Jerome Karle (born June 18, 1918, Brooklyn, New York, U.S.—died June 6, 2013, Annandale, Virginia) was an American crystallographer who, along with Herbert A. Hauptman, was awarded the Nobel Prize for Chemistry in 1985 for their development of mathematical methods for deducing the molecular structure of chemical compounds from the patterns formed when X-rays are diffracted by their crystals.
Karle was a classmate of Hauptman’s at City College in New York, from which they both graduated in 1937. Karle went on to earn a Ph.D. degree in physical chemistry at the University of Michigan in 1943. After working on the Manhattan Project in 1943–46, he joined the Naval Research Laboratory (NRL) in 1946, becoming in 1967 its chief scientist for research on the structure of matter; he retired in 2009.
After World War II, Karle and Hauptman began collaborating at the NRL on the study of crystal structures. The two men devised mathematical equations to describe the arrangements of numerous spots that appear on photographic film as a result of a crystal’s diffraction of X-rays. Their equations enabled the location of atoms within the crystal’s molecules to be pinpointed on the basis of an analysis of the intensity of the spots. After their method was published in 1949, it suffered neglect for some years until Karle’s chemist wife, Isabella, pointed out its potential applications. Gradually, crystallographers began to utilize the method to determine the three-dimensional structure of thousands of small biological molecules, including those of many hormones, vitamins, and antibiotics. Before Karle and Hauptman developed their method, it took two years to deduce the structure of a simple biological molecule; in the 1980s, using powerful computers to perform the complex calculations demanded by their method, the task took about two days.