Erben Mauricio F, Geronés Mariana, Romano Rosana M, Della Védova Carlos O
CEQUINOR (CONICET-UNLP), Departamento de Química, Facultad de Ciencias Exactas, Universidad Nacional de La Plata, C. C. 962 (1900) La Plata, República Argentina.
J Phys Chem A. 2006 Jan 26;110(3):875-83. doi: 10.1021/jp055274t.
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 photoelectron-photoion-photoion coincidence (PEPIPICO) time-of-flight mass spectrometry, were applied. The equivalent-core 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.
通过同步辐射研究了硫代乙酸（CH₃C(O)SH）在S 2p和O 1s光激发后的位点特异性碎片化。测量了总离子产率（TIY）光谱，并应用了多符合技术，包括光电子-光离子符合（PEPICO）和光电子-光离子-光离子符合（PEPIPICO）飞行时间质谱。采用等效核近似来估计电离跃迁值，并对观察到的峰进行了初步归属。通过比较在内层和浅内层壳S 2p和O 1s电离边缘附近的共振能量处收集的质谱，适度观察到了位点特异性碎片化。除了H⁺离子外，在S 2p边缘激发时观察到的最丰富的离子是CH₃CO⁺、SH⁺、S⁺和CH₃⁺。在O 1s区域，大的CH₃CO⁺碎片减少，小的CHₓ⁺（x = 0、1、2、3）、S⁺和SH⁺碎片占主导。讨论了主要离子对产生的解离动力学。在PEPIPICO光谱中观察到了二体和三体解离通道，并提出了解离机制。
