Dresden 2009 – scientific programme

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O: Fachverband Oberflächenphysik

O 46: Time-resolved spectroscopies I

O 46.1: Talk

Thursday, March 26, 2009, 10:30–10:45, SCH A315

Heat transport beyond thermodynamic equilibrium — •Martin Kammler, Anja Hanisch-Blicharski, Boris Krenzer, Simone Möllenbeck, Paul Schneider, and Michael Horn-von Hoegen — Department of Physics, Universität Duisburg-Essen, 47048 Duisburg, Germany

The heat transport of a thermal excited film into the substrate is determined by the thermal boundary resistance at the interface and well described by the Acoustic Mismatch Model (AMM) and Diffuse Mismatch Model (DMM), both well-accepted bulk models. For ultra thin films we observe a deviation for the AMM model.

After excitation of an ultra thin epitaxial Bi(111) film with fs-laser pulses the heat transport into the silicon substrate is determined by studying the cooling process with ultrafast time resolved electron diffraction in RHEED geometry using the Debye Waller effect. For Bi on Si(111) the observed exponential temperature decay time is well described by the AMM and DMM up to only 2.5 nm thin films but not for Bi/Si(001). Here, we observe a slight saturation of the cooling process with a decay constant τ = 500 ps on films thinner then 6 nm; the heat is trapped!