Pine Research MSR 636A, User Manual, Page: 158 / 176

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Diffusion In the context of electrochemistry in liquid solutions,
diffusion is a time-dependent process consisting of
random motion of ions or molecules in solution which
leads to the statistical distribution of these species,
gradually spreading the ions and molecules through
the solution.
Diffusion Coefficient A factor of proportionality representing the amount of
substance diffusing across a unit area through a unit
concentration gradient in unit time.
Diffusion Layer Mass transport to a rotating electrode occurs via a
combination of convection and diffusion. As material
approaches the electrode, diffusion dominates over
convection as the principle means of transport.
Across the very thin layer of solution immediately
adjacent to the electrode, diffusion is essentially the
only means of mass transport. This thin layer is known
as the diffusion layer. The diffusion layer should not be
confused with the stagnant layer. The diffusion layer
exists entirely within the thicker stagnant layer (see
also
Stagnant Layer ).
Disk Insert Some rotating disk and ring-disk electrode tips are
designed to accept interchangeable disk inserts
fabricated from various precious metals and
advanced carbon materials.
Eisenberg Equation The Eisenberg equation describes the mass transfer
limited current at a rotating cylinder electrode.
Electroactive An adjective used to describe a molecule or ion
capable of being oxidized or reduced at an
electrode surface.
Electrode An electrode is an electrical conductor used to make
contact with a nonmetallic part of a circuit.
Electrode Materials Common electrode materials used to fabricate
rotating disk and ring-disk electrodes are gold,
platinum, and glassy carbon. Rotating cylinder
electrodes are usually made from various alloys of
steel, aluminum, or brass.