Combined vacuum ultraviolet laser and synchrotron pulsed field ionization study of C H2 BrCl

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review

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Author(s)

  • Juan Li
  • Jie Yang
  • Yuxiang Mo
  • X. M. Qian
  • Y. Song
  • Jianbo Liu
  • C. Y. Ng

Detail(s)

Original languageEnglish
Article number184304
Journal / PublicationJournal of Chemical Physics
Volume126
Issue number18
Publication statusPublished - 2007

Abstract

The pulsed field ionization-photoelectron (PFI-PE) spectrum of bromochloromethane (C H2 BrCl) in the region of 85 320-88 200 cm-1 has been measured using vacuum ultraviolet laser. The vibrational structure resolved in the PFI-PE spectrum was assigned based on ab initio quantum chemical calculations and Franck-Condon factor predictions. At energies 0-1400 cm-1 above the adiabatic ionization energy (IE) of C H2 BrCl, the Br-C-Cl bending vibration progression (1+ =0-8) of C H2 Br Cl+ is well resolved and constitutes the major structure in the PFI-PE spectrum, whereas the spectrum at energies 1400-2600 cm-1 above the IE (C H2 BrCl) is found to exhibit complex vibrational features, suggesting perturbation by the low lying excited C H2 Br Cl+ (Ã A″2) state. The assignment of the PFI-PE vibrational bands gives the IE (C H2 BrCl) =85 612.4±2.0 cm-1 (10.6146±0.0003 eV) and the bending frequencies 1+ (a1′) =209.7±2.0 cm-1 for C H2 Br Cl+ (X̃ A′2). We have also examined the dissociative photoionization process, C H2 BrCl+h→C H2 Cl+ +Br+ e-, in the energy range of 11.36-11.57 eV using the synchrotron based PFI-PE-photoion coincidence method, yielding the 0 K threshold or appearance energy AE (C H2 Cl+) =11.509±0.002 eV. Combining the 0 K AE (C H2 Cl+) and IE (C H2 BrCl) values obtained in this study, together with the known IE (C H2 Cl), we have determined the 0 K bond dissociation energies (D0) for C H2 Cl+ -Br (0.894±0.002 eV) and C H2 Cl-Br (2.76±0.01 eV). We have also performed CCSD(T, full)/complete basis set (CBS) calculations with high-level corrections for the predictions of the IE (C H2 BrCl), AE (C H2 Cl+), IE (C H2 Cl), D0 (C H2 Cl+ -Br), and D0 (C H2 Cl-Br). The comparison between the theoretical predictions and experimental determinations indicates that the CCSD(T, full)/CBS calculations with high-level corrections are highly reliable with estimated error limits of

Citation Format(s)

Combined vacuum ultraviolet laser and synchrotron pulsed field ionization study of C H2 BrCl. / Li, Juan; Yang, Jie; Mo, Yuxiang et al.
In: Journal of Chemical Physics, Vol. 126, No. 18, 184304, 2007.

Research output: Journal Publications and ReviewsRGC 21 - Publication in refereed journalpeer-review