Publication

Methane monitoring by near infrared photoacoustic spectroscopy: The importance of relaxation phenomena

Luc Thévenaz, Jean-Philippe Besson
2005
Conference Papers

Abstract

The importance of molecular relaxation in photoacoustic spectroscopy is discussed. The particular case of methane monitoring in dry oxygen using a 1.65-μm 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

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https://infoscience.epfl.ch/entities/publication/37eeb28c-d437-4b19-81e6-8d345a79ec60

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Luc Thévenaz, Jean-Philippe Besson
2005
Conference Papers

Abstract

Official source

https://infoscience.epfl.ch/entities/publication/37eeb28c-d437-4b19-81e6-8d345a79ec60

About this result

Related concepts (4)

Photoacoustic spectroscopy

Photoacoustic spectroscopy is the measurement of the effect of absorbed electromagnetic energy (particularly of light) on matter by means of acoustic detection. The discovery of the photoacoustic effect dates to 1880 when Alexander Graham Bell showed that thin discs emitted sound when exposed to a beam of sunlight that was rapidly interrupted with a rotating slotted disk. The absorbed energy from the light causes local heating, generating a thermal expansion which creates a pressure wave or sound.

Infrared spectroscopy

Infrared spectroscopy (IR spectroscopy or vibrational spectroscopy) is the measurement of the interaction of infrared radiation with matter by absorption, emission, or reflection. It is used to study and identify chemical substances or functional groups in solid, liquid, or gaseous forms. It can be used to characterize new materials or identify and verify known and unknown samples. The method or technique of infrared spectroscopy is conducted with an instrument called an infrared spectrometer (or spectrophotometer) which produces an infrared spectrum.

Absorption spectroscopy

Absorption spectroscopy refers to spectroscopic techniques that measure the absorption of electromagnetic radiation, as a function of frequency or wavelength, due to its interaction with a sample. The sample absorbs energy, i.e., photons, from the radiating field. The intensity of the absorption varies as a function of frequency, and this variation is the absorption spectrum. Absorption spectroscopy is performed across the electromagnetic spectrum.

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