Abstract:
The aim of the work was to develop a method of constructing the structure of the near-surface layer of the investigated material by atomic force microscopy. The method is suitable for the study of soft filled materials and consists in creating a three-dimensional image of the structure of a stiff filler hidden under the surface using data from the semi-contact mode of the atomic force microscope (AFM): phase portrait and relief map of the sample surface. In the model, the AFM probe is treated as a spring pendulum with specified (stiffness and resonant frequency) and calculated (effective mass and internal viscosity) parameters. The parameters of the numerical model describe a real experimental setup. The behaviour of the material is described by an elastic model, dissipation is represented by adhesion forces that pull the probe into the material after contact with its surface. For a given material and experiment parameters, the resulting phase shift map is interpreted as the result of rigid objects located at a certain depth. The values of these depths are converted into the topography of hidden subsurface structures.
Keywords:atomic force microscopy, tapping mod, mathematical model of interaction, phase shift, subsurface structure.
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