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In just one month in the 1950s, Rudolph (Rudy) Marcus worked out the theory that for which he became famous. The Marcus theory of electron transfer predicts the rate at which an electron jumps from one molecule to another. This process is fundamental to molecular reactions, biological processes such as respiration and photosynthesis, and the functioning of devices including batteries. He received the Nobel Prize in Chemistry for this insight in 1992.
Marcus’s hallmark was his ability to develop simple equations and models that could capture the essence of messy molecular phenomena. Describing research as “a wonderful way of life”, he continued his scientific investigations with infectious enthusiasm past his 100th year. He has now died aged 102.
Marcus was born on 21 July 1923 in Montreal, Canada, a descendant of Lithuanian Jews. He enjoyed school and was encouraged in intellectual pursuits by his mother, a gifted pianist and singer. His father was a businessman with a love of sports, a passion that Rudy shared.
At McGill University in Montreal, which applied a ‘Jewish quota’ to students at the time, he studied chemistry. He was also fascinated by mathematics and took advanced classes in the subject.
Marcus started his research career as an experimentalist. After a PhD based on wartime research into the chemical behaviour of explosives, he joined Canada’s National Research Council facility in Ottawa. There, between breaking glassware and mopping up spilt mercury — an experience he nonetheless credited with his taste in problems in theoretical chemistry — he taught himself theory. This convinced him that his future lay in applying maths to chemical phenomena.
When he received an offer to work with the theoretician Oscar Rice at the University of North Carolina at Chapel Hill, Marcus moved to the United States with great excitement to start a new scientific life. It was to be a new life in other ways, too: he met his future wife, Laura, shortly after moving there.
Marcus’s work on electron transfer began in the 1950s, at the Polytechnic Institute of Brooklyn in New York. Researchers were trying to understand what governed the rate of certain reactions involving the transfer of a single electron between molecules.
Marcus recognized a key point: that the atoms around the molecules would have to rearrange into a configuration that allowed the electron to hop without violating the conservation of energy. He developed a simple formula to predict the rate of reaction (R. A. Marcus J. Chem. Phys. 24, 966–978; 1956).
Confirmation of this formula came from interactions with experimentalists, such as Norman Sutin, from whose data Marcus could show agreement between theoretical and measured transfer rates. Recognition of its importance followed rapidly and the work garnered wide acclaim.
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