Off-axis cavity-enhanced absorption spectroscopy of 14NH3 in air using a gain-switched frequency comb at 1.514 μm
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Date
43797
Authors
Chandran, Satheesh
Ruth, Albert A.
Martin, Eamonn P.
Alexander, Justin K.
Peters, Frank H.
Anandarajah, Prince M.
Journal Title
Journal ISSN
Volume Title
Publisher
MDPI
Published Version
Abstract
A custom-designed gain-switched frequency comb (GSFC) source was passively coupled to a medium finesse (F ‰ˆ 522) cavity in off-axis configuration for the detection of ammonia (14NH3) in static dry air. The absorption of ammonia was detected in the near infrared spectral region between 6604 and 6607 cmˆ’1 using a Fourier transform detection scheme. More than 30 lines of the GSFC output (free spectral range 2.5 GHz) overlapped with the strongest ro-vibrational ammonia absorption features in that spectral region. With the cavity in off-axis configuration, an NH3 detection limit of ˆ¼3.7 ppmv in 20 s was accomplished in a laboratory environment. The experimental performance of the prototype spectrometer was characterized; advantages, drawbacks and the potential for future applications are discussed
Description
Keywords
Cavity-enhanced absorption spectroscopy , Off-axis alignment , Frequency comb , Gain switching , Near infrared (IR) range , Fourier transform spectroscopy , NH3 sensing , Ammonia detection
Citation
Chandran, S., Ruth, A. A., Martin, E. P., Alexander, J. K., Peters, F. H. and Anandarajah, P. M. (2019) 'Off-Axis Cavity-Enhanced Absorption Spectroscopy of 14NH3 in Air Using a Gain-Switched Frequency Comb at 1.514 μm', Sensors, 19 (23), 5217 (15 pp). doi: 10.3390/s19235217