Abstract
Using model systems consisting of ionic tips interacting with ionic surfaces, we have performed non-equilibrium molecular dynamics simulations of atomic scale imaging in non-contact atomic force microscopy at close approach to the surface, where structurally reversible instabilities consisting of surface atom jumps can lead to a hysteresis in the tip force. This results in dissipated energies comparable to those observed experimentally for similar systems. The development of reversible instabilities is dependent on the nature of the tip and surface, the tip lateral position, distance of closest approach and system temperature. For the first time, we present constant height dissipation images of the MgO(001) surface imaged with an anion terminated MgO tip and the NaCl(001) surface imaged with an anion terminated NaCl tip which show different contrast mechanisms. We also find much larger dissipation energies at low coordinated surface sites. When an MgO tip is brought close to the NaCl(001) surface at low temperatures, a surface atom is permanently pulled away from the surface on retraction; however, we find that the system returns to its original configuration leading to stable imaging at higher temperatures. © 2005 IOP Publishing Ltd.