Photon stimulated ion desorption from condensed thiophene photoexcited around the S1s-edge

Abstract

Photon stimulated ion desorption and Auger decay spectra were measured for condensed thiophene around the S1s-edge. Three kinds of ions, H+, S+, and S2+, were observed as main desorbed species. Partial ion yields (PIY) have been determined for these three fragment ions as a function of the photon energy. It was found that the indirect x-ray induced electron stimulated desorption mechanism plays an important role in H+ ion desorption. For S+ ion desorption, on the other hand, a pronounced enhancement at ∼3eV away from the first core-to-valence resonance was observed in the PIY curve. On the basis of the results for the Auger decay spectra, the enhancement of S+ desorption at ∼3eV away from the first resonance is interpreted in terms of the effective screening of positive holes due to the existence of Rydberg electrons.