Mid-infrared broadband sensing and temperature dependence of trace gas molecular transitions

Al Alexis; Zakaria Juracka; Ibrahim El-K; Mohammad A. Khan

doi:10.1117/12.2651146

8 March 2023 Mid-infrared broadband sensing and temperature dependence of trace gas molecular transitions

Al Alexis, Zakaria Juracka, Ibrahim El-K, Mohammad A. Khan

Proceedings Volume 12428, Photonic Instrumentation Engineering X; 124280K (2023) https://doi.org/10.1117/12.2651146
Event: SPIE OPTO, 2023, San Francisco, California, United States

Abstract

Several environmental trace gas species and toxic chemicals or warfare simulants have fingerprint spectral signatures in the mid-infrared region of the spectrum. For instance, methane, nitrous oxide, and water vapor are critical greenhouse gases relevant for environmental sensing. In contrast, Sarin is one of the most lethal warfare agents that is a highly toxic synthetic chemical organophosphorus compound, which is of interest in defense and security sensing applications. Due to complex chemical structure and significant absorption and collision cross-section, the molecular linewidths of such chemicals can cover a broad range of spectral widths in the mid-infrared region. Detection of such molecules in the mid-infrared region is sensitive, which requires broadly tunable sources and appropriate spectral resolution in detection schemes. We show a rapid detection methodology of atmospheric bands of trace gases in the 7 μm to 8 μm region, which also coincides with the fingerprints region of several hazardous chemicals. Methane absorbs strongly in the wavelength range of 3 μm to 8 μm, and nitrous oxide has absorption from 5 μm to 8 μm. We use molecular rotational-vibrational transitions of carbon and nitrogen trace species to demonstrate well-resolved peaks in the spectral region of 6.88 μm to 7.6 μm for detection. The detection was performed by a continuous wave multiplexed quantum cascade laser source capable of an ultra-wide tuning range from 6.88 μm to 11.05 μm.

Conference Presentation

Citation Download Citation

Al Alexis, Zakaria Juracka, Ibrahim El-K, and Mohammad A. Khan "Mid-infrared broadband sensing and temperature dependence of trace gas molecular transitions", Proc. SPIE 12428, Photonic Instrumentation Engineering X, 124280K (8 March 2023); https://doi.org/10.1117/12.2651146

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