Selective STM imaging of oxygen-induced Cu(1Â 1Â 5) surface reconstructions with tungsten probes

We report on high resolution STM studies of oxygen-induced reconstructed Cu(1 1 5)-O surface. A number of different atomically resolved STM images of the Cu{0 1 4}-O and Cu(0 0 1)-O faces at half-monolayer oxygen coverage demonstrating selective atom visualization have been measured with tungsten probes. For qualitative explanation of the observed features, tight-binding calculations of the density of states (DOS) of the Cu(0 1 4)-O and Cu(0 0 1)-O surfaces as well as of W probes with different atomic arrangements at the tip apex were performed. Analysis of the STM data and results of the electronic structure calculations suggest that partial contribution of different atomic orbitals can be responsible for the observed effects of selective atom visualization. The relative contribution of different electron states depends on the tip-sample distance which, in turn, is determined by applied tunneling parameters as well as the tip and surface electronic structure.