Charge neutralization process of mobile species developed during potentiodynamic conditions. Part 2: Simulation and fit of probe beam deflection experiments

The theoretical model presented in Part 1 is employed to simulate and fit experimental probe beam deflection (PBD) data of Fe(CN) 6 3 - / Fe(CN) 6 4 - and Fe3+/Fe2+ couples collected under voltammetric conditions. The dependence of beam deviation on the diffusion coefficients and on the charges of involved species is described. The fit of voltammetric curves was performed to get the values for the standard potential of each system as well as diffusion coefficients of electroactive species. The data were then employed to fit a set of experimental voltadeflectometric profiles collected at different beam-electrode distances. The least-squares Simplex algorithm was employed to fit proposed functions to experimental data. The data obtained from the fitted voltadeflectometric curves were consistent with values previously reported for chronodeflectometry profiles, supporting the hypothesis that the refraction index not only should be considered a function of the concentration of the neutral salts dissolved, but also depends on the concentration gradient of each soluble species. The effects of the scan rate and the beam-electrode distance are discussed in detail. In relation to this, simple relationships between these adjustable parameters and the angle of the deflected laser beam are also provided. Thus, it is now possible to perform a quantitative analysis on the response of techniques such as PBD when the heterogeneous charge transfer of electroactive species is studied with a cyclic linear potential scan.