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)

A combined electrochemical quartz crystal microbalance (EQCM) and probe bea m deflection (PBD) instrument was used to monitor the mobile species transf ers at the first and second redox steps of thin (Gamma congruent to 5 x 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 pr ofiles calculated from the current and mass responses to that of the measur ed PBD signal, by temporal convolution anaysis, enabled the contributions o f 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 shorteni ng the experimental time scale.