SCANNING ELECTROCHEMICAL MICROSCOPY - A NEW SCANNING-MODE BASED ON CONVECTIVE EFFECTS

A new measuring technique for the scanning electrochemical microscope (SECM) is presented, which we call picking mode. The influence of the tip-surface distance on the current signal is separated from the curre nt due to the electrochemical properties of the surface by this new me thod. Based on convective effects, the fast approach of the tip toward s samples revealed a sharp increase of the tip current close to the sa mples' surface. During this strongly instationary stage, the current i s dominated by convective flows and the influence of the electrochemic al surface properties is negligible. Using this convective current, th e tip-surface distance can be adjusted within a few microns. In a seco nd step after reaching the steady-state transport conditions again, th e electrochemical processes are characterised by the current at this p osition. The capability of the new mode is proven by scanning a bended platinum sheet and a PVC sample. The new method enables the separate acquisition of the height profile due to the surface's morphology and of the topology due to local variations of electrochemical properties.