実験統計物理：臨界カシミア力の微視的研究

胶体体系自世纪初以来一直作为模型物理体系来证明物理学中非常重要的结果。从Perrin的沉降实验解决了原子争议，到最近对胶体玻璃中玻璃化转变的研究[E. Weeks Science 2000]。我们研究了一个潜在的工具来控制这些胶体系统的聚集和迁移：卡西米尔力。我们使用的系统是PMMA-胶体悬浮液，在顺式萘烷和溴环己烷中，具有几种聚合物浓度。我们的目标是测量大的二氧化钛探针胶体，被困在样品内的光镊之间的相互作用。我们希望测量两个探针之间的卡西米尔力，作为距离的函数，也作为探针运动的函数。在我们的研究中，我们开发了几种原创技术：如二元流体的化学和Matlab中的编程图像分析和Labview中的采集例程，以使实验系统化。在过去的一年里，我们完成了光学捕获，并安装了机械载物台和压电载物台，以实现更精细的位置控制和更高的重复性。我们还测量了聚合物浓度对二元液体粘度和表面张力的影响。

Colloidal systems have been since the beginning of the century as model physical systems to prove very important results in physics. From the sedimentation experiments of Perrin, that settled the atomic dispute, to the more recent studies of the glass transition in colloidal glasses [E.Weeks Science 2000]. We study a potential tool to control the aggregation and migration of these colloidal systems : The Casimir Force. The system we are using is a PMMA-colloid suspension, in Cis-Decalin and BromoCyclohexane, with several polymer concentration. Our goal is to measure the interaction between large TiO2 probe colloids that are trapped with optical tweezers inside the sample. We want to measure the casimir force between the two probes, as a function of distance, but also as a function of the probes motion.Throughout our research, we've developed several original techniques: such as a chemistry of the binary fluid and a programming image analysis in Matlab and acquisition routines in Labview to systematize the experiment. In the past year, we have finalized the optical trapping, and installed a mechanical stage, and a piezo stage for finer position control and higher repeatability. We also have measured the impact of the polymer concentration on viscosity and surface tension of the binary liquid.