Calligraphy on self-assembled monolayer of supramolecules

Information storage utilizing the bi-stable state of organic molecules has been a hot topic in molecular electronics, due to the promising future of single molecule devices. We demonstrated in this paper nanometer-scale pattern generation on the self-assembled monolayer of [2]rotaxane. The organic molecules are covalently bonded to the Au(111) surface of the substrate through the di-thiol groups at one end of the molecules. Electric bias was applied between the Au substrate and the conductive tip of a scanning probe microscope to stimulate the pattern generation. The line width and apparent height of the pattern is related to the bias voltage and there exists a threshold, below which no pattern can be generated.