光ピンセットを用いたコロイド結晶およびコロイド粒子間相互作用の研究

我们的主要结果可以分为3个部分。1）胶体聚合物混合物的研究：胶体流体中聚合物的存在的影响可以观察到作为耗尽力以及胶体颗粒之间的桥接相互作用，这两种相互作用导致胶体颗粒之间的吸引相互作用。我们已经研究了这些吸引力的激光镊子技术，并证明了桥接相互作用可以消除添加大量的洗涤剂。因此，我们能够测量耗尽力的净强度以及在无洗涤剂体系中表现为过量吸引力的桥接相互作用。2）带电胶体粒子间弱排斥作用的测定：我们研制了双光束激光光镊系统，并将其应用于去离子溶液中带电胶体粒子间的排斥作用的研究。观察了两个相互作用的胶体粒子在第二个激光焦点处所感受到的电势的变化，并推导出了两个相互作用的胶体粒子之间的净电势。3）胶体晶体的动力学研究：利用胶体晶体中各粒子的数字化图像时间序列，研究了胶体晶体中各粒子的动力学行为。利用粒子位置的时间序列，计算了粒子位置的自相关函数和互相关函数。计算结果与我们将系统视为浸在粘性流体中的真实的晶体的理论相一致。然而，最近邻的互相关函数比我们的理论预测大得多，并且仅定性一致。

Our main results can be separated into 3 parts.1) Study of the Colloid Polymer mixture:The effects of the existence of the polymers in the colloidal fluid can be observed as the depletion force as well as bridging interaction between the colloidal particles and both of these interaction result in the attractive interaction between colloidal particles. We have studied these attractive forces by the laser tweezers technique and have demonstrated that the bridging interaction can be eliminated by the addition of large amount of detergent. Thus we were able to measure the net strength of the depletion force as well as the bridging interaction that appears as the excess attractive force in detergent free system. Our result of the depletion force was in good agreement with the theoretical calculation.2) Determination of the weak repulsive interaction between charged Colloid particles:We have developed the 2 beam laser tweezers system and applied it to study the repulsive interaction between charged colloidal particles in de-ionized solution. Change of the potential felt by the colloidal particle with or without interacting particle in the second laser focus was carefully observed and the net potential between two interacting colloidal particles were deduced. Obtained result was in good agreement with DLVO theory.3) Dynamics of the colloidal crystal:Dynamics of each particle in colloidal crystal was studied using time sequence of digitized images of the crystal particles. Using the time sequence of the position of each particle, we have calculated the self and cross correlation function of the position of the particles. The results was in good agreement with our theory that treat the system as the real crystal immersed in viscous fluid. The cross correlation function of the nearest neighbor was, however, much larger than our theoretical prediction and the agreement was only qualitative.