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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 25: Diffusion and Dynamics
CPP 25.2: Talk
Wednesday, March 25, 2009, 15:45–16:00, ZEU 160
Application of photothermal correlation spectroscopy to the study of hot Brownian motion — •Romy Radünz1, Daniel Rings2, Klaus Kroy2, and Frank Cichos1 — 1Molecular Nanophotonics Group, Institute of Experimental Physics I, University Leipzig, Linnéstraße 5, 04103 Leipzig — 2Soft Condensed Matter Theory, Institute of Theoretical Physics, University Leipzig, Vor dem Hospitaltore 1, 04103 Leipzig
We introduce a new technique for the measurement of tracer dynamics, which is sensitive to single metal nanoparticles down to a radius of 2.5 nm with a time resolution of a few microseconds. The method is based on a fluctuation analysis of a heterodyne photothermal scattering signal, which is recorded in a simple confocal microscopy setup. It exploits the same principles as fluorescence correlation spectroscopy but targets the use of extremely photostable, non-fluorescent, nano-sized tracers as a replacement of fluorescent probes. To validate our approach, we verify that the Stokes-Einstein relation holds for heated diffusing gold nanoparticles, with an effective viscosity and temperature predicted by a semi-quantitative analytical model. We further demonstrate first applications to gold nano-particle diffusion in bio-materials. Due to the photostability and the low size dispersion of gold nanoparticles, the method promises broad applications especially in the field of high throughput biological screening.