Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 63: Posters: Scanning Probe Methods

O 63.16: Poster

Wednesday, April 2, 2014, 17:30–21:00, P2

Measuring near field mediated absolute heat fluxes with the Near Field Scanning Thermal Microscope (NSThM) — •Konstantin Kloppstech, Nils Könne, Achim Kittel, Ludwig Worbes, and David Hellmann — EHF, Fak. V, Inst. f. Physik, CvO Universität Oldenburg

Experimental analysis of near-field heat transfer on the nanoscale by means of absolute fluxes is based on accurate knowledge of our thermocouple sensors thermal resistance. This sensor combines a standard scanning tunneling microscope tip with a coaxial thermocouple, consisting of a thin Pt-wire coated with a 200 nm layer of Au. We present measurements and a wide analysis for our in situ method for measuring the sensors thermal features. Therefore one needs a defined and metrological accessible heat reservoir. That for our sample is held in UHV conditions and consists of a 5 µ m thin and 3-10 mm long tungsten wire which is glued to an electrically insolated copper block. The thin wire is heated with high frequency AC currents and can be described with the 1D heat diffusion equation. The wire is cooled additionally by approaching the thermocouple tip to its middle. From the decrease in heating we determine the heat flux through the thermocouple tip which then can be attributed to the additionally measured thermopower of the tip sensor. To achieve highest precision we have analyzed our system and present besides measurements the major metrological aspects that must be considered. This enables us to locally probe the near field mediated heat fluxes on the nanoscale by means of absolute values.