Berlin 2012 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 6: Scanning probe methods I

O 6.4: Vortrag

Montag, 26. März 2012, 11:15–11:30, MA 043

Spatial variations of heat transfer at nanoscales investigated by Near-field Scanning Thermal Microscopy (NSThM) — •Ludwig Worbes, David Hellmann, Hanna Fedderwitz, Nils Könne, Konstantin Kloppstech und Achim Kittel — EHF/EPKOS, Institut für Physik, Universität Oldenburg

Due to the advance in nanoscience heat transport at small length scales is receiving more attention as a field of fundamental research as well as one influencing future technologies.

The Near-field Scanning Thermal Microscope (NSThM) is a tool to investigate heat transport on a nanoscale[1]. It is based on a UHV-STM, featuring a tunneling probe with an integrated miniaturized thermocouple temperature sensor. Therefore, we can measure the temperature change of the tip due to heat flux between a heated or cooled sample and the probe in the range of distances between (tunnel-) contact and a few nanometers with spatial resolution.

This heat flux can be mediated by different mechanisms: A possible transport mechanism is thermal near field radiation especially relevant for small distances. A strong enhancement of near field heat flux by thin and electrical high resistive layers or adsorbed molecules is predicted by theory [2]. Another possibility is phononic or electronic heat transport through adsorbed molecules forming a molecular junction between sample and probe. We present measurements performed on Au(111) surfaces to discuss the influence of adsorbates.

[1] Uli F. Wischnath et al., Rev. Sci. Instrum. 79, 073708 (2008) [2]A.I. Volotkitin, B. N. J. Persson, Rev. Mod. Phys. 79, 1291 (2007)