The dispersion of the Gd (5d6s)-valence bands has been investigated by mean
s of spin- and angle-resolved photoemission. The spin analysis of various s
pectral features shows that their weak dispersion and unusual broadening is
due to the photoelectron lifetime rather than to correlation induced band
narrowing as previously proposed. These results resolve a long-standing dis
crepancy between theoretical and experimental descriptions of the rare eart
h band structure.