Influence ofkconservation in ultraviolet isochromat spectra from Ni

Calculations of ultraviolet isochromat spectra have been performed using a direct transition model including momentum matrix elements. The results compare favorably with newly presented normal-incidence $k$-resolved inverse-photoelectron spectra on Ni(100) and earlier inverse-photoelectron-spectroscopy (angle-integrated) data on Ni. Density-of-states models, by contrast, are insufficient.