Norman Greenwood (1925-2012) was born in Australia and graduated from Melbourne University before going to Cambridge. His wide-ranging research in inorganic and structural chemistry made major advances in the chemistry of boron hydrides and other main-group element compounds. He also pioneered the application of Mössbauer spectroscopy to problems in chemistry. He was a prolific writer and inspirational lecturer on chemical and educational themes, and held numerous visiting professorships throughout the world.
Rolfe was doing it, Goldanskii was using it in Moscow, and after I came back from this Gordon Conference, I immediately wrote an application to SRC [Science Research Council] for this totally new concept, there was no one in England had applied for it before, I think someone… I think Charles Johnson in Harwell was doing a physics experiment on this. He was testing Einstein’s gravitational theory with it, but in terms of chemistry, no one had put in an application, no one on the selection committee, apparently, knew anything about it, but they knew it was novel, and they knew that Mössbauer had just got a Nobel Prize, so it was worth supporting.
And, in fact, what Mössbauer had discovered was a totally new form of spectroscopy which gave gamma rays of unprecedented precision, so that you could see minute effects... the effects of chemistry on the nucleus. Chemists traditionally learn that radioactivity is independent of the chemical compound. That’s only true to a first approximation. If you look precisely with this enormously closely defined gamma ray, monochromatic, you can detect changes. If a compound is formed, the s-electron density in the nucleus is altered, minutely, and that is what it monitors.
But it does more. Not all nuclei are spherical. Some of them are oblong-shaped. So they would have a quadrupole moment, the positive charge of the nucleus is not just a spherical blob, it is football shaped, so it would have a quadrupole moment. Depending on which way that is aligned to the gamma ray, you will get a quadrupole splitting, depending on what the nuclear spins are. And also if the compound is magnetic. In iron, typically, you get a 6-membered peak, with the intensity ratios 3, 2, 1, 1, 2, 3. So you have an enormously powerful way of looking at things.
Title: The use of Mössbauer spectroscopy in chemistry
Professor Brian FG Johnson FRS, FRSE, FRS Chem, FAcad Eu, FAS. Professor of Inorganic Chemistry University of Edinburgh 1991-1995, Professor of Inorganic Chemistry University of Cambridge 1995-2005, Master Fitzwilliam College Cambridge 1999-2005. Research interests include studies of transition metal carbonyls, organometallic chemistry, nano- particles and homogeneous catalysis. Professor Johnson is the author of over 1000 research articles and papers.
Moscow, Science Research Council, UK, Atomic Energy Research Establishment, Harwell, Nobel Prize in Physics, Mössbauer spectroscopy, Rolfe Herber, VI Goldanskii, Charles Johnson, Rudolf Mössbauer