title: Two-dimensional dynamics of metal nanoparticles on the surface of thin polymer films studied with coherent X rays.
abstract: X-ray photon-correlation spectroscopy is used to measure the dynamic structure factor f(q,tau) of gold particles moving on the surface of thin polymer films. Above the glass transition of the polymer the peculiar form f(q,tau) approximately exp[-(Gamma tau)(alpha)] is found with 0.7 < alpha < 1.5, depending on sample age and temperature. The relaxation rates Gamma scale linearly with q, excluding a simple Brownian diffusive motion. This type of behavior, already observed in aging bulk soft matter systems, is explained by a power law distribution of particle velocities due to ballistic motion.
authors.affiliation: Fachbereich Physik, Universität Dortmund, Otto-Hahn-Strasse 4, 44221 Dortmund, Germany.
authors.forename: S
authors.initials: S
authors.lastname: Streit
authors.forename: C
authors.initials: C
authors.lastname: Gutt
authors.forename: V
authors.initials: V
authors.lastname: Chamard
authors.forename: A
authors.initials: A
authors.lastname: Robert
authors.forename: M
authors.initials: M
authors.lastname: Sprung
authors.forename: H
authors.initials: H
authors.lastname: Sternemann
authors.forename: M
authors.initials: M
authors.lastname: Tolan
mesh_terms: D003198:Computer Simulation; D006046:Gold / Q000737:chemistry*; D008956:Models, Chemical; D009038:Motion; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure*; D011108:Polymers / Q000737:chemistry*; D013052:Spectrometry, X-Ray Emission / Q000379:methods*; D013499:Surface Properties
chemical_list: D011108:Polymers; D006046:Gold