# $talk$ - The pure rotational spectrum of the hydroxymethyl radical reinvestigated to enable its interstellar detection

### Abstract

The hydroxymethyl (CH2OH) and methoxy (CH3O) radicals, products of CH3OH photodissociation, are consideredkey reactive intermediates in the interstellar medium (ISM), and their recombination with other fragments is postulated to lead to the formation of commonly observed complex organic molecules (COMs) as glycolaldehyde, ethanol, ethyleneglycol, and dimethyl ether. Interestingly, despite the recent first laboratory detection of CH2OH pure rotational spectrum [1] and while this isomer is the most thermodynamically stable, only CH3O has so far been detected in the ISM. A plausible explanation to this lack of interstellar detection is the non-observation in the laboratory of the most intense transitions at low temperature.

We have re-investigated the pure rotational spectrum of CH2OH at room temperature in the millimeter-wave domain, using a frequency modulation submillimeter spectrometer, with emphasized searches for the fundamental $b$-type transitionsand those intense at low temperature. The radical was produced by H abstraction from CH3OH using F atoms produced by a microwave discharge. A combined fit of millimeter-wave lines from the literature and our new measurements using a rigid-rotor Hamiltonian yielded a large improvement in the spectroscopic parameters [2] values allowing now confident searches of CH2OH in cold interstellar environments.

[1] C. Bermudez et al., Astronomy and Astrophysics 598, A9 (2017)

[2] O. Chitarra et al., Astronomy and Astrophysics 644, A123 (2020)

Date
Jun 21, 2021 — Jun 25, 2021
Location
Virtual Conference
University of Illinois, USA
##### Olivia Chitarra
###### PhD student

PhD student at Institut des Sciences Moléculaires d’Orsay (ISMO) under the direction of Olivier Pirali and Marie-Aline Martin-Drumel.

##### Marie-Aline Martin-Drumel
###### Researcher

My research interests focus on molecular spectroscopy of stable molecules and reactive species, and its applications for astrophysics and physical-chemistry.

##### Olivier Pirali
###### Director of Research

My research interests includes high resolution molecular spectroscopy, laboratory astrophysics, and THz generation.