PIEZO-OPTICAL STUDY OF EXCITONS IN KI

The effects of a uniaxial stress along 〈001〉 or 〈110〉 direction on the excitonic structures of KI are studied between 5.5 and 7.5 eV at room temperature by a piezo-modulation technique. Stress dichroism leads to the conclusion that either the second or the third peak corresponds to a transition at the Γ point in the Brillouin zone forming a spin-orbit pair with the first exciton and the other to a transition at the L point. The fourth peak is ascribed to a transition at the L point with an overlaping one at the X point. © 1979.