Laboratory for Fundamental BioPhotonics, Institute of Bioengineering, and Institute of Materials Science, School of Engineering, and Lausanne Centre for Ultrafast Science, École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland.
Science. 2017 Aug 25;357(6353):784-788. doi: 10.1126/science.aal4346. Epub 2017 Jul 20.
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 (p) 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.
我们使用结构光照明显微镜，在微观受限的几何形状中，以三维和毫秒时间尺度，对水的界面结构和动力学进行成像。报告的二次谐波图像显示了界面水的取向有序性，这是由水分子和表面电荷之间的电偶极相互作用引起的。这些图像被转换为表面电势图。通过在浸入水溶液的玻璃微毛细管的弯曲和受限表面上跟踪 pH 诱导的化学变化，确定了二氧化硅去质子化反应的空间分辨表面离解常数 (p) 值。由于表面不均匀性，这些值在单个毛细管的壁上从 2.3 到 10.7 变化。还对沿着振荡外电场旋转的水分子进行了成像。
