Intramolecular heavy-atom effect
in the photophysics of organic molecules
Institute of Molecular and Atomic Physics, National Academy of Sciences of Belarus, prosp. F. Skoriny 70, Minsk, 220072, Belarus
This review systematizes the data on the effect of intramolecular spin-orbit perturbations on the photophysics
of organic molecules introduced by heavy atoms (the intramolecular, or ’internal’, heavy-atom effect). The focus is on two
classes of compounds: (1) halogenated derivatives of aromatic
and heteroaromatic compounds and (2) porphin derivatives
(halogenated porphyrins and metalloporphyrins). The enhancement of radiative and nonradiative intercombination transitions
under the heavy-atom effect is responsible for fluorescence
quenching and the shortening of phosphorescence duration.
Photophysical investigations show that the transition probabilities in different channels of deactivation of excited electronic
states exhibit specific dependence on the structure of heavy-atom bearing molecules. This allows one to acquire information on the spin-orbit interaction in molecules and their electronic structure, and to control the parameters of chromophores
and luminophors in optical systems.