Scientists have developed a way to sniff1 out tiny amounts of toxic2 gases -- a whiff of nerve gas, for example, or a hint of a chemical spill -- from up to one kilometer away. The new technology can discriminate3 one type of gas from another with greater specificity than most remote sensors4 -- even in complex mixtures of similar chemicals -- and under normal atmospheric5 pressure, something that wasnt thought possible before.The researchers say the technique could be used to test for radioactive byproducts from nuclear accidents or arms control treaty violations6, for example, or for remote monitoring of smokestacks or factories for signs of air pollution or chemical weapons.You could imagine setting this up around the perimeter7 of an area where soldiers are living, as a kind of trip wire for nerve gas, said lead author Henry Everitt, an Army scientist and adjunct professor of physics at Duke University.The technique uses a form of invisible light called terahertz radiation, or T-rays.Already used to detect tumors and screen airport passengers, T-rays fall between microwaves and infrared8 radiation on the electromagnetic spectrum9.Zapping a gas molecule10 with a terahertz beam of just the right energy makes the molecule switch between alternate rotational11 states, producing a characteristic absorption spectrum fingerprint, like the lines of a bar code.Terahertz sensors have been used for decades to identify trace gases in the dry, low-pressure conditions of interstellar space or in controlled conditions in the lab, where they are capable of unambiguous identification and ultra-sensitive, part-per-trillion detection.
点击收听单词发音
1 sniff vi.嗅…味道；抽鼻涕；对嗤之以鼻，蔑视 参考例句： The police used dogs to sniff out the criminals in their hiding - place.警察用警犬查出了罪犯的藏身地址。 When Munchie meets a dog on the beach, they sniff each other for a while.当麦奇在海滩上碰到另一条狗的时候，他们会彼此嗅一会儿。
相关文章推荐
