Photoionization and Photofragmentation after inner shell excitation in FC(O)SCH3 and CH3C(O)SCH3

MARIANA GERONÉS; MAURICIO F. ERBEN; ROSANA M. ROMANO; CARLOS O. DELLA VÉDOVA

Campinas, Brasil

Otro; 18ª Reunião Anual de Usuários (RAU), Laboratório Nacional de Luz Síncrotron.; 2008

As part of a general project aimed to the understanding of the processes occurring after photoexcitation of molecules belonging to the carbonylsulfenyl family of compounds,1¡5 we present here photoionization and photofragmentation studies of FC(O)SCH3 and CH3C(O)SCH3 in vapour phase after C 1s, O 1s, F 1s and S 1s excitations. The Total Ion Yield (TIY) spectra of FC(O)SCH3 following C 1s excitations are dominated by an intense resonance near 289 eV, accompanied by a series of less intense resonances both at lower and higher energies, while the most intense signal in the spectra of CH3C(O)SCH3 appears close to 287 eV, followed by a series of less intense resonances at higher energies. In the O 1s region, resonances near 531 and 530 eV are the most prominent features of the TIY spectra of FC(O)SCH3 and CH3C(O)SCH3, respectively. The TIY spectra of FC(O)SCH3 in the F 1s region exhibit two signals of similar intensities near 687 and 693 eV. Finally, only one resonance band is observable in the TIY spectra of these two molecules at about 2473 eV when an excitation energy in the S 1s region is used. PEPICO and PEPIPICO spectra for FC(O)SCH3 and CH3C(O)SCH3 were recorded on each resonance, and also below and above the resonance bands. The spectra are observed to depend on the excitation energy. Possible fragmentation mechanisms are deduced from the interpretation of the PEPIPICO spectra.1¡5 we present here photoionization and photofragmentation studies of FC(O)SCH3 and CH3C(O)SCH3 in vapour phase after C 1s, O 1s, F 1s and S 1s excitations. The Total Ion Yield (TIY) spectra of FC(O)SCH3 following C 1s excitations are dominated by an intense resonance near 289 eV, accompanied by a series of less intense resonances both at lower and higher energies, while the most intense signal in the spectra of CH3C(O)SCH3 appears close to 287 eV, followed by a series of less intense resonances at higher energies. In the O 1s region, resonances near 531 and 530 eV are the most prominent features of the TIY spectra of FC(O)SCH3 and CH3C(O)SCH3, respectively. The TIY spectra of FC(O)SCH3 in the F 1s region exhibit two signals of similar intensities near 687 and 693 eV. Finally, only one resonance band is observable in the TIY spectra of these two molecules at about 2473 eV when an excitation energy in the S 1s region is used. PEPICO and PEPIPICO spectra for FC(O)SCH3 and CH3C(O)SCH3 were recorded on each resonance, and also below and above the resonance bands. The spectra are observed to depend on the excitation energy. Possible fragmentation mechanisms are deduced from the interpretation of the PEPIPICO spectra.