Detection and identification of TNT, 2,4-DNT and 2,6-DNT by near-infrared cavity ringdown spectroscopy

A dedicated instrument based on cw cavity ringdown (CRD) spectroscopy has been used to study the feasibility of solid explosive detection in the near infrared. A flash heater was used to evaporate solid samples in a CRD absorption cell. The vapor phase spectra of TNT, 2,4-DNT and 2,6-DNT have been recorded for the first time in the spectral range between 1560 and 1680 nm. Although the three explosives are chemically very similar the recorded spectra are distinct and permit an unambiguous identification of the three pure substances. The fast sample preparation and short detection times render the technique useful for trace detection of solid particles. The detection sensitivity is estimated in the 10–100 ng range and is adequate for trace detection and identification of solid explosives.