Fourier transform incoherent broadband cavity enhanced absorption spectroscopy developed for the study of cold astrophysical anions in a planar laval nozzle expansion

Bejjani, Raghed

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https://hdl.handle.net/2142/107333 Copy

Description

Title

Fourier transform incoherent broadband cavity enhanced absorption spectroscopy developed for the study of cold astrophysical anions in a planar laval nozzle expansion

Author(s)

Bejjani, Raghed

Contributor(s)

• Benidar, Abdessamad
• Georges, Robert

Issue Date

2020-06-22

Keyword(s)

Instrument/Technique Demonstration

Date of Ingest

2020-06-26T03:04:08Z

Abstract

The molecular diversity of cold interstellar medium has been recently enriched with the detection of molecular anions: $C_4H^-$, $C_6H^-$, $C_8H^-$, $C_3N^-$, $C_5N^-$ and $CN^-$. Although by far less abundant than neutrals, anions could play a significant role in the chemistry of molecular clouds\footnote{A. Van Orden, R.J. Saykally, Chem. Rev. 98 (1998) 2313-2358}$^,$\footnote{W. Weltner Jr, R.J. Van Zee, Chem. Rev. 89 (1989) 1713-1747}. With the exception of $C_5N^-$, whose identification in space was based on high-level ab initio calculations\footnote{J. Cernicharo et al. The Astrophysical Journal 688, no 22008: L83 86}, the astronomical detection of these anions was made possible thanks to the laboratory characterization of their rotational spectra. Our ultimate goal is to characterize the anionic carbon chains $C_x^-$ (x = 3, 4, 5,…) through their electronic spectra in order to explain the absorption features already observed one century ago in some diffuse interstellar clouds illuminated by reddened stars. We will represent our new instrument based on a planar de Laval supersonic plasma source coupled to Incoherent Broadband Cavity-Enhanced Absorption Spectroscopy (IBB-CEAS) in conjunction with a high-resolution Fourier transform spectrometer for the detection. Preliminary results obtained on neutral species ($O_2$, $CH_4$, $C_2H_2$) will be presented.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Genre of Resource

Conference Paper / Presentation

Language

eng

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http://hdl.handle.net/2142/107333

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