In memoriam of Academician Alexander A. Kaplyanskii (14.12.1930 — 18.11.2022)
The International Advisory Committee of the Feofilov Symposium on the Spectroscopy of Crystals Doped with Rare-Earth and Transition Metal Ions announces with deep sorrow the passing away of Alexander Alexandrovich Kaplyanskii, Academician of the Russian Academy of Sciences, Head of the Laboratory of the Ioffe Physical-Technical Institute of the Russian Academy of Sciences, Professor, Honorary Doctor of St. Petersburg State University, Honorary Chairman of the Feofilov Symposium.
Academician A.A. Kaplyanskii is a well-known Soviet and Russian physicist, a specialist in the field of optical spectroscopy of solids. A series of his works is devoted to the study of excitons in semiconductors. He discovered the phenomenon of optical anisotropy of cubic crystals in the region of exciton resonance. He found out the splitting of lines of exciton transitions under the action of uniaxial elastic compression of crystals and the exciton structure in the photoconductivity spectra of semiconductors. He discovered the reversible splitting of the spectral lines of impurity spectra in crystals under the action of directed elastic deformation and developed a “piezospectroscopic” method for determining the local symmetry of impurity centers and point defects in crystals.
A.A. Kaplyanskii and his collaborators discovered and studied in detail the ferroelastic phase transition in a new class of dielectric crystals (mercury halides) with unique anisotropic properties.
In a series of works A.A. Kaplyanskii with co-workers studied by optical methods terahertz nonequilibrium phonons in crystalline and non-crystalline dielectrics and semiconductors, in systems with quantum wells, ceramics, fibers: modes of their propagation, scattering by defects, interaction with electronic levels of impurities and excitons, etc.
A.A. Kaplyanskii discovered the spontaneous formation of stable domains of a strong (~10 μV/cm) electric field under the action of optical excitation on impurity dielectrics, established the mechanism of anomalous photoelectric phenomena in ruby. He elucidated the role of the local inversion symmetry of impurity centers in the phenomenon of hole burning in the spectra of impurities.
In recent years, A.A. Kaplyanskii with his co-workers developed research on porous dielectrics, in particular, they observed non-equilibrium subterahertz acoustic oscillations of spherical nanoparticles and studied “photonic crystals”.
A.A. Kaplyanskii graduated from the Faculty of Physics of the Leningrad State University in 1953. After university, he was accepted into the graduate program at the Leningrad Physical-Technical Institute. In 1957, under the guidance of E. F. Gross, he defended his PhD thesis on the problem of detecting and studying the linear structure of the fundamental absorption edge of semiconductors associated with optical excitation of excitons. In 1967, he defended his doctoral dissertation on “Piezospectroscopy of crystals”. He headed the Laboratory of Solid State Spectroscopy at the Ioffe Physical-Technical Institute of the USSR (then Russian) Academy of Sciences. In 1987, he was elected Corresponding Member of the USSR Academy of Sciences; since 2003 — Academician of the Russian Academy of Sciences. Member of the St. Petersburg Scientific Center of the Russian Academy of Sciences. Editor-in-chief of the journal “Physics of Solid State”, member of the editorial board of the journal “Physics-Uspekhi” (Advances in Physical Sciences). Head of the branch of the Chair of Solid State Physics of the Faculty of Physics at the Ioffe Institute.
Winner of numerous awards for scientific achievements. Laureate of the Lenin Prize (as part of a group, 1966) for theoretical and experimental studies of excitons in crystals. Laureate of the State Prize of the USSR (1975) for a series of works on a new optical method for studying complex impurity centers and defects in crystals (1953–1972). He was awarded the Order of Honor (1999). Winner of the Alexander von Humboldt Prize (1997). Laureate of the A.F. Ioffe Prize (2008) for the series of works “Spectroscopic studies of photoelectric phenomena in crystals”. Awarded the Order of Friendship (2010). D. S. Rozhdestvensky Prize winner (together with A.K. Przhevuskiy and S.P. Feofilov, 2013) for the series of works “Spectroscopic studies of the structure of impurity centers and electronic processes in dielectrics containing rare-earth and transition metal ions “. Winner of the Petr N. Lebedev Gold Medal of the Russian Academy of Sciences (2021) — for the series of works “Photonic crystal opal-like structures: synthesis and studies of optical properties”.
The blessed memory of Alexander Alexandrovich Kaplyanskii will forever remain in our hearts.