Magnetic field effects on electron transfer reactions

In the last 50 years, magnetic fields have been shown to affect homogeneous electron transfer reactions where both reactants have unpaired electrons. In this work, magnetic fields are shown to affect both homogeneous and heterogeneous electron transfer reactions in systems where one reactant is a radical. The effects arise through electron-nuclear cross-relaxation. The magnetic field effects are studied at magnetic microparticle/ion exchange polymer (Nafion) composite modified electrodes. This work significantly expands the applicability of magnetic fields to alter kinetic rates and mechanisms, because most electron transfer reactions involve a radical reactant, but few involve radical pairs.; The electron transfer reactions that were studied include self-exchange reactions, heterogeneous electron transfer at an electrode surface, metalloprotein electron transfer reactions, and organic electrochemistry involving free radical intermediates. The rates for heterogeneous electron transfer are calculated from magnetically facilitated homogeneous electron transfer rates in accordance with Marcus theory. The rates of electron transfer between various metalloproteins, and substrates are successfully characterized by a model based on spin diffusion. The magnitude of magnetic effects on the electrochemistry of organic free radicals is predicted from spin and charge density localization.; This work also includes a simulation of the negligible magnetic field effects on mass transport in the modified electrode system.