Optimization of the shearforce signal for scanning electrochemical microscopy and application for kinetic analysis
Résumé
A simple modification of the setup for shearforce control in SECM is proposed. It allows alternately SECM experiment and electrode manipulation and polishing. The good reproducibility of the measurement allows studying some parameters affecting the characteristics of the shearforce signal. A simple protocol is proposed to determine the resonant frequency using the current measurement and to select the optimal frequency for application in SECM. The length of the shearforce approach curve can vary from several hundred of nanometers to several mu m when operating under hydrodynamic control. As shown in this study, the combination of the shearforce signal with the electrochemical feedback measurement allows the determination of the tip-to-sample distance, the apparent disk geometry of the probe and a larger range of heterogeneous kinetics constants. In principle, the proposed protocol is applicable to any SECM experiment involving a non-electrochemical positioning, e.g. AFM-SECM.