University of Illinois Urbana-Champaign

Saturated Absorption Spectroscopy And Two-photon Cavity Ring-down Absorption Spectroscopy For Trace Gas Detection Of Nitrous Oxide

Memovich, Madeline

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FF09_1.pptx
6313.pdf

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https://hdl.handle.net/2142/116775

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Title
Saturated Absorption Spectroscopy And Two-photon Cavity Ring-down Absorption Spectroscopy For Trace Gas Detection Of Nitrous Oxide
Author(s)
Memovich, Madeline
Contributor(s)
Lehmann, Kevin
Issue Date
2022-06-24
Keyword(s)
Spectroscopy as an analytical tool
Abstract
Like Carbon Dioxide (CO$_{2}$), Nitrous Oxide (N$_{2}$O) behaves as a long-lived greenhouse gas. Increases in atmospheric concentrations of N$_{2}$O due to anthropomorphic sources have contributed to stratospheric ozone depletion and climate change. For these reasons it is imperative to formulate effective techniques for trace N$_{2}$O detection. Spectral line resolution and detection sensitivity are crucial for efficient trace gas quantification. One technique which enables the precise determination of the transition frequency between the ground and excited states of an analyte is saturated absorption spectroscopy (SAS). In SAS, counter-propagating beams of the same frequency produce Doppler-free peaks in absorption spectra. Each beam produces opposite Doppler shifts, therefore only atoms/molecules traveling with nearly zero-velocity along the axis of beam propagation couple with both beams, leading to Doppler-free spectral-hole burning. Additionally, cavity enhanced spectroscopic methods, such as the revolutionary cavity ring-down spectroscopy (CRDS), employ the use of a high finesse optical cavity, wherein light is trapped and the concentration of the analyte is determined by the rate of decay of the cavity light. Due to the high intensity of the light inside the optical cavity, this technique is remarkably sensitive, even for the detection of weakly absorbing transitions. However, the high density of one-photon transitions can often lead to spectral overlap and resolution loss. On the other hand, near-resonance two-level transitions, like those found in N$_{2}$O, result in low density spectra. Here we present a novel approach of gaseous N$_{2}$O detection by SAS and two-photon CRDS of the P(18) and Q(18) ro-vibrational transitions.
Publisher
International Symposium on Molecular Spectroscopy
Type of Resource
text
Genre of Resource
Conference Paper / Presentation
Language
eng
Handle URL
https://hdl.handle.net/2142/116775
DOI
https://doi.org/10.15278/isms.2022.FF09
Copyright and License Information
Copyright 2022 held by the authors

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Abstracts & Presentations - 2022 International Symposium on Molecular Spectroscopy PRIMARY