Extended Laboratory Investigation Of The Pure Rotational Spectrum Of The Ch2cn Radical In The (sub-)millimeter Region (79-860 Ghz)

Chitarra, Olivia

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https://hdl.handle.net/2142/116834 Copy

Description

Title

Extended Laboratory Investigation Of The Pure Rotational Spectrum Of The Ch2cn Radical In The (sub-)millimeter Region (79-860 Ghz)

Author(s)

Chitarra, Olivia

Contributor(s)

• Martin-Drumel, Marie-Aline
• Pirali, Olivier
• Hearne, Thomas Sandow

Issue Date

2022-06-21

Keyword(s)

Rotational structure/frequencies

Abstract

The cyanomethyl radical, \chem{CH_2CN}, is considered a key reactive intermediate in the interstellar medium (ISM) since its first detection [1]. To date, the radical has been detected in several environments of the ISM using pure rotational data available in the literature, limited to frequencies below 280 GHz [2,3]. The radical is also postulated to participate to the formation of complex organic molecules, such as cyanoacetaldehyde [4]. To enable the detection of the \chem{CH_2CN} radical in current high frequency astronomical surveys, laboratory re-investigation of its spectrum at submillimeter wavelengths appears essential. We have investigated the pure rotational spectrum of \chem{CH_2CN} at room temperature in the 75-900 GHz domain. The radical was produced using a H-abstraction method from \chem{CH_3CN} using F atoms. To record pure rotational transitions, we used two spectrometers: a commercial broadband chirped-pulse (CP) spectrometer covering the 75-110 GHz spectral region and a tunable single-frequency absorption spectrometer exploiting a frequency multiplication chain with a large spectral coverage (here, 140-900 GHz). A combined fit of the literature data and our newly measured transitions (involving $N$’’ and $K_{a}$’’ up to 42 and 8, respectively) yields to an improvement of the rotational parameters; in particular the $A$ rotational constant and $K$-dependent parameters. This work allows for confident searches of the radical in cold to warm environments of the ISM, over a wide frequency range. In addition, the broadband capacities of the CP spectrometer has also revealed very efficient in the study of discharge products (synthesized by the reaction between \chem{CH_3CN} and F atoms in this work). I will present both aspects of this work: the improvement of the spectroscopy of \chem{CH_2CN} and the analysis of the chemical composition of the discharge by CP spectroscopy. [1] W. M. Irvine et al., The Astrophysical Journal Letters (1988) 334, L107 [2] S. Saito et al., The Journal of Chemical Physics (1997) 107, 1732 [3] H. Ozeki et al., American Astronomical Society (2004) 617, 680 [4] B. Ballotta et al., ACS Earth and Space Chemistry (2021) 5, 1071

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/116834

DOI

https://doi.org/10.15278/isms.2022.TD02

Copyright and License Information

Copyright 2022 held by the authors

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