Kondo Takahiro, Kato Hiroyuki S, Bonn Mischa, Kawai Maki
Institute of material science, University of Tsukuba, 1-1-1 Tennodai, Tsukuba, Ibaraki, 305-8573 Japan.
J Chem Phys. 2007 Sep 7;127(9):094703. doi: 10.1063/1.2770726.
The deposition and the isothermal crystallization kinetics of thin amorphous solid water (ASW) films on both Ru(0001) and CO-precovered Ru(0001) have been investigated in real time by simultaneously employing helium atom scattering, infrared reflection absorption spectroscopy, and isothermal temperature-programmed desorption. During ASW deposition, the interaction between water and the substrate depends critically on the amount of preadsorbed CO. However, the mechanism and kinetics of the crystallization of approximately 50 layers thick ASW film were found to be independent of the amount of preadsorbed CO. We demonstrate that crystallization occurs through random nucleation events in the bulk of the material, followed by homogeneous growth, for solid water on both substrates. The morphological change involving the formation of three-dimensional grains of crystalline ice results in the exposure of the water monolayer just above the substrate to the vacuum during the crystallization process on both substrates.
通过同时使用氦原子散射、红外反射吸收光谱和等温程序升温脱附技术，实时研究了薄非晶态固态水（ASW）膜在Ru(0001)和预覆盖CO的Ru(0001)上的沉积及等温结晶动力学。在ASW沉积过程中，水与基底之间的相互作用严重依赖于预吸附CO的量。然而，发现约50层厚的ASW膜的结晶机制和动力学与预吸附CO的量无关。我们证明，对于两种基底上的固态水，结晶通过材料本体中的随机成核事件发生，随后是均匀生长。涉及形成三维冰晶颗粒的形态变化导致在两种基底上的结晶过程中，基底上方的水单层暴露于真空中。
