Electronic structure ofX2ZrSn- andXZrSn-type Heusler alloys withX=Coor Ni

X-ray photoemission spectroscopy (XPS) measurements have been performed on the intermetallic compounds ${\mathrm{Ni}}_2\mathrm{ZrSn},$ ${\mathrm{Ni}}_x{\mathrm{Zr}}_{1-x}\mathrm{Sn},$ ${\mathrm{Co}}_2\mathrm{ZrSn},$ and ${\mathrm{Co}}_x{\mathrm{Zr}}_{1-x}\mathrm{Sn}.$ The XPS valence bands show a small density of states at the Fermi level, and the position of Co and $\mathrm{Ni}d$ states below this energy. The core level XPS spectra are shifted in comparison with the respective spectra of the pure elements suggesting a redistribution of charge between atoms. XPS valence bands have been compared with total density of states distribution curves by the use of spin-polarized linear muffin-tin orbital calculations.