title: Multiparameter Estimation in Voltammetry When an Electron Transfer Process Is Coupled to a Chemical Reaction.
abstract: Estimation of thermodynamic and kinetic parameters in electrochemical studies is usually undertaken via comparison of the experimental results with theory based on a model that mimics the experiment. The present study examines the credibility of transient d.c. and a.c. voltammetric theory-experiment comparisons for recovery of the parameters needed to model the ubiquitous mechanism when an electron transfer (E) reaction is followed by a chemical (C) step in the EC process ([Formula: see text]). The data analysis has been undertaken using optimization methods facilitated in some cases by grid computing. These techniques have been applied to the simulated (5% noise added) and experimental (reduction of trans-stilbene) voltammograms to assess the capabilities of parameter recovery of E(0) (reversible potential for the E step), k(0) (heterogeneous electron transfer rate constant at E(0)), α (charge transfer coefficient for the E step), and k(f) and k(b) (forward and backward rate constants for the C step) under different kinetic regimes. The advantages provided by the use of a.c. instead of d.c. voltammetry and data optimization methods over heuristic approaches to "experiment"-theory comparisons are discussed, as are the limitations in the efficient recovery of a unique set of parameters for the EC mechanism. In the particular experimental case examined herein, results for the protonation of the electrochemically generated stilbene dianion demonstrate that, notwithstanding significant advances in experiment and theory of voltammetric analysis, reliable recovery of the parameters for the EC mechanism with a fast chemical process remains a stiff problem.
authors.affiliation: School of Chemistry, Monash University , Clayton, Victoria 3800, Australia.
authors.forename: Alexandr N
authors.initials: AN
authors.lastname: Simonov
authors.affiliation: Mathematical Institute, University of Oxford , Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG, United Kingdom.
authors.forename: Graham P
authors.initials: GP
authors.lastname: Morris
authors.affiliation: School of Chemistry, Monash University , Clayton, Victoria 3800, Australia.
authors.forename: Elena
authors.initials: E
authors.lastname: Mashkina
authors.affiliation: Monash eResearch Centre, Monash University , Clayton, Victoria 3800, Australia.
authors.forename: Blair
authors.initials: B
authors.lastname: Bethwaite
authors.affiliation: Mathematical Institute, University of Oxford , Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG, United Kingdom.
authors.forename: Kathryn
authors.initials: K
authors.lastname: Gillow
authors.affiliation: Mathematical Institute, University of Oxford , Radcliffe Observatory Quarter, Woodstock Road, Oxford, OX2 6GG, United Kingdom.
authors.forename: Ruth E
authors.initials: RE
authors.lastname: Baker
authors.affiliation: Department of Computer Science, University of Oxford , Wolfson Building, Parks Road, Oxford, OX1 3QD, United Kingdom.
authors.forename: David J
authors.initials: DJ
authors.lastname: Gavaghan
authors.affiliation: School of Chemistry, Monash University , Clayton, Victoria 3800, Australia.
authors.forename: Alan M
authors.initials: AM
authors.lastname: Bond