Alekseev E. High accuracy microwave spectrometers and microwave spectroscopy of astrophysical and atmospheric molecules

Object of study: rotational spectra of polyatomic molecules in the millimeter- and submillimeter-waves. The purpose of the thesis: obtaining of high-precision data on rotational spectra of molecules of astrophysical and ecological interest. To achieve this goal it is necessary to create a high-precision and fast-scan spectrometers, and to investigate the rotational spectra of molecules using these spectrometers. Methods: direct digital synthesis, indirect frequency synthesis, combined frequency synthesis, the effective Hamiltonian method and the least squares fit. New theoretical and practical results: the present thesis is devoted to a new scientific direction - high-accuracy investigation of the rotational spectra of molecules with Doppler-limited resolution. For the first time the high-accuracy and fast-scan spectrometers were constructed based on the frequency synthesizers, and subkilohertz accuracy of transition frequency measurements has been achieved. High-accuracy data were obtained for isotopic species of methylformate HC18OOH3 and HCO18OH3, and these molecules have been detected in the interstellar medium. Using constructed spectrometers high-precision studies were performed for rotational spectra of a number of astrophysical molecules (glycine, furfural, ethylcarbamate, methylformate, formamide, aziriidine, dimethylsulfoxide , methyl iodide) and for some CFCs, which are of interest for environmental monitoring.