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Modulated resonant versus pulsed resonant photoacoustics intrace gas detection

Bartlome, R. ; Kaučikas, M. ; Sigrist, M.

In: Applied Physics B, 2009, vol. 96, no. 2-3, p. 561-566

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    Titre
    • Modulated resonant versus pulsed resonant photoacoustics intrace gas detection
    Auteur
    • Bartlome, R.. Institute for Quantum Electronics, ETH Zurich, Schafmattstrasse 16, 8093, Zurich, Switzerland
    • Kaučikas, M.. Institute of Physics, Savanoriu 231, 2300, Vilnius, Lithuania
    • Sigrist, M.. Institute for Quantum Electronics, ETH Zurich, Schafmattstrasse 16, 8093, Zurich, Switzerland
    Type de document
    • Postprint
    Identifiant OAI-PMH
    • oai:doc.rero.ch:314458
    Summary
    Modulated resonant photoacoustics is a sensitive technique widely used for trace gas sensing. Generally, a continuous-wave laser is modulated at a frequency corresponding to an acoustic resonance of a photoacoustic cell. Another mode of operation—which we propose to call the pulsed resonant mode—consists in matching the frequency repetition rate of a pulsed laser to an acoustic resonance of the cell. We present a theoretical model to compare the performance of these two configurations. For a given average power of the incoming light inside the cell, the pulsed resonant mode of operation (nanosecond pulses or shorter) produces π/2 times higher photoacoustic signals than the modulated resonant scheme (the latter is optimized for a 50% duty cycle). This result agrees with experiments during which both cases were investigated at 532nm using the same photoacoustic cell containing trace concentrations of NO2