Université de Bordeaux, CNRS, Centre de Recherche Paul Pascal, Avenue A. Schweitzer, F-33600 Pessac, France.
Institute of Solid State Physics, Russian Academy of Sciences, Moscow Region, 142432 Chernogolovka, Russia.
Soft Matter. 2017 May 21;13(19):3649-3663. doi: 10.1039/c6sm02736a. Epub 2017 Apr 27.
We report an experimental investigation of the structure of periodic patterns observed in the meniscus of free-standing smectic films. Combination of polarizing optical microscopy and phase shifting interferometry enabled us to obtain new information on the structure of the meniscus, and in particular, on the topography of the smectic-air interface. We investigate the profile of the undulations in the striped structure in the thin part of the meniscus, change of the stripe period with the meniscus thickness and subsequent transition into a two-dimensional structure. It is shown that the two-dimensional structure has an unusual complex profile of "egg-box" type. The striped texture occurs upon cooling from the nontilted smectic-A to the smectic-C* phase, whereas the two-dimensional pattern is present in both phases. We discuss the possible origin of the modulated structures, the role of the dislocations in the meniscus, the elasticity of smectic layers, and the mechanical stress induced by dislocations.
我们报告了对自由支撑向列膜的弯月面中观察到的周期性图案结构的实验研究。结合偏光显微镜和相移干涉技术，我们能够获得关于弯月面结构的新信息，特别是关于向列-空气界面的形貌。我们研究了弯月面薄部分中条纹结构的波纹轮廓，条纹周期随弯月面厚度的变化以及随后过渡到二维结构。结果表明，二维结构具有不寻常的复杂“蛋盒”型轮廓。带状纹理是从非倾斜向列-A 相冷却到向列-C*相时出现的，而二维图案存在于两个相中。我们讨论了调制结构的可能起源、弯月面中的位错的作用、向列层的弹性以及位错引起的机械应力。
