Title: The effect of atomic force microscope probe size on indentation tests simulated using realistic surface forces

Authors: Michael A. Graham, Zachary C. Grasley, Rashid K. Abu Al-Rub

Addresses: Zachry Department of Civil Engineering, Texas A&M University, 710B CE/TTI, 3136 TAMU, College Station, TX 77843-3136, USA. ' Zachry Department of Civil Engineering, Texas A&M University, 710B CE/TTI, 3136 TAMU, College Station, TX 77843-3136, USA. ' Zachry Department of Civil Engineering, Texas A&M University, 710B CE/TTI, 3136 TAMU, College Station, TX 77843-3136, USA

Abstract: The effects of the size and shape of an indenter tip used in a nanoscale indentation test (such as with an atomic force microscope) are studied using realistic, finite-range surface forces to describe the contact and extended-range interaction of the indenter and sample. Sphero-conical indenters with tips ranging from sharp-pointed to very rounded tips (similar to spherical tips) are studied. A continuum Lennard-Jones adhesion potential and a Poisson-Boltzmann exponential repulsion law are used to study adhesive and repulsive-only interactions, respectively. The size of the tip affects the qualitative response for an adhesive surface force potential, with increasingly rounded tips exhibiting a more pronounced jump into contact and a greater overall adhesion. The effects of tip size are less pronounced for pure repulsion.

Keywords: atomic force microscopy; AFM; size effect; nanoindentation; surface forces; non-local effects; adhesive force; contact force; indenter tips; nanotechnology; indentation tests; simulation.

DOI: 10.1504/IJMSI.2010.035204

International Journal of Materials and Structural Integrity, 2010 Vol.4 No.2/3/4, pp.160 - 169

Published online: 14 Sep 2010 *

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