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Mid-Infrared Generated Laser-Induced Grating Signals in Methane-Containing Gas Mixtures as Indicators of Composition, Pressure, and Temperature

Sahlberg, Anna Lena LU ; Hot, Dina LU ; Li, Zhongshan LU and Kozlov, Dimitrii (2024) In Applied Spectroscopy 78(4).
Abstract

The present work is aimed at studying how spatially periodic modulations of the refractive index of the medium, i.e., laser-induced gratings (LIGs), generated in a gas mixture containing methane (CH4) by nanosecond pulses of resonant mid-infrared laser radiation, can be used to measure various gas parameters. It is investigated to what extent the temporal profiles of the LIG signals, recorded as the power of the diffracted by LIGs continuous wave probe radiation, are specific to the composition, pressure, and temperature of a selected buffer gas. This specificity is illustrated by the LIG signal profiles recorded in the experiments in different gas mixtures under various conditions. Experimental data show that large LIG... (More)

The present work is aimed at studying how spatially periodic modulations of the refractive index of the medium, i.e., laser-induced gratings (LIGs), generated in a gas mixture containing methane (CH4) by nanosecond pulses of resonant mid-infrared laser radiation, can be used to measure various gas parameters. It is investigated to what extent the temporal profiles of the LIG signals, recorded as the power of the diffracted by LIGs continuous wave probe radiation, are specific to the composition, pressure, and temperature of a selected buffer gas. This specificity is illustrated by the LIG signal profiles recorded in the experiments in different gas mixtures under various conditions. Experimental data show that large LIG signals can be obtained even in mixtures with CH4 concentrations as low as ∼100 parts per million due to the strong absorption of the excitation light and subsequent rapid, highly exothermic, and partner-dependent collisional energy exchange of the laser-excited molecules with the environment. These two factors ensure high LIG generation efficiency by a small number of CH4 molecules and high sensitivity of signal strength and profile to variations of gas parameters.

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author
; ; and
organization
publishing date
type
Contribution to journal
publication status
published
subject
keywords
gas sensing, laser-induced grating, LIG, methane detection, mid-infrared excitation, Nonlinear optical spectroscopy
in
Applied Spectroscopy
volume
78
issue
4
pages
423 pages
publisher
Society for Applied Spectroscopy
external identifiers
  • pmid:38373441
  • scopus:85186480665
ISSN
0003-7028
DOI
10.1177/00037028241230340
language
English
LU publication?
yes
additional info
Publisher Copyright: © The Author(s) 2024.
id
94732abc-5102-49e3-8850-6e2a761aecd9
date added to LUP
2024-03-20 13:27:54
date last changed
2024-04-17 13:02:13
@article{94732abc-5102-49e3-8850-6e2a761aecd9,
  abstract     = {{<p>The present work is aimed at studying how spatially periodic modulations of the refractive index of the medium, i.e., laser-induced gratings (LIGs), generated in a gas mixture containing methane (CH<sub>4</sub>) by nanosecond pulses of resonant mid-infrared laser radiation, can be used to measure various gas parameters. It is investigated to what extent the temporal profiles of the LIG signals, recorded as the power of the diffracted by LIGs continuous wave probe radiation, are specific to the composition, pressure, and temperature of a selected buffer gas. This specificity is illustrated by the LIG signal profiles recorded in the experiments in different gas mixtures under various conditions. Experimental data show that large LIG signals can be obtained even in mixtures with CH<sub>4</sub> concentrations as low as ∼100 parts per million due to the strong absorption of the excitation light and subsequent rapid, highly exothermic, and partner-dependent collisional energy exchange of the laser-excited molecules with the environment. These two factors ensure high LIG generation efficiency by a small number of CH<sub>4</sub> molecules and high sensitivity of signal strength and profile to variations of gas parameters.</p>}},
  author       = {{Sahlberg, Anna Lena and Hot, Dina and Li, Zhongshan and Kozlov, Dimitrii}},
  issn         = {{0003-7028}},
  keywords     = {{gas sensing; laser-induced grating; LIG; methane detection; mid-infrared excitation; Nonlinear optical spectroscopy}},
  language     = {{eng}},
  number       = {{4}},
  publisher    = {{Society for Applied Spectroscopy}},
  series       = {{Applied Spectroscopy}},
  title        = {{Mid-Infrared Generated Laser-Induced Grating Signals in Methane-Containing Gas Mixtures as Indicators of Composition, Pressure, and Temperature}},
  url          = {{http://dx.doi.org/10.1177/00037028241230340}},
  doi          = {{10.1177/00037028241230340}},
  volume       = {{78}},
  year         = {{2024}},
}