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

在化学系化学测量和成像计划(CMI)的支持下，纽约州立大学城市学院的卡洛斯·梅里尔斯和纽约大学布鲁克林学院的尼古拉斯·乔万巴蒂斯塔正在使用宿主晶体表面附近的原子缺陷作为纳米级探测器，以表征限制在极小空间(纳米级)内的水分子的结构和运动。强限制作用以对技术应用至关重要的方式改变水，但小样本尺寸和限制表面的非均质性使实验者难以在纳米尺度上提供关于分子行为的详细信息。为了缓解这些限制，梅里尔斯博士和他的学生们正在开发一种基于钻石中个别点缺陷的传感方法，这种方法可以用作一般情况下的少量液体，特别是水的探测器。乔万巴蒂斯塔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合作者之间的毕业生和博士后交流，这一倡议旨在同时丰富所有参与的学生的专业培训和网络机会。促成这一研究计划的是钻石中所谓的氮空位(NV)中心，这是一种顺磁缺陷，其电荷和自旋态可以通过全光学手段制备和读出。总体目标围绕两个研究目标：(I)第一个利用基于NV的新的磁共振波谱方法，研究可变限制条件下的水扩散和通过2D材料工程产生的自组织纳米结构中的表面疏水性；这一努力的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。(2)第二项研究将重点放在外部磁梯度的使用上，这里利用外部磁梯度来非侵入性地探测分子扩散和成像承压水中表面诱导的有序。特别令人感兴趣的是基于2D材料的工程衬底的疏水和亲水部分分离边界上的水合作用的研究。这一努力的结果可能会被证明与各种具有基本和实际重要性的公开问题有关，例如纳米尺度限制和化学反应之间的相互作用，或者承压水在生物过程中的影响，如细胞膜中的离子流动。这一奖项反映了NSF的法定使命，并通过使用基金会的智力优势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.