Limits of imaging resolution for atomic force microscopy of molecules

Abstract

The imaging resolution of an atomic force microscope operating in contact with a Langmuir–Blodgett (LB) film is predicted as a function of applied force, tip radius, adhesive force, and tip and film properties. The elastic modulus and the hardness of the LB film were measured using a nanoindenter and the imaging resolution is predicted using both a simple Hertzian elastic analysis and one that includes adhesive forces between the tip and the sample. For a small applied force (<1 nN) the resolution improves sharply as the tip radius and the adhesive force decrease. The onset of inelastic deformation, however, limits the resolution of the sharpest tips.