Molecular Dynamics, Structure, and Phase Transitions in Liquid-Crystalline Media: Electron-Spin Resonance (ESR) Studies

液晶分子动态结构的研究 利用现代电子自旋共振（ESR）技术。 进一步的研究计划在分子再取向运动 包括本地和远程协同性。 研究a 液晶相动力学的分子水平 过渡利用观察到的临界类型的分歧， 自旋弛豫将继续。 这些研究 用不同尺寸和形状的自旋探针进行。 新二- 维傅里叶变换ESR方法将用于获得 更准确和详细的弛豫数据， 长时和短时分子运动。 二-- 三维电子自旋回波和新的高场ESR方法 将能够研究较大探针的慢运动行为 在较低温度阶段就它们的排序而言， 配置和动力学。 分子描述 液晶中的运动将通过研究 探针在分子水平上的平移扩散 水平（通过自旋交换）和宏观水平（通过ESR- 成像）。 特别强调的是口译 结果在向列-近晶相变和近晶内 分子转动和平动耦合相 运动，我们强大的计算方法将允许更多 根据需要对运动动力学进行复杂建模， 解释这些结果。 这些研究将包括 热致性，定向溶致向列相，和定向 高分子液晶

Studies on the dynamic molecular structure of liquid crystals utilizing modern electron-spin resonance (ESR) techniques. Further studies are planned on molecular reorientational motions including both local and long-range cooperativity. Studies at a molecular level of the dynamics of the liquid crystalline phase transitions utilizing observed critical types of divergences of the spin-relaxation are to be continued. The studies are performed with spin probes of varying size and shape. New Two- Dimensional Fourier Transform ESR methods will be used to obtain more accurate and detailed relaxation data from which to infer both the long-time and short-time molecular motions. Two- dimensional electron-spin-echoes and new high-field ESR methods will enable the study of slow-motional behavior of larger probes in lower temperature phases in terms of their ordering, configuration, and dynamics. The description of molecular motions in liquid crystals will be enhanced by studies of translational diffusion of the probes both at the molecular level (by spin-exchange) and at the macroscopic level (by ESR- imaging). Special emphasis is to be placed upon interpreting results at nematic-smectic phase transitions and within smectic phases in terms of coupled rotational and translational molecular motions, Our powerful computational methods will permit more sophisticated modeling of the motional dynamics as required to interpret these results. These studies will include thermotropics, oriented lyotropic nematics, and oriented polymeric liquid crystals.