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arXiv 1101.0127cond-mat.mtrl-sci
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水蒸气中冰晶生长的化学影响

Chemical Influences on Ice Crystal Growth from Vapor

Kenneth G. Libbrecht, Robert Bell

摘要:

我们提出了一个调查的化学影响冰晶的增长从水蒸气。在一组实验中,我们在蒸汽扩散室中生长冰晶,在0 ℃至-25 ℃的温度下,在不同的背景气体和各种气态化学添加剂中观察晶体形态。在第二组实验中,我们在自由落体流动室中测量了-5 ℃和-15 ℃下的冰晶生长速率,使用正常的实验室空气和超净氮气,有和没有化学添加剂。这些实验的结论包括:1)在一个大气压的氮气中,浓度低于10 ppm的所测试的化学添加剂对冰晶生长形态没有任何可观察到的变化; 2)在超净氮气中的生长与在普通实验室空气中的生长没有显著差异; 3)化学添加剂在-15 ℃比在更高温度下更容易影响板状树枝状生长; 4)化学添加剂倾向于促进柱状晶体的生长而不是板状晶体; 5)在一个大气压下的空气、氮气、氦气、氩气、氢气和甲烷气体中的冰生长产生基本上相同的温度依赖的晶体形态。

英文摘要:

We present an investigation of chemical influences on the growth of ice crystals from water vapor. In one set of experiments, we grew ice crystals in a vapor diffusion chamber, observing crystal morphologies at temperatures from 0 C to -25 C in different background gases and with a variety of gaseous chemical additives. In a second set of experiments, we measured ice crystal growth rates at -5 C and -15 C in a free-fall flow chamber, using normal laboratory air and ultra-clean nitrogen gas, both with and without chemical additives. Conclusions from these experiments include:\ 1) In nitrogen gas at a pressure of one atmosphere, no tested chemical additives at concentrations below 10 ppm produced any observable changes in ice crystal growth morphologies; 2) Growth in ultra-clean nitrogen gas was not significantly different from growth in ordinary laboratory air; 3) Chemical additives affected plate-like dendritic growth at -15 C more readily than growth at higher temperatures; 4) Chemical additives tended to promote the growth of columnar crystals over plate-like crystals; 5) Ice growth in air, nitrogen, helium, argon, hydrogen, and methane gases at a pressure of one atmosphere yielded essentially the same temperature-dependent crystal morphologies.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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