Weeks ER, Crocker JC, Levitt AC, Schofield A, Weitz DA
Department of Physics and Division of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA. Department of Physics and Astronomy, University of Pennsylvania, Philadelphia, PA 19104, USA. Department of Physics and Astro.
Science. 2000 Jan 28;287(5453):627-31. doi: 10.1126/science.287.5453.627.
Confocal microscopy was used to directly observe three-dimensional dynamics of particles in colloidal supercooled fluids and colloidal glasses. The fastest particles moved cooperatively; connected clusters of these mobile particles could be identified; and the cluster size distribution, structure, and dynamics were investigated. The characteristic cluster size grew markedly in the supercooled fluid as the glass transition was approached, in agreement with computer simulations; at the glass transition, however, there was a sudden drop in their size. The clusters of fast-moving particles were largest near the alpha-relaxation time scale for supercooled colloidal fluids, but were also present, albeit with a markedly different nature, at shorter beta-relaxation time scales, in both supercooled fluid and glass colloidal phases.
共聚焦显微镜用于直接观察胶体过冷流体和胶体玻璃中粒子的三维动力学。最快的粒子协同移动；可以识别出这些移动粒子的连接簇；并研究了簇的尺寸分布、结构和动力学。随着接近玻璃化转变，过冷流体中特征簇尺寸显著增长，这与计算机模拟结果一致；然而，在玻璃化转变时，其尺寸突然下降。对于过冷胶体流体，快速移动粒子的簇在α弛豫时间尺度附近最大，但在更短的β弛豫时间尺度下也存在，尽管性质明显不同，在过冷流体和玻璃态胶体相中均如此。
