Electronic Structure of Excitons in KCl

Abstract

The electronic structure of exciton in KCl is analyzed using the valence band structure and wave function of Howland and the effective mass and the wave function of the conduction band calculated by the authors. The effective mass formalism gives 1.1 and 0.28 eV for the binding energies of 1s- and 2s-excitons, respectively. The effect of valence band warping is found to make the J=2 states to interact with the J=1 states and thus to reduce the spin-orbit splitting. This effect is small in the case of Γ₁-exciton in KCl because of small effective mass of the conduction electron. Short range electron-hole exchange interaction estimated from the band wave functions gives a reasonable ratio of intensities of higher and lower energy components for both n=1 and n=2 halogen doublets. Also calculated spin-orbit splittings for n=1 and n=2 states are in good agreement with experiment. The total oscillator strength of this doublet is found to be 0.15.