Ed Soh, P. Mayer, T. Baer
1997
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Journal
International Journal of Mass Spectrometry and Ion Processes
Abstract
Abstract Threshold photoelectron-photoion coincidence (TPEPICO) spectroscopy was employed to study the unimolecular chemistry of metastable ionized 1- and 2-butanethiol. The ions were both found to form two products, m/z 56 (C4H+·8) and m/z 60 (C2H4S+·) corresponding to the losses of H2S and C2H6 respectively. On the basis of their breakdown diagrams, it was evident that these two ions do not interconvert prior to fragmentation. From energetic arguments, the C4H+·8 ion formed by the two thiolswas found to be either 2-butene+· or isobutene+·. This is in contrast to the analogous ionic 1-butanol, which loses only H2O to form methylcyclopropane ions, and 2-butanol, which loses CH3, CH4, C2H5 and C2H6. RRKM theory was used to model the rates for each fragment channel to obtain barrier heights for their formation and aid in identifying the nature of the C4H+·8 ion formed by the two thiols. The ionization energy of 1-butanethiol was determined to be 9.14 ± 0.02 eV and that of 2-butanethiol to be 9.03 ± 0.02 eV.