Elastic Imaging with Nanoscale and Atomic Resolution by Ultrasonic Force Microscopy (UFM)

Abstract

A novel results on the elastic imaging on the nanoscale and atomic resolution using an Ultrasonic Force Microscope (UFM) approach, based on the nonlinear detection of ultrasonic vibration in the Atomic Force Microscope (AFM), are presented. By the imaging of the nanomechanical structure of floppy disk it was undoubtedly demonstrated that the UFM reveals an essentially different kind of image contrast complimentary to those of standard AFM imaging modes — topography, friction force and force modulation modes. A new method of Ultrasonic Force Spectroscopy (UFS) for quantitative evaluation of nanoscale elastic properties by deflection-versus-ultrasonic-amplitude dependencies — z(a) curves — was applied for the evaluation of local elasticity of floppy disk. It is the first time the atomic resolution achieved in UFM is reported and elastic images of mica atomic lattice are given. The high resolution of UFM is explained by the fact, that it operates in transition region of the tip-surface separation (position of initial tip-surface touching), which provides the best conditions for the lateral resolution.