Local Electron Distribution of CO Adsorbed on Ni(100) and Ni(111) Surfaces Studied by Metastable Atom Electron Spectroscopy

摘要

Electron emission spectra caused by thermal collisions of He*(2~3S) metastable atoms with Ni(100)c(2 X 2)-CO and Ni(111)c(4 X 2)-CO were measured to probe the local electron distribution. Our data showed that the 4#sigma#- and 5#sigma#-derived states of CO at hollow sites on Ni(111) are strongly modified in space by mixing with each other, where considerable charge transfer occurs from the C atom to the 0 atom in the 5#sigma#-derived state and in the opposite way in the 4#sigma#-derived state. In contrast, such a heavy charge redistribution was not seen in the case of terminal CO on Ni(100). These findings were in good accordance with the crystal orbital overlap population obtained by density functional theory within the generalized gradient approximation.