THE EFFECT OF A LASER FIELD ON ELECTRON-TRANSFER IN METAL-COMPLEXES - QUANTUM DEGREES OF FREEDOM

The effect of a strong cw laser field on Fe(OH2)(6)(+3) electron transfer in aqueous solution is considered. On the basis of a kinetic master equation for the time-dependent population, an analytical solution for the forward and backward reaction rates is obtained. The presence of a strong ion-ligand vibration at HBAR omega(q) = 432cm(-1) qualitatively changes the intensity dependence of the sum of forward and backward rate constants (denoted as the ''total rate constant''). It is shown that the total rate constant is strongly dependent on the laser frequency. For the symmetric exchange reaction this rate constant exhibits resonances as a function of the cw field amplitude. For the activationless reaction (achievable by application of an additional de field) it decreases sharply with the cw field intensity. It is shown that the asymptotic populations of the reactant and product states are non-Boltzmann; their ratio can be varied by 18 orders of magnitude. Contrary to the case with no ac field, the equilibrium constant exhibits a nonmonotonic dependence on the reaction heat, epsilon. In some regions of epsilon it is insensitive to the reaction heat. The analytical solution is verified via numerical solution of the original master equation. Excellent agreement is obtained. (C) 1995 American institute of Physics.