UNOCCUPIED SURFACE ELECTRONIC-STRUCTURE OF GD(0001)

The unoccupied surface electronic structure of Gd(0001) was investigat ed with high-resolution inverse-photoemission spectroscopy. An empty s urface state near E(F) is observed at GAMMABAR. Two other surface-sens itive features are also revealed at 1.2 and 3.1 eV above the Fermi lev el. Hydrogen adsorption on Gd surfaces was used to distinguish the sur face-sensitive features from the bulk features. The unoccupied bulk-ba nd critical points are determined to be GAMMA3+ at 1.9 eV and A1 at 0. 8 eV.