Energy distribution spectra of photoelectrons excited by monochromatized $\mathrm{Al} K\alpha$ radiation (XPS) from the valence bands of the ${\mathrm{Mg}}_{2}X$ semiconductors are presented. The results are compared with calculated densities of valence states obtained from parametrized tight-binding bands. The nearest-neighbor interaction parameters are determined so as to obtain theoretical total densities of valence states which fit the experimental XPS spectra and partial densities of states which agree with soft-x-ray emission data. The upper, $p$-like valence bands so determined agree well with the empirical pseudopotential calculations of Au-Yang and Cohen while discrepancies appear for the lower $s$ bands. The parameters of the tight-binding model are compared with those reported recently by several authors for the elemental semiconductors.

• Received 23 February 1976

DOI:https://doi.org/10.1103/PhysRevB.14.2559