2012/08/15 by Kristan P. Gurton, Melvin Felton, Richard L. Tober · 1 citation
Engineering · Chemical Engineering · #Advanced Chemical Sensor Technologies #Gas Sensing Nanomaterials and Sensors #Analytical Chemistry and Sensors
paper · doi:10.1364/ol.37.003474
openalex publication_date 2012/08/15 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/31
An optical detection method is presented that is designed to detect and identify the presence of macromolecular gas species (e.g., organophosphate-based nerve agent simulants) at trace level concentrations. The technique is based on a modified version of conventional laser photoacoustic (PA) spectroscopy, in which optical absorption is typically measured using a single laser source. We demonstrate the ability to simultaneously measure multiple absorption-related parameters that serve as a concentration-independent identifier. Three continuous wave mid-infrared laser sources, operating at 8.68, 9.29, and 10.35 μm, are combined and propagated axially through a specially designed flow through PA cell. Each laser is modulated at a different frequency and the resultant acoustic signal(s) are detected and deconvolved using a PC-based 24 bit dynamic signal acquisition device. Species detection and identification is achieved by tabulating independent ratios of the acoustic response for each laser source. Quantitative absorption measured is verified using a Fourier transform infrared spectrometer. Results show good detection and species separation/identification at moderately low ppm concentrations.