Development of methods and theory of DNP enhanced NMR relaxometry for the study of complex fluids and porous media

场循环弛豫法是核磁共振的一种特殊变体，它通过测量不同磁场强度下的弛豫时间来研究慢分子动力学。由于低检测场，该方法基本上保持不敏感，因此无法研究许多系统，如稀释溶液或低灵敏度同位素。在第一个资助期内，我们已经证明，与动态核极化（DNP）相结合可产生高达100倍的信号增强，从而使许多这些系统达到场循环弛豫法。然而，更重要的是获得有关自由基与目标分子相互作用过程的性质的知识，以及如何从实验数据中重建同位素特定的弛豫速率。在扩展期间，我们计划将信号强度进一步增加至少一个数量级，提高稳定性，并实现不同DNP过程的理论描述所需的温度相关测量-这些优化需要使用商业组件。与此同时，我们将应用我们的研究结果，从实验工作的第一阶段，并将集中在表面（固定自由基分析分子动力学的吸附物在双组分系统）和复杂的流体（离子液体，聚合物）与两个或两个以上的组件，可以通过信号增强选择性地解决。

Field Cycling Relaxometry is a particular variant of NMR which studies slow molecular dynamics by measurement of relaxation times at different magnetic field strength. Due to the low detection fields, the method remains fundamentally insensitive, so that many systems such as diluted solutions or low-sensitivity isotopes cannot be studied. During the first funding period we have demonstrated that combination with Dynamic Nuclear Polarization (DNP) generates signal enhancement up to 100fold and thus brings many of these systems within reach of field-cycling relaxometry. More important, however, was acquiring knowledge about the nature of interaction processes of the radicals with the target molecules, and how the isotope-specific relaxation rates can be reconstructed from experimental data. During the extension period we are planning the further increase of signal intensities by at least one order of magnitude, the improvement of stability and the enabling of temperature-dependent measurements required for a theoretical description of the different DNP processes – these optimizations require the use of commercial components. At the same time we will apply our findings from experimental work within the first period and will concentrate on surfaces (immobilization of radicals for analyzing molecular dynamics of adsorbates in bicomponent systems) and complex fluids (ionic liquids, polymers) with two or more components that can be addressed selectively by signal enhancement.