George S. Hammond

George Simms Hammond (May 22, 1921 to October 5, 2005) was an American theoretical chemist born in Auburn, Maine, who studied under Paul Doughty Bartlett and taught at Iowa State University, Caltech, and the University of California, Santa Cruz. He is remembered for Hammond's postulate, a principle describing the structure of the transition state in a chemical reaction, and for research that helped establish organic photochemistry, the study of how molecules react when they absorb light, as a field in its own right. He later served as executive chairman of the Allied Chemical Corporation from 1979 to 1989, and he received the Priestley Medal in 1976 and the National Medal of Science in 1994.