Chronoamperometry
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Chronoamperometry is an electrochemical technique in which the potential of the working electrode is stepped, and the resulting current from faradic processes occurring at the electrode (caused by the potential step) is monitored as a function of time. Most commonly investigated with a three electrode system.
[edit] Example
Anthracene in deoxygenated dimethylformamide (DMF) will be reduced (An + e- -> An-) at the electrode surface that is at a certain negative potential. The reduction will be diffusion-limited, thereby causing the current to drop in time (proportional to the diffusion gradient that is formed by diffusion).
You can do this experiment several times increasing electrode potentials from low to high. (In between the experiments, the solution should be stirred.) When you measure the current i(t) at a certain fixed time point τ after applying the voltage, you will see that at a certain moment the current i(τ) does not rise anymore; you have reached the mass-transfer-limited region. This means that anthracene arrives as fast as diffusion can bring it to the electrode.
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