在线英语听力室_免费在线英语听力学习网站

This is Scientific American's 60-Second Science. I'm Steve Mirsky. Got a minute?.

[Spray sound.] Killing¹ bugs²? No. [Spray sound.] Deodorizing the bathroom? No. [Spray sound.] Checking for explosives, yes. Because chemists at the University of California, San Diego have come up with a spray-on polymer film that can spot residue³ from nitrogen-based explosives such as TNT. It works in as little as 30 seconds.   

When ultraviolet light is shined on a safe, sprayed surface, it glows blue. But when the surface shows traces of a nitrogen-based explosive, it stays dark. Because the explosives soak up the electrons that would emit the blue glow.  The researchers describe the synthesis and properties of their polymers in the Journal of Materials Chemistry.

A single layer of the polymer, about one-thousandth of a gram, is enough for the test. And the polymer is so sensitive, it can detect explosive residues⁴ on the order of a few millionths of a gram. Often more than a thousand times that amount is left on surfaces. The method is so promising⁵, it’s already been featured on an episode of CSI: Miami. Chemists know that’s a technology’s acid test.

Thanks for the minute for Scientific American's 60-Second Science. I'm Steve Mirsky .