UV inverse photoemission study of the empty density of states of the dihydrides of yttrium, lanthanum and cerium☆

Abstract We present UV-BIS spectra ( hv = 9.7 eV) of YH 1.9 , LaH 1.8 and CeH 2.1 . These compounds are metallic and they exhibit a non-vanishing density of states at E F . Two weak, d-derived structures around 1.0–1.5 eV and 2.5–3.0 eV above E F are observed as common features. In the LaH 1.8 spectrum a prominent peak is seen at 5.2 eV. Because the cross section for transitions into empty 4f states is very small at this low photon energy we believe that these are states with considerable 4f-valence band mixing. A relation to earlier core level results is briefly discussed.