Berlin 2005 – wissenschaftliches Programm
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CPP: Chemische Physik und Polymerphysik
CPP 19: Dynamics I
CPP 19.1: Vortrag
Dienstag, 8. März 2005, 09:45–10:00, TU C230
Dynamical Scaling of Single Chains on Adsorbing Substrates: Diffusion Processes — •Radu Descas1,2, Jens-Uwe Sommer2, and Alexander Blumen1 — 1Theoretische Polymerphysik, Universitaet Freiburg Hermann-Herder-Strasse 3, Freiburg, Germany — 2Institut de Chimie des Surfaces et Interfaces, 15, rue Jean Starcky, Mulhouse Cedex, France
We present MC simulations of tethered chains of length N on adsorbing surfaces, analyzing the results using scaling arguments. We investigate the dynamical scaling behavior at the adsorption treshold, єc, by focusing on the end-to-end correlation function [1] and on the mean-square displacement of different monomers of the chain [2]. We find that at єc the dynamic scaling exponent a (which describes the relaxation time of the chain as a function of N) is the same as that of free chains. For є > єc, the time scale for the relaxation in the direction perpendicular to the surface, τ⊥, becomes independent of N; τ⊥ is then the relaxation time of an adsorption blob. In the direction parallel to the surface the motion is similar to that of a two-dimensional chain and is controlled by a time scale given by τ∥∼ N2ν2+1L−2Δν/ν, where ν2 is the Flory exponent in two dimensions, ν is the Flory exponent in three dimensions and Δν=ν2−ν. [1] R Descas, J. -U. Sommer and A. Blumen, J. Chem. Phys 120, 8831, 2004. [2] R Descas, J. -U. Sommer and A. Blumen, to be published.