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"Coulomb Staircase" at Room Temperature in a Self-Assembled Molecular Nanostructure
1R. P. Andres, W. Mahoney, R. G. Osifchin, School of Chemical Engineering, Purdue University, West Lafayette, IN 47907, USA. T. Bein, S. Feng, J. I. Henderson, C. P. Kubiak, Department of Chemistry, Purdue University, West Lafayette, IN 47907, USA. M. Dorogi and R. Reifenberger, Department of Physics, Purdue University, West Lafayette, IN 47907, USA.
Abstract:
Double-ended aryl dithiols [alpha,alpha'-xylyldithiol (XYL) and 4,4'-biphenyldithiol] formed self-assembled monolayers (SAMs) on gold(111) substrates and were used to tether nanometer-sized gold clusters deposited from a cluster beam. An ultrahigh-vacuum scanning tunneling microscope was used to image these nanostructures and to measure their current-voltage characteristics as a function of the separation between the probe tip and the metal cluster. At room temperature, when the tip was positioned over a cluster bonded to the XYL SAM, the current-voltage data showed "Coulomb staircase" behavior. These data are in good agreement with semiclassical predictions for correlated single-electron tunneling and permit estimation of the electrical resistance of a single XYL molecule (approximately18 ± 12 megohms).