Theoretical aspects of probe beam deflection (PBD) as applied to voltammetric studies of redox active species irreversibly adsorbed on a flat electrode surface have been examined using Week's numerical inverse Laplace transform algorithm. Excellent agreement was found between the time-resolved profiles calculated based on this approach and those obtained via conventional space-time discretization techniques over the interval of relevance to actual experimental measurements. In agreement with the behavior reported elsewhere for related systems, the shape of the PBD response is highly sensitive to the distance between the probing beam and the electrode surface. In particular, plots of the dimensionless derivative of the concentration of the electrolyte with respect to the dimensionless distance normal to the electrode surface, (which is proportional to the deflection), θ vs dimensionless time, T (or, equivalently, potential, for voltammetric measurements) for small , yielded curves similar to the voltammetric behavior of a redox active solution phase species in a thin layer cell configuration (which closely resemble the voltammetry of the actual adsorbed redox couple). As was increased, however, the θ vs T curves acquired characteristics reminiscent of solution-phase voltammetry recorded with a microelectrode and farther away with a larger electrode. Further evidence of the accuracy of Week's method was obtained from the analysis of square-wave periodic boundary conditions at the interface, which yielded time-resolved profiles away from the interface, in harmony with the analytical solutions published in the literature.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Renewable Energy, Sustainability and the Environment
- Surfaces, Coatings and Films
- Materials Chemistry