STRONG THERMAL NONEQUILIBRIUM IN HYPERSONIC CO AND CH4 PROBED BY CRDS

Boudon, Vincent

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https://hdl.handle.net/2142/79070 Copy

Description

Title

STRONG THERMAL NONEQUILIBRIUM IN HYPERSONIC CO AND CH4 PROBED BY CRDS

Author(s)

Boudon, Vincent

Contributor(s)

• Kassi, Samir
• Rey, Michael
• Georges, Robert
• Suas-David, Nicolas
• Louviot, Maud

Issue Date

25-Jun-15

Keyword(s)

Instrument/Technique Demonstration

Abstract

A new experimental set-up coupling a High Enthalpy Source (HES) reaching 2000~K to a cw Cavity Ring-Down Spectrometer has been developed to investigate rotationnally cold hot bands of polyatomic molecules in the $[1.5,1.7]$~$mu$m region. The rotational and vibrational molecular degrees of freedom are strongly decoupled in the hypersonic expansion produced by the HES and probed by Cavity Ring-Down Spectroscopy. Carbon monoxide has been used as a first test molecule to validate the experimental approach. Its expansion in argon led to rotational and vibrational temperatures of $6.7pm 0.8$~K and $2006pm 476$~K, respectively. The Tetradecad polyad of methane ($1.67$~$mu$m) was investigated under similar conditions leading to rotational and vibrational temperatures of $13pm 5$~K and $750pm 100$~K, respectively. The rotationally cold structure of the spectra reveals many hot bands involving highly excited vibrational states of methane.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

text

Language

English

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http://hdl.handle.net/2142/79070

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