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

Momentum-resolved inverse photoemission spectra have been taken on Pd(111) at $\hslash \omega =9.7\mathrm{}$ 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.