S 2P EXCITATION AND FRAGMENTATION OF SULFUR AGGREGATES

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. Valenc e states are identified in photoion yield spectra of mass selected S-n (+) cations in combination with extended Huckel calculations. Mass spe ctra, partial ion yields, and photoelectron-photoion-photoion (PEPIPIC O) coincidence spectra an reported, yielding a consistent picture of m assive decay processes occurring in the S 2p regime. PEPIPICO spectra especially give detailed information on the fragmentation mechanisms o f doubly charged aggregates. It is shown that most cation pairs are fo rmed via charge separation originating from S-8(++). We derive values for the kinetic energy releases in multistep fragmentations assuming t hat charge separation is driven by Coulomb explosion. (C) 1998 America n Institute of Physics. [S0021-9606(98)00245-1].