X-Ray Photoelectron Study of the Valence Bands in Cuprous Halides

X-ray photoelectron spectroscopic measurements show that the valence bands of cuprous halides are composed of two separate bands. The transition matrix elements are taken into account in the analysis of the spectra based on the tight-binding approximation for the valence band. It is found for CuCl that the major part of the upper band arises from the $3d$ state of copper and the major part of the lower band from the $3p$ state of chlorine.