High-resolution millimeter-wave spectroscopy of CH${}_2$DCl: paving the way for future astronomical observations of chloromethane isotopologues

Abstract

Chloromethane is the only organochloride detected in space to date. Its recent observation towards the low-mass protostar IRAS 16293-2422 with ALMA offers a prompt for new laboratory studies of CH${}_3$Cl and its isotopologues. Here, we report the investigation of the rotational spectrum of monodeuterated chloromethane CH${}_2$DCl in the frequency region between 90 and 300 GHz. The measurements have been carried out with a frequency-modulation millimeter-wave spectrometer, arranged to perform saturation spectroscopy. From the analysis of hyperfine-resolved spectra of the two chlorine isotopologues CH${}_2$D${}^{35}$Cl and CH${}_2$D${}^{37}$Cl, consistent sets of accurate spectroscopic parameters have been obtained. This work provides reliable spectral predictions which can be used to guide radio-astronomical searches of CH${}_2$DCl in the interstellar medium and represents a solid base for future analyses of high-resolution infrared spectra of monodeuterated chloromethane.

13 pages, 2 figures, 3 tables