Institut für Physik - NMR, Martin-Luther-Universität Halle-Wittenberg, Betty-Heimann-Str. 7, D-06120 Halle, Germany.
Institut für Chemie - Organische Chemie, Martin-Luther-Universität Halle-Wittenberg, Kurt-Mothes-Str. 2, D-06120 Halle, Germany.
Solid State Nucl Magn Reson. 2017 Apr-May;82-83:22-28. doi: 10.1016/j.ssnmr.2017.01.006. Epub 2017 Jan 26.
In recent years, the analysis of proton double-quantum NMR build-up curves has become an important tool to quantify anisotropic mobility in different kinds of soft materials such as polymer networks or liquid crystals. In the former case, such data provides a measure of orientation-dependent residual (time-averaged) dipolar couplings arising from anisotropic segmental motions, informing about the length and the state of local stretching of the network chains. Previous studies of macroscopically ordered, i.e. stretched, networks were subject to the limitation that a detailed build-up curve analysis on the basis of a universal "Abragam-like" (A-l) build-up function valid for a proton multi-spin system was only possible for an isotropic orientation-averaged response. This situation is here remedied by introducing a generic orientation-dependent build-up function for an anisotropically mobile protonated molecular segment. We discuss an application to the modeling of data for a stretched network measured at different orientations with respect to the magnetic field, and present a validation by fitting data of different liquid-crystal molecules oriented in the magnetic field.
近年来，质子双量子 NMR 累积曲线的分析已成为量化不同软物质（如聚合物网络或液晶）各向异性迁移率的重要工具。在前一种情况下，此类数据提供了一种衡量各向异性分子运动引起的与取向相关的剩余（时间平均）偶极耦合的方法，从而了解网络链的长度和局部拉伸状态。以前对宏观有序（即拉伸）网络的研究受到限制，即基于普遍的“Abragam 型”（A-l）累积函数对基于质子多自旋系统的通用累积函数进行详细的累积曲线分析，仅适用于各向同性取向平均响应。通过引入各向异性迁移质子分子段的通用取向相关累积函数，在此处对此情况进行了纠正。我们讨论了一种在磁场不同取向下对拉伸网络数据建模的应用，并通过拟合磁场中取向不同的不同液晶分子的数据进行了验证。
