Polymer takes dim view of explosives

By spraying surfaces with a light-emitting polymer, researchers have taken a step toward making new sensors for traces of common explosives. Such detectors may even prove useful for finding bombs and mines under water.

Although cleaned after touching TNT, left hand leaves traces detected by fluorescent polymer. Right hand touched no TNT. H. Sohn/UCSD

To make the sensitive coating, a team of scientists at the University of California, San Diego modified polytetraphenyl-1,1 silole. This polymer consists of single-atom-thick silicon filaments in a jacket of organic molecules that the researchers refer to as “chicken fat.”

Ordinarily, the polymer glows green under ultraviolet radiation. That’s because the radiation energizes electrons in the silicon, which then emit green light as they naturally fall back to a lower energy state.

However, molecules of TNT and related explosives stick to the chicken fat, says team member William C. Trogler. When they do, certain chemical groups in the explosive molecules suck up excited electrons, snuffing out fluorescence. In the June 1 Angewandte Chemie, Trogler and his colleagues say this simple, light-dimming effect could become the basis of new portable detectors of explosives.

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