Piezoreflectivity Studies of Rb⁺4pCore Excitons in RbBr

Measurements were made to obtain piezoreflectivity spectra of Rb + core excitons in RbBr under a stress along the [011] direction at room temperature. From the dichroism of the spectra, trigonal deformation potentials of structures located at 16.1, 16.5, 17.0, 17.4 and 18.2 eV are determined to be -0.17, -0.48, -0.57, -0.09 and 0.34 eV, respectively. Those deformation potentials are in good agreement with values calculated from the localized excitation model for the core excitons proposed by Satoko and Sugano. It is concluded, therefore, that the excitons located at 16.1and 18.2 eV are mainly of the (4 p ) 5 (5 s ) and (4 p ) 5 (4 d γ) characters, respectively, and that the localized excitation model is useful in the analysis of the core excitons.