# $talk$ - Chirped-pulse millimeter-wave spectroscopy of astrophysical radicals in a pulse jet discharge experiment

### Abstract

A decade ago, the advent of broadband chirped-pulse Fourier-transform microwave spectrometers revolutionized rotational spectroscopy in the centimeter-wave region [1]. Commercial solution are available in the millimeter-wave region, and new molecular spectroscopy investigations can now be undertaken.

Motivated by the prospect of enabling new interstellar detections, we have developed a new set-up associating a broadband chirped-pulse Fourier-transform millimeter-wave (W-band) spectrometer and a supersonic jet chamber. Radicals are produced by an electric discharge in the high pressure part of the jet and reactive species are directly probed by the radiation at temperatures as low as few Kelvin.

Using different organic precursors such as acetonitrile (CH3CN), methanol (CH3OH) or allene (C3H4), we were able to study rich discharge mixtures. Among others, we were able to produce and detect the cyanomethyl radical (CH2CN) [2], the methoxy radical (CH3O) [3] and cyclopropenylidene (c-C3H2) [4] in the vibrational ground state and in several vibrational excited states. In the presentation, technical details of the set-up will be provided, together with the preliminary results we obtained.

[1] Brown, G. G et al., Review of Scientific Instruments 79, 053103 (2008)

[2] Saito, S. and Yamamoto, S., The Journal of Chemical Physics 107, 1732 (1997)

[3] Endo, Y. et al., The Journal of Chemical Physics 81, 122-135 (1984)

[4] Thaddeus, P. et al., The Astrophysical Journal 299, L63-L66 (1985)

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.

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

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

##### 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.