400 MHz NMR-Spectrometer for 9,4 T Magnet

扩散是自然界中普遍存在的过程，脉冲场梯度核磁共振是一种强大的实验技术，可以探测微米范围内最相关的长度尺度上的扩散过程。在非均质、多孔材料中，除了复杂的结构外，在孔隙空间中发生的不同类型的相变和传输关系进一步复杂化了传输过程。他们的理解可能为更深入地了解孔隙空间中发生的各种平衡和非平衡过程以及复杂孔隙网络的结构特征奠定了新的途径，包括分级孔隙系统。这项具有挑战性的任务将通过以下方式来解决：(I)通过自制的脉冲场梯度单元来补充核磁共振波谱仪，该单元允许探测低至数百纳米的扩散过程，并通过使用魔角旋转扩散核磁共振来选择光谱选择性；(Ii)通过现场压力和温度变化设备，可以选择在整个样品中保持其梯度。在后一种情况下，核磁共振微成像(Micro-MRI)能力将用于非平衡和稳态过程的空间分辨测量。补充性“动态”成像，其中所探测的扩散模式用于阐明有序和无序孔隙系统的局部结构属性，高分辨率显微成像研究将用于更好地理解微结构和磁共振对比图之间的关系。

Diffusion is a ubiquitous process in nature and pulsed field gradient NMR is a powerful experimental technique to probe diffusion processes on the most relevant length scale in the micrometer range. In heterogeneous, porous materials - besides complex structure - transport relationships and different types of phase transitions occurring in the pore spaces further complicate the transport processes. Their understanding may lay down a new approach for obtaining deeper insight into various equilibrium and non-equilibrium processes occurring in the pore spaces and for structural characterization of complex pore networks, including hierarchical pore systems. This challenging task will be addressed by complementing the NMR spectrometer (i) by a home-built pulsed field gradient unit that allows for probing diffusion processes down to hundred nanometers with the option of spectral selectivity by using magic angle spinning diffusion NMR and (ii) by in-situ pressure and temperature variation equipment with the option to maintain their gradients across the sample. In the latter case, the NMR microimaging (micro-MRI) capability will be used for spatially-resolved measurements of non-equilibrium and steady-state processes. Complementary “dynamic” imaging, where the diffusion patterns probed are used for elucidating the local structural properties of ordered and disordered pore systems, and high-resolution microimaging studies will be used to better understand the relationship between microstructure and MRI contrast maps.