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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 15: Diffusion and Transport Processes

CPP 15.8: Talk

Tuesday, March 27, 2007, 16:30–16:45, H47

PhoCS - Photothermal Correlation Spectroscopy — •Romy Radünz and Frank Cichos — Molecular Nanophotonics, Universität Leipzig, Linnéstraße 5, 04103 Leipzig

Fluorescence correlation spectroscopy (FCS) is a versatile tool to explore molecular dynamics with single molecule sensitivity. It is widely used in exploring biophysical processes even in living cells. However, it is based on fluorescence and therefore suffers from photophysical weaknesses of the chromophores, such as photoblinking, photobleaching or weak signal to background contrast due to autofluorescence. We present results of a new experimental technique called photothermal correlation spectroscopy (PhoCS). PhoCS employs a photothermal contrast mechanism to detect non-fluorescent nanoparticles of only a few nanometers in size. Light, which is absorbed by the particle is released as heat and induces a local refractive index change around the nanoparticle, which is optically detected. This contrast mechanism is used to generate timetraces of nanoparticle diffusion in an equivalent way as it is done in FCS. Thus PhoCS opens new ways of local dynamic measurements with nanometer sized photostable tracers.