Molecular packing changes of alkanethiols monolayers on Au(111) under applied pressure
- Departamento de Intercaras y Crecimiento, Instituto de Ciencia de Materiales de Madrid. Consejo Superior de Investigaciones Cientificas (CSIC), Cantoblanco 28049-Madrid, (Spain)
- Materials Science Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720 (United States)
A study of the changes of molecular packing in self-assembled monolayers of alkylthiols on Au(111) induced by external pressure is presented. Atomic force microscopy (AFM) is used to apply pressure and to measure the height of islands of alkanethiols partially covering the gold surface. The islands are made of ordered straight chain alkylthiol molecules tilted from the surface normal. Their height was found to decrease in a stepwise manner as a function of the load applied by the tip. Simultaneous stepwise increases in friction force were observed. A simple geometrical model involving the interlocking of alkyl chains at specific molecular tilt angles can explain the observations. According to the model, tilts in both the nearest neighbor and the next-nearest neighbor directions are necessary. (c) 2000 American Institute of Physics.
- OSTI ID:
- 20217181
- Journal Information:
- Journal of Chemical Physics, Journal Name: Journal of Chemical Physics Journal Issue: 6 Vol. 113; ISSN JCPSA6; ISSN 0021-9606
- Country of Publication:
- United States
- Language:
- English
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