Herzberg, Gerhard (1904-)

German-born Canadian physicist who used spectrocopy to determine the electronic structure and geometry of molecules, especially free radicals (atoms or groups of atoms that possess a free, unbonded electron). Nobel Prize for Chemistry 1971. Herzberg was born in Hamburg and studied at the Technische Universität in Darmstadt, at Göttingen, and in the UK at Bristol. In 1935, with the rise to power of Adolf Hitler, he fled to Canada, where he became professor of physics at the University of Saskatchewan, Saskatoon, and director of the Division of Pure Physics for the National Research Council in Ottawa 1949-69. He spent 1945-49 at the Yerkes Observatory in Wisconsin, USA. Depending on the conditions, molecules absorb or emit electromagnetic radiation of discrete wavelengths. The radiation spectrum is directly dependent on the electronic and geometric structure of an atom or molecule. Herzberg discovered new lines in the spectrum of molecular oxygen; called Herzberg bands, these spectral lines have been useful in analysing the upper atmosphere. He also discovered the new molecules phosphorus nitride and phosphorus carbide; proved the existence of the methyl and methylene free radicals; and demonstrated that both neutrons and protons are part of the nucleus. In addition, Herzberg interpreted the spectral lines of stars and comets, finding that a rare form of carbon exists in comets. He showed that hydrogen exists in the atmospheres of some planets, and identified the spectra of certain free radicals in interstellar gas.