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Differential stress induced by thiol adsorption on facetted nanocrystals

Watari, M; McKendry, RA; Vögtli, M; Aeppli, G; Soh, YA; Shi, XW; Xiong, G; ... Robinson, IK; + view all (2011) Differential stress induced by thiol adsorption on facetted nanocrystals. Nature Materials , 10 (11) 862 - 866. 10.1038/NMAT3124. Green open access

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Abstract

Polycrystalline gold films coated with thiol-based self-assembled monolayers (SAM) form the basis of a wide range of nanomechanical sensor platforms. The detection of adsorbates with such devices relies on the transmission of mechanical forces, which is mediated by chemically derived stress at the organic-inorganic interface. Here, we show that the structure of a single 300-nm-diameter facetted gold nanocrystal, measured with coherent X-ray diffraction, changes profoundly after the adsorption of one of the simplest SAM-forming organic molecules. On self-assembly of propane thiol, the crystal's flat facets contract radially inwards relative to its spherical regions. Finite-element modelling indicates that this geometry change requires large stresses that are comparable to those observed in cantilever measurements. The large magnitude and slow kinetics of the contraction can be explained by an intermixed gold-sulphur layer that has recently been identified crystallographically. Our results illustrate the importance of crystal edges and grain boundaries in interface chemistry and have broad implications for the application of thiol-based SAMs, ranging from nanomechanical sensors to coating technologies.

Type: Article
Title: Differential stress induced by thiol adsorption on facetted nanocrystals
Open access status: An open access version is available from UCL Discovery
DOI: 10.1038/NMAT3124
Publisher version: http://dx.doi.org/10.1038/NMAT3124
Language: English
Additional information: Copyright © 2011 Macmillan Publishers Limited. All rights reserved.
Keywords: self-assembled monolayers, surface stress, cantilever arrays, phase retrieval, gold, binding, strain
UCL classification: UCL > Provost and Vice Provost Offices
UCL > Provost and Vice Provost Offices > UCL BEAMS
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences
UCL > Provost and Vice Provost Offices > UCL BEAMS > Faculty of Maths and Physical Sciences > London Centre for Nanotechnology
URI: http://discovery.ucl.ac.uk/id/eprint/1329417
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