Evidence of Site-Specific Fragmentation on Thioacetic Acid, CH3C(O)SH, Irradiated with Synchrotron Radiation around the S 2p and O 1s Regions

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

JOURNAL OF PHYSICAL CHEMISTRY A

Año: 2006 vol. 110 p. 875 - 883

1089-5639

Site-specific fragmentations following S 2p and O 1s photoexcitation of thioacetic acid, CH3C(O)SH, have been studied by means of synchrotron radiation. Total ion yield (TIY) spectra were measured and multicoincidence techniques, which include photoelectron-photoion coincidence (PEPICO) and  photoelectronphotoion-photoion coincidence (PEPIPICO) time-of-flight mass spectrometry, were applied. The equivalentcore approximation was employed in order to estimate ionization transition values, and the observed peaks were tentatively assigned. A site-specific fragmentation is moderately observed by comparing the mass spectra collected at resonant energies around the inner and shallow inner shell S 2p and O 1s ionization edges. Beside H+ ion, the most abundant ions observed at the S 2p edge excitation were CH3CO+, SH+, S+, and CH3 +. At the O 1s region the large CH3CO+ fragment was depressed, and small CHx + (x ) 0, 1, 2, 3), S+, and SH+ fragments were dominant. The dissociation dynamic for the main ion-pair production has been discussed. Two- and three-body dissociation channels have been observed in the PEPIPICO spectra, and the dissociation mechanisms were proposed.3C(O)SH, have been studied by means of synchrotron radiation. Total ion yield (TIY) spectra were measured and multicoincidence techniques, which include photoelectron-photoion coincidence (PEPICO) and  photoelectronphotoion-photoion coincidence (PEPIPICO) time-of-flight mass spectrometry, were applied. The equivalentcore approximation was employed in order to estimate ionization transition values, and the observed peaks were tentatively assigned. A site-specific fragmentation is moderately observed by comparing the mass spectra collected at resonant energies around the inner and shallow inner shell S 2p and O 1s ionization edges. Beside H+ ion, the most abundant ions observed at the S 2p edge excitation were CH3CO+, SH+, S+, and CH3 +. At the O 1s region the large CH3CO+ fragment was depressed, and small CHx + (x ) 0, 1, 2, 3), S+, and SH+ fragments were dominant. The dissociation dynamic for the main ion-pair production has been discussed. Two- and three-body dissociation channels have been observed in the PEPIPICO spectra, and the dissociation mechanisms were proposed.