Page 67 - Analytical Electrochemistry 2d Ed - Jospeh Wang

52 STUDY OF ELECTRODE REACTIONS

FIGURE 2-18 SECM image of a gold minigrid surface. (Reproduced with permission from
reference 57.)

FIGURE 2-19 Single-molecule detection with SECM. Molecule A is trapped between the
tip and the surface. (Reproduced with permission from reference 58.)

the tip over the substrate surface. Recently introduced commercial SECM instru-
ments (64) will undoubtedly increase the scope and power of SECM.

2-4 ELECTROCHEMICAL QUARTZ CRYSTAL MICROBALANCE

The electrochemical quartz crystal microbalance (EQCM) is a powerful tool for
elucidating interfacial reactions based on the simultaneous measurement of electro-
chemical parameters and mass changes at electrode surfaces. The microbalance is
based on a quartz crystal wafer, which is sandwiched between two electrodes, used
to induce an electric ®eld (Figure 2-20). The ®eld produces a mechanical oscillation