Berlin 2005 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 34: Poster

DY 34.80: Poster

Montag, 7. März 2005, 15:30–18:00, Poster TU D

Controlling of fractal dimension and symmetry of growing Xenon dendrites — •Marco Fell, Herman M. Singer und Jörg H. Bilgram — Laboratorium für Festkörperphysik, ETH, CH-8093 Zürich, Switzerland

Xenon dendrites, grown in supercooled melt ( Δ T ∼ 100−200 mK ), show characteristic sidebranching frequencies depending on supercooling. They are statistically symmetric and the contours’ outlines have a characteristic fractal dimension, depending on growth morphology (dendrite, dublon and seaweed) but not on supercooling.

In our experiments we disturb the free growth by heating of the melt. The crystal stops growing or begins to melt, depending on power and duration of heating. After stopping the heating, the liquid xenon cools down and growth restarts. Interestingly four absolutely symmetrical lobes start to grow at the main tip.

Repeating this process is found to lead to a new growth morphology, characterized by a lower fractal dimension, an average curvature of the contour lower than the ones found in other morphologies and a new hidden length scale.