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形式，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。由于检测范围小，该方法从根本上仍然不灵敏，因此许多体系，如稀溶液或低灵敏度同位素，无法进行研究。在第一个资助期，我们已经证明，与动态核极化(DNP)相结合产生高达100倍的信号增强，从而使许多这样的系统达到场循环弛豫测量的范围。然而，更重要的是获得关于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重建同位素特定驰豫速率。在延长期内，我们计划将信号强度进一步提高至少一个数量级，提高稳定性，并实现对不同DNP过程进行理论描述所需的温度依赖测量--这些优化需要使用商业组件。同时，我们将在第一阶段应用我们的实验工作结果，并将重点放在表面(用于分析双组分体系中吸附分子动力学的自由基的固定)和具有两个或更多组分的复杂流体(离子液体、聚合物)，这些可以通过信号增强来选择性地解决。

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.