Departmental Papers (MEAM)

Document Type

Journal Article

Date of this Version

March 1996


Copyright (1996) American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics. Reprinted in Journal of Vacuum Science and Technology, Volume 14, Issue 2, March 1996, pages 1289-1295.
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NOTE: At the time of publication, author Robert W. Carpick was affiliated with the University of Wisconsin. Currently (June 2007), he is a faculty member in the Department of Mechanical Engineering and Applied Mechanics at the University of Pennsylvania.


We have studied the variation of frictional force with externally applied load for a Pt-coated atomic force microscope tip in contact with the surface of mica cleaved in ultrahigh vacuum. At low loads, the frictional force varies with load in almost exact proportion to the area of contact as predicted by the Johnson-Kendall-Roberts (JKR) theory [K. L. Johnson, K. Kendall, and A. D. Roberts, Proc. R. Sec. London Ser. A 324, 301 (1971)] of elastic adhesive contacts. The friction-load relation for a deliberately modified tip shape was proportional to an extended JKR model that predicts the area-load relation for nonparabolic tips, The tip shape was determined experimentally with a tip imaging technique and was consistent with the predicted friction behavior. This demonstrates that the frictional force is proportional to the area of contact between the tip and sample. Using the JKR/extended JKR model, interfacial surface energies and shear strengths can be estimated.


platinum, mica, sliding friction, ultrahigh vacuum, probes, shear properties, surface energy, interfaces, forces, atomic force microscopy



Date Posted: 25 June 2007

This document has been peer reviewed.