Fingerprinting Malathion Vapor: a Simulant for VX Nerve Agent

摘要

Being motivated by the possibility of fingerprinting and detecting VX nerve agent, we have investigated its stimulant, i.e. malathion vapor, which is less toxic and commercially available, in the far-infrared/THz transition region and THz frequency range. Such a spectroscopic study was carried out by using Fourier transform infrared spectroscopy (FTIR). Our intention is to obtain a specific spectroscopic signature of VX nerve agent as a chemical warfare agent. Following our experimental result, we have successfully observed eleven new absorption peaks from malathion vapor in the spectral ranges from 15 cm~(-1) to 68 cm~(-1) and from 75 cm~(-1) to 640 cm~(-1). Specifically, in the far-infrared/THz transition region, we have observed eight peaks and whereas in the THz region we have identified three relatively weak transition peaks. In addition, we have investigated the dependence of the absorption spectra on temperature in the range from room temperature to 60°C. In both of the frequency ranges, we have found that absorption coefficients significantly increase with increasing temperature. By comparing the transition peaks in the two frequency ranges, we have concluded that the frequency range of 400-640cm~(-1) is an optimal range for fingerprinting this chemical specie. We have designated two peaks for effectively and accurately identifying the VX nerve agents and one peak for differentiating between malathion and VX nerve agent.