1904-

German-born, Canadian physicist who made significant contributions to a number of areas of science, including molecular spectroscopy, astrophysics, physical chemistry, and quantum mechanics. He is best known for his studies of the structure and geometry of free radicals for which he was awarded the 1971 Nobel Prize in chemistry. He determined the chemical composition of comets through spectroscopic studies, investigated chemical reactions in gases, and studied free radicals as intermediate agents in chemical reactions.