The p-d hybridization of the valence bands of copper indium disulfide has been studied by photoreflectance. A simple model has been used to measure the separation E between the p and d levels, the interaction strength M between these levels, the d-electron contributions x0 to the E0 energy level, and x1 to the E0 + DELTA-0 energy level. Our results confirm that the d-electron contributions decrease when the temperature is increased. Our measurements of x0 and x1 agree with the calculation of Yoodee et al.
