Recent progress in the investigation of core hole-induced photon stimulated desorption from adsorbates: excitation site-dependent bond breaking, and charge rearrangement

We report photon stimulated desorption (PSD) of neutral and ionic molecules and atoms from CO chemisorbed on Ru(001) and Cu(111), and from N2 chemisorbed on Ru(001). Comparing branching ratios and spectral features for the O1s and N1s regions, we demonstrate that desorbing neutrals and ions are supplementary probes for the entire region of one- and multi-electron excitations, bearing valuable information on the transfer of energy and charge. For the primary [N1s]π∗ excitation of N2/Ru(001), we find excitation site-dependent branching into desorption of N02, N0 and N+. PSD of neutral N atoms predominates for excitations of the N atom close to the surface, whereas mainly neutral N2 molecules and N+ ions are ejected for excitations of the outer N atom. At the Ru 3p substrate thresholds we find significant enhancements of the N+ and N2+ yields from N2/Ru(001), and discuss the electronic nature of the underlying energy transfer mechanism.