10min:

J. ORPHAL, N. IBRAHIM, Laboratoire Interuniversitaire des Systémes Atmosphériques (LISA), CNRS UMR 7583, Université de Paris-XII, 91405 Créteil Cedex, France; C. E. FELLOWS, Laboratório de Espectroscopia e Laser, Instituto de Física, Universidade Federal Fluminense, Niterói, Rio de Janeiro, Brazil.

Diiodomethane, CH₂I₂, is an important molecule in marine photochemistry. CH₂I₂ is produced by algae\footnotemark[1] and its photolysis is a source for tropospheric iodine which is very reactive towards other organic species and ozone; it is also an important source for marine particle formation\footnotemark[2]. CH₂I₂ is a rather heavy molecule and has low-lying vibrational modes, leading to a very dense spectrum. Its ground\footnotemark[3] and first excited\footnotemark[4] vibrational states have been studied in the past using Fourier-transform microwave spectroscopy. Very recently, quantitative infrared absorption spectra of CH₂I₂ were recorded at a spectral resolution of 0.1 cm^-1 as part of the PNNL database of gas-phase infrared spectra.\footnotemark[5]

In this paper we present the first high-resolution spectra of the ₁ and ₆ bands of CH₂I₂ in the 3.3 µm region, recorded with a Bruker IFS-120 HR Fourier-transform spectrometer, using CH₂I₂ at its saturated vapour pressure at room temperature, with an absorption path of 300 cm and a spectral resolution of 0.002 cm^-1.