Berlin 2005 – wissenschaftliches Programm

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M: Metallphysik

M 14: Wachstum

M 14.6: Vortrag

Freitag, 4. März 2005, 16:00–16:15, TU H2038

Interacting Xenon Dendrites — •Oliver Wittwer und Jörg Bilgram — Laboratorium für Festkörperphysik, ETH, CH 8093 Zürich, Switzerland

In our experiments we investigate in situ three dimensional pattern formation of xenon crystals during free growth. Well known morphologies are dendrites, doublons and seaweed. We also observe triplons and quadruplons. The transition from dendrite to doublon has gained interest since it has been discovered in metallic samples [1]. Transitions between these morphologies can be initiated in our experiments by changing the temperature distribution in the environment of a growing crystal [2].

In this communication we report on periodic oscillations in growth velocity induced by the interaction of two dendrites growing close to each other. The amplitude of these oscillations is in the range of 20 % of tip velocity and increasing with time. These oscillations have to be compared with the growth velocity of a freely growing isolated dendrite where fluctuations in growth rate (mainly due to pixel noise) are below ± 1.5 % of tip velocity at the same experimental conditions.

[1] K. Dragnevski, R. F. Cochrane, and A. M. Mullis, Phys. Rev. Lett. 89, 215502 (2002)

[2] I. Stalder and J. H. Bilgram, Europhys. Lett. 56, 829 (2001)