Evolution of the Dendritic Instability in Solidifying Succinonitrile

The evolution of morphological instability in solidifying succinonitrile has been investigated with high-resolution videomicroscopy. Quantitative analysis of the early development of the instability has demonstrated the critical role of noise, and indicates significant disagreement with predictions of the Mullins-Sekerka theory. The ratio of the tip radius ${\rho }^{*}$ of the steady-state dendrites to the length scale ${\lambda }_{max}$ of the initial instability was found to be approximately 0.5, in reasonable agreement with a recent theoretical prediction of Barbieri, Hong, and Langer.