Enhanced photon stimulated ion-desorption yields from chemisorbed molecules through bond-selective core-electron excitation

The photon-stimulated ion desorption from deuterated formic acid chemisorbed on Si(100) has been studied by bond-selective C 1s electron excitation. Each ion yield strongly depends on the excitation energy. It is found that the excitation to a particular antibonding orbital enhances ion yields, which follows a rupture of the bond to have been specified. The results show applicability of the two-hole one-electron mechanism for core-excited ion desorption in adsorbates. Also discussed are electronic relaxation via Anger processes and the neutralization effects of the substrate on ion desorption.