Experimental Study of Reaction Kinetics by Light Scattering. I. The Polarized Rayleigh Component

Spectral studies of scattered laser light have been conducted in multicomponent solutions where spontaneous fluctuations of the various molecular species occur about the chemical equilibrium. The spectral line broadening observed in these systems reflects the rate of return to equilibrium of these spontaneous fluctuations, and is characteristic of the reaction rates of chemical reactions occurring about the equilibrium. The reaction (Me2+(H2O)SO42−)Aq ⇆ (MeSO4)Aq has been singled out for investigation. Results of the studies on solutions of ZnSO4 and MnSO4 by the scanning Fabry–Perot interferometer and photon counting technique are in reasonable agreement with the data obtained by ultrasonic relaxation spectroscopy. The enthalpies of activation calculated for the process are: ZnSO4, ΔHb‡ = 3.72 kcal/mole; and MnSO4, ΔHb‡ = 6.15 kcal/mole.