Richard Ernst: The Tool-Maker of Modern Chemistry
Somewhere over the Atlantic in October 1991, a Swiss chemist was invited forward into the cockpit of an airliner and handed a radio message: he had won the Nobel Prize in Chemistry. It was an oddly fitting delivery for Richard Ernst, a man whose entire career consisted of building the instruments through which other people would see. He never claimed more for himself than that. He described himself, disarmingly, as a "tool-maker" rather than a scientist — which understated by some distance what his tools made possible.
A Winterthur Childhood, and an Uncle's Chemicals
Ernst was born on 14 August 1933 in Winterthur, Switzerland, to Robert Ernst and Irma Ernst-Brunner. He grew up in a house his grandfather, a merchant, had built in 1898 — the kind of solid Swiss continuity that tends to produce either conformists or people who quietly do something strange in the attic. Ernst did the latter. At thirteen he discovered a chemistry collection left behind by a late uncle and began working through it with more enthusiasm than caution, producing explosions that alarmed his parents.
The other passion arrived earlier and never left. He played the cello and for a time considered composition as a career. The two interests were less opposed than they look: both are exercises in resolving complex superimposed signals into something the ear or the eye can read, and Ernst would spend his professional life doing precisely that with the frequencies emitted by atomic nuclei.
ETH Zurich
He took his diploma in chemistry at ETH Zurich in 1957, qualifying as a Diplomierter Ingenieur Chemiker, and stayed for a doctorate in physical chemistry, completed in 1962. The dissertation was on nuclear magnetic resonance — the phenomenon by which atomic nuclei placed in a magnetic field absorb and re-emit radio waves at frequencies that betray their chemical surroundings. In principle NMR could reveal the structure of any molecule. In practice, in 1962, it was agonisingly insensitive: samples had to be large, measurements slow, and anything dilute or complicated — which is to say, anything biological — was out of reach.
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In 1963 Ernst joined Varian Associates in California as a scientist, and there produced the innovation that changed the field. Conventional NMR swept slowly through frequencies one at a time. Ernst's approach was to strike the sample with a short pulse that excited all frequencies at once, then use Fourier transformation to unpick the resulting jumble of overlapping signals into a spectrum. The gain in sensitivity was enormous. Experiments that had been impossible became routine; molecules that had been invisible because they were present in only trace quantities became legible. At Varian he also developed noise decoupling techniques, another means of cleaning up crowded spectra.
Fourier transform NMR is the reason chemistry today can determine the structure of an unknown compound in an afternoon rather than a season, and it is the direct ancestor of magnetic resonance imaging, the technology that turned the same physics into a way of looking inside a living human body without cutting it open.
The Second Dimension
Ernst returned to ETH Zurich in 1968 as a lecturer, became assistant professor in 1970, associate professor in 1972 and, in 1976, Full Professor of Physical Chemistry. He directed the Physical Chemistry Laboratory and there developed the second great advance of his career: two-dimensional NMR, together with a suite of novel pulse techniques.
If Fourier transform NMR made spectra faster, two-dimensional NMR made them intelligible. By spreading the information across two frequency axes, Ernst's methods disentangled spectra that were hopelessly congested in one dimension and, crucially, revealed which nuclei were coupled to which — that is, which atoms sat near which. That is structural information. It is what allowed NMR to move from small molecules to proteins and nucleic acids, and it is why structural biology today has two great methods rather than one.
The Nobel Prize and the Honours That Followed
The 1991 Nobel Prize in Chemistry was awarded to Ernst alone, "for his contributions to the development of the methodology of high resolution nuclear magnetic resonance (NMR) spectroscopy" — an unusually plain citation for an unusually consequential body of work.
The rest arrived in sequence: the Marcel Benoist Prize in 1985, the John Gamble Kirkwood Medal in 1989, and in the Nobel year itself both the Wolf Prize in Chemistry and the Louisa Gross Horwitz Prize. He received the Tadeus Reichstein Medal in 2000 and the Order of the Star of Romania in 2004, and was elected a Foreign Member of the Royal Society in 1993. He held honorary doctorates from six institutions and belonged to the US National Academy of Sciences, the German National Academy of Sciences Leopoldina, the Russian Academy of Sciences, the Korean Academy of Science and Technology, the Bangladesh Academy of Sciences and, from 2002, the Estonian Academy of Sciences as a foreign fellow.
Tibetan Scrolls and Retirement
Ernst retired in 1998, but the tool-maker's habit did not. He was a serious collector of Tibetan scroll art, and rather than admiring it passively he turned his own instruments on it, analysing the pigments to determine where the paints had come from and how old the scrolls were. Music and art remained the counterweight to the laboratory throughout his life.
He married Magdalena Kielholz, and they had three children: Anna Magdalena, Katharina Elisabeth and Hans-Martin Walter.
Winterthur, 2021
Richard Ernst died on 4 June 2021 in Winterthur, the town where he was born, at the age of eighty-seven. His instruments outlived him in every chemistry department and every hospital radiology suite on earth — a rather large legacy for a man who insisted he only made the tools.
