Ion and Solvent Transfer Discrimination at a Poly(o-toluidine) Film Exposed to HClO4 by Combined Electrochemical Quartz Crystal Microbalance (EQCM) and Probe Beam Deflection (PBD)

Abstract

A combined electrochemical quartz crystal microbalance (EQCM) and probe beam deflection (PBD) instrument was used to monitor the mobile species transfers at the first and second redox steps of thin (Γ ≅ 5 × 10-8 mol cm-2) poly(o-toluidine) films exposed to either 0.01, 0.1, or 1.0 mol dm-3 HClO4 aqueous electrolyte. A comparison of the predicted PBD profiles calculated from the current and mass responses to that of the measured PBD signal, by temporal convolution anaysis, enabled the contributions of cation (H+), anion (ClO4-), and solvent (H2O) transfer at the first redox step to be discriminated quantitatively. A further separation of the slow moving solvent counter flux from fast ion exchange was possible by shortening the experimental time scale.