S 2p excitation and fragmentation of sulfur aggregates

Abstract

Synchrotron radiation from the storage ring BESSY-I is used to excite the S 2p regime (150-190 eV) of sulfur aggregates S-n, n = 2-8. Valence states are identified in photoion yield spectra of mass selected S-n(+) cations in combination with extended Huckel calculations. Mass spectra, partial ion yields, and photoelectron-photoion-photoion (PEPIPICO) coincidence spectra an reported, yielding a consistent picture of massive decay processes occurring in the S 2p regime. PEPIPICO spectra especially give detailed information on the fragmentation mechanisms of doubly charged aggregates. It is shown that most cation pairs are formed via charge separation originating from S-8(++). We derive values for the kinetic energy releases in multistep fragmentations assuming that charge separation is driven by Coulomb explosion. (C) 1998 American Institute of Physics. [S0021-9606(98)00245-1].