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Zeitschrift für Naturforschung A

A Journal of Physical Sciences

Editor-in-Chief: Holthaus, Martin

Editorial Board: Fetecau, Corina / Kiefer, Claus

IMPACT FACTOR 2016: 1.432

CiteScore 2017: 1.30

SCImago Journal Rank (SJR) 2017: 0.403
Source Normalized Impact per Paper (SNIP) 2017: 0.632

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Volume 49, Issue 10


Double Modulation Technique in Pulsed Jet Experiments with Tunable Diode Lasers

I. Pa
  • I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, D-50937 Köln, Germany
  • Institute of Spectroscopy, Academy of Sciences of Russia, 142092 Troitsk, Moscow Region, Russia.
  • Other articles by this author:
  • De Gruyter OnlineGoogle Scholar
/ M. Hepp / R. Philipp / R. Schieder / G. Winnewisser
Published Online: 2014-06-02 | DOI: https://doi.org/10.1515/zna-1994-1001


A double modulation technique was used to achieve higher sensitivity in absorption measure­ ments with a pulsed supersonic jet. The wavelength of a lead-salt diode laser was modulated at a frequency of 10 kHz and detected at twice the frequency by a lock-in amplifier, reducing significantly the influence of the low frequency excess laser noise. The output of this lock-in amplifier was measured by a boxcar integrator, driven at 80 Hz, the frequency of the pulsed jet. In case the duration of the jet pulse is long enough, a second lock-in amplifier can also be used instead of the boxcar integrator. The optical path of the diode laser radiation through the jet was increased 16 times by using White type multireflection optics. The achieved value for the minimum detectable absorption of Ar - CO complexes in the jet was 2 x 10-5 in relative absorption, limited by the excess noise of the diode laser.

About the article

Received: 1994-07-27

Published Online: 2014-06-02

Published in Print: 1994-10-01

Citation Information: Zeitschrift für Naturforschung A, Volume 49, Issue 10, Pages 913–919, ISSN (Online) 1865-7109, ISSN (Print) 0932-0784, DOI: https://doi.org/10.1515/zna-1994-1001.

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© 1946 – 2014: Verlag der Zeitschrift für Naturforschung. This work is licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 3.0 License. BY-NC-ND 3.0

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