Abstract:
This paper details an experimental and theoretical investigation into the
electronic structure of the highly ionic, alkali oxide, potassium oxide (K2O). The
experiments were carried out using the relatively new technique of electron momentum
spectroscopy. This is an electron impact technique that is capable of measuring the
electron intensity distribution as a function of energy and momentum. Calculations were
performed within the linear combination of atomic orbitals approximation using both
Hartree-Fock and density functional theory formalisms. We have been able to map the
band dispersions and intensities in the oxygen valence bands and potassium 3p and 3s
bands for the first time. Overlap of the O 2s and K 3p binding energy peaks makes it
difficult to extract the bandgaps involving either of these bands. The O 2p and K 3s peaks
are resolved, however, and we observe a gap of 30.4 ± 0.2 eV. This value is reproduced
by the PBE0 calculation. Intensities within the s-bands are reproduced well by all our
calculations, whereas the observed p bands show anomalous intensity at the Γ-point,
which is not present in any of the calculations.
