COMPARATIVE ANALYSIS OF THE CAPABILITIES OF SPECTRAL METHODS IN STUDYING INTERNAL ROTATION OF COMPOUNDS OF THE BENZOIC SERIES

Abstract

t. In the review the comparison of the methods used to study internal rotation (IR) in the ground (S0) and excited (S1) electronic states for compounds of the benzoic series C6H5–COR, where R = H, F, CI. In (S0) electronic state differences in the values of (0-v) transitions of torsional vibration for studied compounds are revealed in the methods of analysis of the vibrational structure of n-π* transition of high-resolution UV absorption spectra and IR-Fourier-spectra. The reasons for such differences are established. In the excited (S1) state for benzaldehyde a comparison was made between the method of analyzing the vibrational structure of n-π* transition of high-resolution UV absorption spectra and the method of analyzing the excitation spectra of sensitized phosphorescence of this compound in a cooled jet. It is concluded that the method of analyzing the vibrational structure of n-π* transition of high-resolution UV absorption spectra of vapors of the investigated compounds is more reliable and accurate when studying (IR) in both electronic states.