May 2, 1922–June 18, 1989

BY C. BRADLEY MOORE

GEORGE PIMENTEL WAS AN INTENSE man with a contagious enthusiasm for science, teaching, sports, and all things new and challenging. He was a master of empirical physical models. Pimentel was always looking for the biggest challenges and for truly new phenomena. He was not easily discouraged. When a small spot on his retina kept him from becoming one of the first scientist astronauts, he built a new kind of infrared spectrometer to go look at Mars. In every aspect of his professional life he attacked the big problems head on, and yet at the personal level he always made time to bring along a student or help a friend. He was an enthusiastic and competitive sportsman. His level of exertion and commitment was at least the maximum possible in everything that he did.

George Pimentel’s research has had a profound effect on chemistry.¹ The common thread of his research was a desire to understand unusual chemical bonding situations and their consequences for structure and chemical reactivity. The information he obtained on marginal species, on chemical reactions, and on photochemical processes is a key part of the base upon which our understanding of chemical reactions and molecular structure is founded. His fearless