HeI Photoelectron and Valence Synchrotron Photoionization Studies of the Thioester Molecule CH3C(O)SCH3: Evidence of Vibronic Structure

MARIANA GERONÉS; ANTHONY J. DOWNS; MAURICIO F. ERBEN; MAOFA GE; ROSANA M. ROMANO; LI YAO; CARLOS O. DELLA VÉDOVA

JOURNAL OF PHYSICAL CHEMISTRY A

AMER CHEMICAL SOC

Año: 2008 vol. 112 p. 5947 - 5953

1089-5639

One of the simplest thioester molecules, S-methyl thioacetate, CH3C(O)SCH3, has been investigated on the basis of its HeI PhotoElectron Spectrum (PES) and of valence photoionization studies using synchrotron radiation in the same energy range. In the second series of experiments, Total Ion Yield (TIY), PhotoElectron PhotoIon COincidence (PEPICO) and Partial Ion Yield (PIY) spectra have been recorded. It is found that the photodissociation behavior of  CH3C(O)SCH3 can be divided into three well-defined energy regions. Vibronic structure was observed in the valence synchrotron photoionization process, being associated with wavenumbers of 912, 671, 1288, 1690, and 1409 cm–1 for the bands at 12.82, 13.27, 15.66, 15.72, and 17.42 eV, respectively. Evaluation of the PES, in concert with the synchrotron photoionization measurements, and complemented with high level ab initio calculations, thus provides unusually detailed insights into the valence ionization processes of this molecule.