Dresden 2006 – wissenschaftliches Programm

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SYSS: Structure Formation and Self-Organization in non-equilibrium Systems

SYSS 1: Structure Formation and Self-Organization in non-equilibrium Systems I

SYSS 1.7: Vortrag

Donnerstag, 30. März 2006, 11:15–11:30, BAR Sch\"o

Xenon Dendrites: Onset and Amplitude of Sidebranches — •Oliver Wittwer and Jörg Bilgram — Laboratorium für Festkörperphysik, ETH, CH 8093 Zürich, Switzerland

The initiation of sidebranches of three dimensional xenon dendrites has been studied. The sidebranches of dendrites growing in a steady state are initiated by selective amplification of thermal noise in the region of the dendrite tip. Measurements of the amplitudes of sidebranches as a function of the distance behind the tip have been compared with theoretical predictions for non-axisymmetric needle cystals [1]. Noise initiated sidebranches start to grow 3-7 tip radii behind the tip. The sidebranches growing at the four fins are not correlated and the amplitudes measured in our experiments are in quantitative agreement with the theoretical predictions.

We have also found a second type of sidebranch initiation: External perturbations lead to sidebranches starting to grow directly at the tip. They are highly correlated at the four fins and their amplitudes are higher than the ones of noise initiated sidebranches.

[1] E. Brener, Phys. Rev. Lett. 71, 3653 (1993)