Dresden 2011 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 11: Poster: New Instruments and Methods

CPP 11.5: Poster

Montag, 14. März 2011, 17:30–19:30, P2

Modeling Photothermal Detection, 3 Ways to make it Quantitative — •Markus Selmke, Marco Braun, and Frank Cichos — Universität Leipzig, Experimental Physik I, mona, Deutschland

Photothermal spectroscopy has been long used to quantitatively study the absorption of liquids and materials in numerous variants, such as photothermal beam deflection spectroscopy and thermal-lens spectroscopy. While recent developments have pushed the sensitivity of its microscopic counterpart up to the level of a single quantum dot or even a single molecule, the technique has lost its quantitative character due to the complexity of the signal creation in a microscopy volume. Thus a quantitative description is missing and even the simple signal shape in axial photothermal scans of single metal nanoparticles remains unclear. Here we present 3 different quantitative descriptions reproducing the photothermal detection phenomena and parameter-dependencies while providing a thorough understanding of the signal generation. Full ab-initio EM-field calculations as well as simple Ray-Optics and Diffraction treatments are shown to agree well among each other and establish the interpretation in terms of an intuitive thermal lens mechanism. Application to experiments enable the extraction of absorption cross-sections from the photothermal signal of single nanoparticles.