NSF-DFG Confine: Spin-Probe-Enabled Sensing of Fluids in Confined Geometries and Interfaces

在化学系化学测量与成像项目（CMI）的支持下，纽约市属城市学院的Carlos Meriles和纽约市属布鲁克林学院的Nicolas Giovambattista正在利用宿主晶体表面附近的原子缺陷作为纳米级探针，来表征在极小空间（纳米尺度）内水分子的结构和运动。强约束以技术应用的核心方式改变水，但是小样本尺寸和约束表面的非均质性使得实验家很难提供纳米尺度上分子行为的详细信息。为了减轻这些限制，Meriles博士和他的学生正在开发一种基于钻石中单个点缺陷的传感方法，这种方法可以作为少量液体的探测器，特别是水。Giovambattista博士和他的学生正在使用计算机模拟和理论建模来帮助解释来自这些点缺陷辅助测量的信号。活动还包括美国与德国斯图加特大学的合作伙伴之间的毕业生和博士后交流，这一举措旨在同时丰富所有参与学生的专业培训和交流机会。金刚石中所谓的氮空位（NV）中心，是一种顺磁缺陷，其电荷和自旋状态可以通过全光学方法制备和读出。总体目标围绕两个研究重点：(i)第一个是利用新的基于nv的磁共振波谱方法来研究通过2d材料工程生产的特殊纳米结构中可变约束和表面疏水性下的水扩散；这项工作的另一部分是开发适用于重水的替代传感策略，该领域的活动包括实验和路径积分分子动力学模拟。（ii）第二个研究重点集中在外部磁梯度的使用上，这里利用非侵入性探针分子扩散和封闭水中表面诱导的图像顺序。特别感兴趣的是在基于二维材料的工程基板的疏水和亲水部分分离边界处的水化研究。从这项努力中得出的结果可能被证明与各种具有基础和实际重要性的开放性问题相关，例如纳米尺度限制与化学反应性之间的相互作用，或者限制水在生物过程中的影响，如细胞膜中的离子流。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

With support from the Chemical Measurement and Imaging Program (CMI) in the Division of Chemistry, Carlos Meriles of CUNY City College and Nicolas Giovambattista of CUNY Brooklyn College are using atomic defects near the surface of a host crystal as nanoscale probes to characterize the structure and motion of water molecules confined to extremely small spaces (at the nanometer scale). Strong confinement modifies water in ways that are central to technological applications, but the small sample dimensions and the heterogeneities of the confining surfaces makes it challenging for experimentalists to provide detailed information on the molecular behavior at the nanoscale. To mitigate these limitations, Dr. Meriles and his students are developing a sensing approach based on individual point defects in diamond that can serve as a detector of small amounts of liquids in general, and water, in particular. Dr. Giovambattista and his students are using computer simulations and theoretical modeling to help interpret the signals that come from these point-defect-aided measurements. Activities also include the exchange of graduates and postdocs between the US and collaborators at the University of Stuttgart in Germany, an initiative aimed at simultaneously enriching the professional training and networking opportunities of all participating students. Enabling this research program is the so-called nitrogen-vacancy (NV) center in diamond, a paramagnetic defect whose charge and spin states can be prepared and readout by all-optical means. The overarching goals revolve around two research thrusts: (i) The first one capitalizes on novel NV-based magnetic resonance spectroscopy methods to investigate water diffusion under variable confinement and surface hydrophobicity within ad-hoc nanostructures produced via 2D-material engineering; also part of this effort is the development of alternative sensing strategies adapted to heavy water, an area where activities include both experiments and path-integral molecular dynamics simulations. (ii) The second research thrust zeroes in on the use of external magnetic gradients, here leveraged to non-invasively probe molecular diffusion and image surface-induced order in confined water. Of special interest is the investigation of hydration at boundaries separating hydrophobic and hydrophilic sections of engineered substrates based on 2D materials. The results derived from this effort may prove relevant to various open problems of fundamental and practical importance, such as the interplay between nanoscale confinement and chemical reactivity, or the impact of confined water in biological processes such as ion flow in cell membranes.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.