| Abstract
| - A method is presented for depositing mixed self-assembled monolayers (SAMs) of dodecanethiol (C12) and 4‘-methyl-1,1‘-biphenyl-4-butane (H3C−C6H4−C6H4−(CH2)4−SH, BP4) by insertion of BP4 into a closely packed SAMof dodecanethiol on Au(111). Insertion takes place at defect sites such as domain boundaries or etch pits in the goldsurface that are characteristic of C12 monolayers on gold. With a lower probability, insertion also occurs beside defectsites inside dodecanethiol domains. Insertion at defect sites results in domains of BP4, whereas insertion into C12domains leads to isolated BP4 molecules. The isolated BP4 molecules are shown not to move at room temperature.By comparing the apparent height of the isolated BP4 molecules and BP4 domains, it is proposed that the isolatedmolecules have the same conformation as in the full-coverage phase. A simple two-layer model is proposed tocharacterize the current transport through BP4. The decay constant β for the phenylene groups is deduced from theapparent STM heights of the inserted BP4 islands compared to the STM heights of the C12 closely packed monolayers.
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