Valence-band photoemission in UO 2 (111) near the 5d resonant photon energy
1987; American Physical Society; Volume: 35; Issue: 11 Linguagem: Inglês
10.1103/physrevb.35.5761
ISSN1095-3795
AutoresL. E. Cox, W. P. Ellis, Robert D. Cowan, J. W. Allen, S.-J. Oh, I. Lindau, Bradford B. Pate, A. J. Arko,
Tópico(s)Radioactive element chemistry and processing
ResumoPronounced Fano-like resonant effects are observed in the photoemission spectra of the localized U 5f and O?p ndash---U?f,6d--- bonding bands of ${\mathrm{UO}}_{2}$ when photon energies near the U 5${d}_{3/2}$,5/2 thresholds (105 and 97.1 eV, respectively) are employed. The constant-final-state spectra are well described by calculated transition energies and oscillator strengths for the 5${d}^{10}$5${f}^{2}$${\ensuremath{\rightarrow}}^{h\ensuremath{\nu}}$5${d}^{9}$5${f}^{3}$ process; also, the decay rates of the intermediate-state multiplets are in qualitative agreement with the observed width of the spectral features. Distinctly different constant-initial-state (CIS) spectra are obtained at the intensity maximum of the U 5f photopeak and at the minimum between the 5f peak and the O 2p bonding band. Calculated decay rates indicate that this results from variations in the branching ratio for decay of intense intermediate-state multiplets into $^{2}\mathrm{F}_{5/2}$ and $^{2}\mathrm{F}_{7/2}$ final states. Resonant effects in the O?p ndash---U?f,6d--- bonding band show the bonding participation of U orbitals; moreover, the higher intensity of the CIS spectrum obtained near the top of the bonding band agrees with band-structure calculations showing most of the U 5f character in this region.
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