Optical Constants and Excition States in KCl Single Crystals. III. The Spectra of Conductivity and of Energy Loss

Abstract

The spectra of conductivity σ( E ) and of energy loss Im{ ε ( E ) ^-1 } of KCl single crystals are studied as functions of temperature of the ranged of 10°K to 573°K in the intrinsic region to 12 eV. It is shown that σ( E )-spectra in the chlorine doublet region can be decomposed in the whole range of temperature into the two components of asymmetric Lorentzian from with positive degree of asymmetries. This allows the study of the temperature dependences of those quantities which are characteristic of an asymmetric Lorentzian function, and the derivation of the mean energy values of various kinds of phonons effective to each of the above quantities, thus leading to an increasing recognition of an importance of exciton-phonon interaction in the process of photon absorption. The oscillator strength of chlorine doublet is estimated as a whole as 0.56±0.09. The oscillator strength of the higher energy component of this doublet is found to increase linearly with increase in temperature accompanying the compensating decrease in the oscillator strength of the lower energy component, indicating the interband interaction. A tentative interpretation is given on the spectrum in the region up to 13.4 eV.