X-ray Science Division, Advanced Photon Source, Argonne National Laboratory, Argonne, IL 60439, USA.
Proc Natl Acad Sci U S A. 2012 Oct 9;109(41):16463-8. doi: 10.1073/pnas.1210732109. Epub 2012 Sep 24.
The floating water bridge phenomenon is a freestanding rope-shaped connection of pure liquid water, formed under the influence of a high potential difference (approximately 15 kV). Several recent spectroscopic, optical, and neutron scattering studies have suggested that the origin of the bridge is associated with the formation of anisotropic chains of water molecules in the liquid. In this work, high energy X-ray diffraction experiments have been performed on a series of floating water bridges as a function of applied voltage, bridge length, and position within the bridge. The two-dimensional X-ray scattering data showed no direction-dependence, indicating that the bulk water molecules do not exhibit any significant preferred orientation along the electric field. The only structural changes observed were those due to heating, and these effects were found to be the same as for bulk water. These X-ray scattering measurements are supported by molecular dynamics (MD) simulations which were performed under electric fields of 10(6) V/m and 10(9) V/m. Directional structure factor calculations were made from these simulations parallel and perpendicular to the E-field. The 10(6) V/m model showed no significant directional-dependence (anisotropy) in the structure factors. The 10(9) V/m model however, contained molecules aligned by the E-field, and had significant structural anisotropy.
浮桥水现象是一种独立的绳状纯液态水连接，在高电势差（约 15 kV）的影响下形成。最近的一些光谱学、光学和中子散射研究表明，桥的起源与液体中各向异性水分子链的形成有关。在这项工作中，对一系列浮桥水进行了高能 X 射线衍射实验，作为外加电压、桥长和桥内位置的函数。二维 X 射线散射数据没有方向依赖性，表明沿电场方向的体相水分子没有表现出任何明显的择优取向。仅观察到由于加热引起的结构变化，这些效应与体相水相同。这些 X 射线散射测量得到了在 10(6) V/m 和 10(9) V/m 电场下进行的分子动力学 (MD) 模拟的支持。从这些模拟中进行了与 E 场平行和垂直的方向结构因子计算。10(6) V/m 模型的结构因子没有明显的方向依赖性（各向异性）。然而，10(9) V/m 模型包含了由 E 场排列的分子，具有显著的结构各向异性。
