Measuring the interaction force between a tip and a substrate using a quartz tuning fork under ambient conditions

Tuning forks mounted with sharp tips provide an alternate method to silicon microcantilevers for probing the tip-substrate interaction in scanning probe microscopy. The high quality factor and stable resonant frequency of the tuning fork allow accurate measurements of small shifts in the resonant frequency as the tip approaches the substrate. To permit an accurate measure of surface interaction forces, the electrical and piezomechanical properties of a tuning fork has been characterized using techniques derived from scanning probe microscopy. After proper calibration, representative interaction force data for a conventional Si tip and an HOPG substrate are obtained under ambient conditions.