Regensburg 2013 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 58: Poster Session III (Solid-liquid interfaces; Scanning probe and other methods; Electronic structure theory; Spin-orbit interaction)

O 58.54: Poster

Mittwoch, 13. März 2013, 18:15–21:45, Poster B1

In situ characterization of thermal resistance of sensor tips of a near-field scanning thermal microscope (NSThM) — •Konstantin Kloppstech, Nils Könne, Ludwig Worbes, and Achim Kittel — EHF, Inst. f. Physik,CvO Universität Oldenburg

The experimental analysis of near-field heat transfer by means of absolute fluxes is based on accurate knowledge of the thermal resistance of the thermocouple sensor. We present an accurate in situ method for the determination of the sensor’s thermal resistance which can be applied for each sensor right before the scanning procedure. Therefore a sample holder consisting of a 5µm thin and 3-10mm long tungsten wire which is glued to an isolated copper block is realized. The wire itself is mechanically pre-tensioned to minimize thermal vibrations because it is heated via a high frequency current. By this a temperature profile will develop along the wire resulting in a measurable change in electric resistance. Parasitic heat-drain channels can be neglected, because the experiment is performed in UHV. The determination of the thermal resistance of the tip is performed in two steps. First, the mean temperature rise is calculated for various values of heating power. Thermal resistance of the wire is determined by fitting the curve of temperature change versus heating power. Second, the tip is being approached to the wire resulting in a second channel for heat drain. The thermal resistance of the tip is then calculated from the resulting temperature change for different heating powers of the coupled system. This can be done by means of solving a 1d heat transfer equation, which describes the coupled systems of wire and tip.