Publication Details (including relevant citation information):
Scudiero, L., Hipps, K. W. The Journal of Physical Chemistry C 2007 111 (47) 17516-17520
Abstract: The controlled manipulation of a physisorbed self-assembled monolayer is demonstrated at room temperature for the first time. Patterns are drawn in a NiOEP monolayer supported on freshly cleaved highly ordered pyrolytic graphite (HOPG) surface using a scanning tunneling microscope (STM) under ambient conditions. STM images acquired before and after pattern formation at low gap resistance reveal the creation of molecule-free regions. In these cleared regions, STM images display the two-dimensional HOPG lattice with atomic spacing of 2.5 Å and pattern depth of about 1.2 Å, typical of the STM apparent height for a monolayer NiOEP film on graphite. These molecule-free regions are created by removal of NiOEP molecules from the surface when the STM is operated at a very high current set point (tunneling resistance of about 120 MΩ or less) as confirmed by the absence of molecular buildup around the patterned areas in the STM images. We show that the removed molecules are not collecting at the boundaries of the scanned regions and discuss their fate. Once the molecular film is damaged, the size of the uncovered area keeps on growing with subsequent scans. We also observe that two different monolayer structures (triclinic and tetragonal) form under the same experimental conditions.
Address (URL): http://dx.doi.org/10.1021/jp075175a