Regensburg 2010 – scientific programme
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O: Fachverband Oberflächenphysik
O 22: Methods: Scanning probe techniques III
O 22.8: Talk
Tuesday, March 23, 2010, 12:15–12:30, H32
Observing a qPlus sensor oscillate — Joachim Welker, •Alfred J. Weymouth, and Franz J. Giessibl — Institute for Expermental and Applied Physics, University of Regensburg, Germany
The qPlus sensor [1] has been widely used in FM AFM for investigations of various surfaces. The qPlus sensor consists of a quartz tuning fork with one prong fixed to a massive substrate, so that the motion is can be described as harmonic oscillator. Real time observation of the oscillations of a qPlus sensor would require a high-speed video recorder with a framerate on the order of 50 kHz. However, by using a stroboscopic light with frequency flight=fqPlus± Δ f, the oscillation of the sensor can be recorded at the beat frequency Δ f with a much lower frame rate. This allows us to explore the single harmonic oscillation motion that is used to model the movement of the tip. In the new three-contact design of the qPlus sensor, a gold wire is used to bias the tip for STM operations. This measurement also provides information about the role of the gold wire on tip oscillations.
[1] F. J. Giessibl, et al., Nanotechnology 15, S79-S86 (2004)