Revealing Water Films Structure from Force Reconstruction in Dynamic AFM
Revealing Water Films Structure from Force Reconstruction in Dynamic AFM
复制标题
DOI：
10.1021/acs.jpcc.5b02411
复制
发表时间：
2015-04-16
影响因子：
3.7
通讯作者：
Verdaguer, Albert
中科院分区：
文献类型：
--
作者：
Calo, Annalisa;Domingo, Neus;Verdaguer, Albert
与表面接触的水膜的结构对许多重要的界面过程有直接的影响，从生物学到气候学，以及在冰核形成中。在这里，我们报告了在环境条件下，单个冰状水层被吸附在表面上的探测。用调幅原子力显微镜(AM-AFM)在(111)BaF2表面上重建的力分布，其晶格常数接近于六角形冰(I-h)中面对水分子的距离，在吸引区显示出周期性为3.7埃的特征振荡。这个距离与双层i-h冰的厚度相匹配，并且在(111)CaF2表面上的力分布中是不存在的，因为它显示了不同的晶格参数。测得与表面接触的第一水层的厚度为2.6埃，对应于从文献中的计算预测的高密度液膜结构。我们的结果表明，尽管在BaF2晶体上没有观察到第一水层的外延i-h生长，但i-h和BaF2晶格参数的匹配确实导致了水膜的强烈有序化和类冰结构的形成，即使在室温下也是如此。
The structure of water films in contact with surfaces has direct implications in many important interfacial processes, from biology to climatology, as well as in ice nucleation. Here we report on the detection of individual ice-like water layers adsorbed on surfaces in ambient conditions. Reconstructed force profiles obtained in amplitude modulation atomic force microscopy (AM-AFM) on top of (111) BaF2 surfaces, with a lattice constant close to the distance of facing water molecules in hexagonal ice (I-h), showed characteristic oscillations in the attractive regime with a periodicity of 3.7 angstrom. This distance matches the thickness of a bilayer of I-h ice and is absent in force profiles on (111) CaF2 surfaces, which show a different lattice parameter. A thickness of 2.6 angstrom is measured for the first water layer in contact with the surface, corresponding to a high-density liquid film structure predicted from calculations in the literature. Our results indicate that, although epitaxial I-h growth of the first water layer on BaF2 crystals is not observed, the matching of the lattice parameter between I-h and BaF2 does induce a strong ordering of the water films and the formation of ice-like structures, even at room temperature.