With the tip of an STM, Cu can be dissolved from an electrode at potentials at which Cu dissolution should normally not occur. The dissolution process takes place only underneath the tip allowing for a nanometer scale patterning of the Cu surface. The dissolution rate is shown to depend sensitively on the tip potential as well as on the electrode potential. The electrochemical conditions are also given at which the tip influence is negligible and surfaces can be safely imaged. An explanation for the tip-induced metal dissolution on the basis of a direct charge transfer to the tip is offered.

The self-assembled monolayers (SAMs) of normal alkanes (nCnH2n-2) with different carbon chain lengths (n=14±38) in the interfaces between alkane solutions (or liquids), and the reconstructed Au (111) surfaces have been systematically studied by means of scanning tunneling microscopy (STM). In contrast to previous studies, which concluded that some n-alkanes (n=18-26) can not form well-ordered structures on Au (111) surfaces, we observed SAM formations for all these n-alkanes without any exceptions. We find that gold reconstruction plays a critical role in the SAM formation. The alkane monolayers adopt a lamellar structure in which the alkane molecules are packed side-byside, to form commensurate structures with respect to the reconstructed Au (111) surfaces. The carbon skeletons are found to lie flat on the surfaces, which is consistent with the infrared spectroscopic studies. Interestingly, we find that two-dimensional chiral lamellar structures form for alkanes with an even carbon number due to the specific packing of alkane molecules in a tilted lamella. Furthermore, we find that the orientation of alkane molecules deviates from the exact [011≈]direction, because of the intermolecular interactions among the terminal methyl groups of neighboring lamellae; this results in differences of molecular orientation between mirror structures of adjacent zigzag alkane lamellae. Structural models have been proposed, that shed new light on monolayer formation.