A VARIANT OF DESCRIBING ADHESION INTERACTION IN THE PROBE-SAMPLE SYSTEM OF AN ATOMIC-FORCE MICROSCOPE

摘要

The paper presents a variant of describing the adhesion interaction in the probe–sample system of an atomic-force microscope constructed within the framework of the deformable solid mechanics. The variant is based on the concept of nonlocal pair and triple potential interactions of particles of a continuous elastic medium with account for the criteria of thermodynamicity and stability of both the discrete system of interacting material points and the system of infinitesimal particles constituting a continuous medium. In this case, the potentials of interaction of continuous medium particles are considered as the limits of analogous potentials of the interaction of particles forming an infinite sequence of discrete systems with distance between them, their masses, momenta, and energy tending to zero. The parameters of the interparticle potentials and the characteristics of the adhesive interaction between the sample and the probe are expressed in terms of the characteristics of the elastic state — Young's modulus and Poisson's ratio — under the assumption of their homogeneity, linear elasticity, and the isotropy of their materials. In order to verify the qualitative and quantitative adequacy, the model developed is used to calculate the dependence of the force of the van der Waals interaction between the probe (platinum) and the sample (graphite) on the distance between them. The results of calculation are in satisfactory agreement with the available data.