Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 43: Poster Session II - MA 141/144 (Surface Spectroscopy on Kondo Systems; Frontiers of Surface Sensitive Electron Microscopy; Methods: Scanning Probe Techniques+Electronic Structure Theory+Other; Time-Resolved Spectroscopy of Surface Dynamics with EUV and XUV Radiation; joined by SYNF posters)

O 43.14: Poster

Dienstag, 26. Februar 2008, 18:30–19:30, Poster F

Signature of a nanoparticle in the evanescent heat transfer measured by NSThM — •Uli F. Wischnath, Joachim Welker, and Achim Kittel — Univ. Oldenburg, Energy and Semiconductor Research, D-26129 Oldenburg, Germany

The Near-field Scanning Thermal Microscope (NSThM) allows the investigation of the heat transfer by evanescent fields in the direct vicinity of a sample that is at a distance between 1 and 100 nm. It is based on a variable-temperature ultra high vacuum scanning tunneling microscope (VT-UHV STM) with a probe designed as a thermocouple in order to measure thermal properties. The STM abilities of the microscope are used for the spatial control of the temperature probe.

For the work presented here nanoparticles were deposited on a flat surface by dip coating and scanned with the NSThM in constant current mode. They show a typical feature in the heat transfer image: higher values compared to the one on the flats are surrounding the particles whereas right on top of the particle the values are lower than the ones on the flats.

These findings might be explained by calculations which have been made by theoreticians for a similar case: A maximum in the heat transfer is found for a sphere (representing the probe) scanned in a constant height over a surface with a sphere on top at the position where the two spheres start to overlap.