Study of Self-Assembled Monolayers of Biphenyl Derivatives by Scanning Probe Microscopies

Akihiko Nakasa, Kazuto Yagi, Uichi Akiba, and Masamichi Fujihira

Department of Biomolecular Engineering, Tokyo Institute of Technology,
4259 Nagatsuta, Midori-ku 226-8501, Japan

We studied surface potentials of biphenyl methane thiols derivatives with various terminal groups (X-C6H4-C6H4-CH2SH: X= CH3, H, COOH, F, Cl, CF3) chemisorbed on Au(111) substrates by scanning surface potential microscopy (SSPM). It was found by friction force microscopy (FFM) and scanning tunneling microscopy (STM) that the biphenyl methane thiol derivatives were densely packed in the same way as alkane thiols. It was concluded from this result that dependence of surface potentials on the terminal groups could be related to dipole moments of the biphenyl methane thiol derivatives.