Dresden 2009 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 39: POSTERS Colloids and Liquids

CPP 39.20: Poster

Donnerstag, 26. März 2009, 17:00–19:30, P3

Controlled optical heating of single metal nanoparticles in an optical trap — •Spas Nedev, Romy Radünz, and Frank Cichos — Molecular Nanophotonics Group, Institute of Experimental Physics I, University Leipzig, Linnéstraße 5, 04103 Leipzig

Recently a technique called photothermal correlation spectroscopy has been developed by our group. This technique is based on a heterodyne photothermal detection of gold nanoparticles, where a laser heats a particle periodically and a probe laser detects the light scattered by the refractive index gradient caused by the local temperature field around the particle. If these particles are suspended in a liquid and freely diffusing, the heating will cause an enhanced Brownian motion in a local viscosity and temperature field. Within this study we are trying to disentangle all different contributions to the mobility of the particle by trapping gold nanoparticles in an optical tweezer and heating them in a controlled way with a second laser at the plasmon resonance. The positional fluctuations of the particle are studied as a function of the heating laser intensity to yield an effective trap stiffness due to the modified temperatures and viscosities. As a result of these experiments we hope to shine light on hot particle diffusion as well as on thermal boundary resistances between the nanoparticle and the liquid.