Momentum-dependent effects in 4fphotoemission spectra from strongly correlatedCeBe13

We have studied the mixed-valent compound ${\mathrm{CeBe}}_{13}$ using a combination of high-resolution angle-resolved resonant photoemission and x-ray absorption. Based on the angle and temperature dependence of the intensity of the ${\mathit{f}}^1$ peak at the Fermi level, we conclude that the 4f state is most likely a narrow band with a bandwidth of ∼50 meV, and may cross the Fermi level. The temperature dependence of the valence band photoemission spectroscopy can be accounted for by conventional thermal broadening effects. A mean valence of v∼3.04 is extracted from ${\mathit{M}}_{4,5}$ absorption spectra which agrees with ${\mathit{L}}_{\mathrm{III}}$ edge measurements, however the temperature dependence is negligible. A large amplitude anisotropy is observed in the ${\mathit{f}}^0$ peak, as well as about 0.1 eV of dispersion. Residual gas dosing in the submonolayer regime suggests that much of the ${\mathit{f}}^0$ intensity is surface related. © 1996 The American Physical Society.