Mechanical response of nanometer thick self-assembled monolayers on metallic substrates using classical nanoindentation

We report here on the mechanical response of thiolate self-assembled monolayers, a few nanometers thick, on gold and silver substrates, using ultra-low load contact probing (the limit of the nanoindentation method used) with a relatively large spherical diamond tip. Careful analysis of a large number of experimental data points enabled us to differentiate the effects stemming from the substrate, the loading rate, and the orientation and reactivity of the molecules. Three distinct patterns for the responses of the monolayers were observed, giving insight into the mechanical response of thiol modified metal surfaces. (C) 2011 American Institute of Physics. [doi:10.1063/1.3663363]