Magnetic focusing of redox molecules at ferromagnetic microelectrodes

The electrochemical behavior of Fe and Ni disk-shaped microelectrodes (25 to 250 mu m radius) in a uniform magnetic field (1 T) is reported. Magnetization of the ferromagnetic microelectrode generates a magnetic field gradient across the depletion layer that can be used to focus paramagnetic molecules toward the electrode surface. The magnetic force acting on the depletion layer is given by F-del B = (chi/mu)B .del B, when chi and mu are the volume magnetic susceptibility and magnetic permeability of the depletion layer, respectively, and B is the magnetic field. Magnetic field focusing of the nitrobenzene radical anion at Fe and Ni microelectrodes is demonstrated. (C) 1999 Elsevier Science S.A. All rights reserved.