Direct probing of the adsorbate-substrate chemical bond using angle-dependent x-ray-emission spectroscopy

Angle-dependent x-ray-emission spectroscopy is a method for studying adsorbed molecules, which makes it possible to directly probe the electronic states responsible for the surface chemical bond. This technique allows the separation of the adsorbate density of states both in terms of atomic site and orbital symmetry. This is demonstrated for CO adsorbed on Ni(100) and Cu(100). The occupied part of the 2π-3d adsorbate-substrate bond, projected on the C and O atoms, is observed directly. © 1995 The American Physical Society.