Souda Ryutaro
Advanced Materials Laboratory, National Institute for Materials Science, 1-1 Namiki, Tsukuba, Ibaraki 305-0044, Japan.
J Phys Chem B. 2005 Nov 24;109(46):21879-83. doi: 10.1021/jp054047o.
The interaction of hexane with amorphous solid water has been investigated in terms of the surface diffusion, hydrogen bond imperfections, hydrophobic hydration, crystallization, and glass-liquid transition. The hexane exhibits two main peaks in temperature-programmed desorption: one is ascribed to a complex formed at the surface or subsurface sites (135 K) and the other is caused by a bulk complex (165 K). The latter is associated with the presence of frozen-in imperfections in hydrogen bonds and formed provided that the annealing temperature of the film is below 130 K, whereas the former is created even when the film is annealed up to 150 K. Thus, the hexane-water interaction is hardly characterized by simple physisorption. The hexane is incorporated in the bulk during reorganization of hydrogen bonds due to rotational and translational diffusions of water molecules above 120-140 K, whereas the surface complex is formed even below 120 K due to the surface diffusion of molecules. The film undergoes abrupt dewetting at 165 K as a consequence of the glass-liquid transition. The slow evolution of the fluidity in the supercooled liquid phase may be responsible for the delay of the structural relaxation (165 K) relative to the onset of the translational molecular diffusion (135-140 K).
已从表面扩散、氢键缺陷、疏水水合作用、结晶以及玻璃-液体转变等方面对己烷与非晶态固体水的相互作用进行了研究。己烷在程序升温脱附过程中呈现出两个主要峰：一个归因于在表面或次表面位点形成的络合物（135K），另一个由本体络合物引起（165K）。后者与氢键中存在的冻结缺陷有关，且当薄膜的退火温度低于130K时形成，而即使薄膜退火至150K时也会形成前者。因此，己烷与水的相互作用很难用简单的物理吸附来表征。由于水分子在120 - 140K以上的旋转和平动扩散，己烷在氢键重组过程中被纳入本体，而由于分子的表面扩散，即使在120K以下也会形成表面络合物。由于玻璃-液体转变，薄膜在165K时会发生突然的去湿现象。相对于平动分子扩散的起始温度（135 - 140K），过冷液相中流动性的缓慢演变可能是结构弛豫延迟（165K）的原因。
