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Instruments de Mesure Multi-Polluants par Spectroscopie Infrarouge basés sur des Lasers Fibrés et par Génération de Différence de Fréquences : Développement et Applications

Abstract : At present the detection of VOC and other anthropic trace pollutants is an important challenge in the measurement of air quality. Infrared spectroscopy, allowing spectral regions rich in molecular absorption to be probed, is a suitable technique for in-situ monitoring of the air pollution. Thus the aim of this work was to develop instruments capable of detecting multiple pollutants for in-situ monitoring by IR spectroscopy. A first project benefited from the availability of the telecommunications lasers emitting in near-IR. This instrument was based on an external cavity diode laser (1500 - 1640 nm) in conjunction with a multipass cell (100 m). The detection sensitivity was optimised by employing a balanced detection and a sweep integration procedure. The instrument developed is deployable for in-situ measurements with a sensitivity of < 10-7 cm-1Hz-1/2 and allowed the quantification of chemical species such as CO2, CO, C2H2, CH4 and the determination of the isotopic ratio 13CO2/12CO2 in combustion environment The second project consisted in mixing two near-IR fiber lasers in a non-linear crystal (PPLN) in order to produce a laser radiation by difference frequency generation in the middle-IR (3.15 - 3.43 µm), where the absorption bands of the molecules are the most intense. The first studies with this source were carried out on detection of ethylene (C2H4) and benzene (C6H6). Developments, characterizations and applications of these instruments in the near and middle IR are detailed and the advantages of the 2 spectral ranges is highlighted.
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https://tel.archives-ouvertes.fr/tel-00124729
Contributor : Julien Cousin <>
Submitted on : Thursday, January 25, 2007 - 4:59:42 PM
Last modification on : Tuesday, January 5, 2021 - 10:58:02 AM
Long-term archiving on: : Tuesday, September 21, 2010 - 12:19:07 PM

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  • HAL Id : tel-00124729, version 2

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Julien Cousin. Instruments de Mesure Multi-Polluants par Spectroscopie Infrarouge basés sur des Lasers Fibrés et par Génération de Différence de Fréquences : Développement et Applications. Physique Atomique [physics.atom-ph]. Université du Littoral Côte d'Opale, 2006. Français. ⟨tel-00124729v2⟩

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