Study of charge transfer mechanism of PEDOT polymer for detection of solid TEX and CL-20 explosives using pulsed photoacoustic technique

We report the use of PEDOT polymer (poly (2, 3-dihydrothieno [3,4-b] dioxane-5,7-diyl) as a sensing medium for the detection of solid secondary explosives like TEX and CL-20 in solid form using pulsed photoacoustic (PA) technique under visible 532 nm wavelength. The PEDOT polymer (poly (2, 3-dihydrothieno [3,4-b] dioxane-5,7-diyl) plays the role of an optode or an effective sensing medium for the detection of explosives when mixed in equal proportion and subjected to 532 nm wavelength obtained from Q-switched Nd: YAG laser without any chemical treatment. The study reveals that one milligram of PEDOT is sufficient to initiate the charge transfer mechanism between the positive charge on the oxidized PEDOT and the lone pairs of electrons on the oxygen atoms of the nitro group of the explosives. The strength of the enhanced PA signal for TEX and CL-20 was of the order of 65.38 and 1.77 times, respectively. However, the same experiment was repeated with non-explosive samples such as NaNO₂ and NaNO₃, separately mixed with PEDOT. The obtained peaks of PA spectra were very weak, broaden and distorted in nature and occupies less than 3 kHz frequency rage and 3.5 times less than the PA signal of pure PEDOT. The estimated minimum detection limit of the solid explosives, CL-20 and TEX were of the order of 0.33 ng and 1.03 ng, respectively.