Experimental verification of the Smoluchowski theory for a bimolecular diffusion-controlled reaction in liquid phase

The Smolucohwski theory for diffusion-controlled reactions in solution in the steady state condition, was experimentally verified. The diffusion coefficient of the reactant and the reaction rate were simultaneously determined. The diffusion coefficient of the diphenylmethyl radical was determined by the transient gradient method, and the self-termination reaction rate of the radical was determined by the transient absorption method. The results show that the reaction distance based on the Smoluchowski theory using the experimentally determined diffusion coefficients and the rate constants does not coincide with the vfW radius of the radical, suggesting that the activation process exists after the formation of the encounter complex.