Detection of gaseous nerve agent simulants with broadband photoacoustic spectroscopy

While recent high-profile assassination attempts have once again brought nerve agents (NAs) into the spotlight, the current portfolio of NA sensors lack a sufficient combination of high performance and field-deployability. Here, we report a novel optical sensor for the detection of gaseous NAs with a potential to fill this gap. The technique is based on Fourier transform spectroscopy with a supercontinuum (SC) light source and cantilever-enhanced photoacoustic detection providing fast multi-species gas sensing with high sensitivity and selectivity in a sample volume of 7 ml, which becomes advantageous when analysing limited NA samples in the field. We study the fundamental C–H stretch bands of four known NA simulants and achieve detection limits of 64–530 ppb in one minute and recovery times of a few minutes. In the near future, the technique has significant potential to improve through the development of more powerful SC sources further in the mid-infrared region.