Evidence for 6d valence states in -U, UGa2, and UGa3 as revealed by resonant photoemission

We have studied -uranium, UGa2, and UGa3 with resonant photoemission. In agreement with Iwan, Koch, and Himpsel, we find for -U a 2-eV photoemission feature in the off-resonance spectrum at h=94 eV, which they have interpreted as a 5f shake-up satellite. In contrast, we show that this feature can be related to valence states of U because of (i) its sensitivity to O2 exposure and (ii) its occurrence in UGa2 and UGa3 at 1.4 eV, suggesting 6d valence-band emission as its origin. © 1985 The American Physical Society.