Theory of Electronic Relaxation in solution with ultra-short sink of different shapes: An exact analytical solution

We propose a very simple one dimensional analytically solvable model for understanding the problem of electronic relaxation of molecules in solution. This problem is modeled by a particle diffusing under the influence of parabolic potential in presence of a sink of ultra-short width. The diffusive motion is described by the Smoluchowski equation and shape of the sink is represented by 1) ultra-short Gaussian, 2) ultra-short exponential and 3) ultra-short rectangular function at arbitrary position. Rate constants are found to be sensitive to the shape of the sink function, even though the width of the sink is too small. This model is of considerable importance as a realistic model in comparison with the point sink model for understanding the problem of electronic relaxation of a molecule in solution.