Integrated Approach for Modeling the Emission Fluorescence of 4-(N,N-Dimethylamino) benzonitrile in Polar Environments

A stochastic model for the interpretation of the emission fluorescence of 4-(N,N-dimethylamino)benzonitrile (DMABN) is discussed. We proceed by reviewing the stochastic modeling approach (Polimeno, A.; Barbon, A.; Nordio, P. L.; Rettig, W. J. Phys. Chem. 1994, 98, 12158), in which internal degrees of freedom are coupled with an effective solvent relaxation variable. Potential energy surfaces are obtained using a reliable but computationally cost-effective quantum mechanical (QM) approach, and estimates of dissipative parameters are calculated on the basis of direct hydrodynamic arguments. Emission fluorescence is estimated by solving numerically a diffusion/sink/source equation for the stationary population of excited state and compared to emission fluorescence of DMABN measured experimentally.