Trapping of Methanol, Hydrogen Cyanide, andn-Hexane in Water Ice, above Its Transformation Temperature to the Crystalline Form
Trapping of Methanol, Hydrogen Cyanide, andn-Hexane in Water Ice, above Its Transformation Temperature to the Crystalline Form
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在高于其结晶形式的转变温度下将甲醇、氰化氢和正己烷捕获在水冰中
DOI：
10.1006/icar.1996.5654
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发表时间：
1997
期刊：
影响因子：
3.2
通讯作者：
A. Bar
中科院分区：
文献类型：
--
作者：
G. Notesco;A. Bar
实验发现HCN和n-C6 H14在140 K和CH 3OH在160 K下与水蒸气在冷板上共沉积时，被捕获在水冰中。在这样的温度下，至少有一部分水冰是晶状的。这三种气体具有相对较高的升华温度，而先前研究的气体Ar、Kr、N2、CO、CH 4和N2具有较低的升华温度，它们仅被困在无定形水冰中，直到100 K。看来，在冷板上的气体-水蒸气混合物的共沉积期间，决定水冰捕集气体的效率的主要因素是待捕集的气体的升华温度。在共沉积过程中，那些具有高升华温度的分子在水冰的孔中停留的时间更长，这些孔向表面开放，直到它们被额外的冰层覆盖。只有甲醇似乎形成笼形水合物，与D。Blake等人（1991），Science 254，548-551），其指出了冰中气体分子与水分子相互作用的重要性。因此，在天王星-土星区域及其亚星云中形成的彗星和冰冷的卫星可以捕获CH 3 OH，HCN和重烃，而在天王星-海王星区域，土星亚星云（泰坦）外围和柯伊伯带行星之外形成的彗星和冰冷的卫星也可以捕获升华温度较低的气体。
Abstract HCN and n -C 6 H 14 were found experimentally to be trapped in water ice, when codeposited with water vapor on a cold plate, at 140 K and CH 3 OH even at 160 K. At these temperatures at least part of the water ice is cystalline. These three gases have relatively high sublimation temperatures, whereas the gases studied earlier, Ar, Kr, Xe, CO, CH 4 , and N 2 , which have lower sublimination temperatures, are trapped only in amorphous water ice, up to ∼100 K. It seems that the major factor determining the efficiency of gas trapping by water ice, during codeposition of a gas–water vapor mixture on a cold plate, is the sublimation temperatures of the gases to be trapped. Those with a high sublimation temperature remain, during codeposition, longer in the pores of the water ice which are open to the surface, until they are covered by additional ice layers. Only methanol seems to form a clathrate hydrate, in agreement with the experimental results of D. Blake et al. (1991), Science 254, 548–551), which points to the importance of the interaction of the gas molecules with the water molecules in the ice. Consequently, comets and icy satellites that were formed in the Jupiter–Saturn region and their subnebulae could trap CH 3 OH, HCN, and heavy hydrocarbons, whereas comets and icy satellites that were formed in the Uranus–Neptune region, at the outskirts of the Saturnian subnebulae (Titan), and beyond the planets in the Kuiper belt could trap also gases having lower sublimation temperatures.