Pressure Dependence of the Q-factor of Cantilevers Used for NC-AFM

Abstract

We implement a test bed allowing the characterisation of cantilevers used in non-contact atomic force microscopy under controlled atmospheric conditions prior to using the cantilevers in a force microscope. The effective Q-factor of two types of cantilevers is measured as a function of the ambient pressure varied from 10^-8 mbar to normal pressure. The Q-factor is found to be almost constant up to a pressure in the range of 10^-2 to 10^-1 mbar and then decreases by about three ordes of magnitude when increasing the pressure further to normal pressure. The pressure dependence of the effective Q-factor is approximated by analytical models based on the intrinsic damping of the cantilever, mounting losses and pressure dependent terms accounting for damping in the molecular flow and viscous regimes. The experimental data can be well described by the models in both regimes. [DOI: 10.1380/ejssnt.2011.30]