Parallel Session: High-resolution, Contributed Talk (15min)

Millimeter and sub-millimeter spectroscopic studies of astrophysical relevant radicals Illustration with the CH2CN radical

O. Chitarra1, J. Spaniol1, B. Gans1, T. Hearne1, J. Loison2, O. Pirali1, M. Martin-Drumel1*
1Institut des Sciences Moleculaires d’Orsay, 2Institut des Sciences Moleculaires

Radical species are suspected to be involved in gas phase reactions occurring in the interstellar medium (ISM) [1] 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 [4]. 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.

[1]: Cernicharo, J. et al., Astronomy & Astrophysics Letters2021, 647, L10
[2]: Saito, S. and Yamamoto, S., The Journal of Chemical Physics, 1997, 107, 1732-1739
[3]: Ozeki, H. et al., The Astrophysical Journal, 2004, 617, 680-684
[4]: Irvine, W. M. et al., The Astrophysical Journal Letters, 1988, 334, L107-L111