The quantitative infrared and NIR spectrum of CH2I2 vapor: vibrational assignments and potential for atmospheric monitoring
Other literature type
Johnson, T. J.
Sharpe, S. W.
(issn: 1680-7324, eissn: 1680-7324)
Diiodomethane (CH<sub>2</sub>I<sub>2</sub>) 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 CH<sub>2</sub>I<sub>2</sub> has been acquired at 0.1 cm<sup>-1</sup>
resolution. Two strong b<sub>2</sub> symmetry A-type bands at 584 and
1114 cm<sup>-1</sup> are observed, but are not resolved when broadened to 760 Torr
with nitrogen and appear as B-type. In contrast, the b<sub>1</sub> symmetry C-type
bands near 5953, 4426 and 3073 cm<sup>-1</sup> are resolved with rotational
structure, including Q-branches with widths ≤1 cm<sup>-1</sup>. The
quantitative infrared and near-infrared vapor-phase spectra (600–10 000 cm<sup>-1</sup>)
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 C<sub>2<i>v</i></sub> point group.