A new strategy for collection of high-temperature broad-band absorption spectra for gas-phase molecules in the mid-infrared

Ding, Yiming

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https://hdl.handle.net/2142/107428 Copy

Description

Title

A new strategy for collection of high-temperature broad-band absorption spectra for gas-phase molecules in the mid-infrared

Author(s)

Ding, Yiming

Contributor(s)

• Hanson, Ronald K.
• Johnson, Sarah E.
• Strand, Christopher L.

Issue Date

2020-06-26

Keyword(s)

• Intensities
• transition moments
• cross sections

Abstract

\begin{wrapfigure}{r}{0pt} \includegraphics[scale=0.28]{Ethylene_nu_7_band_995K_2.3atm.eps} \end{wrapfigure} To address the notable lack of knowledge on high-temperature absorption cross sections of important molecular species in combustion and exoplanets, a new strategy is proposed and deployed to collect broad-band absorption spectra in shock-heated gases. The methodology utilizes a broad-scan, rapid-tuning external-cavity quantum cascade laser in conjunction with a shock tube and is capable of providing quantitative spectroscopic information across full vibrational bands spanning over 200 \wn within 6 ms ($>$ 30,000 \wn/s), with a spectral resolution between 0.3 – 0.6 \wn. This experimental approach is demonstrated with absorption spectra measurements on the \nub{7} vibrational band of ethylene (\chem{C_2H_4}) from 8.4 $\mu$m to 11.7 $\mu$m at temperature/pressure conditions between 800 – 1600 K, 1 – 5 atm. The measured spectra are compared against spectral simulations using existing spectroscopic databases, showing better agreement with the line list of Rey et al.\footnote{M. Rey, T. Delahaye, A. V. Nikitin, and V. G. Tyuterev, “First theoretical global line lists of ethylene ($^{12}$\chem{C_2H_4}) spectra for the temperature range 50-700 K in the far-infrared for quantification of absorption and emission in planetary atmospheres,” Astron. Astrophys., vol. 594, pp. 1–16, 2016.} than of HITRAN 2016\footnote{I. E. Gordon et al., “The HITRAN2016 molecular spectroscopic database,” J. Quant. Spectrosc. Radiat. Transf., vol. 203, pp. 3–69, 2017.}. With the current set of instruments available, this methodology could be applied to numerous gas-phase molecules that have attractive absorption features in the spectral range of 3.6 – 11.7 $\mu$m and opens an efficient pathway towards improving knowledge on radiation absorption in the mid-infrared at high temperatures.

Publisher

International Symposium on Molecular Spectroscopy

Type of Resource

Text

Language

eng

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http://hdl.handle.net/2142/107428

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Copyright 2020 is held by the Author(s)

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