Russian scientists are working on a small, though very effective, portable gas analyzer. This device works similarly to a well-trained dog’s nose, but with a very important distinction – in addition to detection of hazardous substances in the air, the device will determine their amount and chemical structure.

Said analyzer is developed in Russian Institute of Solid State Physics. Physicists expect air inlet to continuously pump air through two special filters. One of these filters consists of artificial sapphire plates, pierced with very thin capillaries (less than 0.5 mm in diameter). Why do we need such an exotic and expensive filter? Sapphire plates regularly receive electric discharge, and its flame burns organic impurities. After that emission spectrum reveals chemical composition of plasma – such technique is called atomic emission spectral analysis. Said technique is known for a long time, but existing spectrometers are large, heavy and expensive equipment. Russian researchers have found a way to make a spectrometer light and compact.

Let us return to sapphire – this mineral possesses really priceless properties for this kind of analysis. Sapphire sustains intensive electric fields and high temperatures, thus one filter can be used over and over again. Moreover, its dielectric properties allow generating discharges of required power without spending much energy, resulting in a small-size device.

However, determining elemental composition of a sample is only half the work, since atoms of various elements form absolutely different substances. That is why scientists suggest using second filter as an independent source of information about impurities.

This time filter serves as an accumulator of analyzed substances. Authors expect to use the same sapphire plates with capillaries, but walls of said capillaries will be covered with a special coating. Required molecules precipitate and concentrate on the coating, and small molecules of main air components (nitrogen, oxygen and water vapour) pass easily. Concentrating filter allows analyzing concentrated molecules via so-called Raman scattering. For this purpose filter undergoes laser irradiation (sapphire is transparent in wide optical spectral region and resists high laser beam intensity), and analyzed molecules interact with laser according to their chemical structure and scatter it. At this stage researchers are able to determine structure of required substances.

Computer receives information about both spectrum types (vibration spectra of impurities and atomic emission spectra of their atoms and molecules), processes data and compares them with a database of standard spectra of various potentially hazardous substances. In case of sample corresponding with standard, computer immediately reacts, displaying information of hazardous substance concentration and identity.

Sad fact is that described device does not exist – scientists need adequate funding to finish it. Without money the device is unlikely to appear in nearest future.

Source:
    Russian Science News

Kizilova Anna