scholarly journals Cavity Ring-Down Spectroscopy for Molecular Trace Gas Detection Using A Pulsed DFB QCL Emitting at 6.8 µm

Photonics ◽  
2020 ◽  
Vol 7 (3) ◽  
pp. 74
Author(s):  
Komlan S. Gadedjisso-Tossou ◽  
Lyubomir I. Stoychev ◽  
Messanh A. Mohou ◽  
Humberto Cabrera ◽  
Joseph Niemela ◽  
...  

A trace gas sensor based on pulsed cavity ring-down spectroscopy (CRDS) was developed for measurement of the ν4 fundamental vibrational band of ammonia (NH3) centered at 1468.898 cm−1. A pulsed distributed feedback quantum cascade laser (DFB-QCL) operating at 6.8 µm (1470.58 cm−1) quite well covered the absorption band of the ammonia and strong fundamental vibrational absorption bands of different molecular gases in this unexplored region. The cavity was partially evacuated down to 0.4 Atm by a turbo-molecular pump to reduce the partial interference between the NH3 spectra and water near the absorption peak of ammonia. A sensitivity of nine parts per billion was reached for a measurement time of 120 s as well as an optical path length of 226 m. The device demonstrated high spectral performance and versatility due to its wide tuning range, narrow linewidth, and comparatively high-energy mid-IR radiation in the relatively unexplored 6.8 µm region, which is very important for high-resolution spectroscopy of a variety of gases.

2016 ◽  
Vol 24 (5) ◽  
pp. 5523 ◽  
Author(s):  
Laura E. McHale ◽  
Arsineh Hecobian ◽  
Azer P. Yalin

2020 ◽  
Vol 639 ◽  
pp. A142 ◽  
Author(s):  
A. Trokhimovskiy ◽  
V. Perevalov ◽  
O. Korablev ◽  
A. F. Fedorova ◽  
K. S. Olsen ◽  
...  

The atmosphere of Mars is dominated by CO2, making it a natural laboratory for studying CO2 spectroscopy. The Atmospheric Chemistry Suite (ACS) on board the ExoMars Trace Gas Orbiter uses solar occultation geometry to search for minor atmospheric species. During the first year of ACS observations, the attention was focused on the spectral range covering the methane ν3 absorption band, 2900–3300 cm−1, which has previously been observed on Mars. No methane was detected by ACS; instead, an improvement of the data processing has led to the identification of 30 weak absorption lines that were missing from spectroscopic databases. Periodic series of absorptions up to ~1.6% deep are observed systematically around the position of the methane Q-branch when the line of sight penetrates below 20 km (creating an optical path length of 300–400 km, with an effective pressure of a few millibar). The observed frequencies of the discovered lines match theoretically computed positions of the P-, Q-, and R-branches of the magnetic dipole and electric quadrupole 01111-00001 (ν2 + ν3) absorption bands of the main CO2 isotopologue; neither band has been measured or computed before. The relative depths of the observed spectral features support the magnetic dipole origin of the band. The contribution of the electric quadrupole absorption is several times smaller. Here we report the first observational evidence of a magnetic dipole CO2 absorption.


1995 ◽  
Vol 66 (4) ◽  
pp. 2821-2828 ◽  
Author(s):  
Rienk T. Jongma ◽  
Maarten G. H. Boogaarts ◽  
Iwan Holleman ◽  
Gerard Meijer

2002 ◽  
Author(s):  
Jerome Morville ◽  
Marc Chenevier ◽  
Alexander A. Kachanov ◽  
Daniele Romanini

2001 ◽  
Vol 41 (2) ◽  
pp. 111-116 ◽  
Author(s):  
Daniel Kleine ◽  
Manfred Mürtz ◽  
Jörg Lauterbach ◽  
Hannes Dahnke ◽  
Wolfgang Urban ◽  
...  

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