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

TL;DR

This study measures the millimeter-wave rotational spectrum of monodeuterated chloromethane CH$_2$DCl, providing precise spectral data to aid future astronomical detection of chloromethane isotopologues in space.

Contribution

It offers the first detailed laboratory spectroscopic analysis of CH$_2$DCl in the 90-300 GHz range, enabling improved astronomical searches and spectral modeling.

Findings

Accurate hyperfine-resolved spectra of CH$_2$D$^{35}$Cl and CH$_2$D$^{37}$Cl obtained.

Reliable spectral predictions established for interstellar detection.

Foundation laid for high-resolution infrared spectral analysis.

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.