University of Illinois Urbana-Champaign

High-temperature Hypersonic Laval Nozzle For Non-lte Cavity Ringdown Spectroscopy

Dudás, Eszter

Content Files
4799.pdf
TB11_4799.pdf

Permalink

https://hdl.handle.net/2142/111187

Description

Title
High-temperature Hypersonic Laval Nozzle For Non-lte Cavity Ringdown Spectroscopy
Author(s)
Dudás, Eszter
Contributor(s)
  • Suas-David, Nicolas
  • Charles, Christine
  • Kassi, Samir
  • Kulkarni, Vinayak
  • Brahmachary, Shuvayan
  • Benidar, Abdessamad
  • Georges, Robert
Issue Date
2021-06-22
Keyword(s)
Instrument/Technique Demonstration
Date of Ingest
  • 2021-09-24T21:09:12Z
  • 2022-01-21T16:10:58Z
Abstract
"The SMAUG apparatus (Spectroscopy of Molecules Accelerated in Uniform Gas flows) was developed to produce hot spectra of various molecules of interest for hot astrophysical atmospheres, like the one surrounding hot Jupiters, reaching up to 2500 K. High-temperature IR spectroscopic data is needed to retrieve temperature and concentration profiles from astronomical spectra. A small dimension Laval nozzle connected to a compact high enthalpy source equipped with cavity ringdown spectroscopy (CRDS) is used to produce high-resolution infrared spectra of polyatomic molecules in the 1.67~$\mu$m region.$^{a}$. The experimental setup can operate according to two complementary working regimes: non-local thermodynamic equilibrium (non-LTE) (vibrationally hot and rotationally cold) and LTE conditions, to interpret the complex pattern of highly-excited vibrational states. Two different gases, carbon monoxide (CO) and methane (CH$_{4}$) were used as test molecules. Using non-LTE conditions vibrational (T$_{vib}$) and rotational (T$_{rot}$) temperatures were extracted from the recorded infrared spectrum leading to T$_{vib}$~=~1346(52)~K and T$_{rot}$~=~12(1)~K for CO. A rotational temperature of 39(3)~K was measured for CH4, while two vibrational temperatures were necessary to reproduce the observed intensities. The population distribution between vibrational polyads was correctly described with T$_{vib,I}$~=~825(50)~K"" , while the population distribution within a given polyad was modelled correctly by T$_{vib,II}$~=~39(5)~K"" , testifying to a more rapid vibrational relaxation between the vibrational energy levels constituting a polyad. Using a “post-shock CRDS” technique CO and CH$_{4}$ LTE spectra were recorded at 950 K and 1400 K.\\ $^{a}$\textit{E.Dud$\acute{a}$s \emph{et al.} High-temperature hypersonic Laval nozzle for non-LTE cavity ringdown spectroscopy. J Chem Phys 2020;152:134201. https://doi.org/10.1063/5.0003886.}"
Publisher
International Symposium on Molecular Spectroscopy
Type of Resource
Text
Genre of Resource
Conference Paper / Presentation
Language
eng
Permalink
http://hdl.handle.net/2142/111187
DOI
10.15278/isms.2021.TB11

Owning Collections

Abstracts & Presentations - 2021 International Symposium on Molecular Spectroscopy PRIMARY