INVERSE-PHOTOEMISSION STUDY OF THE CU(100)C(2X2)-MN PHASE

Momentum- (k) resolved inverse photoemission spectroscopy (KRIPES) has been used to investigate the electronic structure of Mn deposited on Cu(100), including the substitutional surface alloy phase Cu(100)c(2 x 2)-Mn. A well-resolved unoccupied state 2.0 eV above the Fermi level is found to be associated with the Mn adsorbate; this state shows no evidence of dispersion in either perpendicular or parallel electron momentum and is associated with a localized Mn 3d state. This result is consistent with previous evidence that the Mn remains in an atomic-like high-spin ground state in this surface, and contrasts with its behaviour in thicker Mn films. Measurements following exposure of the surface to oxygen show a greatly enhanced oxidation rate, with evidence of bulk oxide formation not possible on the clean Cu(100) surface at room temperature under high-vacuum conditions.