Scanning Tunneling Microscopy Studies of Self-Assembled Monolayers of Alkanethiols on Gold

S. J. Stranick, M. M. Kamna, K. R. Krom, A. N. Parikh, D. L. Allara, and P. S. Weiss*

Journal of Vacuum Science and Technology B 12, 2004 (1994).

We have used scanning tunneling microscopy to probe the molecular scale structures of pure and mixed composition self-assembled monolayers of CH3(CH2)15SH and CH3O2C(CH2)15SH on gold. A predominant defect structure is found for both films and is assigned as a void defect in the thiolate overlayer. The mixed composition films are observed to phase segregate into domains of the pure component thiolates. Time-lapse series of scanning tunneling microscope images reveal kink-driven motion at step edges and exchange of thiolate molecules on terraces.