BETA-MOLECULAR REARRANGEMENT PROCESS, BUT NOT AN ALPHA-PROCESS, AS GOVERNING THE HOMOGENEOUS CRYSTAL-NUCLEATION RATE IN A SUPERCOOLED LIQUID

The time dependence of the growth rate of homogeneous-nucleation-based (HNB) crystallization in o-terphenyl was tracked by a temperature-jum p method through microscopic observations, and HNB crystallization was found to proceed at a steady rate, specified by the tracking temperat ure just after the jump. Two sets of numerical computations were carri ed out according to a classical homogeneous nucleation theory for the temperature-jump experiment on alternative assumptions that the homoge neous nucleation process is governed by the alpha-molecular rearrangem ent process or by the beta-process in the liquid. From a comparison be tween the experimental and calculated results, the homogeneous nucleat ion, and thus the crystal growth as well, were concluded to be governe d by the beta-rearrangement process rather than the alpha-process, dif ferently from the common recognition that they are governed by the lat ter.