High-resolution spectroscopic study of spectrum of CH37Cl3 isotopologue of gaseous chloroform in 2-mm wavelength range
V.L. Vaks1,2,3, E.G. Domracheva1,2, M.B. Chernyaeva1,2, V.A. Anfertev1,2, A.K. Tretyakov3, Yu.V. Kistenev3,4
1Federal research center Institute of Applied Physics of the Russian Academy of Sciences named after A.V. Gaponov-Grekhov, The Institute for Physics of Microstructures of the RAS, Nizhny Novgorod, Russia
2Lobachevsky State University of Nizhny Novgorod, Nizhny Novgorod, Russia
3National Research Tomsk State University, Tomsk, Russia
4V.E. Zuev Institute of Atmospheric Optics of Siberian Branch of the Russian Academy of Science, Tomsk, Russia
Keywords: chlorine-containing atmospheric gases, chloroform, rotational spectrum, terahertz high-resolution nonstationary spectroscopy
Abstract
Chloroform is one of dangerous pollutants in the atmosphere. To control it in the atmosphere by absorption spectroscopy, it is necessary to know the position of its spectral lines. In this work, the absorption spectra of CH37Cl3 isotopologue of gaseous chloroform are measured using a high-resolution nonstationary spectrometer in the frequency range 118-175 GHz, where spectroscopic data for this compound are absent. The identification of the chloroform lines presented in the literature and assigned to the vibrational state v2 for CH35Cl3 is refined and their belonging to CH37Cl3 isotopologue is shown. The experimental results are compared with our theoretical estimates of absorption lines centers of the rotational spectrum of this molecule in the same spectral range. Absorption lines of CH37Cl3 isotopologue in the ground state were detected and identified in the spectral subranges near 131.4, 137.6, 150.1, and 156.4 GHz. Based on the experimental spectra, we have estimated the molecular constants B = 3129.56 MHz, DJ = 1.34 kHz, and DJK = -2.25 kHz with RMSE = 7.84 ´ 10-2 MHz, which determine transition frequencies in absorption spectra parts near 150,1 GHz and 156.4 GHz more accurately than molecular constants given in the literature ( B = 3129.61 MHz, DJ = 1.37 kHz, and DJK = -2.28 kHz with RMSE = 11.55 × 10-2 MHz). The results can be used for controlling the content of chloroform in the atmosphere.
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