Rapid and sensitive quantification of isotopic mixtures using a rapidly-swept external cavity quantum cascade laser

Brian E. Brumfield; Matthew S. Taubman; Mark C. Phillips

doi:10.3390/photonics3020033

Rapid and sensitive quantification of isotopic mixtures using a rapidly-swept external cavity quantum cascade laser

Brian E. Brumfield, Matthew S. Taubman, Mark C. Phillips

Research output: Contribution to journal › Article › peer-review

13 Scopus citations

Abstract

A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D₂O and HDO at a rate of 40 Hz (25-ms measurement time). The chemical mixtures were generated by evaporating D₂O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H₂O to produce HDO. Fluctuations in the ratio of D₂O and HDO on timescales of < 1 s due to the combined effects of plume transport and the H/D exchange chemical reaction are observed. Noise-equivalent concentrations (1σ) (NEC) of 147.0 ppbv and 151.6 ppbv in a 25-ms measurement time are determined for D₂O and HDO, respectively, with a 127-m optical path. These NECs are improved to 23.0 and 24.0 ppbv with a 1-s averaging time for D₂O and HDO, respectively. NECs < 200 ppbv are also estimated for N₂O, 1,1,1,2-tetrafluoroethane (F134A), CH₄, acetone and SO₂ for a 25-ms measurement time. The isotopic precision for measurement of the [D₂O]/[HDO] concentration ratio of 33‰ and 5‰ is calculated for the current experimental conditions for measurement times of 25 ms and 1 s, respectively.

Original language	English (US)
Article number	33
Journal	Photonics
Volume	3
Issue number	2
DOIs	https://doi.org/10.3390/photonics3020033
State	Published - Jun 1 2016
Externally published	Yes

Keywords

External cavity quantum cascade laser
Infrared spectroscopy
Trace-gas sensing

ASJC Scopus subject areas

Atomic and Molecular Physics, and Optics
Instrumentation
Radiology Nuclear Medicine and imaging

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10.3390/photonics3020033

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title = "Rapid and sensitive quantification of isotopic mixtures using a rapidly-swept external cavity quantum cascade laser",

abstract = "A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D2O and HDO at a rate of 40 Hz (25-ms measurement time). The chemical mixtures were generated by evaporating D2O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H2O to produce HDO. Fluctuations in the ratio of D2O and HDO on timescales of < 1 s due to the combined effects of plume transport and the H/D exchange chemical reaction are observed. Noise-equivalent concentrations (1σ) (NEC) of 147.0 ppbv and 151.6 ppbv in a 25-ms measurement time are determined for D2O and HDO, respectively, with a 127-m optical path. These NECs are improved to 23.0 and 24.0 ppbv with a 1-s averaging time for D2O and HDO, respectively. NECs < 200 ppbv are also estimated for N2O, 1,1,1,2-tetrafluoroethane (F134A), CH4, acetone and SO2 for a 25-ms measurement time. The isotopic precision for measurement of the [D2O]/[HDO] concentration ratio of 33‰ and 5‰ is calculated for the current experimental conditions for measurement times of 25 ms and 1 s, respectively.",

keywords = "External cavity quantum cascade laser, Infrared spectroscopy, Trace-gas sensing",

author = "Brumfield, {Brian E.} and Taubman, {Matthew S.} and Phillips, {Mark C.}",

note = "Publisher Copyright: {\textcopyright} 2016 by the author.",

year = "2016",

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doi = "10.3390/photonics3020033",

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AU - Brumfield, Brian E.

AU - Taubman, Matthew S.

AU - Phillips, Mark C.

PY - 2016/6/1

Y1 - 2016/6/1

N2 - A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D2O and HDO at a rate of 40 Hz (25-ms measurement time). The chemical mixtures were generated by evaporating D2O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H2O to produce HDO. Fluctuations in the ratio of D2O and HDO on timescales of < 1 s due to the combined effects of plume transport and the H/D exchange chemical reaction are observed. Noise-equivalent concentrations (1σ) (NEC) of 147.0 ppbv and 151.6 ppbv in a 25-ms measurement time are determined for D2O and HDO, respectively, with a 127-m optical path. These NECs are improved to 23.0 and 24.0 ppbv with a 1-s averaging time for D2O and HDO, respectively. NECs < 200 ppbv are also estimated for N2O, 1,1,1,2-tetrafluoroethane (F134A), CH4, acetone and SO2 for a 25-ms measurement time. The isotopic precision for measurement of the [D2O]/[HDO] concentration ratio of 33‰ and 5‰ is calculated for the current experimental conditions for measurement times of 25 ms and 1 s, respectively.

AB - A rapidly-swept external-cavity quantum cascade laser with an open-path Herriott cell is used to quantify gas-phase chemical mixtures of D2O and HDO at a rate of 40 Hz (25-ms measurement time). The chemical mixtures were generated by evaporating D2O liquid near the open-path Herriott cell, allowing the H/D exchange reaction with ambient H2O to produce HDO. Fluctuations in the ratio of D2O and HDO on timescales of < 1 s due to the combined effects of plume transport and the H/D exchange chemical reaction are observed. Noise-equivalent concentrations (1σ) (NEC) of 147.0 ppbv and 151.6 ppbv in a 25-ms measurement time are determined for D2O and HDO, respectively, with a 127-m optical path. These NECs are improved to 23.0 and 24.0 ppbv with a 1-s averaging time for D2O and HDO, respectively. NECs < 200 ppbv are also estimated for N2O, 1,1,1,2-tetrafluoroethane (F134A), CH4, acetone and SO2 for a 25-ms measurement time. The isotopic precision for measurement of the [D2O]/[HDO] concentration ratio of 33‰ and 5‰ is calculated for the current experimental conditions for measurement times of 25 ms and 1 s, respectively.

KW - External cavity quantum cascade laser

KW - Infrared spectroscopy

KW - Trace-gas sensing

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Rapid and sensitive quantification of isotopic mixtures using a rapidly-swept external cavity quantum cascade laser

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