SURFACE-ANALYSIS BY SCANNING ELECTROCHEMICAL MICROSCOPY - RESOLUTION STUDIES AND APPLICATIONS TO POLYMER SAMPLES

Resolution studies of scanning electrochemical microscopy (SECM) have been performed in the feedback mode and in the generator/collector mod e at circular model structures. A quantitative correlation of the loss in resolution and the increase in distance between tip and sample is found. Measuring a band electrode of just 500 nm width, the high sensi tivity of the SECM in identifying chemically active sites is proven. A pplied to polymer samples, the chemical composition was determined in the feedback mode at high lateral resolution. The difference in electr ical conductivity allows one to distinguish between doped and undoped parts of a polyaniline film. By scanning above a blend consisting of p olypyrrole and polypropylene, a map of the local chemical composition was obtained. In this context, the influence of the tip overpotential on the image is discussed.