Regensburg 2016 – scientific programme

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O: Fachverband Oberflächenphysik

O 33: Photonics and Nanooptics I: Infrared Spectroscopy

O 33.12: Talk

Tuesday, March 8, 2016, 13:15–13:30, H4

Resonances from thermal waves using photothermal deflection microscopy — •André Heber, Markus Selmke, and Frank Cichos — Universität Leipzig, Exp. Phys. I, Molecular Nano-Photonics Group, 04103 Leipzig, Germany

A gold nanoparticle is heated by a harmonically modulated pump laser which is fixed in space. This configuration results in a thermal wave centred around the nanoparticle. The thermal wave is exponentially damped with a decay-length corresponding to a single thermal wavelength. We co-align a second laser beam which is non-absorbed and steerable to measure deflections induced by refractive index changes due to the optical heating. This setup enables the detection of the thermal wave's resonances in the components in phase and out-of-phase with the pump. The deflection signal depends on the distance. The externally controllable offset provides a well-defined length scale which can be used to quantify the thermal diffusivities from these resonances in combination with a ray optics model.