Millimeter and sub-millimeter spectroscopic studies of astrophysical relevant radicals Illustration with the CH2CN radical
Radical species are suspected to be involved in gas phase reactions occurring in the interstellar medium (ISM)  and their detection gives important insights about the chemistry happening in the ISM. To support ongoing searches of these species, laboratory spectroscopy is essential.
We developed several experimental set-up to study the high resolution spectra of radical species in a large spectral range covering the millimeter and sub-millimeter wave regions. In particular, we led new high-resolution studies in the (sub)millimeter-wave region on the cyanomethyl radical (CH2CN) from 140 GHz up to 900 GHz. The pure rotational spectrum of the radical, produced by H abstraction of acetonitrile by F atoms, was recorded thanks to a frequency multiplication chain spectrometer. Previous laboratory investigations [2,3] only measured transitions up to about 300 GHz allowing for the detection of CH2CN in the ISM . We completed the spectroscopic characterization at higher frequencies and, in this talk, I will present our measurements yielding an improvement of its spectroscopic parameters.
With the aim of studying new reactive species, we are also developing a new set-up based on the coupling of a pulsed jet discharge with a commercial broadband W-band spectrometer (BrightSpec, 75-110 GHz). I will present the preliminary results we obtained on the CH2CN radical observed at a rotational temperature of about 10 K.
: Cernicharo, J. et al., Astronomy & Astrophysics Letters, 2021, 647, L10
: Saito, S. and Yamamoto, S., The Journal of Chemical Physics, 1997, 107, 1732-1739
: Ozeki, H. et al., The Astrophysical Journal, 2004, 617, 680-684
: Irvine, W. M. et al., The Astrophysical Journal Letters, 1988, 334, L107-L111