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O: Fachverband Oberflächenphysik

O 97: Scanning probe techniques: Method development II

O 97.13: Vortrag

Donnerstag, 15. März 2018, 18:15–18:30, MA 005

Characterising NC-AFM cantilevers by opto-mechanical forces — •Alexander von Schmidsfeld and Michael Reichling — Universität Osnabrück

Cantilevers are harmonic oscillators that are designed to have a high sensitivity for the detection of minute external forces typically used in non-contact force microscopy (NC-AFM ) to detect forces originating from the tip-sample interaction.

We use opto-mechanical forces acting in the light field of an interferometer for measuring the displacement of an oscillating cantilever for a complete characterization to derive the eigen-frequency (f_0), Quality-factor (Q) oscillation amplitude (A) and cantilever stiffness (k_0) of the cantilever.

As the radiation pressure acting on the cantilever can be determined and the interferometer provides a precise, intrinsically calibrated displacement measurement, these for the interpretation of NC-AFM images crucial properties can be determined with remarkable precision. Due to the sinusoidal intensity modulation of the light intensity an amplitude dependent frequency shift is observed enabling the comparison of the opto-mechanical force to the restoring force. By exactly characterizing the interferometer the light intensity inside the cavity formed by fiber and cantilever and thus the opto-mechanical force can be determined with high precision.