Vacuum ultraviolet (VUV) pulsed field ionization-photoelectron and VUV-IR photoinduced Rydberg ionization study of trans-dichloroethene

Research output: Journal Publications and Reviews (RGC: 21, 22, 62)21_Publication in refereed journalpeer-review

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Original languageEnglish
Pages (from-to)9637-9644
Journal / PublicationJournal of Physical Chemistry A
Volume108
Issue number45
Publication statusPublished - 11 Nov 2004
Externally publishedYes

Abstract

The vacuum ultraviolet (VUV) pulsed field ionization-photoelectron (PFI-PE) spectrum for trans-dichloroethene (trans-ClCH=CHCl) has been measured in the energy range 77 600-79 200 cm -1. On the basis of the spectral simulation of the origin VUV-PFI-PE vibrational band, we have determined the IE-(trans-ClCH=CHCl) to be 77 678.4 ± 2.0 cm -1 (9.630 97 ± 0.000 25 eV). The vibrational bands resolved in the VUV-PFI-PE spectrum of trans-ClCH=CHCl are assigned on the basis of ab initio vibrational frequencies and calculated Franck-Condon factors for the ionization transitions, yielding eight vibrational frequencies v 1 + = 163 cm -1, v 3 + = 367 cm -1, v 4 + = 871 cm -1, v 5 + = 915 cm -1, v 6 + = 944 cm -1, v 8 + = 1235 cm -1, v 9 + = 1258 cm -1, v 10 + = 1452 cm -1. The distinct feature of the VUV-PFI-PE spectrum is the strong vibrational progression of the v 3 + (C-Cl stretching) mode of trans=ClCH-CHCl +, which is consistent with the theoretical geometry calculation, predicting a significant change in the C-Cl bond distance upon photoionization of trans-ClCH.=CHCl. We have also determined the frequency (3068 cm -1) for the v 11 + (C-H stretching) vibrational mode of trans-ClCH=CHC1 + by employing the VUV-IR-photoinduced Rydberg ionization (VUV-IR-PIRI) method. The VUV-IR-PIRI spectra for trans-ClCH=CHCl prepared in the effective principal quantum numbers, n* = 14 and 36, are found to be identical, supporting the previous conclusion that the Rydberg electron behaves as a spectator; i.e., the Rydberg electron orbital is conserved during the IR excitation of the ion core.

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