Spin-probe-enabled sensing of fluids in confined geometries and interfaces

当固体表面限制流体分子时，以增强的粘度、局部有序或集体运动的形式，其实际影响包括从摩擦学和材料处理到膜物理学的范围。限制也影响离子传输和/或速率和化学反应中的平衡浓度，所有这些都使得小流体体积的物理化学成为广泛关注的主题。然而，研究这些效应是非常困难的，主要是由于缺乏具有所需灵敏度和空间或时间分辨率的实验方法。这个问题在非均相系统中特别严重，在催化或生物科学中很常见，因为从宏观信号中提取典型的微小限制信号通常是不切实际的困难。在这里，我们建议探索一种新的途径，通过使用近表面的点缺陷在固体作为本地，纳米探针调查封闭的流体。我们确定了两个互补的研究前沿：第一个是利用新的NV基于磁共振光谱的方法来调查可变限制和表面疏水性下的水扩散，这一努力的一部分也是适应重水，一个领域，我们将结合联合收割机实验和路径积分分子动力学模拟的新的传感策略的发展。第二项研究推力零上使用外部铁磁尖端诱导梯度，我们将利用非侵入性探测分子扩散和图像表面诱导的秩序在承压水。在这里，我们将重点转移到调查ofmesoscale流体系统，其中使用的顺磁缺陷仍然几乎未被探索。为此，我们介绍了各种实验协议，我们阐明与磁共振技术，我们帮助先锋调查在受控条件下的模型流体的纳米体积。在采取这条路线时，我们利用了磁共振技术的高超多功能性，我们在这里利用它在广泛的时间尺度上同时提取封闭环境中的流体结构和动力学。因此，这一建议的智力价值在于我们选择解决的科学问题的基本价值，我们旨在探索的创新测量策略，以及我们采取的综合方法-同时结合纳米纤维，分子动力学建模和测量。

When a solid surface confines the molecules of a fluid, new dynamicsemerges e.g., in the form of enhanced viscosity, local order, or collective motion ⎯ whose practical impact encompasses areas ranging from tribology and materials processing to membrane physics. Confinement also affects ion transport and/or the rate andequilibrium concentration in a chemical reaction, all of which makes the physical chemistry of small fluid volumes the subject of broad interest. Studying these effects, however, is notoriously difficult, mainly due to the lack of experimental methods with the required sensitivity and spatial or time resolution. This problem is particularlyacute in heterogeneous systems, common in catalysis or the biological sciences, because extracting the typically minute signatures of confinement from the macroscopic signals is often impractically difficult. Here we propose to explore a new route toinvestigating confined fluids through the use of near-surface point defects in solids as local, nanoscopic probes. We identify two complementary research fronts: The first one capitalizes on novel NV based magnetic resonance spectroscopy methods to investigatewater diffusion under variable confinement and surface hydrophobicity; also part of this effort is the development of novel sensing strategies adapted to heavy water, an area where we will combine experiments and path-integral molecular dynamics simulations. The second research thrust zeroes in on the use of external ferromagnetic-tip-induced gradients that we will leverage to non-invasively probe molecular diffusion and image surface-induced order in confined water. Here we shift the focus to the investigation ofmesoscale fluidic systems, where the use of paramagnetic defects remains virtually unexplored. To this end we introduce various experimental protocols, which we articulate with magnetic resonance techniques we helped pioneer to investigate nanoscopic volumes of model fluids under controlled conditions. In taking this route, wecapitalize on the superb versatility of magnetic resonance techniques, which we leverage here to simultaneously extract fluidic structure and dynamics in confined environments over a broad time scale. The intellectual merit of this proposal resides, therefore, in thefundamental value of the scientific problem we choose to tackle, the innovative measurement strategies we aim to explore, and the integrated approach we take — simultaneously combining nanofabrication, molecular dynamics modeling, and measurement.