Cavity-enhanced Absorption for Trace Gas Detection with Frontier
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چکیده
Detecting gases at low concentrations with FT-IR requires long pathlengths to increase absorption. The conventional approach employs a multi-pass White Cell where the light beam is reflected between two mirrors that are angled so that the beam emerges past one of the mirrors after a number of reflections, giving pathlengths up to tens of meters. In cavity-enhanced measurements, a highly collimated beam is reflected between two mirrors with a small amount of radiation emerging through the mirrors at each reflection. By using highly reflective mirrors the effective pathlength can be several thousand times greater than the separation between the mirrors. This gives the possibility of detecting gases at low concentrations in relatively small volumes, for example in looking for metabolites in breath.
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Sensitive trace gas detection with cavity enhanced absorption spectroscopy using a continuous wave external-cavity quantum cascade laser
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