Interstellar H sub(3) super(+) and HCS super(+) Ions Produced in the Dissociative Photoionization Process of CH sub(3)C(O)SCH sub(3) in the Proximity of the Sulfur 2p, Carbon 1s, and Oxygen 1s Edges

In this work we present a study of the dissociative photoionization of S-methyl thioacetate [CH sub(3)C(O)SCH sub(3)] by using multicoincidence time-of-flight mass spectrometry and synchrotron radiation in the S 2p, C 1s, and O 1s edges. Total and partial ion yield spectra together with photoelectron-photoion coincidence (PEPICO) and photoelectron-photoion-photoion coincidence (PEPIPICO) spectra were measured. Fragmentation patterns deduced from PEPICO and PEPIPICO spectra at the various excitation energies show a moderate site-specific fragmentation. The dissociation dynamic for the main ion-pair production is discussed. Two-, three-, and four-body dissociation channels have been observed in the PEPIPICO spectra, and the dissociation mechanisms are proposed. The interstellar HCS super(+) and H sub(3) super(+) ions can be observed during the synchrotron experiments reported in the present work.