Pendery J S, Atherton T J, Nobili M, Petschek R G, Lacaze E, Rosenblatt C
Department of Physics, Case Western Reserve University, Cleveland, OH 44106, USA.
Soft Matter. 2015 Mar 21;11(11):2220-7. doi: 10.1039/c4sm02891k.
A polyimide substrate was scribed using the stylus of an atomic force microscope, then covered with a nematic liquid crystal. The fiber from a near field scanning optical microscope was immersed into the liquid crystal and rastered approximately 80 nm above the surface, thereby obviating smearing effects that occur in thicker samples. By appropriate averaging of multiple data sets, a histogram of the "frozen-in" director deviation Δφ from the average easy axis was obtained, having a full-width-half-maximum of ∼0.02 rad. Additionally, the spatial autocorrelation function of Δφ was extracted, where the primary correlation length was found to be comparable to, but larger than, the liquid crystal's extrapolation length. A secondary characteristic length scale of a few μm was observed, and is thought to be an artifact due to material ejection during the scribing process. Our results demonstrate the utility of nanoscale imaging of the interface behavior inside the liquid crystal.
使用原子力显微镜的探针在聚酰亚胺基板上进行划痕，然后覆盖向列型液晶。将近场扫描光学显微镜的光纤浸入液晶中，并在表面上方约80 nm处进行光栅扫描，从而避免了在较厚样品中出现的涂抹效应。通过对多个数据集进行适当平均，获得了“冻结”指向矢相对于平均易轴的偏差Δφ的直方图，其半高宽约为0.02弧度。此外，提取了Δφ的空间自相关函数，发现其主要相关长度与液晶的外推长度相当，但大于外推长度。观察到一个几微米的次要特征长度尺度，认为这是划痕过程中材料喷射造成的假象。我们的结果证明了对液晶内部界面行为进行纳米级成像的实用性。
