Brillouin, Leon

French-American physicist and son of Marcel Brillouin (1854-1948) and Charlotte Mascart, who was herself the daughter of E. Mascart (1837-1908), a well-known French physicist of the 19th century. Léon Brillouin was educated at the École Normale Supérieure (1908-1912), as was his father before him. He was professor at the Sorbonne (1928), and subsequently professor at the College de France (1932-1949), again following his father's footsteps.

During the war, Léon Brillouin emigrated to the United States, where he became a professor at the University of Wisconsin (1941) and Harvard (1946). He became an American citizen in 1949, was appointed director of Electronic Education at IBM (1948-53), and was elected a member of the National Academy of Sciences in 1953. From 1953 to his death in 1969, he was a professor at Columbia University in New York City.

Léon Brillouin specialized in quantum mechanics, and developed the BWK method of approximating solutions to the Schrödinger equation in 1926. He discovered the famous "Brillouin zones" of solid state physics, which are named in his honor. During his career, he authored more than 200 papers (his biography lists 212 of them) and about 15 books.