Simulation of Electrochemiliminescence Produced by a High Frequency Square Wave Potential Waveform. Effects of the Ohmic Drop and of the Cell Time constant on the Electrode Potential, the Current and the Light Emission

Different aspects of the electrochemiluminescence process produced by a high frequency square-wave polarization at ultramicroelectrodes were studied by means of the digital simulation technique employing the finite difference Hopscotch algorithm in one dimension. The simulation allowed the deconvolution of the charging and faradaic currents and provided the real polarization potential. In particular, the theoretical study demonstrated that the IR drop and the cell time constant, R(u)C(dl), affect the shape of the potential waveform which delay and modify the faradaic current and therefore the light emission peaks correspondingly. Suitable plots enable systems characterized by values of the dimensionless annihilation constant (lambda = kt(s)c(A)) greater than 1000 to be distinguished when the responses around the peak maxima are considered, The influence of lambda on the shape and position of the reaction layer was also rationalized together with the influence of different diffusion coefficients. The existence of multiple emitting zones, which arise from the reaction layers of previous steps, was also observed.