Dresden 2011 – wissenschaftliches Programm
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CPP: Fachverband Chemische Physik und Polymerphysik
CPP 11: Poster: New Instruments and Methods
CPP 11.6: Poster
Montag, 14. März 2011, 17:30–19:30, P2
Photothermal Detection: New Experimental Perspectives from a Quantitative Theory — •Marco Braun, Markus Selmke, and Frank Cichos — Molecular Nanophotonics Group, University of Leipzig, Linnéstraße 5, D - 04103 Leipzig
Photothermal microscopy has been used successfully for the detection of non-fluorescent nano-objects as gold nanoparticles, quantum dots or carbon nanotubes. Recently, the sensitivity of the method was improved to detect even single molecules only by absorption of light. The technique nevertheless suffers from a lack of a fundamental quantitative description. Within our group, a new Mie-like ab-initio EM-scattering theory was developed, capable to predict the photothermal signal in a quantitative manner. Experimental data will be presented supporting this theory and showing that the technique is based on the formation of a thermal nano-lens. This allows to investigate the temperature fields induced by a single optically heated nanoparticle. The gained insight opens up the opportunity of new applications of photothermal detection beyond the imaging of absorbing nano-objects. The absorption cross-section σabs may be extracted directly from the photothermal signal. Moreover, the theory suggests the application of dual focus photothermal correlation spectroscopy to probe the dynamics of absorbing nanoparticles.