Rapid, broadband sensing of chemical warfare simulants using mid-infrared spectroscopy

Several chemical warfare chemicals have fingerprint spectral signatures in the mid-infrared region of the spectrum. For instance, Sarin is one of the most lethal warfare agents that is a highly toxic synthetic chemical organophosphorus compound. Due to complex chemical structure and large absorption and collision cross-section, the molecular linewidths of such chemicals can cover a broad range of spectral width. Detection of such molecules in the mid-infrared region is sensitive which requires broadly tunable sources and detection methods. We show a rapid detection methodology of such chemicals using proxy methane and nitrous oxide atmospheric bands in the 7 mu m to 8 mu m region which also have fingerprints region of several hazardous chemicals. Methane absorbs strongly in the wavelength range of 3 mu m to 8 mu m, nitrous oxide has absorption from 5 mu m to 8 mu m. As the large wavelength range that they have covered, we use molecular rotational-vibrational transitions of CH4 - N(2)Oand well-resolved peaks in the spectral region of 6.88 mu m to 7.6 mu m 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 mu m to 11.05 mu m.