Abstract
The unoccupied electronic structure of Bi2CaSr2Cu2O8 crystals cleaved in ultrahigh vacuum has been investigated with k-resolved inverse photoelectron spectroscopy. A number of dispersing structures are observed close to the Fermi level, corresponding to rapidly dispersing Cu-O and Bi-O conduction bands. An expected band crossing at the Fermi level of Cu-O bands is observed, although the bandwidth of these states is found to be much smaller than that predicted in several band structure calculations. Likewise, two Bi-O bands are found to have less dispersion than predicted and these bands are also more separated from each other throughout the Brillouin zone.