ADSORPTION OF CN ON NI(110) - AN EXPERIMENTAL AND THEORETICAL-STUDY

Saturation exposure of the Ni(110) surface to C2N2 at room temperature yields a well ordered c(2 x 2) CN overlayer with four characteristic ionisations that show distinctive angular effects in angle resolved ul traviolet photoemission spectroscopy (ARUPS) using polarised synchrotr on radiation. Good azimuthal ordering is observed and application of s election rules indicates that the CN lies parallel to the surface with its molecular axis oriented along the [110BAR] azimuthal direction. L inear combination of Gaussian-type orbitals local density functional ( LCGTO-LDF) cluster calculations probing various probable adsorption si tes and geometries find CN lying flat in the grooves bridging second l ayer substrate atoms to be the favoured site. Bonding is effectuated m ainly by ionic and lateral pi interaction. The barrier toward an uprig ht orientation is calculated to be small. The good agreement between t he experimental and theoretical results allows a reassessment of previ ously published photoemission data from other CN adsorption system