Ivan Vasilyevich Obreimov (8.03.1894—2.12.981) was a Soviet experimental physicist and an academician (1958; corresponding member 1933). He was born in Annecy (France). He graduated from Petrograd University (1915). In 1919-24 he worked at the State Optical Institute, in 1924 — 29 at the Leningrad Physico-Technical Institute, in 1929 — 41 at the Kharkov Physico-Technical Institute (director in 1929 —32), in 1942—44 at the State Optical Institute, in 1944 — 54 at the Institute of Organic Chemistry of the USSR Academy of Sciences, in 1954-65 at the Institute of Organoelement Compounds of the USSR Academy of Sciences, and from 1965 at the Institute of General and Inorganic Chemistry of the USSR Academy of Sciences.
His research was in crystal physics, molecular spectroscopy, organic optics and optical engineering. He developed a method of growing single crystals from the melt (the Obreimov — Shubnikov method), methods of measuring refractive indices, and a method of determining dispersion over a wide spectral interval (the Obreimov method). He put forward (in the early 1920s) the idea that the structure of the spectrum of a molecular crystal is discrete at sufficiently low temperatures, and proved it (1928) by direct experiment on the spectrum of azobenzene. Subsequently (1930 — 41), together with A. F. Prikhotko, this idea was confirmed by a large body of spectral material, and the low-temperature spectroscopy of molecular crystals was begun. He built an all-quartz interferometer for low-temperature work and carried out a study of the diffraction of light at the edge of plane-parallel plates (USSR State Prize, 1946). He initiated (1948) research on the dispersion of light in molecular crystals. He carried out the first studies of the basic mechanisms of plastic deformation in crystals, the formation and development of slip bands and twins, and laid the foundations of the theory of the kinetics of dislocations. He built a number of spectral instruments.
He created a school of physicists (L. V. Shubnikov, A. F. Prikhotko, A. V. Stepanov, P. G. Strelkov, R. I. Garber, N. A. Brilliantov, V. S. Startsev and others). S. I. Vavilov Gold Medal (1959).