Ionic Fragmentation Mechanisms of 2,2,2-Trifluoroethanol Following Excitation with Synchrotron Radiation

• Published in: Chemphyschem Vol. 16; no. 2; pp. 322 - 330
• Main Authors: Bava, Yanina B., Berrueta Martínez, Yanina, Moreno Betancourt, Angélica, Erben, Mauricio F., Cavasso Filho, Reinaldo L., Della Védova, Carlos O., Romano, Rosana M.
• Format: Journal Article
• Language: English
• Published: Weinheim WILEY-VCH Verlag 02.02.2015; WILEY‐VCH Verlag; Wiley Subscription Services, Inc
• Subjects: gas-phase reactions; ionization potentials; photochemistry; radicals; valence isomerization; ionization potentials; gas-phase reactions; radicals; photochemistry; valence isomerization
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201402669

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 1 s, O 1 s and F 1 s orbitals to vacant molecular orbitals are determined. A site‐specific C 1 s 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. Breaking it down: The most important photofragmentation channel of gaseous 2,2,2‐trifluoroethanol (TFE) after photoionization in the valence‐electron energy region results in CH2OH+ and CF3. (see figure). After core‐shell electron excitations, several fragmentation mechanisms involving two positive ions are observed, the most abundant of which produce H+.