  Numerical simulation is used to characterise double potential step
chronoamperometry at a microband electrode for a simple redox process A + e-
goes to B, under conditions of full support such that diffusion is the only
active form of mass transport. The method is shown to be highly sensitive for
the measurement of the diffusion coefficient of both A and B, and is applied to
the one electron reduction of decamethylferrocene (DMFc), DMFc - e- goes to
DMFc+, in the room temperature ionic liquid 1-propyl-3-methylimidazolium
bistrifluoromethylsulfonylimide. Theory and experiment are seen to be in
excellent agreement and the following values of the diffusion coefficients were
measured at 298 K: D_(DMFc) = 2.50 x 10^(-7) cm^(2) s^(-1) and D_(DMFc+) = 9.50
x 10^(-8) cm^(2) s^(-1).
