Polarization of the Fluorescence Excited in the P- and R Branches of the Vibronic Lines of Jet-Cooled Complex Molecules

A model is suggested to calculate the degree of polarization of the fluorescence of jet-cooled polyatomic molecules excited within the P- and R branches of the rotational contour of the vibronic line by light not providing resolution of the rotational structure. These dependences are calculated and compared with experimental data for molecules belonging to different types of asymmetric tops with different intramolecular orientation of the fluorescence transition dipole moment: anthracene; anthracene + Ar; 1,4-diaminoanthraquinone; indole; tetracene, and triphendioxazine.