Electron momentum distribution in cadmium sulfide.

Abstract

The isotropic and the directional electron momentum distributions in cadmium sulfide are studied by Compton scattering technique. The isotropic Compton profile has been measured from a polycrystalline CdS (wurtzite structure) sample and the directional profiles from the planes (0001) and (101\ifmmode\bar\else\textasciimacron\fi{}0) of single crystals, using 59.537-keV \ensuremath{\gamma} rays. The spherically averaged and directional ([0001], [101\ifmmode\bar\else\textasciimacron\fi{}0], and [112\ifmmode\bar\else\textasciimacron\fi{}0]) Compton profiles have been calculated with use of linear combinations of atomic orbitals based on the symmetrical orthogonalization method. The experimental isotropic profile is found to be in quite good agreement with the theoretical one calculated with use of wave functions for free ${\mathrm{Cd}}^{2+}$ ion and ${\mathrm{S}}^{2\mathrm{\ensuremath{-}}}$ ion in a spherical potential. The experimental and the calculated anisotropies are found to be in disagreement. The present calculational method is suitable for ionic solids, but our results for CdS reflect the need to take into account the partial covalent nature of the bonds between Cd and S.