Tóth-Katona Tibor, Eber Nándor, Buka Agnes
Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, Budapest, Hungary.
Phys Rev E Stat Nonlin Soft Matter Phys. 2011 Jun;83(6 Pt 1):061704. doi: 10.1103/PhysRevE.83.061704. Epub 2011 Jun 14.
The temporal evolution of the spatially periodic electroconvection (EC) patterns has been studied within the period of the driving ac voltage by monitoring the light intensity diffracted from the pattern. Measurements have been carried out on a variety of nematic systems, including those with negative dielectric and positive conductivity anisotropy, exhibiting "standard EC" (s-EC), those with both anisotropies negative exhibiting "nonstandard EC" (ns-EC), as well as those with the two anisotropies positive. Theoretical predictions have been confirmed for stationary s-EC and ns-EC patterns. Transitions with Hopf bifurcation have also been studied. While traveling had no effect on the temporal evolution of dielectric s-EC, traveling conductive s-EC and ns-EC patterns exhibited a substantially altered temporal behavior with a dependence on the Hopf frequency. It has also been shown that in nematics with both anisotropies positive, the pattern develops and decays within an interval much shorter than the period, even at relatively large driving frequencies.
通过监测从空间周期性电对流（EC）图案衍射的光强度，研究了在驱动交流电压周期内该图案的时间演化。已对多种向列相系统进行了测量，包括具有负介电各向异性和正电导率各向异性的系统（呈现“标准EC”（s-EC））、两种各向异性均为负的系统（呈现“非标准EC”（ns-EC））以及两种各向异性均为正的系统。对于静态s-EC和ns-EC图案，理论预测已得到证实。还研究了霍普夫分岔引起的转变。虽然行波对介电s-EC的时间演化没有影响，但行波导电s-EC和ns-EC图案表现出显著改变的时间行为，且依赖于霍普夫频率。研究还表明，在两种各向异性均为正的向列相中，即使在相对较高的驱动频率下，图案在比周期短得多的时间间隔内形成和衰减。
