Ion Focusing in a Magnetic Field: The Electrochemical Vortex and Ion Beam

摘要

Magnetohydrodynamic vortex flow between two disk-shaped ultramicroelectrodes (UME) in the presence of a uniform external magnetic field (approx 1 Tesla) is reported. UmE's of radii between 25 and 250 #mu#m are oriented in a face-to-face configuration, and separated by an electrolytic solution containing a redox-active species. When the redox species is reduced or oxidized, the interaction of the divergent flux of charge-carrying ions with the magnetic field induces a rotational solution flow at the electrode. The interaction of flows arising at each electrode can be used to focus electrogenerted ions into torus-shaped volumes, ion beams, and rotating circular sheets. Ions that are generated at one UME can be transported in narrow ion beams (approx 25 #mu#m diameter) through the solution over distances of several millimeters without significant thermal spreading. Magnetic field-induced flow patterns are visualized by videoenhanced microscopy and by electrochemically-generated chemiluminescence.