Regensburg 2007 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 22: POSTER: INTERNAL SYMPOSIUM Optical Spectrosopy

CPP 22.10: Poster

Mittwoch, 28. März 2007, 16:00–18:30, Poster B

Photothermal Microscopy of Single Gold Nanoparticles in Polymers — •Romy Radünz and Frank Cichos — Molecular Nanophotonics, Universität Leipzig, Linnéstraße 5, 04103 Leipzig

Photothermal microscopy is an optical imaging technique, which is based on the release of heat of an absorbing nanoobject to its local surrounding. The temperature rise in the surrounding induces a local refractive index change, which can be detected optically. Thus non-fluorescent nanoobjects such as gold particles of only a few nanometer in size become visible. It is generally expected that the photothermal signal scales with the volume of the nanoobject due to the dependence of the absorption cross-section on the volume. We show that this relation does not hold due to the influence of the nanoparticle surface on the heat transfer from the gold particle to the environment. Numerical calculations and experimental results demonstrate that the dependence of the photothermal signal on the particle size is weaker than expected due to the surface conductivity of the nanoparticle. As a consequence, this type of experiments provides new routes to explore local thermal properties as well as the physics of heat conduction on the nanoscale.