AVS 53rd International Symposium
    Surface Science Thursday Sessions
       Session SS2+NS+TF-ThA

Paper SS2+NS+TF-ThA5
Mechanical Properties of Alkanethiol Monolayers on Gold: A Force Spectroscopy Approach

Thursday, November 16, 2006, 3:20 pm, Room 2004

Session: Tribology
Presenter: G. Oncins, University of Barcelona, Spain
Authors: G. Oncins, University of Barcelona, Spain
C. Vericat, University of Barcelona, Spain
F. Sanz, University of Barcelona, Spain
Correspondent: Click to Email
Since the discovery of the self-assembling process of alkanethiol molecules on gold, these monolayers have been a matter of increasing interest not only from the point of view of basic surface science, but also due to their many applications in nanotechnology.@footnote 1@ Their mechanical properties have been widely studied by several techniques, especially by scanning probe microscopy.@footnote 2@ The growth mechanism of these monolayers on gold in vacuum has been followed by in situ Scanning Tunnelling Microscopy (STM).@footnote 3@ Atomic Force Microscopy (AFM) has proved to be suitable to study the topography and mechanical properties of alkanethiol monolayers under compression.@footnote 4@ In this contribution, we used Force Spectroscopy to study the behavior of alkanethiol monolayers deposited on a (111) monocrystalline gold surface in an electrolyte aqueous solution. The analysis of the force curves shows that the tip indents the monolayer in a stepped way and that the force at which these stepped events have place depends on the compactness of the monolayer. Thanks to newly developed models to calculate the mechanical constants of monolayers on hard substrates,@footnote 5@ we were able to calculate the different values of Young's modulus for alkanethiol monolayers of different compactness and chain length. @FootnoteText@ @footnote 1@J. C. Love, L. A. Estroff, J. K. Kriebel, R. G. Nuzzo and G. M. Whitesides, Chem. Rev., 2005, 105, 1103.@footnote 2@R.W. Carpick, M. Salmeron, Chem. Rev., 1997, 97, 1163.@footnote 3@G.E. Poirier, Langmuir, 1999, 15, 1167.@footnote 4@E. Barrena, C. Ocal, M. Salmeron, J. Chem. Phys., 2000, 113(6), 2413.@footnote 5@E.K. Dimitriadis, F. Horkay, J. Maresca, B. Kachar, R.S. Chadwick, Biophys. J., 2002, 82(5), 2798.