Coupling states intramolecular dynamics, adiabatic

In the excited state, the redistribution of electrons can lead to localized states with distinct fluorescence spectra that are known as intramolecular charge transfer (ICT) states. This process is dynamic and coupled with dielectric relaxations in the environment [16]. This and other solvent-controlled adiabatic excited-state reactions are discussed in [17], As shown in Fig. 1, the locally excited (LE) state is populated initially upon excitation, and the ICT state appears with time in a process coupled with the reorientation of surrounding dipoles. 

Generally, one has to consider two-dimensional diffusion equations to incorporate the relaxation dynamics from both slow x and fast q coordinates. In the case where the fluctuations of the intramolecular vibrational modes are very fast compared with the solvent relaxation, the adiabatic elimination pro-cedure can lead the two-dimensional diffusive equations to onedimensional ones. Denoting P x,i) and P2 x,t) as the population distributions of the donor and the acceptor states at a given x and time t, respectively, one obtains the one-dimensional coupled diffusion-reaction equations ... 

J. Giraud-Girard, J. Manz, and Ch. Scheurer, Twist Dynamics of 9-(N-Carbazolyl)-Anthracene Effects of Intramolecular Vibrational Redistribution and Non-Adiabatic Transitions in Coupled Bright and Dark States , Z. Phys. D 39, 291 (1997). 

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