Nature of chemical bond in AmO2

Abstract

The participation of Am6p,5f electrons in the chemical bond in AmO2 was studied. Analysis of the structure of the AmO2 X-ray photoelectron spectrum (XPS) in the valence electron binding energy (BE) range (from 0 to ~35 eV), taking into account the results of relativistic calculation of the AmO8 cluster (D4h) reflecting the nearest surrounding of the Am atom in AmO2, showed that electrons of outer (from 0 to ~15 eV, OVMO) and inner (from ~15 to ~35 eV, IVMO) valence molecular orbitals (MO) noticeably contribute to the structure of the valence electron spectrum. The filled Am5f states appear in the AmO2 OVMO BE range. The atomic orbitals (AO) of Am6p electrons participate in the formation of not only IVMO but also OVMO. The filled Am6p3/2 and O2s AO participate in the IVMO formation to the greatest extent. The MO composition and sequent order was determined, and the quantitative MO scheme for AmO2 was constructed. The bonding and antibonding contributions of electrons of different MO in the AmO8 cluster were estimated. The MO scheme has fundamental significance not only for understanding the nature of the chemical bond in this dioxide, but also for interpreting the structure of other X-ray spectra of AmO2.