Hydrogen Bonds under Extreme Conditions: Nuclear Quantum Effects and Hydrogen Bond Symmetrisation Probed with 1H-NMR in Diamond Anvil Cells

氢键在自然界中普遍存在，并且通常影响氢键合材料的结构和电子性质，其程度仍然没有完全理解。这类材料包括地球和行星体内的许多矿物和材料;因此，对氢键的压力效应的研究不仅对基础物理和化学很重要，而且对宏观“全球尺度”的地球和行星科学也很重要。因此，在本研究中，我们将以高压冰和含水矿物为例，利用新近发展起来的金刚石对顶砧高压核磁共振技术，研究即使在室温下也会发生的罕见的压力诱导核量子效应。这些方法为这些奇异的量子现象提供了一个独特的Vantage，这些现象无法用高压研究界使用的类似光谱方法检测到。在这种程度上，难以捉摸的过渡从高压冰VII到X将进行调查，据报道，这发生在70和150 GPa之间。在此压力范围内，氢键的对称双阱势允许质子隧穿穿过能垒。阐明这些综合效应可能会回答现代高压科学中一些最有争议的问题，例如氢向地球内部区域的传输。氢键对称性预计将是不同化合物高压行为的普遍特征（特别是δ-AlOOH、MgSi 2 O 6 H2、FeOOH），通过核磁共振技术在兆巴压力下研究它们（以及单晶X射线衍射和振动光谱等补充技术），我们期望揭示质子压力引起的氢键中的质子核量子效应。

Hydrogen bonds are ubiquitous in nature and often influence structural and electronic properties of hydrogen bonded materials to a degree which is still not fully understood. This class of materials include numerous minerals and materials within the Earth and planetary bodies; thus, investigations of pressure effects on H-bonds are not only important for basic physics and chemistry, but also matter greatly for geo-and planetary sciences on a macroscopic "global scale". Therewith, in this proposal, rarely observedpressure induced nuclear quantum effects occurring even at ambient temperatures will be investigated on the example of high pressure ices and hydrous minerals, by means of a newly developed high pressure NMR technique in diamond anvil cells (DACs). These methods provide a singular vantage point of these exotic quantum phenomena, which cannot be detected with comparable spectroscopic methods used within the high pressure research community. To this extent, the elusive transition from high pressure ice VII to X will be investigated, which has been reported to occur between 70 and 150 GPa. Within this pressure range, the symmetric double-well potential of the hydrogen bond allows for proton tunneling across the energy barrier. Elucidation of these combined effects might answer some of the most controversial questions in modern high pressure sciences, such as the hydrogen transport into regions of Earth's interior.Hydrogen bond symmetrisation is expected to be a general feature in high-pressure behaviour of different compounds (particularly delta-AlOOH, MgSi2O6H2, FeOOH), and by studying them at megabar pressures by means of NMR (and complimentary techniques like single-crystal X-ray diffraction and vibrational spectroscopies), we expect to reveal regularities in pressure induced proton nuclear quantum effects in H-bonds.