Dresden 2006 – wissenschaftliches Programm

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O: Oberflächenphysik

O 26: Particles and clusters I

O 26.8: Vortrag

Dienstag, 28. März 2006, 17:30–17:45, WIL A317

Dynamics of gold nanoparticles on the surface of thin polymer films — •Simone Streit¹, Henning Sternemann¹, Christian Gutt², Virginie Chamard³, Aymeric Robert⁴, and Metin Tolan¹ — ¹Exp. Physik I, Universität Dortmund, 44221 Dortmund, Germany — ²DESY (HASYLAB), Notkestr. 85, 22607 Hamburg, Germany — ³LTPCM, 1130 rue de la piscine, 38402 St Martin d’Hères, France — ⁴ESRF, BP 220, 38043 Grenoble Cedex, France

Surface x-ray photon correlation spectroscopy (XPCS) is used to measure the dynamic structure factor S(q,τ) of nanometer sized gold particles moving on the surface of thin polymer films. Above the glass transition of the polymer the dynamic structure factor is found to follow the peculiar form S(q,τ) ∼ exp[−(t/τ)^α]. For the exponent a value α=1.5 is observed, representing a faster than exponential decay of the correlation function. A dispersion relation from q=0.01 to 0.06 Å⁻¹ is obtained, corresponding to lengthscales of several hundred Å. The relaxation time τ scales as q⁻¹ in contrast to the q⁻² behavior of simple Brownian diffusive motion. This type of correlation function corresponds to a power law distribution of particle velocities which has also been observed e.g. in aging bulk soft matter systems. The special form of the dynamic structure factor characterizes the hyperdiffusive motion of the gold nanoparticles.