Piezoreflectance Study on the Electron-Hole Exchange Interaction of the Γ Excitons in KBr

Abstract

Piezoreflectance spectra of KBr have been measured at room temperature in the photon energy range from 5.0 to 7.6 eV in order to investigate the effects of the electron-hole exchange interaction on the spin-orbit split Γ excitons. From the dichroism due to the stress-induced splitting of the excitons and also from their energy difference and intensity ratio in an unstressed crystal, the exchange energy is determined to be 0.07 eV, about one-fourth of the magnitude reported earlier. The piezospectrum calculated with the value is in good agreement with the experimental one.