Isotope selective analysis of CO2 with tunable diode laser (TDL) spectroscopy in the NIR

  • The performance of a home-built tunable diode laser (TDL) spectrometer, aimed at multi-line detection of carbon dioxide, has been evaluated and optimized. In the regime of the (30<SUP>0</SUP>1)<SUB>III</SUB> / (000) band of <SUP>12</SUP>CO<SUB>2</SUB> around 1.6 μm, the dominating isotope species <SUP>12</SUP>CO<SUB>2</SUB>, <SUP>13</SUP>CO<SUB>2</SUB>, and <SUP>12</SUP>C<SUP>18</SUP>O<SUP>16</SUP>O were detected simultaneously without interference by water vapor. Detection limits in the range of few ppmv were obtained for each species utilizing wavelength modulation (WM) spectroscopy with balanced detection in a long-path absorption cell set-up. High sensitivity in conjunction with high precision —typically ±1‰ and ±6‰ for 3% and 0.7% of CO<SUB>2</SUB>, respectively— renders this experimental approach a promising analytical concept for isotope-ratio determination of carbon dioxide in soil and breath gas. For a moderate <SUP>12</SUP>CO<SUB>2</SUB> line, the pressure dependence of the line profile was characterized inThe performance of a home-built tunable diode laser (TDL) spectrometer, aimed at multi-line detection of carbon dioxide, has been evaluated and optimized. In the regime of the (30<SUP>0</SUP>1)<SUB>III</SUB> / (000) band of <SUP>12</SUP>CO<SUB>2</SUB> around 1.6 μm, the dominating isotope species <SUP>12</SUP>CO<SUB>2</SUB>, <SUP>13</SUP>CO<SUB>2</SUB>, and <SUP>12</SUP>C<SUP>18</SUP>O<SUP>16</SUP>O were detected simultaneously without interference by water vapor. Detection limits in the range of few ppmv were obtained for each species utilizing wavelength modulation (WM) spectroscopy with balanced detection in a long-path absorption cell set-up. High sensitivity in conjunction with high precision —typically ±1‰ and ±6‰ for 3% and 0.7% of CO<SUB>2</SUB>, respectively— renders this experimental approach a promising analytical concept for isotope-ratio determination of carbon dioxide in soil and breath gas. For a moderate <SUP>12</SUP>CO<SUB>2</SUB> line, the pressure dependence of the line profile was characterized in detail, to account for pressure effects on sensitive measurements.show moreshow less

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Metadaten
Author:Gerald Hörner, Steffen Lau, Zoltan Kantor, Hans-Gerd Löhmannsröben
URN:urn:nbn:de:kobv:517-opus-10167
Series (Serial Number):Postprints der Universität Potsdam : Mathematisch-Naturwissenschaftliche Reihe (paper 020)
Document Type:Postprint
Language:English
Year of Completion:2004
Publishing Institution:Universität Potsdam
Release Date:2006/11/01
Tag:Diodenlaserspektroskopie
Isotope ratio; carbon monoxide; diode laser spectroscopy
GND Keyword:Isotopenverhältnis; Kohlendioxid
Source:Hörner et al. Analyst Vol.129, No. 8; 772-778 (2004)
RVK - Regensburg Classification:VE 9908
Organizational units:Mathematisch-Naturwissenschaftliche Fakultät / Institut für Chemie
Dewey Decimal Classification:5 Naturwissenschaften und Mathematik / 54 Chemie / 540 Chemie und zugeordnete Wissenschaften
Notes extern:
This paper was published in:
The Analyst, 129 (2004), pp. 772-778
ISSN: 0003-2654
DOI:10.1117/10.1039/b404552c

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