ABSTRACT
Scanning electrochemical microscopy (SECM) and related ultramicroelectrode (UME) methods have proven powerful for measuring the kinetics of homogeneous reactions coupled to heterogeneous electron transfer. For this type of investigation, the tip and substrate are both electrodes and one can usefully consider the tip/substrate electrode con–guration as a variable gap ultrathin layer cell. In essence, the gap thickness determines the diffusional transit time of chemical species between the tip and substrate and hence the range of timescales that can be studied.
