Photon-stimulated desorption ofH+ions from OH on Ti and Cr: Comparison with bulk solidH2O

An interpretation and comparison of photon-stimulated desorption yields of ${\mathrm{H}}^{+}$ ions from OH on Ti and Cr and from bulk solid ${\mathrm{H}}_2$O indicate that desorption occurs through two entirely different mechanisms. The first involves in intramolecular excitation of the OH adsorbate producing a $H^{+}$ yield similar to that in bulk ${\mathrm{H}}_2$O. The second involves metal core-level excitation followed by Auger decay and is an example of molecular adsorbate dissociation arising from a metal-substrate Auger decay. This is a further generalization of the Knotek-Feibelman model applicable for desorption in ionic systems.