Valence band structure and decay process in the inner-shell excitation of boron oxide

The electronic structure and radiative/non-radiative decay processes in the inner-shell excitation of B2O3 were investigated using soft x-ray emission and photoelectron spectroscopy. Based on density of states calculations, the electronic structure of B2O3 as probed by x-ray emission spectroscopy (XES) and photoelectron spectroscopy (PES) arises from hybridized sp2-planar B— O bonding in B— O3 triangular units. A fairly non-dispersive band structure was also suggested by excitation energy-dependent XES. XES and PES indicated both a resonant radiative decay process and a resonant non-radiative decay process with π* excitation at the B K threshold. A small resonant radiative decay peak was observed with π* excitation at the O K threshold, probably due to a more weakly bound π* state at the O K threshold than at the B K threshold.