Electronic Properties of FC(O)SCH₂CH₃. A Combined Helium(I) Photoelectron Spectroscopy and Synchrotron Radiation Study

Abstract

The valence electronic properties of S-ethyl flouromethanethioate (S-ethyl fluoromethsanethioate), FC(O)SCH2CH3, were investigated by means of He(I) photoelectron spectroscopy in conjunction with the analysis of the photofragmentation products determined by PEPICO (phtoelectron-photoion-coincidence) by using synchrotron radiation in the 11.1-21.6 eV photon energy range. The first band observed at 10.28 eV in the HeI photoelectron spectrum can be assigned with confidence to the ionization process from the HOMO [nπ(S) orbital], which is described as a lone pair formally localized on the sulfur atom, in agreement with quantum chemical calculations using the outer valence Green function method [OVGF/6-311++G (d,p)]. One of the most important fragmentation channels also observed in the valence region corresponds to the decarbonylation process yielding the [M-CO](·+) ion, which is clearly observed at m/z = 80. Moreover, S 2p and S 2s absorption edges have been examined by measuring the total ion yield spectra in the 160-240 eV region using variable synchrotron radiation. The dynamic of ionic fragmentation following the Auger electronic decay has been evaluated with the help of the PEPIPICO (photoion-photoion-photoelectron-coincidence spectra) technique.

Preparation and Spectroscopic Studies of FC(O)SSCl

“…The third potential, at 11.83 eV, was assigned to the ionization of electrons located in an orbital with n σ O character, in accord with the theoretical predictions (see Figure ). This assignment also agrees with those proposed for related molecules [10.74 eV for ClC(O)SCH 2 CH 3 , 10.88 eV for ClC(O)SCH 3 , 11.3 eV for FC(O)SSCH 3 , 11.32 eV for ClC(O)SCl, 11.37 eV for FC(O)SCH 2 CH 3 , 11.42 eV for ClC(O)SSCl and 12.1 eV for FC(O)SCl] …”

Photoelectron Spectroscopy and Ionic Fragmentation of OSeCl2 and Its Analogue OSCl2 under VUV Irradiation

“…Signatures of charge redistribution across the molecules were observed, especially for the larger ethylselenol molecule. Moreover, from the kinetic energy distribution of the ionic fragments, details of the Coulomb explosion processes were revealed. , Studies concerning shallow- and inner-core electrons in sulfur-containing compounds as well as studies in the valence region have been analyzed by our research group by using synchrotron radiation and multicoincidence techniques. , …”

“…12,13 Studies concerning shallow-and inner-core electrons in sulfur-containing compounds as well as studies in the valence region have been analyzed by our research group by using synchrotron radiation and multicoincidence techniques. 14,15 Following these analyses, we became interested in molecules constituted by formal chalcogen substitution, i.e., the selenium analogues of the sulfur species. To our knowledge, synchrotronbased studies on the Se 3p and/or 3s shallow-core level for gasphase selenium-containing molecules have not been performed up to now.…”