Conradi M, Zorko M, Musevic I
Institute of Metals and Technology, Ljubljana, Slovenia.
Opt Express. 2010 Jan 18;18(2):500-6. doi: 10.1364/OE.18.000500.
We present an experimental analysis of different equilibrium orientations and light driven transformations of Janus particles in the nematic liquid crystal 5CB. Depending on the preparation technique of homeotropic (DMOAP) and planar (Au) hemispheres we have observed two types of director field configurations: dipolar-like in the case of Au/DMOAP capped colloids and boojum-like in the case of DMOAP/Au capped colloids. Using the manipulation of Au/DMOAP capped colloids with laser tweezers we report on light driven irreversible orientational transformations into Saturn-ring and a novel, boojum-ring configuration. On the contrary, boojum-like DMOAP/Au capped colloids can act as rotators when exposed to the laser filed. Observed rotation is continuous around an axis perpendicular to the laser beam axis, with the frequency increasing linearly with the laser power.
我们展示了对向列型液晶5CB中Janus粒子不同平衡取向和光驱动转变的实验分析。根据垂直取向（DMOAP）和平行取向（Au）半球的制备技术，我们观察到了两种类型的指向矢场构型：对于Au/DMOAP包覆的胶体，呈偶极状；对于DMOAP/Au包覆的胶体，呈类布儒姆状。通过使用激光镊子操纵Au/DMOAP包覆的胶体，我们报道了光驱动的不可逆取向转变为土星环和一种新型的布儒姆环构型。相反，类布儒姆状的DMOAP/Au包覆胶体在暴露于激光场时可充当旋转器。观察到的旋转是围绕垂直于激光束轴的轴连续进行的，频率随激光功率线性增加。
