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Machine Design

Instant, Remote, And Portable Detection Of Explosives

A team of University of Florida researchers has invented a way to rapidly detect traces of TNT or other hidden explosives simply by shining a light on any potentially contaminated object, whether it's a speck of dust in the air or the surface of a suitcase.

Instant, remote, and portable detection of explosives

The process provides instant results, gives no false positives, can be used remotely, and is completely portable. These attributes will make this method indispensable at all levels of law enforcement, from local police to homeland security.

The method uses photoluminescence spectroscopy, a technique that casts light on a material and measures the range and intensity of the wavelengths of light the material produces in response. The wavelength of the emitted light varies depending on the chemical structure of the material.

Using photoluminescence to reveal the presence of TNT is similar to how ultraviolet light makes white clothes glow, but in this case the black light is a laser. Beaming a laser at a sample causes light to reemit at specific wavelengths that are different for each material as a sort of photoluminescent fingerprint.

TNT's fingerprint is a sharp, distinct peak just outside the red portion of the spectrum that includes visible light. TNT shares this characteristic peak with other explosive materials, such as plastic explosives and nitroglycerin, but not with safe materials.

The key to this common attribute lies in the fact that all explosives contain at least two nitro groups-molecules made up of one nitrogen atom bound to two oxygen atoms.

The UF discovery was prompted by a request from the U.S. Army Research Office that challenged universities to find a way to make inexpensive, quick, and reliable explosive detection systems. One of the university's graduate students tested TNT in the lab's photoluminescence spectrometer. With its high resolution, the machine scanned across the entire light spectrum and caught the explosive's elusive signal.

The advantage of photoluminescence based explosive detection is that it can be remotely applied. Additionally it is not time consuming and does not require expensive machines or trained dogs.

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