%0 Journal Article
%T The dynamics of excited state structural relaxation of 4-dimethylaminobenzonitrile (DMABN) and related compounds
%A Valery Volchkov
%A Lyubov' Uzhinova
%A Boris Uzhinov
%J International Journal of Photoenergy
%D 2006
%I Hindawi Publishing Corporation
%X The excited state structural relaxation of 4 -dimethylaminobenzenes with various para-acceptor substituents having double-band emission, local excited (LE) and charge transfer (CT), has been investigated. Fluorescence measurements at different temperatures and in different solvents have confirmed the existence of viscosity-dependent, temperature, and polarity-activated relaxation. The kinetics analysis has shown that the radiative deactivation rate constants of the individual LE and CT states differ by 7 ¨C 112 -fold. The dipole moment changes at the excitation for CT states are significantly larger than those for LE states. The spectral-kinetics behavior of compounds studied agrees with the models A¡ú A   ¡ú B   or A¡ú A     B   , where A   is the local excited planar and B   is the relaxed twisted state of the molecule. The rate constants of the twisted state formation have been calculated in the temperature range 293 ¨C 77 K. The activation energies of forward process for compounds studied have been estimated.
%U http://www.hindawi.com/GetArticle.aspx?doi=10.1155/IJP/2006/81896