Articles | Volume 6, issue 9
Atmos. Chem. Phys., 6, 2581–2591, 2006
https://doi.org/10.5194/acp-6-2581-2006
Atmos. Chem. Phys., 6, 2581–2591, 2006
https://doi.org/10.5194/acp-6-2581-2006

  04 Jul 2006

04 Jul 2006

The quantitative infrared and NIR spectrum of CH2I2 vapor: vibrational assignments and potential for atmospheric monitoring

T. J. Johnson, T. Masiello, and S. W. Sharpe T. J. Johnson et al.
  • Pacific Northwest National Laboratory, Richland, WA 99354, USA

Abstract. Diiodomethane (CH2I2) has recently become a molecule of significant atmospheric interest as it can contribute to coastal IO formation. As part of the PNNL database of gas-phase infrared spectra, the quantitative absorption spectrum of CH2I2 has been acquired at 0.1 cm-1 resolution. Two strong b2 symmetry A-type bands at 584 and 1114 cm-1 are observed, but are not resolved when broadened to 760 Torr with nitrogen and appear as B-type. In contrast, the b1 symmetry C-type bands near 5953, 4426 and 3073 cm-1 are resolved with rotational structure, including Q-branches with widths ≤1 cm-1. The quantitative infrared and near-infrared vapor-phase spectra (600–10 000 cm-1) are reported for the first time. Some bands are discussed in terms of their potential for atmospheric monitoring and theoretical detection limits on a selected basis. FT-Raman spectra and ab initio calculations are used to complete vibrational assignments in the C2v point group.

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