| Issue |
J. Phys. IV France
Volume 125, June 2005
|
|
|---|---|---|
| Page(s) | 7 - 10 | |
| DOI | https://doi.org/10.1051/jp4:2005125002 | |
J. Phys. IV France 125 (2005) 7-10
DOI: 10.1051/jp4:2005125002
Methane monitoring by near infrared photoacoustic spectroscopy: The importance of relaxation phenomena
S. Schilt1, J.-Ph. Besson2 and L. Thévenaz11 Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology, 1015 Lausanne, Switzerland
2 Nanophotonics and Metrology Laboratory, Swiss Federal Institute of Technology, 1015 Lausanne, Switzerland
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Abstract
The importance of molecular relaxation in photoacoustic spectroscopy is discussed. The particular case of methane monitoring in dry oxygen using a 1.65-
m laser-based photoacoustic sensor is reported. The slow vibration-to-translation energy transfer occurring in this gas mixture results in a drastic reduction of the detection sensitivity. A quadratic response of the sensor to the methane concentration is also reported and explained by molecular relaxation effects.
© EDP Sciences 2005