Photoemission study of the electronic structure of Am, AmN, AmSb, and Am2O3 films -: art. no. 115122

Thin films of Am, AmN, AmSb, and Am2O3 have been prepared by sputter deposition. Their electronic structures have been studied by x-ray and ultraviolet photoelectron spectroscopy (XPS and UPS, respectively). Care has been taken to achieve high-purity Am films. While the Am UPS spectrum reveals the presence of a conduction band, practically no such signature appears in the spectra of AmN, AmSb, and Am2O3, categorizing the later compounds as semiconductors or insulators. We present a consistent explanation of the peak structures in both the 5f valence-band and 4f core-level spectra in terms of final-state screening channels. In all four Am systems, we find the 5f electrons to be largely localized. The XPS core-level spectrum of Am metal indicates some residual 5f hybridization, which is substantially suppressed in AmN, AmSb, and Am2O3. We observe nearly no difference between the AmN and AmSb and Am2O3 spectra suggesting a similar 5f configuration, even though, in general, nitrides and antimonides are more covalent than oxides. The measured photoemission spectra are consistent with a 5f (6) ground-state configuration for all four systems.