Very easy kinetics determination for feedback curves with a microdisk SECM tip and rather rapid substrate reaction

A new description of the steady-state feedback currents in SECM (scanning electrochemical microscopy) experiments using a micro-disk with rather irreversible rapid kinetics reaction at the substrate is discussed. In this case, the feedback approach curve can be very accurately deduced from a simple translation of the pure positive feedback curve along the tip-substrate distance axis. The shifting between both curves gives directly the inverse value of the kinetics parameter. The accuracy of this kinetics determination is discussed in comparison with previously published results. This method allows dimensionless kinetics parameters comprised between 2 and 100 with dimensionless distance values comprised between 0.2 and I to be easily and accurately determined. Another sound advantage of this method is that the results are valid for any kind of microdisk, which was not the case for the previously used analytical approximations. (c) 2006 Elsevier B.V. All rights reserved.