Interview w i t h Sir George P o r t e r by Peter Farago
Farago: What influencedyou to chwse a career in chemistry? Porter: i have been interested in chemistry since I was about eight, but it was certainly M. G. Evans. Professor of Physical Chemistry at Leads, who made me really interested in physical chemistry. His lectures were marvellous: he was a great enthusiast for chemistry. In the middle of my chemistry degree-three years at Leeds-there was a program called the Hankey Scheme, which was designed to turn useless chemists and b i o b gists into something useful for the war effort. We were asked to continue our degree studies but to take up radiophysics as well in the iast year or two of our degree. We weren't toid why, but we were toid it had very high priwiy. In my final year I probably spent more time on radiophysics than on chemistry. After graduating we went to Aberdeen UniversW and oW another term m radiophysics there. WB were Men toid what it was all about-it was radar, of course. For the next four and a half years in the Navy I spent a lot of my time learning about pulse techniqws in radar-rnkrawcond pulses of electromagnetic radiation. I am sure that eventually this gave me the idea of using intense pulses of radiation to solve the problem which i was set when I went to CambrMge. The Navy was a tumino point in the sense that I had time to think deeply, and when I came out I was absolutely clear what I wanted to do: research in the natural sciences, and that is ail I wouid ever want to do. Farago: What were the circumstances surrounding your going up to Cambridge? Porter: Cambridge was a name to conjure with-certainly there were names to conjure with who had been at Cambridge. I knew of Professor Norrish through my degree work, and I wrote also to Adrian (now Lord Adrian), because I knew that great things . were ha~pening .. .in his laboratory. He replied very kindly saying it wouM be possible for me to work in his demrtment but. in the event, i stuck to my last and went for physicaichemistry. Farago: You went up to Cambridge in 1945,as a PhD student. got your PhO and became a demonstrator m 1949. One of your contributions at that time was that you knew about electronics.
At that time in Cambridge, equipment was remarkably primitiw. One made one's own oscilloscopes. You measured an absorption spectrum point by point, and calculating machines were almost always mechanical ones. The original problem Nwrish put to me was to try to find out more about the C& radical. and this we dM by the Paneth mirror, flow method. We used an army searchfight Nwish had obtained from the army. This had to nm on 110 V DC, which we did not have, at least not enough of it. so we had a large army Diesel engine on the back of a lorry which was parked outside the Cavendish Laboratory. When /arrived on a cold winter morning my first ,bb was to start this by hand. This work was never very successful. On a visit to collect a new lamp for the searchlight I saw flash lamps being made at Siemens in Preston, and immediately all the pulse techoiquas of radio clicked into I was obvious that this was Me way to tackle place, and / 7 is fair to say that, although it is now one of the problem. t a number of techniques for the study of very short-iived intermediates, in 1947 this introduced the idea into chemistry of using pulses of energy to study hanslent phenomena, and it is still the most powerfui method for the study of free radicals and excited states. Farago: Whet was the general status of fast reaction studies at this time? One illustration of the status was that even the word "mik Porter: lisecond was almost unknown in the chemical laboratow-you . . talked about IF3seconds. Sir Henry MeIviIle. who was Chairman of the Faraday fiscussion on the i a b b molecule in 1947,summarized the prevailing attitude in his introductory statement that intermediates with lifetimes as short as I l T ~ e c o n d sare far beyond direct ~hysical measurement. ~y 1950 we were already down to A n t s 1.000 times faster than that. By 1967 we were a million. and now we are a billion times faster still. Porter:
Dr. Porter, Director and Fullerinn Professor of Chemistry at the Royal Institution, was ca-recipient of the 1967 Nobel Prize in Chemistry (with Professors R. G . W. Norrish and N. Eiger). Volume 52, Number 11, November 1975 / 703
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Would it be reasonable to suggest that, buWing on what Nonish had done, you conceived the idea of pulses which ultimately led to these very short time intervals7 Porter: Yes. Half the bank is to set the Dmblem: Ronald Norrish had certainly given me an important problem which was cleanV stated. it was to obtain the spactrum of s M - t v e d subs&nces. Norrish and I had been using continuous sources, and we triad to see the spectrum of free radicals which we knew tved for I T 3 sec. it is now obvious that one should not use a continuous sourca, but one much more intense and comparable in duratbn Wnh the lifetime of the transient s m l e s . Ow first work was ent* in the gas phase, largely on combustion and chain reactions followinq on from Nor&h8sinterests. But during my last two y e a i at Cambridge 1 appliad the technique to the direct study of excited states. Maurice Windsor, who was a student of mine, was able to observe for the f i s t time the triplet state absorptions in solution, and Frank Wright observed them for the first time in the gas phase. Another new technique I started with hvin Norman at that time was to trap radicals in glasses, so that they become permanently stabilized. This was a completely new idea as far as I was concerned. and it worked beautifully. I discovered later that G. N. Lewis had done somethima similar durina the war, but it hadn't been followed up. k t r i x isolatloi is now quite a well known and useful technbue. I wanted to fdlow UD all these ideas at that time and1 fen that a change of anvironment was necessary. h Research Association was Going to the ~ r k Rayon m s i b k a mistake. but it suited what I wanted to do. and it bmadeMd my experience of research. John Wilson, who was Director, gave encouragement to many scientists over many years. Bill Moffan was one of his pmteg& at that time. I went as depufy director, and I quickly learned that. if one is in an industrial concern, one's employers are enmed to practical resuits. In the long run the work which I started there,continued by ourselves and by many other people, has improved our understanding of why dyed plastics and f b r s degrade in sunlighc so the o@nal purpose of the appointment was justified. But I realzed that eventually the work would be too restrictive for me and I was only there for a year. Farago: h 1955 you went to Sheffield as Pmfessor of Physical Chemistry. What ideas did you have in mind whan you got there? There were many things I wanted to do. The University of Porter: Sheffleld had been founded in 1900, and it was a @, rather small university. 1was the first professor of physical chemistry, and the university, and the department of chemistry in particular, expanded enormously while I was there. R. D. Haworth contributed greatly to this and I was very much involved. As far as the research was concerned. I fen it was necessary to show how much wider me applications of flash photolysis were than those in use at that time. Many ma,br uses today are outside physical chemistw: the oraanic ohotochamists. biochemists.. .~ h o toblok&ts and so forth are increasin& finding the method valuable. At Sheffiakl we develoDed the technioue in a number of ways. and showed how if could be applied to o w n i c chemistry and biochemistry. We extended it into the vacuum u&iokt, to microbeam work and when, in 1960, the laser was discovered, I realized immediately that flash photolysis was going to be far more important than it had been, though it was a very long time before the laser did evatything that one needed for flash photolysis. Laser technology in Britain-or the absence and slowness of it-has bean one of the difficuities of this field; people working in America had very great advantages here: we had to buv most of our eauioment from America.. and aet . it rather later. We had, before the laser, realized of course that there were many things happening beyond the micro-
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second reg&. Potentially all we had to do was to get shorter flashes, and almost evetything else would follow. The laser has solved all these problems. This was begun at SheffieM, but it did not really take off until I came here, to the Royallnstitution. You.came here from an established Chair and a large research school to a place with a vast background of traditions and a very hlgh reputatation and very ilnle money. What made you come7 Sir La wrance Pragg, who was the Royal lnstiiution's director at ths time, invifad me to give some lectures here. I was soon doing it fairly regularly, so they made me a vidting professor, and than when Sir Lawrence retired I was invited to become Diractor. By this time I knew the RI extremely well. Sir Lawrence Bragg did not hUe any of the diffcufiies; he told me what they were, and it was a challenge. it seemed to me, and still does, a place worth a lot of effort and sacrifice, and worth preserving. Few things would distress me more as far as Great Britain is concerned than if it let the Royal lnstitution disappear. SheffieM had a very successful chemistry department; I think we had something of a record in the number of staff during that time who lefi to become professors at other universities. I did not feel that I was needed any more. Here in the Royal Institution the challenge still r& mains: it stlX has its difficuities, lergely financial. h these dfficuit times, when even universI% are suffarlng, you can imagine what it is tke for a charity that gets no government grant whatsoever to cover its overhead expenses. But my research is well supported, by tha Sciance Research Council in particular, and this is what miters most to me. When 1 started photochemistry it was very interesting, but it was a very small area of sclenca and had few applications-it was almost entirely an academic subject. fi is now an enormously broad subject, absolutely fascinating, with the widest possible implications. I am !dry lucky to have been a photochamist over the last 25 years and if I were starting again, I would still be a photochemist. Photochemistry is really the chemistry of the excited state. When I startedphotochemistryand physical chemistry one talked less about the excited state as a chemical species than about the free radicals and other products formed from if. Now, the thermodynamics, the kinetics and the structure of the excned state are the basis of ail our photophysical end photochemical work. The development of the tachniqms which have enabled us to look at the excited states directly has been very exciting. Flash photolysis is the most powerful of the lot: it is faster than any other. We can now go down to a picosecond, and we are beginning to think about time and resolution of a femtosecond. If we manage that, it is the end of chemistry: we shall have covered the whole of chemistry in the time scale, because the uncertainty principle tells us that in that time the uncertainty in the energy of the chemical bond we measure is as great as the energy of the bond itself. it has been very satisfying. There is a lot to do now, using these techniques, but what is now interesting me most is that photochemistry is at the basis of life-past present and future. The origin of ffe was largek photochemical. Today photochemical reactions are the source of our food and fossil fuels. i also hoid the vlew that our future, both from a food and an anergy point of view, may well have to depend largely on photochemistry applied to solar energy. The only aitarnative is nuclear energy, which certainly has ,Is problems, end it would be wise to have somathing else up our sleeves. All this fits together extremely wall and forms a vary broad canvas for my interests and my research. Wouldyou like to hazarda guess on the state of the art of photochemistry in five years' time?
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i WWld that within tive years we shall be doing experk ~ we shall ments in the femtwecond r e ; in 0 t h words, have reached the limit as far as time is concerned. it is now also realized that solar energy is potentially important and must be looked at, and i think therefore there wlX be immense acNvity and interest amongst ail photochemists in photowitaic and photogalvanic devices, and in photochemical reactions which use visible light and store energy. The main disadvantage of solar energy, in this country in particular, is that it is erratic, and therefore any really successful solar energy utilization must have storage. And this brings you to chemistry right away, because the only satisfactory way to store energy is chemically. You can store it mechanicaily by pumping water uphiii, but that is abouf all Better stin is to pmduce the fuel right away: to do what nature has done for us so we!/ over so many milI h s of years and produced our fossii fuels. They are running out: we are living on capital, and we must learn to live on income--solar energy income. So photosynthesis, not necessarily photosynthesis in the blohyicai sense, but photosynthesis of (let us say) hydrogen from water, or methanol, which is a suitable motor fuel, from carbon dioxide and water, is one of the great practical challenges of pmtochemistry. P h o t o c h e ~ h yis akeady the biggest manufacturing process of ail. Farego: Do your ideas imply that photochemistry has been and will increasingly be utifized in a muitidisoiplnary approach, to solve problems such as energy and f w d production? Porter: I am sure they do, aithough the multidisciplinary problems I have just outlined of pmducing a fuel from sunlight are essentiaily chemical. The main interdisciplinary aspect is that we shail learn, and we are learning a great deal by lwking at how nature does it; so we are working in c o k oration with botanists end biologists and biochemists, etc. in trying to find out the mechanism of photosynthesis: this is one of my main interests now. A vast amount of effoti has. over the last 30 years, gone into photosynthesis, but the primary processes which occur just afier the absorp tlon of light in about a billionth of a second are stiiia mystery. One of the main problems we are trying to resolve at the present time is how the light harvesting mechanism of the chloroplast works, and how we can cany it over 6& rectly to the dyestuff or whatever it is which we use to coliect the sunlght in the h s t place. it is a problem which has to be solved before we can get further. Farap: How do you see the hnwe of the Royalinstitutbn? The Ri is a research laboratory and it is of a viable size: Pwfec there are about 20 people in my research group, and it works very well. I think you do gain something from working in a place which has traditions, where such people as Oavy and Faraday and Young and Lord Rayieigh and the Braggs and Rumford and Dewar and others have worked. Providing that our research is supported adequately, we have the same facilities as a university, and our research is tied closely wifh that at University College London horn the point of view of students' degrees and so forth. One gets support for research work, much as a universify does: the support is for the project, fortuneterY, and the Science Research Council has been very helpful and has given me adequate support for this work. But of course the Royal institution has the other function of using its great theatre here, and its position in the center of London to continue b OWtradiiion, which is to tell peopieother scientists, laymen, and especially children-how exciting science is, how wonderfui it aii is, how important it aii is, and to do so as far as possible in an entertaining and elegant manner, with demonstrations and so forth. This I believe is a very i m m e n t thing to do, probabw m e im portant than ever in these days, and i regard our theatre here as the London repertory theatre of science: it is one of the oldest theatres in London, and certainly the only one in the worid of anything like ifs size andage which is wholly devoted to science and its exposition to the public. We
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have now 400 schoolchiwen here nearly every day dMng term. We are continuing very much h Un, tradnlon of Faraday and LJavy in this, wiih aii modern advantages such as television, and we have quite a close cooperation with the BBC. i am sure Michael Faraday would have appeared on television regularly. What shWM the scientist do to be able to communicate successfuily through the media which actuaiw exist7 I am not one of those who believe that every scientist should feel that he must communicate, as part of his duty, any more than every scientist should regard teaching as part of his duty. If he feeis he is not gocdat it, he is not interested in t or it interferes wiih his research, then he should not be blamed for not doing it. I hope that that wouid not be frue of the majority of scientists. How should one communicate? Every method of communication should be tried. One must not be too snobbish about using competition programs such as the "Young Scientist of the Year" Competition, which has been very successful, as long as one does not cheapen science in any way. Then you must make it as simple as possible. Some scientists seem to want to make it as compkated as possible to show how clever they are. But what one says must always be sound, and it must not cheapen science or destroy its integrity in any way. Wnh that one restriction, no hotds are barred, every method is worth trying. 00 you think the scientific community ought to appreciate the efforts at communication more than it does at the m ment? Yes i do. I think there is a resistance and a snobbishness in many scientists against those who try to communicate. Some scientists seem to have a feeling that one must not talk about anyihing but one's own work, and one musf tell the whole story or none. i think it is terribly important that there should be a better understanding of science, from many points of view: if people understwd the methods of science better, they might cany them over to their everyday lives and their politics. They would understand how difficuit it is to find the truth, and how important it is to cinC cize every step in an argument. t . is one reason why I believe science is worth getting over to the public, but aiso because ihe public are ihe people who are responsibie for science. We are toid that scientists have to be responsible, and of course they have, but the scientists' main responsibifityis to advise, to inform, and to communicate. The people must know what the problems arethey must understand something about science and technology because we ilve in a scientific and technokyicai worm, and decisions are made by politicians elected by these people. You conceive the role of the scientist in public life, the scientist in society, as a learned adviser rather than a leader? The trouble with scientists who become leaders, men of action, is that they cease to be scientists. There is a dichotomy here which is not resolvable uniass the scientist is merely an adviser. i don't think the scientist is more quafified to make decisions outside the scientific field than any other person of similar inteiligence and education, and there are weii qualified scientists who disagree heartily with other well quafified scientists on absolutely -amental issues. If you look back and then look forward, how would you imagine your nexi 20 years? I have really achieved all my ambhions as far as position is concerned. There is one ambition which you can never fuifii, and that is the ambition of discovering the truth, of increasing natural knowledge, because there is so much we don't know. So that i have infinite ambition remaining, and it is now almost exciusively in one area, and that is to improve natural knowiedge further: in other words, to continue with my research. i am happier being a photochem ist than being anyihing else and i hope this wili be true, still, in 20 years time. Voiume 52, Number 11, November 1975 / 705
