APPLICATION OF POLARON MODEL TO F' CENTER

An approach for calculating the effects of electronic and ionic polarizations on a simple two-electron center such as the F' center is developed from the polaron model of electron-excess color centers. This approach and that described in a more recent work are applied to the study of effects of electronic and ionic polarizations on F′ centers in KCl, KBr, and NaCl. From the comparison of the obtained theoretical results with experimental results of F′ bands, we discuss which approach is more appropriate in treating the effects of crystalline polarization on the system of two trapped electrons. In addition, the possibility that the F′ center in a typical alkali halide has a weakly bound excited state to which the optical transition can be made is shown. The wave functions and optical absorptions of F′ centers in KCl, KBr and NaCl are also discussed. © 1969.