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Proceedings Paper

Diode laser overtone spectroscopy of atmospheric trace species
Author(s): Alessandro Lucchesini; D. Pelliccia; Iginio Longo; C. Gabbanini; S. Gozzini
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Paper Abstract

This work is based on the use of diode lasers as spectroscopic sources for the observation and study of weak overtone bands of the NIR. The diode laser emission wavelength can be scanned around a gas resonance by sweeping its injection current, permitting a direct observation of an absorption line-shape. The resolution is limited principally by the effective laser linewidth, generally approximately equals 20 MHz in free running mode. The signal-to-noise ratio is increased by using the frequency modulation technique, and the excess laser amplitude 1/f noise is reduced by working at high frequencies. Since detectors operating at high frequencies are expensive and less sensitive, a good compromise is the two-tone frequency modulation technique, which uses two close high frequencies and collects the beat signal at lower frequency. Pressure broadening coefficients have been measured for some acetylene and ammonia absorption lines in the 790 nm bands and new lines have been observed. Pressure shift of two acetylene lines have been examined. It is shown that this spectroscopic apparatus can extract very weak signals from the background and can be a good choice when the space occupied by the spectrometer needs to be restricted into small volumes.

Paper Details

Date Published: 30 September 1994
PDF: 10 pages
Proc. SPIE 2266, Optical Spectroscopic Techniques and Instrumentation for Atmospheric and Space Research, (30 September 1994); doi: 10.1117/12.187586
Show Author Affiliations
Alessandro Lucchesini, Istituto di Fisica Atomica e Molecolare del CNR (Italy)
D. Pelliccia, Istituto di Fisica Atomica e Molecolare del CNR (Italy)
Iginio Longo, Istituto di Fisica Atomica e Molecolare del CNR (Italy)
C. Gabbanini, Istituto di Fisica Atomica e Molecolare del CNR (Italy)
S. Gozzini, Istituto di Fisica Atomica e Molecolare del CNR (Italy)


Published in SPIE Proceedings Vol. 2266:
Optical Spectroscopic Techniques and Instrumentation for Atmospheric and Space Research
Jinxue Wang; Paul B. Hays, Editor(s)

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