Berlin 2012 – scientific programme

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O: Fachverband Oberflächenphysik

O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)

O 35.117: Poster

Tuesday, March 27, 2012, 18:15–21:45, Poster B

(contribution withdrawn, duplicate of O 35.123) Investigations by intermittent contact AFM on free-standing static and mechanically vibrating nanowires — •Moid Bhatti, Ivo Knittel, and Uwe Hartmann — Institut für Experimentalphysik, Uni Saarland

The scanning speed of the atomic force microscope (AFM) is mainly limited by the resonant frequency of the (conventionally micron-sized) cantilever (fc) and the feedback control loop for height control with piezo resonant frequency fz. A reduction of the cantilever size leads to a higher fc for instance a nano-sized cantilever has fc typically in MHz range. Scanning at such high speeds will require a correspondingly fast feedback control loop (high fz). Besides, an understanding of the interaction between a sample surface and a static or oscillating nanowire (NW) or ``nanocantilever (NC)" is required.

We have been studying the contact mechanics of the cantilever-sample system in the context of dynamic mode AFM using NCs of various types: (1)Nanowires grown on a substrate. (2)Carbon nanotubes attached to an AFM cantilever. (3)Focused-Ion-Beam (FIB)-structured AFM cantilevers. (4)FIB-structured NC at the tip of an optical fiber whereby the light transmission capability of the fiber can be utilized for the integrated detection of the NC oscillating at its tip.

We will present distance-dependent resonance curves and show various oscillatory states of an AFM cantilever interacting with a static NW and of NCs tapping on a sample surface. NWs were excited piezoelectrically and electrostatically up to 100 MHz. The detection of such vibrations is discussed.