Diode laser spectroscopy of methyl chloride near 14 μm toward its detection in the stratosphere

• Published in: Journal of molecular spectroscopy Vol. 128; no. 2; pp. 433 - 443
• Main Authors: Betrencourt, Michel, Morillon-Chapey, Mireille, Blanquet, Ghislain, Walrand, Jacques
• Format: Journal Article
• Language: English
• Published: San Diego, CA Elsevier Inc 01.04.1988; Elsevier
• Subjects: Atomic and molecular physics; Exact sciences and technology; Infrared spectra; Molecular properties and interactions with photons; Molecular spectra; Physics; High resolution; Hot band; Methyl chloride; Rotational constant; Isotopic species; Centrifugal distortion constant; Experimental study; Absorption spectrum; Rovibrational analysis; Coriolis coupling; Rovibrational transition; Near infrared spectrum; Chlorine Organic compounds; Saturated aliphatic compound; Gaseous state; Molecular constant
• ISSN: 0022-2852; 1096-083X
• DOI: 10.1016/0022-2852(88)90160-9

Detection of CH 3Cl in the Earth's atmosphere by infrared techniques is a subject of current interest. The ν 3 band, centered at 732 cm −1, has lines as strong as those of ν 1, centered at 2970 cm −1, and we show that they can be useful for a high-resolution detection. A complete study of the absorption spectrum of this molecule in the region 660–770 cm −1 has been performed. On spectra recorded using a tunable diode laser spectrometer, with the spectral resolution limited by the Doppler width (0.0014 cm −1), we have assigned the ν 3 band lines related to four isotopic species: 12CH 3 35Cl, 12CH 3 37Cl, 13CH 3 35Cl, and 13CH 3 37Cl. In addition, the hot band 2 ν 3 - ν 3 for 12CH 3 35Cl has been observed. The calculated molecular constants reproduce, for each band, the observed wavenumbers with a rms deviation of 6 × 10 −4 cm −1. The ν 3 band centers have been found to be 732.8421 and 727.0295 cm −1 for the two main isotopic species, 12CH 3 35Cl and 12CH 3 37Cl, respectively. The feasibility of detection of methyl chloride in the stratosphere is discussed.