Berlin 2012 – wissenschaftliches Programm

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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 35.123: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster B

Investigations on nanowire-cantilever interactions — •Moid Bhatti, Ivo Knittel, and Uwe Hartmann — Institut für Experimentalphysik, Universität des Saarland

High speed (video rate and beyond) atomic force microscopy (AFM) requires a height feedback with a bandwidth of 100 kHz and more, for which solutions are emerging. On the other hand, cantilevers with resonant frequencies (f) in the MHz range are required. Nano-sized cantilevers with f in the MHz range can fulfill this requirement. However, an understanding of the interaction between a sample and a static or oscillating nanowire (NW) or nanocantilever (NC) is needed.

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)NWs grown on a substrate (whose dynamic behavior is equivalent to a cantilever with a NW attached to it). (2)Carbon nanotubes attached to an AFM cantilever. (3)Focused-Ion-Beam-(FIB)-structured AFM cantilevers. (4)A 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 a NC tapping on a sample. A dedicated piezoelectric element was excited to vibrations of up to 100 MHz. The detection of such vibrations is discussed besides a technique for the electrostatic excitation of mechanical vibrations of free-standing NWs in MHz range.