Obituary of Karl Rebane

On November 4, 2007, Dr. Karl K. Rebane, 81, died after a short illness. Dr. Rebane was a scientist internationally known for investigations of zero phonon lines and electron-vibration interactions in the spectra of defects in crystals, and served as Professor Emeritus of the Tartu University, former Director of the Institute of Physics in Tartu and President of the Estonian Academy of Sciences (EAS). Dr. Rebane received a PhD in Solid State Theory in 1955 from the Leningrad (St. Petersburg) University and a Doctor of Science degree in Theoretical Physics in 1964 from the Institute of Physics of the Belarusian AS at Minsk. He joined Tartu University in 1955 where he held both teaching and administrative positions, including Professor and Chair of the Experimental Physics Department (1958-60), and Professor and Chair of the Joint Department of Laser Optics at the Institute of Physics and Tartu University (1974-1993).

In 1956, Dr. Rebane began his life-long research appointment with the Institute of Physics and Astronomy (IPA), and later, with the Institute of Physics of the EAS. In the Estonian Academy of Sciences he served in various positions including Vice-President (1968-1973), and President (1973-1990). His scientific interests and vision in combination with his administrative talents led to the establishment in 1973 of the Institute of Physics of the EAS in Tartu, where he served as its first director from 1973 to 1976.

Dr. Rebane taught many important courses at Tartu University including all basic courses in Theoretical Physics. His very clear understanding of the subject made him a very good teacher and a graduate student adviser. Many of his former students became the core of the Solid State Theory Department and the Laser and Solid State Spectroscopy Laboratories at IPA and, later, at the Institute of Physics.

Dr. Rebane’s research included pioneering investigations in several areas of optical spectroscopy of solid states. He and his students and coworkers developed a theory of optical spectra of impurities in solids based on interaction of optical electrons with lattice vibrations, and with the vibrations of impurities and impurity-induced modes. He was particularly interested in the appearance of very narrow zero phonon lines in low temperature spectra of solids (optical analog of the Mössbauer effect), which he called a beautiful phenomenon and which formed a basis for the later development of high resolution selective spectroscopy and single-molecular spectroscopy of impure solids. This theory was successfully applied to explain the multiple line structure (Shpol’skii effect) in low-temperature spectra of matrix-isolated organic molecules. He presented the results of his group’s research in the text Impurity Spectra of Solids: Elementary Theory of Vibrational Structure (first published in Russian, and later translated into English). This book became an essential textbook for graduate students and young scientists on the spectroscopy of crystals. He and his coworkers made substantial contributions to the theory of the vibrational relaxation in optical emission and provided a unified description of optical emission as a secondary emission which includes luminescence, scattering and hot luminescence. Other areas of his broad research interests and contributions were Mössbauer spectroscopy, persistent spectral hole-burning and its application to high resolution spectroscopy and frequency-domain optical storage, time-and-space holography, single-molecule spectroscopy, applications of high resolution spectroscopy to DNA sequencing studies, and energy and entropy in ecology.

Dr. Rebane was a Member of the Estonian Academy of Sciences, the Russian (former USSR) Academy of Sciences and several international Academies. In addition, Dr. Rebane was honored with many awards including the USSR Academy of Sciences Lebedev Gold Medal in 1981. He was the author or co-author of about 300 scientific papers and five books. He was active in several national and international scientific organizations and served as a member of the Council and the Executive Committee of European Physical Society in 1977- 1986 and as Vice-president of the International Commission for Optics in 1989-1991. He was one of the organizers of series of US-USSR Bi-National Symposia on optical phenomena (1975-1990) which helped to move forward and to improve scientific relations between the US and the (then) Soviet science community. This led to many important collaborations, a number of which continue to this very day.

While serving in high-rank administrative positions in the repressive system of the former USSR, Dr. Rebane was able to keep his decency and independence. We will sorely miss him personally and professionally. His legacy is the scientific work he did, the Institute he built, and many of us will long treasure his memory.