Ionic fragmentation mechanisms of 2,2,2-trifluoroethanol following excitation with synchrotron radiation

Abstract

Gaseous 2,2,2-trifluoroethanol (TFE) is excited with synchrotron radiation between 10 and 1000 eV and the ejected electrons and positive ions are detected in coincidence. In the valence-electron energy region, the most abundant species is CH2OH+. Other fragments, including ions produced by atomic rearrangements, are also detected; the most abundant are COH+, CFH2 + and CF2H2 +. The energies of electronic transitions from C 1s, O 1s and F 1s orbitals to vacant molecular orbitals are determined. A site-specific C 1s excitation is observed. The photofragmentation mechanisms after the excitation of core-shell electrons are inferred from analysis of the shape and slope of the coincidence between two charged fragments in the bi-dimensional coincidence spectra. The spectra are dominated by islands that correspond to the coincidence of H+ with several charged fragments. One of the most important channels leads to the formation of CH2OH+ and CF3 + in a concerted mechanism.