de Aguiar Hilton B, McGraw Joshua D, Donaldson Stephen H
Département de Physique , Ecole Normale Supérieure/PSL Research University, CNRS , 24 rue Lhomond , 75005 Paris , France.
Gulliver CNRS UMR 7083 , PSL Research University, ESPCI Paris , 10 rue Vauquelin , 75005 Paris , France.
Langmuir. 2019 Dec 3;35(48):15543-15551. doi: 10.1021/acs.langmuir.9b01889. Epub 2019 Jul 29.
Modern interfacial science is increasingly multidisciplinary. Unique insight into interfacial interactions requires new multimodal techniques for interrogating surfaces with simultaneous complementary physical and chemical measurements. Here, we describe the design and testing of a microscope that incorporates a miniature surface forces apparatus (μSFA) in sphere vs flat geometry for force-distance measurements, while simultaneously acquiring Raman spectra of the confined zone. The simple optical setup isolates independent optical paths for (i) the illumination and imaging of Newton's rings and (ii) Raman scattering excitation and efficient signal collection. We benchmark the methodology by examining Teflon thin films in asymmetric (Teflon-water-glass) and symmetric (Teflon-water-Teflon) configurations. Water is observed near the Teflon-glass interface with nanometer-scale sensitivity in both the distance and Raman signals. We perform chemically resolved, label-free imaging of confined contact regions between Teflon and glass surfaces immersed in water. Remarkably, we estimate that the combined approach enables vibrational spectroscopy with single water monolayer sensitivity within minutes. Altogether, the Raman-μSFA allows exploration of molecular confinement between surfaces with chemical selectivity and correlation with interaction forces.
现代界面科学越来越具有多学科性。要深入了解界面相互作用，就需要新的多模态技术，以便通过同时进行互补的物理和化学测量来探测表面。在此，我们描述了一种显微镜的设计与测试，该显微镜集成了一个微型表面力装置（μSFA），采用球体与平面几何结构进行力-距离测量，同时获取受限区域的拉曼光谱。简单的光学设置为（i）牛顿环的照明和成像以及（ii）拉曼散射激发和高效信号收集分离了独立的光路。我们通过研究不对称（聚四氟乙烯-水-玻璃）和对称（聚四氟乙烯-水-聚四氟乙烯）配置下的聚四氟乙烯薄膜对该方法进行了基准测试。在距离和拉曼信号方面，均以纳米级灵敏度在聚四氟乙烯-玻璃界面附近观察到了水。我们对浸没在水中的聚四氟乙烯和玻璃表面之间的受限接触区域进行了化学分辨、无标记成像。值得注意的是，我们估计这种组合方法能够在几分钟内实现具有单水单层灵敏度的振动光谱分析。总之，拉曼-μSFA能够以化学选择性探索表面之间的分子受限情况，并与相互作用力建立关联。
