Page 24 - Analytical Electrochemistry 2d Ed - Jospeh Wang
P. 24
1-2 FARADAIC PROCESSES 9
(a)
(b)
FIGURE 1-3 Planar (a) and spherical (b) diffusional ®elds at spherical electrodes.
current±potential curves and the corresponding concentration±distance pro®les (for
selected potentials along the scan) are shown in Figure 1-4. As will be discussed in
Section 4-5.4, shrinking the electrode dimension to the micrometer domain results in
a sigmoidal-shaped voltammetric response under quiescent conditions, characteristic
of the different (radial) diffusional ®eld and higher ¯ux of electroactive species of
ultramicroelectrodes.
FIGURE 1-4 Concentration pro®les (left) for different potentials during a linear sweep
voltammetric experiment in unstirred solution. The resulting voltammogram is shown on the
right, along with the points corresponding to each concentration gradient. (Reproduced with
permission from reference 1.)
