Evidence for a covalent surface KCN species on Pd(100) from inter- atomic Auger transitions.

Abstract

The He i and Ne ii uv spectra and ${\mathrm{He}}^{\mathrm{*}}$ Penning ionization electron spectra of coadsorbed K and CN annealed to above 800 K show extra features, not present in Ne i and ${\mathrm{Ne}}^{\mathrm{*}}$ spectra, that are observed at constant kinetic electron energies. Using the observed valence levels of ${\mathrm{KCN}}_{\mathrm{ads}}$ and the excitation energies, the extra features are shown to result from interatomic Auger transitions involving a K(3p) hole and mixed K-CN states. This strong interadsorbate interaction is attributed to the formation of molecular orbitals of a more covalently bonded KCN molecule.