Photoemission spectra and band structures of d -band metals. XI. Inverse photoemission from Pd(111)

Momentum-resolved inverse photoemission spectra have been taken on Pd(111) at ω=9.7 eV. In addition to the unoccupied part of the d band, we observe an s,p peak which disperses, but lies somewhat higher in energy (by ~ 0.5 eV) than a bulk direct-transition peak predicted by band-structure calculations. The s,p peak does not fall in the fundamental s,p gap, and is therefore not attributable to a surface state. A step structure close to the vacuum level is attributed to band-gap emission and image-potential states.