:59 So you'll always

00:34:01 have to build your own instruments.

00:34:03 But it's nice to have

00:34:05 the commercial ones.

00:34:07 What I was going to ask was to go back

00:34:09 to the 30s, for instance, when you moved

00:34:11 to the University of Saskatchewan.

00:34:13 You had to develop a new lab again

00:34:15 and rebuild some instruments

00:34:17 and you were just talking about similar

00:34:19 experiences.

00:34:21 What were the skills that you had to put

00:34:23 into designing a laboratory

00:34:25 to do spectroscopic work in those days?

00:34:27 Well,

00:34:29 it's just some good sense, I would say.

00:34:33 I mean, in my

00:34:35 own case, the main point was,

00:34:37 first of all, to get a good grating.

00:34:39 I was very lucky to get

00:34:41 two very outstanding

00:34:43 gratings from

00:34:45 R.W. Wood.

00:34:47 The first one I got in Darmstadt

00:34:49 and the

00:34:51 second one I got in Saskatoon.

00:34:53 The one in Darmstadt,

00:34:55 nobody knows what happened to it during the war.

00:34:57 It was heavily bombed and all that.

00:34:59 But I remember the first time I visited

00:35:01 at Johns Hopkins University,

00:35:03 I visited R.W. Wood.

00:35:05 That was foresighted of you.

00:35:07 Yes.

00:35:09 No, but that was after the war, you see.

00:35:11 The first question he asked,

00:35:13 what happened to my grating that I sent you?

00:35:15 Because that was the best one he had ever ruled.

00:35:17 The Darmstadt one?

00:35:19 And he had never been able to quite

00:35:21 reproduce the quality of that grating.

00:35:23 You know, when I was

00:35:25 working with Paul Cross

00:35:27 at Stanford, I did my PhD

00:35:29 thesis with him, which was a purely

00:35:31 theoretical thesis.

00:35:33 But

00:35:35 he wanted

00:35:37 a grating spectrograph to be built,

00:35:39 eagle-mounting grating spectrograph.

00:35:41 And he alleged that I should do

00:35:43 some experimental work in spectroscopy,

00:35:45 even though my thesis was going to be

00:35:47 theoretical, to get balance and whatnot.

00:35:49 That way he got me to work and

00:35:51 help him build his grating.

00:35:53 And we got an R.W. Wood grating

00:35:55 and it arrived, you see.

00:35:57 And we had explicitly told the

00:35:59 chap in the receiving room,

00:36:01 now for heaven's sakes, don't open this thing or whatnot.

00:36:03 Just let us know and we'll come and open it

00:36:05 for you, you see.

00:36:07 Well, the scoundrel had opened it.

00:36:09 And not only that,

00:36:11 you know how your grating is a round,

00:36:13 concave mirror

00:36:15 with the grating,

00:36:17 a rectangular grating pattern

00:36:19 sort of set into this circle.

00:36:21 What do you suppose was on the

00:36:23 outer edge a thumbprint?

00:36:25 Exactly.

00:36:27 We looked at that

00:36:29 and caught our breath

00:36:31 and wondered, you see.

00:36:33 And I guess

00:36:35 that the guy at least had

00:36:37 the common sense not to put his thumb

00:36:39 right on the grating area.

00:36:41 But

00:36:43 it certainly was

00:36:45 a frightening thing

00:36:47 to see.

00:36:49 You also needed photographic

00:36:51 plates and electronic equipment.

00:36:53 What were some of the other components

00:36:55 that went into building

00:36:57 machines at that time?

00:36:59 When I built machines, of course

00:37:01 it was photographic.

00:37:03 And fortunately

00:37:05 Eastman Kurek

00:37:07 were still delivering plates.

00:37:09 It's getting more and more difficult

00:37:11 to get good plates.

00:37:13 It's still possible.

00:37:15 It's still possible, yes.

00:37:17 But what isn't?

00:37:19 Well, there's an awful lot of just plain

00:37:21 machine design skill.

00:37:23 You may have your own

00:37:25 machinist. We had a very good

00:37:27 machinist in the chemistry department

00:37:29 at Stanford

00:37:31 when I was a graduate student

00:37:33 and at Minnesota when I went to

00:37:35 Minnesota

00:37:37 in 1940.

00:37:39 You had your own machinist for quite a while.

00:37:41 And I had my own machinist

00:37:43 when I was really running a laboratory

00:37:45 during the war

00:37:47 for ten years or so after the war.

00:37:49 But you've got to design

00:37:51 these machines, and there are such things.

00:37:53 I had a very good student

00:37:55 when he was designing something,

00:37:57 you see, and he was

00:37:59 telling Mr. Grapp

00:38:01 how he had it sort of drawn out

00:38:03 very nicely.

00:38:05 And he said, here I want a tapered

00:38:07 locating pin so I could slide

00:38:09 this unit on top

00:38:11 of this flat surface, you see.

00:38:13 Then that locating pin

00:38:15 would go right down into this tapered

00:38:17 hole just below it.

00:38:19 Well, Bill had designed

00:38:21 it all right, except that tapered hole

00:38:23 went down about halfway through this rather

00:38:25 thick plate, and it was a blind

00:38:27 hole, you see.

00:38:29 Fortunately, Grapp

00:38:31 was a very good machinist, and he said,

00:38:33 I see you just sort of push it

00:38:35 down. He says, yes, just tap it into the hole,

00:38:37 you see, and it's going to be a tapered pin, a tapered

00:38:39 hole. It'll

00:38:41 pull it right into the right spot.

00:38:43 And Grapp says, mm-hmm. How do you get the pin

00:38:45 out?

00:38:47 He looked at it.

00:38:51 You see?

00:38:53 That's the way you develop a graduate student.

00:38:55 But that's what you mean by common sense.

00:38:57 Yeah.

00:38:59 Well, it shows that experimental science

00:39:01 is a very complicated activity

00:39:03 that people don't often understand

00:39:05 just how complicated it is.

00:39:07 During the war, I mentioned

00:39:09 building a very fast infrared

00:39:11 spectrometer, fast for its day,

00:39:13 and we did some pretty good chemistry with it.

00:39:15 We had a very bad fire

00:39:17 in the laboratory

00:39:19 we were using, and it burned down the whole building,

00:39:21 you see, and of course all of my

00:39:23 lovely equipment with it.

00:39:25 Until you've seen a

00:39:27 15-foot

00:39:29 grating

00:39:31 spectrometer dangling

00:39:33 at the end of a steam shovel,

00:39:35 you haven't seen anything.

00:39:37 But anyway,

00:39:39 so the question was, I gathered my

00:39:41 crew together after the fire, and we

00:39:43 licked our wounds and said, okay, we'll rebuild.

00:39:45 We had the money

00:39:47 to do it. That was fine.

00:39:49 And immediately, my

00:39:51 machinist and my

00:39:53 young fellows, they

00:39:55 set to work on how to

00:39:57 improve the design of

00:39:59 this fast scanning infrared

00:40:01 spectrometer. And I made

00:40:03 what I think was the right decision and a very

00:40:05 sensible decision, but it was sure hard

00:40:07 for me to make and terribly

00:40:09 hard for me to enforce. I said, no,

00:40:11 we're not going to improve the instrument

00:40:13 because we want to do some chemistry,

00:40:15 and if we

00:40:17 improve the instrument, we won't

00:40:19 have it back and working again

00:40:21 probably for

00:40:23 perhaps six months

00:40:25 because we'll be improving the instrument. We'll

00:40:27 rebuild it exactly the way it was

00:40:29 before. Oh no, you don't want to do

00:40:31 that, Doc.

00:40:33 But you know, it only took us about six

00:40:35 weeks to

00:40:37 we still had

00:40:39 a number of the drawings even,

00:40:41 and

00:40:43 so it's

00:40:45 quite a business building your own

00:40:47 games.

00:40:49 Fun though.

00:40:51 It sounds it. Let me ask you,

00:40:53 let's go off in a slightly different direction

00:40:55 if we could for a while.

00:40:57 By the 1945

00:40:59 or so, the second volume, I believe,

00:41:01 of your treatise on molecular

00:41:03 structure and molecular spectra had appeared,

00:41:05 and that certainly brought

00:41:07 together quite a bit of the work that had been going

00:41:09 on in the previous years.

00:41:11 Using that as a kind of a jumping off point,

00:41:13 could we talk about the state of the art

00:41:15 in understanding of molecular spectroscopy

00:41:17 around 1945?

00:41:19 Dr. Hertzberg

00:41:21 was just showing me the

00:41:23 manuscript

00:41:25 for a

00:41:27 not really a revised version,

00:41:29 it's an updated and corrected

00:41:31 reprinting, I suppose that's the

00:41:33 right thing to say, of that

00:41:35 wonderful book.

00:41:37 You're quite right,

00:41:39 it wrapped up everything

00:41:41 that was known about infrared and Raman

00:41:43 spectra and all the

00:41:45 vibrational assignments that were then known.

00:41:47 Most of them wrong.

00:41:49 To no

00:41:51 fault of yours.

00:41:53 You must have spent a lot of time in the

00:41:55 library pulling all that

00:41:57 stuff together and critically

00:41:59 reviewing it.

00:42:01 I remember, I think I had

00:42:03 an assignment on something like

00:42:05 nickel carbonyl, which was a very bad

00:42:07 assignment, actually.

00:42:09 Lee Jones revised it properly

00:42:11 later on, and on dimethylacetylene,

00:42:13 which was a splendid assignment.

00:42:15 And

00:42:17 you didn't like either one of them.

00:42:19 And I agreed with you on

00:42:21 nickel carbonyl, but I thought that you were

00:42:23 being awfully sniffy,

00:42:25 if I may say so, about some very

00:42:27 fine vibrational assignment

00:42:29 work on dimethylacetylene, which

00:42:31 has stood up all these years, but you

00:42:33 were dubious about it.

00:42:35 I don't blame you, it was a difficult assignment

00:42:37 and it was, the only reason I knew

00:42:39 it was right at that time was it was my

00:42:41 18th try.

00:42:43 And it held together on all the criteria,

00:42:45 you see, and it's held up ever since.

00:42:47 Dimethylacetylene,

00:42:49 you said?

00:42:51 Dimethylacetylene, yeah.

00:42:53 I must look that up in the new version.

00:42:59 There have been subsequent assignments

00:43:01 refining some of the CH stretches by

00:43:03 5 or 10 wave numbers and so forth,

00:43:05 but mine is essentially the

00:43:07 one that has stood up.

00:43:09 At that time, I know

00:43:11 early on, at the beginning of our

00:43:13 conversation, we were talking about the work in the

00:43:15 1920s on some

00:43:17 isoelectronic systems

00:43:19 and very small molecules,

00:43:21 and then by the time you had

00:43:23 begun working at Harvard, you were now looking at

00:43:25 molecules like ethane, dimethylacetylene,

00:43:27 which were somewhat larger.

00:43:29 What would you say, based

00:43:31 on your recollection of the state of the

00:43:33 art about 1945, how well did we

00:43:35 understand polyatomic versus diatomic

00:43:37 systems?

00:43:39 Oh, I think we really

00:43:41 understood it reasonably well.

00:43:43 I mean, the theory was well developed.

00:43:45 We had...

00:43:47 Far rigid molecules.

00:43:49 I mean, the sort of stuff that, well, John Haugen

00:43:51 has been doing it, of course,

00:43:53 recently.

00:43:55 But that wasn't even

00:43:57 touched.

00:43:59 Internal rotation was a great problem

00:44:01 about which I made one of the more

00:44:03 serious mistakes I've ever made.

00:44:05 Van der Waals molecules,

00:44:07 of H2O.

00:44:09 That's right.

00:44:11 That's still a very hot...

00:44:13 That's all new.

00:44:15 I had a hard time

00:44:17 when I prepared this reprint

00:44:19 not to be carried away

00:44:21 and dig into all this

00:44:23 stuff. I mean, then I could spend the next

00:44:25 five years doing nothing else.

00:44:27 So I

00:44:29 just prepared a simple

00:44:31 reprint with corrections

00:44:33 for the identifications.

00:44:35 So the molecules that you had in the

00:44:37 45 book are

00:44:39 in this book, but you didn't add any

00:44:41 extra, any further molecules.

00:44:43 Or maybe you did,

00:44:45 but not very many.

00:44:47 I added one

00:44:49 or two, but that's about

00:44:51 what it amounts to.

00:44:53 I'm adding to the volume

00:44:55 three, I'm adding H3.

00:44:57 The electron.

00:44:59 Strangely.

00:45:01 And I'm adding

00:45:03 a completely revised version of CH2.

00:45:05 You understand

00:45:07 about H3. Well, I was

00:45:09 just going to ask you, you really need to explain that

00:45:11 for us. That's Dr. Hertzberg's

00:45:13 pet molecule.

00:45:15 Since 1975.

00:45:17 I was going to say for about the last

00:45:19 ten years or so. Yeah, for the last ten years.

00:45:21 No, 79 it was.

00:45:23 I was

00:45:25 really quite pleased about that, but

00:45:27 it was so easy.

00:45:29 H3.

00:45:31 I found a spectrum.

00:45:33 I won't

00:45:35 give all the details. I found

00:45:37 this spectrum, and I thought my

00:45:39 technician had made some foolish error

00:45:41 that just doesn't

00:45:43 exist. I mean, in hydrogen

00:45:45 you find something completely

00:45:47 new, and when the hydrogen

00:45:49 spectrum had been studied for 50 years

00:45:51 or longer,

00:45:53 but then it suddenly

00:45:55 occurred to me that

00:45:57 well, I won't go through the details,

00:45:59 but there was

00:46:01 something irregular about it,

00:46:03 and it finally turned

00:46:05 out to be the spectrum

00:46:07 of triatomic hydrogen in

00:46:09 excited states. Of course, we all

00:46:11 know that the ground state of H3 doesn't

00:46:13 exist. I mean, a hydrogen atom

00:46:15 and a hydrogen molecule don't attract one another

00:46:17 except for a very

00:46:19 tiny Van der Waals interaction,

00:46:21 so that the ground state is

00:46:23 dissociative, but

00:46:25 the excited states, when you take one

00:46:27 electron away

00:46:29 and put it into a

00:46:31 big orbit, then

00:46:33 you get states that are stable,

00:46:35 and the

00:46:37 spectrum is so convincing

00:46:39 that there is absolutely no problem,

00:46:41 no question that here is the

00:46:43 spectrum of H3

00:46:45 in excited states, in Rydberg

00:46:47 states, and

00:46:49 that has

00:46:51 been generally accepted, but it could

00:46:53 have been found 50 years earlier,

00:46:55 and it was in a

00:46:57 convenient spectral region

00:46:59 of all things.

00:47:01 Why nobody saw it?

00:47:03 I looked through

00:47:05 Dicke, you know, published

00:47:07 this, or rather posthumously,

00:47:09 this big volume of all

00:47:11 the lines of molecular

00:47:13 hydrogen from the visible into the

00:47:15 infrared,

00:47:17 and it's not there.

00:47:19 And

00:47:21 why we were so lucky, I don't know,

00:47:23 there it was, and it was

00:47:27 just one of those

00:47:29 cases where you don't have to work for

00:47:31 years and years to find something new.

00:47:33 Serendipity. Serendipity

00:47:35 is the word I was looking for.

00:47:37 Is that the case where, I think it was

00:47:41 you were very busy, I heard

00:47:43 you tell a tale anyway, and

00:47:45 Shoesmith, I guess. No, that was for

00:47:47 CH2. Oh, that was for CH2.

00:47:49 I'm fonder of

00:47:51 CH2 even than I am of

00:47:53 H3 with regard to...

00:47:55 It's one of the younger children, you see.

00:47:57 Well, yeah, H3 is.

00:47:59 I found

00:48:01 when I was looking through all this stuff that I

00:48:03 had collected in my files about

00:48:05 Dr. Hertzberg, I found

00:48:07 occasion, I think we said

00:48:09 it was 71 or something like that, when

00:48:11 he had visited Minnesota and given

00:48:13 a seminar naturally, and I had introduced him,

00:48:15 and it was just at that time

00:48:17 that

00:48:19 he had

00:48:21 correctly licked

00:48:23 CH2. You see,

00:48:25 back in... That was ten years earlier,

00:48:27 actually. Was it?

00:48:29 Oh, yeah, okay.

00:48:31 But back in the 40s,

00:48:33 you were looking for CH2

00:48:35 and you found this spectrum

00:48:37 which you thought was CH2

00:48:39 and

00:48:41 it's one of those lovely boo-boos

00:48:43 science, civic literature has,

00:48:45 you see, and it was actually

00:48:47 CH3 you finally found.

00:48:49 No, it was C3.

00:48:51 It was something new,

00:48:53 but it wasn't CH2.

00:48:55 It was only years later, you see, that Dr. Hertzberg

00:48:57 got back to CH2

00:48:59 and really

00:49:01 got its spectrum,

00:49:03 analyzed it completely,

00:49:05 nailed it down until there wasn't a

00:49:07 whipper left in it, you see, with all

00:49:09 the use of deuterium isotopes,

00:49:11 and I think you even used C12, didn't you?

00:49:13 C13, yes.

00:49:15 It was down and down in Columbus

00:49:17 that had us all just cheering,

00:49:19 you see, because

00:49:21 here was not only

00:49:23 Dr. Hertzberg

00:49:25 having made a mistake in being honest

00:49:27 and admitting it, you see, but going back

00:49:29 and licking the problem.

00:49:31 And so I

00:49:33 found my little introduction

00:49:35 for Dr. Hertzberg

00:49:37 at his seminar at Minnesota

00:49:39 and I said that

00:49:41 I admired Dr. Hertzberg

00:49:43 and his superb spectroscopy,

00:49:45 as we all do,

00:49:47 but I loved him for making a big

00:49:49 boo-boo on CH2

00:49:51 because that made spectroscopy

00:49:53 something that was done, you know, not by

00:49:55 a computing machine or by

00:49:57 an inspired genius that no human being

00:49:59 could touch, but

00:50:01 a normal human endeavor

00:50:03 that real people did

00:50:05 and made mistakes at and licked their

00:50:07 mistakes, much better than

00:50:09 your H3. Oh, that's a

00:50:11 good one. Obviously, I liked

00:50:13 this introduction when he made it.

00:50:15 He repeated it now.

00:50:17 Well, one

00:50:19 thing we might talk about a little bit is

00:50:21 you'll have to correct me

00:50:23 if I characterize this inaccurately,

00:50:25 but H3, C3,

00:50:27 these are not,

00:50:29 these aren't the sorts of entities that chemists

00:50:31 usually play around with a lot.

00:50:33 On the other hand, you were talking earlier in your

00:50:35 papers in the early 40s and late 40s

00:50:37 on internal rotations of molecules

00:50:39 and the planar vibrations

00:50:41 of benzene. Those

00:50:43 are the kinds of things that I can see chemists

00:50:45 worrying about. They're my type of spectra.

00:50:47 Why don't we talk a little bit about

00:50:49 the differences between the way physicists

00:50:51 look at spectra and interpret them,

00:50:53 the kinds of questions that

00:50:55 physicists ask, and the sorts of questions

00:50:57 that chemists want to use spectroscopy

00:50:59 for?

00:51:01 Well, we were

00:51:03 talking a little bit

00:51:05 outside about some of these

00:51:07 differences and

00:51:09 the fact that

00:51:11 I know we mentioned

00:51:13 David Dennison, who was an outstanding

00:51:15 molecular spectroscopist, of course.

00:51:17 And a physicist. And a physicist

00:51:19 and an outstanding physicist

00:51:21 and

00:51:23 he didn't understand

00:51:25 chemical bonds even as well as you do,

00:51:27 sir.

00:51:29 But he did

00:51:31 have other valuable viewpoints.

00:51:33 He taught me quite a few things.

00:51:35 He taught me how

00:51:37 the fact that infrared is

00:51:39 a particularly rich

00:51:41 and helpful spectroscopic

00:51:43 region for

00:51:45 determination of chemical

00:51:47 structure for the chemist to use.

00:51:49 That that was not just

00:51:51 a quirk of the instrument makers or a

00:51:53 whim of

00:51:55 some chemist

00:51:57 or whatnot, but that was

00:51:59 dropped straight out

00:52:01 from the fact that the only forces

00:52:03 acting in chemical

00:52:05 activities are

00:52:07 basically Coulomb forces.

00:52:09 And that the

00:52:11 magnitude of H is

00:52:13 whatever it is, and the magnitude

00:52:15 of masses

00:52:17 is whatever

00:52:19 they are, electronic and nuclear

00:52:21 masses.

00:52:23 And of course

00:52:25 the magnitude of the electronic

00:52:27 charge, the basic electronic

00:52:29 charge.

00:52:31 And you put these together with not even

00:52:33 a Schrodinger equation, but just a very simple

00:52:35 basic ideas of

00:52:37 the Heisenberg uncertainty principle, you see.

00:52:39 And out comes the fact that

00:52:41 your chemical

00:52:43 bonds are going to be

00:52:45 on the order of, you don't get any

00:52:47 chemical bonds, but you get inter-nuclear

00:52:49 distances, and they're going to

00:52:51 be on the order of angstroms,

00:52:53 rather than

00:52:55 10 to the minus 12 centimeters or

00:52:57 meters. They're going to be on the order

00:52:59 of angstroms. And that

00:53:01 the strength of chemical bonds

00:53:03 is going to be, as I put it,

00:53:05 100

00:53:07 kilocalories on down,

00:53:09 or as Dr. Hertzberg puts it,

00:53:11 4 eV, 4 electron

00:53:13 volts, you see. But that's the general

00:53:15 magnitude of it.

00:53:17 And that

00:53:19 there will be these vibrational transitions

00:53:21 because that

00:53:23 Coulomb force is going to have a

00:53:25 very sharp

00:53:27 bottom well, you see.

00:53:29 And the

00:53:31 heights of those

00:53:33 from the ground state to the first

00:53:35 excited state is going to be

00:53:37 a little less

00:53:39 on the order of a thousand wave

00:53:41 numbers. Maybe a little more, but

00:53:43 down to quite a little bit less.

00:53:45 And that's in the infrared.

00:53:47 Now that,

00:53:49 I would never have thought

00:53:51 of it. That's not the way a chemist thinks.

00:53:53 Not this chemist, anyway.

00:53:55 But that is the way

00:53:57 that a physicist thinks. I think that's a

00:53:59 typical

00:54:01 physicist's tackling of a

00:54:03 problem.

00:54:05 And it's very valuable.

00:54:07 But

00:54:09 chemical bonds?

00:54:11 But don't forget

00:54:13 the photochemist.

00:54:15 I mean, the photochemist needs excited

00:54:17 states of a molecule.

00:54:19 And it's these excited states

00:54:21 that the physicist also is interested in.

00:54:23 Oh, that's right. Sure, there's

00:54:25 overlap. Only then can you determine

00:54:27 dissociation energies and this sort of thing.

00:54:29 That's right.

00:54:31 You have to get up there.

00:54:33 So you do have to

00:54:35 study the ultraviolet spectrum as

00:54:37 well, even if your interests are

00:54:39 mainly chemical. Yes, that's right.

00:54:41 But not for the same purposes.

00:54:43 And then you come to things like H3.

00:54:45 You excite

00:54:47 H2 to excited states.

00:54:49 We had one interesting fact

00:54:51 that I could have shown with a slide,

00:54:53 and that is the fact that

00:54:55 we had this excitation of H3

00:54:57 and

00:54:59 we had a novel

00:55:01 excitation by means of a mixture

00:55:03 with argon. I won't go into the details.

00:55:05 And with

00:55:07 the mixture with argon,

00:55:09 the whole spectrum of H2

00:55:11 in this

00:55:13 that was underlying, obviously,

00:55:15 the H3 spectrum was absent.

00:55:17 And we had a clear, simple spectrum of

00:55:19 H3 in this particular region.

00:55:21 And we were

00:55:23 quite surprised. And up to this day, I'm not

00:55:25 entirely clear whether

00:55:27 I have the right explanation for

00:55:29 this

00:55:31 selection, this shrinking

00:55:33 that we removed the spectrum

00:55:35 of H2. And we had removed

00:55:37 it before simply by a photographic

00:55:39 trick by

00:55:41 putting a negative

00:55:43 of the hydrogen spectrum

00:55:45 on top of that spectrum and then removing

00:55:47 the hydrogen spectrum artificially.

00:55:49 But this was naturally in a mixture

00:55:51 of H2 and argon.

00:55:53 There you are.

00:55:55 No, don't misunderstand

00:55:57 me. You don't, of course.

00:55:59 After all, I'm a fellow of the American

00:56:01 Physical Society, too, you know, just like

00:56:03 you're a chemist.

00:56:05 But

00:56:07 I'm more a chemist.

00:56:09 That's why I told

00:56:11 Dr. Hertzberg I think he and I go

00:56:13 very well as a matched pair on this

00:56:15 eminent chemist series, you see,

00:56:17 because he's not much of a chemist,

00:56:19 but he's very eminent.

00:56:21 And I'm much more of a chemist

00:56:23 and a very good one, but I'm a little less

00:56:25 eminent than Dr. Hertzberg.

00:56:27 So the average is just right.

00:56:29 So we make a good matched pair.

00:56:31 And the physicist's viewpoint

00:56:33 versus chemist's viewpoint

00:56:35 is, I think, another...

00:56:37 There's a different sort of

00:56:39 feeling about molecules.

00:56:41 Sanichiro

00:56:43 Mizushima, of course you knew.

00:56:45 You know, when he retired

00:56:47 from the University of Tokyo,

00:56:49 the

00:56:51 Japanese steel industry

00:56:53 was just setting up a

00:56:55 brand new and very good

00:56:57 basic research laboratory on

00:56:59 ferrous metals and things of that sort

00:57:01 just south of Tokyo.

00:57:03 And they

00:57:05 asked Mizushima, who, of course,

00:57:07 was retiring from the university

00:57:09 early on, as the Japanese professors

00:57:11 do, and

00:57:13 if he would come and be the head of the laboratory.

00:57:15 So he did this,

00:57:17 you see, and I was in Japan shortly

00:57:19 thereafter, and he asked me to come out and visit

00:57:21 him, which I did and enjoyed it very much.

00:57:23 And I said,

00:57:25 but, Mizushima

00:57:27 sensei,

00:57:29 why are

00:57:31 you any good out here

00:57:33 in a steel laboratory?

00:57:35 You're not a metallurgist.

00:57:37 No, he said, we have many

00:57:39 metallurgists, but he said, you know,

00:57:41 he said, none of them

00:57:43 think in

00:57:45 terms of a chemical bond.

00:57:47 And he said, I do, of course.

00:57:49 And he said, you know,

00:57:51 it's very useful even in

00:57:53 thinking about metals.

00:57:55 And he said, I have found that

00:57:57 I can join with my metallurgists

00:57:59 who are very good and they know very many

00:58:01 things, and I have found actually

00:58:03 that because I approach

00:58:05 problems thinking always of chemical bonds,

00:58:07 even in metals,

00:58:09 that I am useful

00:58:11 and I, every so often,

00:58:13 I can make an intelligent suggestion.

00:58:15 So,

00:58:17 there you are.

00:58:19 People do approach things differently, and it's

00:58:21 very useful to have several

00:58:23 different viewpoints on problems.

00:58:25 And I think spectroscopy is a

00:58:27 field where the

00:58:29 complementary perspectives of physicists and

00:58:31 chemists really come together very

00:58:33 nicely, more than in many other fields.

00:58:35 Not to mention astronomers.

00:58:37 Not to mention astronomers, yes.

00:58:39 We just have a couple of minutes left.

00:58:41 I wanted to just ask one last question

00:58:43 of each of you.

00:58:45 And it's not an easy one.

00:58:47 What would you think the biggest change has

00:58:49 been in science in your career?

00:59:03 I would suppose one of the biggest

00:59:05 developments, of course, has been the

00:59:07 computer, which has

00:59:09 made things possible

00:59:11 that were not possible. I mean, even

00:59:13 if you come to straight spectroscopy,

00:59:15 you want to resolve,

00:59:17 shall we say,

00:59:19 the electronic spectrum of benzene

00:59:21 vapor into its rotational

00:59:23 structure, which has now been

00:59:25 done up

00:59:27 to a point. You could not

00:59:29 do it without

00:59:31 a huge computer. It just couldn't be

00:59:33 done. Because the material, the amount

00:59:35 of data that you

00:59:37 have is so large

00:59:39 that you just couldn't handle it.

00:59:41 And so, well, that's

00:59:43 one of the things that strikes on

00:59:45 as an answer to this question. I don't know whether

00:59:47 that's the best... I had the same thing

00:59:49 in mind, the computer

00:59:51 and its effects,

00:59:53 which have been unforeseeable,

00:59:55 at least by me.

00:59:57 In fact, when the University of

00:59:59 Minnesota got its first

01:00:01 computer, I thought,

01:00:03 you know, this isn't going to make a particle of difference

01:00:05 for me, because I don't handle

01:00:07 thousands of rotational lines.

01:00:09 I handle a few

01:00:11 infrared and Raman fundamentals at a time.

01:00:13 And after we got

01:00:15 the thing, I think by the

01:00:17 end of the first year, I was the biggest user

01:00:19 of the university's computer on the campus.

01:00:21 Because, well,

01:00:23 have you ever solved by hand

01:00:25 the eigenvalues of

01:00:27 a seven-by-seven

01:00:29 secular equation?

01:00:33 It can't be done.

01:00:35 You can't get them all right by hand.

01:00:37 You just put in

01:00:39 mistakes at a rate

01:00:41 that defeats you.

01:00:43 I tried.

01:00:45 That gets us right back to the beginning, talking about

01:00:47 the eigenvalues of a secular

01:00:49 equation, because, of course, it was Schrodinger's

01:00:51 paper that you began to talk about

01:00:53 at the beginning. Well, we could

01:00:55 go on for days, I think.

01:00:57 It's really been very interesting talking with you

01:00:59 both about your own careers

01:01:01 and development of molecular spectroscopy.

01:01:03 And I'd like to thank you both for taking the time

01:01:05 to chat with us.

01:01:07 Thank you for taking the time.

01:01:09 Very enjoyable conversation.

01:01:11 Thank you.

01:01:25 Thank you.