When monitoring surface processes and chemical surface reactions, it often is of great importance to be able to monitor chemical surface changes with lateral resolution down to the nanometer scale. We demonstrate that using an oscillating tip in the contact mode of the AFM, chemical contrast can be visualized. The technique of Chemical Contrast Imaging (CCI) is described, and examples for imaging surface reactions are given, including carbon layer deposition and carbon layer etching.

At higher forces in the range between 100 nN and 10 µN, the AFM tip can be used as a “chemical pen” to induce chemical processes locally at predefined positions. In this way, local etching can be induced, and tribo-chemical as well as tribo-electrochemical processes can be studied with lateral resolution on the nm scale. Site-selective AFM-tip induced molecular exchange reactions on the nm-scale are demonstrated for different systems, including polymer brushes, and the corresponding structuring mechanisms are discussed.

AFM topography (left) and chemical contrast due to different tip-sample interaction (right) on a droplet-etched silicon wafer surface. Scale: 12 µm x 12 µm.

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