Savage J R, Blair D W, Levine A J, Guyer R A, Dinsmore A D
Department of Physics, University of Massachusetts Amherst, Hasbrouck Lab 411, 666 North Pleasant Street, Amherst, MA 01003, USA.
Science. 2006 Nov 3;314(5800):795-8. doi: 10.1126/science.1128649.
We studied the kinetics of sublimating crystals with single-particle resolution by experiments with colloidal spheres and by computer simulations. A short-range attraction between spheres led to crystallites one to three layers thick. The spheres were tracked with optical microscopy while the attraction was reduced and the crystals sublimated. Large crystallites sublimated by escape of particles from the perimeter. The rate of shrinkage was greatly enhanced, however, when the size decreased to less than 20 to 50 particles, depending on the location in the phase diagram. At this size, the crystallites transformed into a dense amorphous structure, which rapidly vaporized. The enhancement of kinetics by metastable or unstable phases may play a major role in the melting, freezing, and annealing of crystals.
我们通过胶体球实验和计算机模拟，以单粒子分辨率研究了升华晶体的动力学。球体之间的短程吸引力导致形成了一到三层厚的微晶。在降低吸引力并使晶体升华的过程中，用光学显微镜跟踪球体。大的微晶通过粒子从周边逸出而升华。然而，当尺寸减小到小于20至50个粒子时（取决于相图中的位置），收缩率会大大提高。在这个尺寸下，微晶转变为致密的无定形结构，并迅速汽化。亚稳或不稳定相导致的动力学增强可能在晶体的熔化、凝固和退火过程中起主要作用。
