New technique for easily identifying explosives in luggage

January 24, 2007
Prof. Itozaki, Dr Tachiki and Dr He
Prof. Itozaki, Dr Tachiki and Dr He

Scientists in Japan have developed a new technique for sensing explosives in luggage and landmines. The paper, published today in the Institute of Physics journal Superconductor Science and Technology describes how radio waves can be used to identify specific explosives, such as TNT. The new method could be used in future to screen baggage at airports.

The new technique has advantages over traditional methods of detection: unlike x-rays that are currently used in airport security, it can distinguish between different types of white powder from flour and salt to drugs and explosives. It can also be used to detect landmines, an advance on the traditional method of using a metal detector which cannot distinguish between bits of metal in the ground and an actual mine.

Professor Hideo Itozaki, one of the authors of the paper at Osaka University said: “Until now it has been very difficult to detect specific explosives such as TNT because they contain atoms of nitrogen that vibrate at very low frequencies.

The natural frequency at which the nucleus of an atom vibrates at is called its resonant frequency and the lower this is, the harder it is to detect what atoms are present in a molecule which in turn makes it harder to define what the molecule or substance is.”

The technique relies on nitrogen nuclear quadrupole resonance (NQR) which detects atoms of nitrogen (an element found in many explosives, including TNT) in different positions in a molecule. For example an atom of nitrogen attached to a carbon atom will have a different resonance to one attached to an oxygen atom. Because the molecular structure of each explosive is different, the resonant frequency will be different.

Professor Itozaki continued: “We have successfully developed a machine that can pick up very low resonant frequencies by using a SQUID (superconducting quantum interference device). The SQUID operates at a temperature of 77 Kelvin (minus 196 degrees centigrade) which we achieve by using liquid nitrogen. This will not hinder the equipment from being used in places such as airports as liquid nitrogen is becoming much easier to deal with and is already routinely used in hospitals and laboratories.”

Source: Institute of Physics

Explore further: Scientists explore the origins of energy in chemical reactions using experimental quantum chemistry

Related Stories

What is a Wolf-Rayet star?

February 6, 2015

Wolf-Rayet stars represent a final burst of activity before a huge star begins to die. These stars, which are at least 20 times more massive than the Sun, "live fast and die hard", according to NASA.

Aligned carbon nanotube / graphene sandwiches

September 12, 2014

By in situ nitrogen doping and structural hybridization of carbon nanotubes (CNTs) and graphene via a two-step chemical vapor deposition (CVD), scientists have fabricated nitrogen-doped aligned carbon nanotube/graphene (N-ACNT/G) ...

Recommended for you

New surfaces delay ice formation

October 6, 2015

If you've ever waited on an airport runway for your plane to be de-iced, had to remove all your food so the freezer could defrost, or arrived late to work because you had to scrape the sheet of ice off your car windshield, ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.