Hannover 2010 – scientific programme

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MO: Fachverband Molekülphysik

MO 29: Poster: Experimental Techniques

MO 29.1: Poster

Thursday, March 11, 2010, 16:00–18:30, Lichthof

A versatile setup for single particle tracking — •Dominique Ernst and Jürgen Köhler — Experimental Physics IV, University of Bayreuth, 95440 Bayreuth, Germany

We present a novel technique to perform automated single particle tracking in 3 dimensions with high spatial and temporal resolution. In order to do so, we create a light orbit with a focussed laser beam and project that light orbit with a homebuilt fluorescence microscope into the plane of the sample. For tracking the movement of a fluorescing nanoparticle (microsphere, molecule), the particle is initially located in the centre of the orbit. Subsequently, we detect the fluorescence intensity of the nanoparticle as a function of its position, recalculate the direction of the movement from the change of the emission intensity, and compensate the movement of the nanoparticle with the aid of a piezostage. The trajectory of the nanoparticle is reconstructed from the feedback-loop of the piezo. To access the 3rd dimension we employ two light orbits that are slightly displaced along the axis of the orbits perpendicular to the plane of the rings enclosing the nanoparticle in the geometrical centre.