Potential dependent change in local structure of ferrocenyl-terminated molecular islands by electrochemical frequency modulation atomic force microscopy

Electroactive ferrocenylundecanethiol (FcC(11)H(22)SH) islands embedded in a n-heptanethiol (C7H15SH) self-assembled monolayer matrix on Au(111) were studied under potential control in 0.1M HClO4 aqueous solution using electrochemical frequency modulation atomic force microscopy. Signal of local structural change on the Fc islands upon oxidation from Fc(0) to Fc(+) was obtained in topography as a reversible process; however, the magnitude of the change was far less than expected in contrast to the case of the previous study for FcC(11)H(22)SH islands embedded in C10H21SH. Different degrees of freedom for the structures of the Fc islands originating from different molecular lengths for surrounding matrix molecules perhaps provide the distinct contrast between the two systems. (C) 2010 American Vacuum Society. [DOI: 10.1116/1.3316501]