Hartung-Gorre Verlag
Inh.: Dr. Renate Gorre D-78465 Konstanz / Germany Fon: +49 (0)7533 97227 Fax: +49
(0)7533 97228 www.hartung-gorre.de |
S
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Series
in Quantum Electronics
edited
by
Henry Baltes, Peter Günter, Ursula Keller,
Fritz K. Kneubühl †, Walter Lukosz,
Hans Melchior, Markus W. Sigrist
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Vol. 11 Irio G. Calasso Photoacoustic and Photothermal Laser Spectroscopy Applied to Trace Gas Detection and Molecular Dynamics. 1st edition 1999. VI, 110
pages, € 64,00. |
This thesis deals with photoacoustic (PA) and photothermal (PT) studies on gas mixtures by using a
continuously tunable high pressure CO2 laser and a microphone or a HeNe laser probe
beam. A new theoretical approach allows a generally valid description of the
gas density variation after laser pulse excitation. This model has been applied
for the investigation of microphone characteristics suitable to increase the
signal-to-noise ratio (SNR) in pulsed photoacoustics
and for the analysis of measured PT beam deflection (PTBD) signals for the
derivation of molecular relaxation rates and thermal conductivities of gases.
In view of optimizing the performance for pulsed PA detection with microphones
in a non-resonant cell, the dependence of the SNR on the microphone
responsivity and bandwidth has been investigated for the first time both
theoretically and experimentally. This permits to select the most appropriate
microphone for maximum detection sensitivity. An example of a PA investigation
is given for a mixture of six CO2 isotopes. This study
allowed the quantitative analysis of the mixture and the determination of
previously unknown absorption cross sections. Furthermore,
vibrational-translational (V-T) relaxation rates are derived for various gases
and gas mixtures from PTBD signal shapes. From the same signals, thermal
conductivity data are deduced simultaneously.
Keywords: photoacoustic (PA) and photothermal (PT)
studies, Laser Spectroscopy, Trace Gas Detection,
Molecular Dynamics
Direkt bestellen bei / to order directly from: Hartung.Gorre@t-online.de
Hartung-Gorre
Verlag / D-78465 Konstanz / Germany
Telefon:
+49 (0) 7533 97227 Telefax: +49 (0) 7533
97228
http://www.hartung-gorre.de eMail: verlag@hartung-gorre.de