Relationship between Friction and Molecular Structure: Alkylsilane Lubricant Films under Pressure

E. Barrena; S. Kopta; D. F. Ogletree; D. H. Charych; Miquel Salmeron

doi:10.1103/PhysRevLett.82.2880

Relationship between Friction and Molecular Structure: Alkylsilane Lubricant Films under Pressure

E. Barrena, S. Kopta, D. F. Ogletree, D. H. Charych, and Miquel Salmeron

Phys. Rev. Lett. 82, 2880 – Published 5 April 1999

Abstract

We demonstrate that energy losses during friction of alkylsilane self-assembled monolayers with sharp atomic force microscope tips can be correlated to molecular events occurring at specific threshold loads. Under these loads, discrete molecular tilts occur, which are dictated by the geometrical requirements of the close packing of molecules. The barriers overcome during these tilt events give rise to discrete changes in the frictional forces.

Received 17 November 1998

DOI:https://doi.org/10.1103/PhysRevLett.82.2880

Authors & Affiliations

E. Barrena^*, S. Kopta^†, D. F. Ogletree, D. H. Charych^‡, and Miquel Salmeron^§

Materials Sciences Division, Lawrence Berkeley National Laboratory, University of California, Berkeley, California 94720

^*Permanent address: Instituto de Ciencia de Materiales de Madrid, CSIC, Madrid, Spain.
^†Permanent address: Institute of Physics, University of Basel, Basel, Switzerland.
^‡Present address: Chiron Technologies, Emeryville, CA.
^§To whom correspondence should be addressed.