Dynamic Nuclear Polarisation And Non-Equilibrium Physics

动态核极化（DNP）是一种可以增强信号的技术，因此可以增强磁共振成像（MRI）和核磁共振（NMR）光谱的灵敏度。MRI是医学诊断中的关键模态之一，并且NMR光谱被广泛用于生物分子研究中的结构研究和材料研究中的探测分子性质。这些技术的基本原理是检测弱样品磁化强度，该弱样品磁化强度是由于将样品（如NMR光谱学的情况下的小样品或如医学全身成像的情况下的大样品）放置在由磁体产生的强磁场中而产生的。强磁场在原子水平上与一些原子核（例如氢1H或稳定的碳同位素13 C）以及任何未成对电子相互作用，因为这些原子核或电子也具有磁矩。在一个简单的解释中，我们可以设想原子核或未成对电子与外部磁场的方向平行或不平行排列。在与磁场平行和反平行排列的核的数量上存在几ppm量级的小差异，这两组之间的差异产生了MRI或NMR中使用的信号。如果有可能将所有的细胞核排列在同一方向上，信号将显著增加。然而，样品中的热能通常会阻止完美的对齐，但已经表明，原子核可以在未成对电子的帮助下对齐。在电子的帮助下排列原子核的过程称为DNP。基本的物理学是复杂的，因为所有的原子核相互作用，以及与电子和对齐过程遵循量子力学的规则。有趣的是，我们最近发现，在一个包含许多相互作用的原子核和一个电子的大系统中，一些动力学方面与包含大量相互作用粒子的其他系统的性质相同，例如在玻璃化转变中改变其状态的系统。在我们的项目中，我们将研究DNP和其他非平衡系统之间的联系，以找出这些系统是否具有更多的共同属性，这些属性可能可以通过一般化规则来描述。此外，我们建议开发模型，预测系统的动态DNP实验过程中的许多核。这里的目标是获得足够的洞察力，以便通过在更短的时间内提供更高的信号增强来使DNP实验更有效。

Dyamic Nuclear Polarisation (DNP) is a technique that makes it possible to enhance the signal and hence the sensitivty of magnetic resonance imaging (MRI) and nuclear magnetic resonance (NMR) spectroscopy. MRI is one of the key modalities in medical diagnostics and NMR spectroscopy is widely used in biomolecular research for structural investigation and in material research for probing molecular properties. The fundamental principle of these techniques is the detection of a weak sample magnetisation that arises from placing the sample (small as in the case of NMR spectroscopy or large as in the case of medical whole body imaging) in a strong magnetic field generated by a magnet. The strong magnetic field interacts on the atomic level with some nuclei (e.g. hydrogen 1H or the stable carbon isoptope 13C) and also any unpaired electron since these nuclei or the electron have also a magnetic moment. In a simple explanation one can envisage the nuclei or the unpaired electron to either align parallel or unparallel with the direction of the external magnetic field. There is a small difference in the order of a few ppm in the number of nuclear that align parallel and antiparallel with the magnetic field and this difference between these two groups gives rise to the signal used in MRI or NMR. If it would be possible to align all nuceli in the same orientation the signal would dramatically increase. However, the thermal energy in the sample usually prevents the perfect alignment but it has been shown that the nuclei can be aligned with the help of unpaired electrons. The process of aligning nuclei with the help of electrons is called DNP. The underlying physics is complex because all nuclei interact with each other as well as with the electron and the alignment process follows the rules of quantum mechanics. Interestingly, we have recently discovered that some of the dynamical aspects in a large system containing many interacting nuclei and an electron are identical to properties of other systems containing a large number of interacting particles such as for instance systems changing their state in a glass transition. In our project we will investigate the links between DNP and other non-equilibrium systems to find out whether such systems share more common properties which perhaps can be described by generalising rules. Furthermore, we propose to develop models that predict the dynamics of systems of many nuclei during DNP experiments. The goal here is to gain enough insight so that DNP experiments can be made more efficient by providing even a higher signal enhancement in a shorter time.