Imaging surfaces with water The surfaces of real materials are often highly chemically heterogeneous, and the reported values of even simple properties such as surface acidity can vary widely in many cases. Macias-Romero et al. developed a microscope that images surfaces on the basis of second-harmonic generation from the orientation of interfacial water (see the Perspective by Hunger and Parekh). They followed the deprotonation of silica along glass micropipettes by changing solution pH and found many regions where the surface acidity deviated strongly from the average for the entire micropipette. Science, this issue p. 784; see also p. 755 A wide-field second-harmonic–generation microscope images surfaces by probing the orientation order of interfacial water. We imaged the interfacial structure and dynamics of water in a microscopically confined geometry, in three dimensions and on millisecond time scales, with a structurally illuminated wide-field second harmonic microscope. The second harmonic images reported on the orientational order of interfacial water, induced by charge-dipole interactions between water molecules and surface charges. The images were converted into surface potential maps. Spatially resolved surface acid dissociation constant (pKa,s) values were determined for the silica deprotonation reaction by following pH-induced chemical changes on the curved and confined surfaces of a glass microcapillary immersed in aqueous solutions. These values ranged from 2.3 to 10.7 along the wall of a single capillary because of surface heterogeneities. Water molecules that rotate along an oscillating external electric field were also imaged.

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限制条件下表面化学和动力学的光学成像

用水对表面进行成像 真实材料的表面通常具有高度的化学异质性，在许多情况下，即使是表面酸度等简单属性的报告值也会有很大差异。Macias-Romero 等人。开发了一种显微镜，该显微镜根据界面水的方向产生的二次谐波对表面进行成像（参见 Hunger 和 Parekh 的观点）。他们通过改变溶液的 pH 值来跟踪二氧化硅沿玻璃微量移液器的去质子化过程，发现许多区域的表面酸度与整个微量移液器的平均值严重偏离。科学，这个问题 p。784; 另见第。755 宽视场二次谐波产生显微镜通过探测界面水的取向顺序对表面进行成像。我们使用结构照明的宽视场二次谐波显微镜在微观限制的几何形状、三维和毫秒时间尺度上对水的界面结构和动力学进行了成像。二次谐波图像报告了由水分子和表面电荷之间的电荷偶极相互作用引起的界面水的取向顺序。图像被转换成表面电位图。通过跟踪浸入水溶液中的玻璃微毛细管的弯曲和受限表面上的 pH 诱导化学变化，确定二氧化硅去质子化反应的空间分辨表面酸解离常数 (pKa,s) 值。由于表面异质性，这些值沿单个毛细管壁的范围从 2.3 到 10.7。