Nobel Prize Recipient. He was a German-born American physicist, who received professional recognition after being awarded the 1925 Nobel Prize in Physics, sharing the coveted award with Gustav Hertz. The two scientists received the award according to the Nobel Prize committee, "for their discovery of the laws governing the impact of an electron upon an atom." He actually received the award in 1926. Born into a Jewish household, he began his academic career at the University of Heidelberg, where he studied chemistry, and then moved to the University of Berlin, to study physics, where he received his Ph.D. in 1906. He briefly worked at the University of Frankfurt am Main and then returned to Berlin as a Privatdozent in 1911 and was named full professor in 1916. During this time in Berlin, he worked with Hertz on inelastic electron collisions in gases that led to the award of the Nobel Prize in Physics. He volunteered for World War I and was injured in a gas attack in 1917 while working with Fritz Haber's chemical warfare battalion, and was awarded the Iron Cross First Class. In 1920, he was named Professor of Experimental Physics at the University of Göttingen. With his student Edward Condon, he developed the Franck-Condon Principle in quantum mechanics. In 1933, with the rise of the Nazi Party and their antisemitic agenda, he raised an uproar by resigning from his post with his Jewish background, though he was semi-protected due to his veteran status. In the same year, he escaped the politics of the Nazi Regime to the United States as a full professor at Johns Hopkins University in Baltimore, which had a new laboratory furnished by the Rockafeller Foundation, and then to the University of Chicago in 1938. He became a naturalized United States citizen on July 21, 1941. While at Chicago, he was tapped to be the head of the metallurgical laboratory in the Manhattan Project and worked on the construction of the plutonium atomic bomb. With the surrender of the Nazi Forces on May 7, 1945, he had second thoughts concerning the use of the atomic bomb, and in June of 1945 he approached the United States Secretary of War with the Franck Report, in which he and other scientists recommended against the use of the atomic bomb on Japan. The atomic bomb was dropped on Japan that August. After the war, he changed the focus of his research to photosynthesis, as he was upset by the use of the bomb in World War II. His research met with the "Warburg controversy", which centered on the quantum yield of photosynthesis and after years of research, was resolved after his death. He became Emeritus Professor in 1947 and was awarded the Max Planck Medal in 1951 and the Rumford Prize in 1955, the latter for his photosynthesis work. His research declined starting in 1959 with his unreliable health situation. He married twice: First in 1907 Ingrid Josephson, a Swedish pianist, who died in 1942 after a long illness. The couple had two daughters. His second wife was Hertha Sponer. He died suddenly of a heart attack while on a visit to Germany, but his remains were repatriated to Chicago and buried next to his first wife. A huge collection of his professional papers is archived at the library at the University of Chicago.