DENDRITIC SOLIDIFICATION OF XENON

Experiments on xenon dendrites growing in a three-dimensional volume o f pure, supercooled melt have been performed. The shapes of the dendri tes have been determined with high lateral resolution. The dendrites g row in a stable mode and do not show oscillations in the growth veloci ty nor in the curvature of the dendrite tip. The dendrites do not have the shape of a paraboloid of revolution. Surface anisotropies determi ne the shape of the dendrites. Four fins grow along a dendrite. The co ntour of these fins can be described by a power law z similar to \x\(b eta) with beta approximate to 1.67. These experimental results are in agreement with the analytical work of E. Brener [Phys. Rev. Lett. 71 ( 1993) 3653]. Both experiments and analytical work are compatible with the assumption that thermal fluctuations initiate side branching. Tip oscillations can be excluded.