UC San Diego researchers have developed a simple fast and inexpensive sensor to detect trace amounts of explosives. A silicon polymer has been made into a \\\"nanowire\\\"" 2000 times thinner than a human hair that detects compounds such as picric acid nitrobenzene (NB) dinitrotoluene (DNT) and trinitrotoluene (TNT) in air or seawater or on surfaces. The sensor uses a thin film of photoluminescent polysilole that can also be sprayed on solid surfaces such as filter paper. Wherever the polymer comes into contact with molecules of explosive material the fluorescent signal is quenched. This polysilole is stable in air water acids common organic solvents and seawater-containing bioorganisms. TNT vapor in air is detected to 4 ppb (parts per billion) within 10 minutes; in sea water 50 ppb TNT and 6 ppb Picric Acid can be detected. Picric Acid is a substance commonly used in letter bombs. A hand or object that has been in contact with even tiny amounts of TNT may be readily imaged by pressing it to a piece of paper spraying the paper with a 0.1 M toluene solution of the polymer and observing the paper with the naked eye under a black light. Applications: This technology has myriad applications in forensic science law enforcement and the military. In addition it could be used to map pollution from munitions manufacturing and storage and to locate unexploded land or sea mines to facilitate their removal."
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