FRANKFURT A new sensor device makes it easier to detect even the most tiny traces of explosives in the soil, air and in water, reports Germany's applied chemistry journal *** Angewandte Chemie ***.

According to DPA, the basis of the new device is a thin film made of polysilole polysilole compound which shows a reaction under ultraviolet light when it comes into contact with molecules of the compounds TNT and picric acid, two of the most important explosives.

There are plenty of applications for the device in countries where ammunition left over from wars still comes to light, especially in Germany where thousands of bombs and shells were left over from World War II. Many pose a danger to shipping in the Baltic Ocean.

The development by researchers William Trogler and Michael Sailor of the University of California in San Diego is particularly significant since many of the current detection methods are suitable for finding explosive traces in the air but not in water.

Polysilole is a long, spiral-shaped string of mainly silicon atoms which generate a small cloud of electrons. Ultraviolet light normally stimulates them and they give off energy in the form of visible light but when coupled with molecules of TNT (trinitrotoluene) and picric acid, the electron cloud is modified and no light is given off.

The sensor is so accurate that it can detect 50 molecules among a billion (50 parts per billion, PPB), say the researchers which means the device would be able to find traces of a sugar cube diluted in a tank containing 2.7 million liters of liquid.

The method could be useful for crimebusters since it could clearly distinguish between a glove which had come into contact with TNT even if it had been cleaned afterwards.