実験統計物理：臨界カシミア力の微視的研究

胶体体系自本世纪初以来一直作为物理模型体系被证明是物理学中非常重要的成果。从解决原子争端的Perrin的沉淀实验，到最近对胶体玻璃中玻璃转变的研究(E.Week Science 2000)。我们研究了一种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。我们使用的体系是PMMA胶体悬浮液，在顺式十氢化氢和溴代环己烷中，具有几个聚合物浓度。我们的目标是测量大尺寸的二氧化钛探针胶体之间的相互作用，这些胶体被光钳捕获在样品中。我们希望测量两个探头之间的卡西米尔力，作为距离的函数，也作为探头运动的函数。通过我们的研究，我们开发了几种原创技术：例如二元流体的化学和在MatLab中编程的图像分析，以及在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，并安装了机械工作台和压电工作台，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.