We present a set of angle-integrated inverse-photoemission data on ${\mathrm{Fe}}_2$${\mathrm{O}}_3$ taken in the ultraviolet region (12.1–24.2 eV) in the isochromat mode. The photon-energy dependence of the spectra gives direct insight into the orbital origin of the empty electron states in the oxide. The results are discussed in terms of the available theories based on a cluster model with configuration interaction, which reproduce quite well the direct-photoemission results. It is shown that these calculations are less satisfactory in fitting the electron-addition spectroscopy of empty states. We suggest that this might be due to an overestimation of U, the on-site d-d Coulomb correlation energy.

• Received 25 April 1991

DOI:https://doi.org/10.1103/PhysRevB.44.10444