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

摘要

Diiodomethane (CHI) has recently become a molecule ofsignificant atmospheric interest as it can contribute to coastal IOformation. As part of the PNNL database of gas-phase infrared spectra, thequantitative absorption spectrum of CHI has been acquired at 0.1 cmresolution. Two strong b symmetry A-type bands at 584 and1114 cm are observed, but are not resolved when broadened to 760 Torrwith nitrogen and appear as B-type. In contrast, the b symmetry C-typebands near 5953, 4426 and 3073 cm are resolved with rotationalstructure, including Q-branches with widths ≤1 cm. Thequantitative infrared and near-infrared vapor-phase spectra (600–10 000 cm)are reported for the first time. Some bands are discussed interms of their potential for atmospheric monitoring and theoreticaldetection limits on a selected basis. FT-Raman spectra and ab initio calculations areused to complete vibrational assignments in the C point group.