Using the methods of multi-frequency spectroscopy for sensing

Nowadays the development of analytical spectroscopy with high performance, sensitivity and spectral resolution is attended. In the paper the method of two-frequency THz spectroscopy as well as the laboratory model of the spectrometer with using two independent radiation sources and a single detector of THz radiation are presented. The preliminary measurements have testified this new direction of analytical spectroscopy to open widespread trends of its using for various basic and applied problems of physics, chemistry, astronomy, medicine and biology. First of all, there are laboratory modeling the processes of atmospheric and space chemistry, studying of their dynamics as well as transformations and changes of mixture composition. Besides, the method presented can be applied for investigations of fast processes, detecting the intermediate and short time living products of chemical reactions.