Electron-ion coincidences studies of the fragmentation of thiophene and of tetrahydrothiophene upon core ionization

We have measured the fragment ion spectra of thiophene and tetrahydrothiophene in coincidence with selected Auger final states following the ionization of a S 2p or C 1s core electron. Contrary to our earlier observations for diatomic and triatomic molecules, for thiophene and tetrahydrothiophene the fragmentation is quite unselective to the extent that many of the fragmentation channels are open immediately at the Auger threshold. Moreover, the kinetic energy released in the fragmentation is largely independent of the energy of the Auger final state.