Detection of explosive materials by differential reflection spectroscopy

It is shown that traces of 2,4,6-trinitrotoluene (TNT) display strong and distinct structures in differential reflectograms, near 420 and 250 nm. These characteristic peaks are not observed from moth balls, nail polish, polyvinyl chloride, starch, soap, paper, epoxy, aspirin, polycarbonate, aspartame, polystyrene, polyester, fertilizer, or sugar, to mention a few substances which may be in or on a suitcase. The described technique for detection of TNT,is fast, inexpensive, reliable, and portable and does not require contact with the surveyed substance. Moreover, we have developed a curve recognition program for field applications of the technique. The origin, of the spectra is discussed. (c) 2006 American Institute of Physics.