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BP: Fachverband Biologische Physik

BP 1: Imaging

BP 1.3: Vortrag

Montag, 16. März 2015, 10:15–10:30, H 1028

Single laser beam photothermal microscopy — •Andre Heber, Markus Selmke, Marco Braun, and Frank Cichos — Molecular Nanophotonics Group, Institute of Experimental Physics I, Leipzig University, 04103 Leipzig, GERMANY

Photothermal microscopy enables the selective detection of single absorbing nanoparticles and molecules in the presence of scatterers. It is based on refractive index changes upon optical excitation. Typically, it utilises two different laser beams at distinct wavelengths to induce and detect changes of the optical properties in the vicinity of an absorbing nanoobject. Here, we show that a single modulated heating laser with an intensity offset suffices to selectively image absorbers. The modulated optical heating creates a thermal wave around the absorber and results in a retardation of the refractive index field. The out-of-phase component of the scattering on the heated nanoparticle and the refractive index profile provides a selective contrast for absorbers. The use of a single laser beam simplifies the application of photothermal microscopy in existing microscopy schemes.