Dresden 2009 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 1: Statistical physics I (general)

DY 1.1: Hauptvortrag

Montag, 23. März 2009, 10:15–10:45, HÜL 386

Heat transfer on the nanometer scale --- Near-field thermal scanning microscopy — •Achim Kittel — Institute of Physics, University of Oldenburg, Carl-von-Ossietzky Str. 9-11, 26129 Oldenburg, Germany

Every body at a finite temperature emits heat radiation. Beside the propagating modes there exist evanescent modes which only can contribute to the heat transfer on short distances. Their contribution to the total heat transfer overcomes the one of the propagating modes at distances well below one micrometer between two bodies. Understanding the evanescent modes and the physics of the electromagnetic fluctuations at the nanometer scale will help to understand the coupling between nanoscale particles. The new possibilities of scanning probe microscopy offer experimental access to investigate these phenomena. Heat transfer mediated by the evanescent modes is detected by means of a modified scanning tunneling microscope (STM), whose tip is functionalized as a coaxial thermocouple with dimensions in the range of a few hundred nanometers. During the measurements the temperature of the sample can be reduced to about 110K or raised to 350K while the tip holder is kept at room temperature. By this means, the heat transfer between the cooled or heated sample and the tip can be measured while scanning over the surface at the tunnel distance. By retracting the tip from the surface the heat transfer in dependence on the distance can be studied. Methods of the experiment will be introduced and results of the measurements are presented and compared to model calculations.