Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 53: Organische Dünnschichten V

O 53.1: Vortrag

Mittwoch, 9. März 2005, 10:45–11:00, TU EB420

Dynamics of colloidal thin films at the nanometer scale using surface XPCS — •Simone Streit¹, Henning Sternemann¹, Virginie Chamard², Michael Sprung¹, Christian Gutt¹, Anders Madsen³, and Metin Tolan¹ — ¹Exp. Physik I, Universität Dortmund, 44221 Dortmund — ²LTPCM, St Martin d’Hères, France — ³ESRF, Grenoble, France

The surface dynamics at the nanometer scale of thin polymer films decorated with gold clusters was investigated using x-ray photon correlation spectroscopy (XPCS) in grazing incidence geometry. The scattering signal from polystyrene films (80-100 nm thick) with different molecular weights (34.4 and 220 kg/mol) and rather large nominal gold thicknesses (1-2 nm) was measured by a CCD as a function of time for temperatures in the range of 290 to 450 K. Capillary waves motion at the polymer surface as well as surface diffusion of the nanoparticles have already been observed for length scales of about 10 nm, leading to viscosity values much higher than the ones already known for the bulk. In this experiment we confirmed the large surface viscosity and investigated the q-parallel dependence of the relaxation time for different temperatures. q-parallel values from 0.1 to 1 nm⁻¹ were measured simultaneously, thus leading to the direct observation of surface dynamics on nanometer length scales.