Dresden 2014 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 48: Scanning Probe Methods I
O 48.3: Vortrag
Mittwoch, 2. April 2014, 11:00–11:15, GER 38
Tuning Fork Force Sensor: Spring Constant and Q-Factor in Experiment and Simulation — •Marvin Stiefermann1, Jens Falter1, Harald Fuchs2, Henrik Hölscher3, and André Schirmeisen1 — 1Institute of Applied Physics (IAP), Justus-Liebig-University Giessen, Germany — 2Center for Nanotechnology (CeNTech) and Institute of Physics, University of Münster (WWU), Münster, Germany — 3Institute of Microstructure Technology (IMT), Karlsruhe Institute of Technology (KIT), Eggenstein-Leopoldshafen, Germany
Force spectroscopy in non contact-atomic force microscopy (nc-AFM) has recently been used to determine absolute forces on individual atoms and molecules. Particular impressive results at cryogenic temperatures have been achieved using tuning fork based sensors in the "qPlus" design. However, reliable interpretation of force spectroscopy results require a precise calibration of the tuning fork spring constant. Here we present a comprehensive and straightforward calibration analysis based on experimental determination and FEM simulation of the tuning fork spring constant. We find that the beam formula widely used in the literature systematically overestimates the spring constant. However, we show that a origin shift of the beam can be used to correct this effect for most cases. Further, we find that already a small tilt angle of the tip glued to the prong strongly influences the spring constant, explaining the large scatter of our experimental calibration values. Further we present FEM simulations monitoring the influence of different tuning fork setups, adhesives and tip positions on the Q-Factor.