Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 35: Poster Session II (Polymeric biomolecular films; Nanostructures; Electronic structure; Spin-orbit interaction; Phase transitions; Surface chemical reactions; Heterogeneous catalysis; Particles and clusters; Surface magnetism; Electron and spin dynamics; Surface dynamics; Methods; Electronic structure theory; Functional molecules)

O 35.113: Poster

Dienstag, 27. März 2012, 18:15–21:45, Poster B

On the characterization of thermal properties of Near-field scanning thermal microscope (NSThM) thermocouple-sensors by means of 3-ω technique — •Konstantin Kloppstech, David Hellmann, Ludwig Worbes, Nils Könne, Hanna Fedderwitz, and Achim Kittel — EHF, Fak. V, Physik, Carl von Ossietzky Universität Oldenburg

The experimental analysis of near-field heat transfer from defined surfaces by a NSThM is founded on accurate knowledge of thermal properties of the thermocouple sensor, particularly the thermal resistance κ. The fact that the sensor consists of a multi-material system complicates common analysis methods. The 3ω method provides an alternative for determining κ and in addition to this the effective heat capacity c_p and the Seebeck-coefficient S. The method bases on a very small AC heating current at angular frequency ω which is sent through a wire, resulting in a temperature and thus in a resistance fluctuation at 2ω. This periodic change in resistance leads to an alternating voltage at 3ω angular frequency, from which κ, c_p, and S can be determined. In our approach we use a 5 µ thin glass fiber coated with 2 nm Pt and 80 nm Au whose thermal properties are determined with the 3-ω method in a first step. Held in UHV the glass fiber is approached with a NSThM sensor adding a second channel for heat drain, resulting in a measurable change in κ that gives access to κ of the sensor. As the 3-ω method relies on established theoretical formulation it gives access to a value of thermal resistance and an exact error estimation. In summary we show that this method is first class in characterizing NSThM-sensors.