Dresden 2017 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 53: Posters - Active Matter
DY 53.5: Poster
Donnerstag, 23. März 2017, 17:00–19:30, P1A
Hot Brownian Nanoswimmers — •Romy Schachoff1, Katrin Günther2, Michael Mertig2, and Frank Cichos1 — 1Universität Leipzig, Germany — 2Technische Universität Dresden, Germany
Hot Brownian swimmers are thermally anisotropic Brownian particles driven by optical heating. Geometric asymmetry of the swimmers establishes an asymmetric temperature profile in the surrounding solvent upon particle heating. The thermo-osmotic flow along the surface of the swimmer leads to a phoretic self-propulsion. We studied hot Brownian swimmers that are synthesized from a gold nano particle of 50 nm in diameter and a tail of a DNA helix bundle (6HB) of a length of 400 nm. Here, the highly localized optical heating of the nanoparticles creates a steep temperature gradient over the DNA tail. The overall change in the diffusion coefficient for the chosen particle complex will be only in the per mille region, since rotational brownian motion randomizes the direction of propulsion. The ballistic propulsion is retained only for times shorter than the rotational diffusion time that scales with the radius cubed. We use our unique split focus geometry in twin-focus photothermal correlation spectroscopy to detect small flow velocities on small length and time scales (nm/ms) to show a clear swimmer characteristic of the gold nanoparticle DNA complex in dependence of the heating power that is clearly distinguishable from pure hot Brownian motion that is performed by heated gold nanoparticles themselves. Further, the split focus is arranged perpendicular to the optical axis to neglect flow velocities that are exerted by radiation pressure.