CHANGES IN ELECTRON LOCALIZATION AND DENSITY-OF-STATES NEAR E(F) ACROSS THE NONMETAL-METAL TRANSITION IN MG OVERLAYERS

A nonmetal-to-metal transition in Mg monolayers on Mo(112) has been in dicated by photoemission and resonant photoemission. The dramatic chan ges of the density of states, the dispersion of bands near E(F), and s creening are observed across the nonmetal-to-metal transition. The cha nges of the resonance photon energy and the intensity of Mg 2p --> eps ilond excitation, with different coverages, indicate that there exists a correlation between the electronic structure (particularly final-st ate screening effects) and the overlayer structure. The commensurate-t o-incommensurate transition beyond 0.5 monolayer of coverage correspon ds to the overlayer nonmetal-to-metal transition, which is due to the hybridization of Mg s and p bands and represents a transition from a l ocalized (bondlike) to a delocalized (bandlike) phase for divalent ato ms.