A theoretical study on mass sensitive surface analysis and subsurface imaging with dynamic force microscopy

The possibility of identifying surface atoms according to their mass and of imaging the subsurface region with dynamic force microscopy (DFM) is theoretically investigated by performing numerical simulations on simple model systems. The method consists of measuring the effect of the stochastic motion of surface atoms on the dynamics on the DFM lever, i.e. the effect of Brownian dissipation. In the model adopted for the simulations, the random properties of surface atoms are calculated within the harmonic approximation and are assumed to be independent of the tip–surface interaction. The analysis indicates that the detection of Brownian dissipation is enhanced by driving the lever with small amplitude and may require a lever with large quality factor and natural frequency.