Compton profiles of lutetium and lutetium dihydride

Compton profiles for polycrystalline Lu and Lu${\mathrm{H}}_{2.05}$ have been determined by Compton scattering of 320-keV photons from a ${}_{}{}^{51}{}_{}{}^{}\mathrm{Cr}$ source. The profiles for pure Lu have been corrected for multiple scattering and compared to a renormalized-free-atom model for the conduction electrons. The Compton profile for metallic Lu suggests an electronic configuration close to $5d^{1}6s^2$. A model for the dihydride based on a band-structure calculation by Switendick in which a new band of antibonding hydrogen wave functions accommodates the two extra electrons per Lu${\mathrm{H}}_2$ explains the experimental Compton profile in a satisfactory way.