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  • Interband cascade laser absorption sensor for sensitive measurement of hydrogen chloride in smoke-laden gases using wavelength modulation spectroscopy

This content will become publicly available on November 11, 2025

Title: Interband cascade laser absorption sensor for sensitive measurement of hydrogen chloride in smoke-laden gases using wavelength modulation spectroscopy
A tunable interband cascade laser sensor, based on wavelength modulation absorption spectroscopy near 3.73 µm, was developed to measure hydrogen chloride gas concentration in smoke-laden environments associated with the overhaul stages of firefighting. Wavelength selection near 2678cm−1targets the P(0,9) transition within the fundamental vibrational band of HCl, chosen for its absorption strength and isolation from CO2, H2O, and CH4, as well as proximity to absorption features of other toxicant gases of interest in firefighting applications. Both scanned-wavelength direct absorption with a Voigt lineshape-fitting routine and a wavelength modulation spectroscopy absorption method are employed to recover species concentration. The laser sensor is paired with a compact commercial off-the-shelf 1 m multipass optical gas cell modified to use polished Alloy 20 steel mirrors for increased corrosion resistance against humid and acidic gases, and it is tested by sampling effluent gases from pyrolyzing and burning solid samples of polyvinyl chloride under a radiant heating apparatus in a laboratory fume hood. The wavelength modulation spectroscopy method is demonstrated to enable measurement at the near-ppm-level within a compact form-factor and to provide insights into the thermochemical pyrolysis processes that lead to the formation of hydrogen chloride when polyvinyl chloride is exposed to radiant heating.  more » « less
Award ID(s):
2339502 2135789
PAR ID:
10554533
Author(s) / Creator(s):
; ; ;
Publisher / Repository:
Optical Society of America
Date Published:
Journal Name:
Applied Optics
Volume:
63
Issue:
33
ISSN:
1559-128X; APOPAI
Format(s):
Medium: X Size: Article No. 8517
Size(s):
Article No. 8517
Sponsoring Org:
National Science Foundation
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