Murata Ken-Ichiro, Asakawa Harutoshi, Nagashima Ken, Furukawa Yoshinori, Sazaki Gen
Institute of Low Temperature Science, Hokkaido University, Kita-ku, Sapporo 060-0819, Japan;
Graduate School of Sciences and Technology for Innovation, Yamaguchi University, Yoshida, Yamaguchi 753-8512, Japan.
Proc Natl Acad Sci U S A. 2016 Nov 1;113(44):E6741-E6748. doi: 10.1073/pnas.1608888113. Epub 2016 Oct 17.
Since the pioneering prediction of surface melting by Michael Faraday, it has been widely accepted that thin water layers, called quasi-liquid layers (QLLs), homogeneously and completely wet ice surfaces. Contrary to this conventional wisdom, here we both theoretically and experimentally demonstrate that QLLs have more than two wetting states and that there is a first-order wetting transition between them. Furthermore, we find that QLLs are born not only under supersaturated conditions, as recently reported, but also at undersaturation, but QLLs are absent at equilibrium. This means that QLLs are a metastable transient state formed through vapor growth and sublimation of ice, casting a serious doubt on the conventional understanding presupposing the spontaneous formation of QLLs in ice-vapor equilibrium. We propose a simple but general physical model that consistently explains these aspects of surface melting and QLLs. Our model shows that a unique interfacial potential solely controls both the wetting and thermodynamic behavior of QLLs.
自迈克尔·法拉第对表面熔化做出开创性预测以来，人们普遍认为，被称为准液体层（QLLs）的薄水层会均匀且完全地覆盖冰表面。与这种传统观念相反，我们在理论和实验上均证明，QLLs具有不止两种润湿状态，且它们之间存在一级润湿转变。此外，我们发现QLLs不仅如最近报道的那样在过饱和条件下形成，在欠饱和条件下也会形成，但在平衡状态下不存在QLLs。这意味着QLLs是通过冰的气相生长和升华形成的亚稳态瞬态，这对在冰 - 气平衡中预设QLLs自发形成的传统理解提出了严重质疑。我们提出了一个简单但通用的物理模型，该模型能够一致地解释表面熔化和QLLs的这些方面。我们的模型表明，一个独特的界面势单独控制着QLLs的润湿和热力学行为。
