Durham, NC - Scientists have developed a
way to sniff out tiny amounts of toxic gases -- a whiff of nerve gas,
for example, or a hint of a chemical spill -- from up to one kilometer
The new technology can discriminate one type of gas from
another with greater specificity than most remote sensors -- even in
complex mixtures of similar chemicals -- and under normal atmospheric
pressure, something that wasn’t thought possible before.
researchers say the technique could be used to test for radioactive
byproducts from nuclear accidents or arms control treaty violations, 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 perimeter 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.
used to detect tumors and screen airport passengers, T-rays fall
between microwaves and infrared radiation on the electromagnetic
Zapping a gas molecule with a terahertz beam of just the
right energy makes the molecule switch between alternate rotational
states, producing a characteristic absorption spectrum “fingerprint,”
like the lines of a bar code.