Method of infrared (IR) spectroscopy (devices are Bruker IFS125HR, Nicolet 6700) – registration of vibrational-rotational spectra of substances in gaseous, liquid and solid states by  measuring transmitted through the sample or reflected from it continuous  infrared radiation. There is the absorption of molecules of the substance of this radiation with the simultaneous excitation of vibrations of molecules. Vibrations of bonds between atoms of molecules occur when dipole moment of these bonds is changing. Spectrum is the dependence of the intensity of the absorption from frequency. It used to obtain information about the structure and properties of the investigated substances and their interaction with each other in the case of appearance of molecular complexes (for example – complexes with hydrogen bond) or clusters. High resolution spectroscopy, up to 0.001 cm-1 (Bruker IFS125HR), serves to study of properties of systems of atmosphere gases of the Earth and to modelling of atmospheric composition of other planets. A source of radiation for such measurements can serve the Sun. The attenuated total reflection accessory (ATR) allows analyzing opaque or high absorbed IR radiation samples, for example, aqueous solutions, powders, polymers, tissue sections and minerals.