Inner valence region of CO adsorbed on Pd(100)

The inner valence region of CO/Pd(100) p(2√2×√2)R45° has been studied by angular resolved photoemission at the Pd 4d Cooper minimum, and with resonant Auger spectroscopy at photon energies corresponding to the C 1s and O 1s x-ray absorption (XA) maxima of the unoccupied parts of the 2π*-Pd 4d hybrid (2πun). Previously unobserved inner valence states are revealed in the direct photoemission and are compared with resonant Auger results. The interpretation and assignment of the different spectral features to different main final state configurations are based on energy, symmetry and intensity arguments, as well as comparisons with previous results.