UNOCCUPIED ELECTRONIC STATES OF THE FES2(100) SURFACE STUDIED BY INVERSE-PHOTOEMISSION

Inverse photoemission spectra have been measured to study unoccupied e lectronic states from an FeS2(100) single crystal along the Gamma-X sy mmetry line with normal incidence electrons at energies between 20 and 40 eV. Two main features of the spectra are found, corresponding to d irect bulk transitions into unoccupied iron 3d(e(g)) and sulphur 3p(si gma) states, respectively, followed by a prominent minimum and a onse t of a band with a wide structure due to mainly transitions into Fe 4s p-S 3d bands. These peaks are located at 1.4 and 3.0 eV above the Ferm i level for an initial electron energy of 19.8 eV. They disperse accor ding to band-structure calculations. The onset of the Fe 4sp-S 3d band s is about 5.0 eV above the Fermi level. The experimental results obta ined here are in a reasonable agreement with band-structure calculatio ns for FeS2, and with previous results of optical, BIS and XAS measure ments.