This paper describes a unique set of apparatus created at NPO State Institute of Applied Optics for the investigation of complex molecules at high temperatures under vacuum and the results of a study of the fine-structure fluorescence spectra of complex molecules of aromatic compounds obtained using this apparatus. A comparative analysis is given of the quasiline spectra of the molecules of certain aromatic compounds at low temperatures, obtained under conditions of matrix isolation and jet-cooled gas flows. Starting from the concept of the formation and origin of the fine-structure spectra of complex molecules developed earlier by the authors, two groups of spectroscopic effects are considered that make it possible to determine the elementary processes that control the conversion of the photon absorbed by the molecule. The first group includes the regularities describing how the quasi-lines of the fine-structure spectra depend on the energy of the excitation quanta, while the second includes the regularities associated with the multiplet structure of the individual lines of the fine structure.
E. A. Vandyukov, Yu. S. Demchuk, and S. O. Mirumyants, "High-temperature fine-structure fluorescence spectroscopy of free polyatomic molecules of complex organic compounds," J. Opt. Technol. 70, 534-543 (2003)