Mandelshtam, Leonid Isaakovich

Born Apr. 22 (May 4), 1879, in Mogilev; died Nov. 27, 1944, in Moscow. Soviet physicist; one of the founders of the school of Soviet radio physicists. Academician of the Academy of Sciences of the USSR (1929; corresponding member, 1928).

In 1897, Mandel’shtam entered Novorossiia University in Odessa but was expelled for participating in student riots. He continued his education in Strasbourg, where he specialized in the study of electromagnetic oscillations under C. F. Braun. In 1914 he returned to Russia. In 1922 he became a consultant at the Central Radio Laboratory in Leningrad, and 1925, a professor at Moscow University, where his work with G. S. Landsberg began.

Mandel’shtam’s series of lectures and seminars greatly raised the level of physics instruction in the university and provided training for many famous Soviet physicists. In 1934 he began working at the Institute of Physics of the Academy of Sciences of the USSR. His main works were in optics, theoretical physics, radiophysics, and electronics. In 1907 he was the first to prove that the scattering of light in optically homogeneous media is due to the occurrence of microinhomogeneities (fluctuations in density). In 1918 he predicted the appearance of the fine structure of the Rayleigh line (a similar theory was published in 1922 by L. Brillouin). This phenomenon was detected by Mandel’shtam and Landsberg in crystals and by E. F. Gross in liquids. In 1928, Mandel’shtam and Landsberg discovered the phenomenon of the change in frequency upon the scattering of light in crystals—the Raman effect—independently of C. Raman and K. S. Krishnan.

Together with N. D. Papaleksi, Mandel’shtam wrote fundamental works on the nonlinear theory of oscillations. He suggested a new method for exciting electric oscillations and in 1931 built the first AC parametric alternator with periodically changing induction. In 1938, Mandel’shtam and Papaleksi developed the radiointerferometry method for precise measurement of distances, which is used widely in geodesy, hydrography, and other fields. Mandel’shtam received the V. I. Lenin Award (1931), the State Prize of the USSR (1942), the Order of Lenin, and the Order of the Red Banner of Labor.