FEFF analysis of americium oxides.

The Am N_4,5 (4d_3/2 and 4d_5/2) and Am O_4,5 (5d_3/2 and 5d_5/2) x-ray absorption spectroscopy (XAS) of americium sesquioxide (Am₂O₃) and americium dioxide (AmO₂) has been evaluated with FEFF, a Green's function–based, multiple scattering code. Taking guidance from the intermediate coupling model (ICM), applicable to local and nonmagnetized samples, it is possible to completely reconstruct the experimental results for the N_4,5 spectra, including the observed differences between the Am₂O₃ and the AmO₂ cases. Although complicated by a more asymmetric line shape and difficult background variations, the FEFF analysis confirms the absence of core hole angular momentum coupling in Am O_4,5 spectroscopy. [ABSTRACT FROM AUTHOR]