Llombart Pablo, Noya Eva G, Sibley David N, Archer Andrew J, MacDowell Luis G
Departamento de Química-Física (Unidad de I+D+i Asociada al CSIC), Facultad de Ciencias Químicas, Universidad Complutense de Madrid, 28040 Madrid, Spain.
Instituto de Química Física Rocasolano, CSIC, Calle Serrano 119, 28006 Madrid, Spain.
Phys Rev Lett. 2020 Feb 14;124(6):065702. doi: 10.1103/PhysRevLett.124.065702.
Understanding the wetting properties of premelting films requires knowledge of the film's equation of state, which is not usually available. Here we calculate the disjoining pressure curve of premelting films and perform a detailed thermodynamic characterization of premelting behavior on ice. Analysis of the density profiles reveals the signature of weak layering phenomena, from one to two and from two to three water molecular layers. However, disjoining pressure curves, which closely follow expectations from a renormalized mean field liquid state theory, show that there are no layering phase transitions in the thermodynamic sense along the sublimation line. Instead, we find that transitions at mean field level are rounded due to capillary wave fluctuations. We see signatures that true first order layering transitions could arise at low temperatures, for pressures between the metastable line of water-vapor coexistence and the sublimation line. The extrapolation of the disjoining pressure curve above water-vapor saturation displays a true first order phase transition from a thin to a thick film consistent with experimental observations.
了解预熔膜的润湿性需要知道该膜的状态方程，而这通常是无法获得的。在此，我们计算了预熔膜的分离压力曲线，并对冰上的预熔行为进行了详细的热力学表征。对密度分布的分析揭示了从一到两个以及从两个到三个水分子层的弱分层现象的特征。然而，紧密遵循重整化平均场液态理论预期的分离压力曲线表明，沿着升华线在热力学意义上不存在分层相变。相反，我们发现由于毛细波涨落，平均场水平的转变是圆滑的。我们看到在低温下，对于水汽共存的亚稳线和升华线之间的压力，可能会出现真正的一级分层转变的迹象。在水汽饱和度以上对分离压力曲线的外推显示出从薄膜到厚膜的真正一级相变，这与实验观察结果一致。
