Direct Visualization of Quasi-Liquid Layers on Ice Crystal Surfaces Induced by Hydrogen Chloride Gas
Direct Visualization of Quasi-Liquid Layers on Ice Crystal Surfaces Induced by Hydrogen Chloride Gas
复制标题
氯化氢气体诱导的冰晶表面准液态层的直接可视化
DOI：
10.1021/acs.cgd.6b00044
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发表时间：
2016
期刊：
影响因子：
--
通讯作者：
Y. Furukawa
中科院分区：
文献类型：
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作者：
K. Nagashima;G. Sazaki;T. Hama;H. Asakawa;K. Murata; Y. Furukawa
冰晶的表面融化在冰面上形成准液体层（QLL），并影响各种各样的自然现象。由于QLL增强了冰云中的各种化学反应，因此大气气体形成QLL的研究一直很深入。然而，这些研究是使用光谱技术进行的，空间分辨率低。在这里，我们展示了第一个直接可视化的QLL在冰基面上的氯化氢（HCl）气体（模型大气气体）的存在下，通过先进的光学显微镜，它可以可视化单个0.37 nm厚的基本步骤的冰晶表面。我们发现，HCl气体在-15.0 ° C至-1.5 °C的温度范围内诱导了具有液滴形状的QLL的出现，而在没有HCl气体的情况下没有QLL出现。这一结果表明，吸附在冰晶表面的HCl气体可能改变了冰晶的表面结构，从而导致随后的冰表面融化。我们还观察到了运动，形状的变化，和分裂的液滴QLL时，水蒸气不饱和。在欠饱和条件下液滴QLL的长期（1 h）存在强烈表明液滴QLL是化学稳定的HCl溶液。
Surface melting of ice crystals forms quasi-liquid layers (QLLs) on ice surfaces, and affects a wide variety of natural phenomena. Since QLLs enhance various chemical reactions in ice clouds, the formation of QLLs by atmospheric gases has been studied intensively. However, such studies were performed using spectroscopy techniques, which have low spatial resolution. Here we show the first direct visualization of QLLs on ice basal faces in the presence of hydrogen chloride (HCl) gas (model atmospheric gas) by advanced optical microscopy, which can visualize individual 0.37 nm-thick elementary steps on ice crystal surfaces. We found that the HCl gas induced the appearances of QLLs with a droplet shape in the temperature range from −15.0 to −1.5 °C, where no QLL appears in the absence of HCl gas. This result indicates that HCl gas adsorbed on ice crystal surfaces probably changed the surface structure of ice crystals and then induced the subsequent melting of ice surfaces. We also observed the movement, shape change, and splitting of the droplet QLLs when water vapor was undersaturated. The long-term (1 h) existence of the droplet QLLs under the undersaturated conditions strongly suggests that the droplet QLLs were thermodynamically stable HCl solutions.