氦气在氩霜表面吸附的巨正则蒙特卡洛模拟

Grand canonical Monte Carlo simulation of helium adsorption on argon frost

为了从微观角度解释深冷霜在低温下对不凝性气体的吸附机理,采用巨正则蒙特卡洛方法对氦气在氩霜狭缝孔结构中的吸附过程进行模拟。研究了粒子的局部密度随压力变化的分布,获得了氦气在不同孔宽和温度条件下的吸附等温线。模拟结果表明,在相同温度和孔宽下,压力越高粒子在孔内的局部密度越大,且最大值的位置不随压力变化。在温度为4.2 K时,孔宽越大霜层对氦气分子的吸附作用力越小,当孔宽大于1.5 nm时,吸附等温线基本重合。系统的温度越低,起始的吸附压力越小。

Adsorption behavior of helium on argon frost has been simulated by using the grand canonical Monte Carlo method to understand the adsorption mechanism of non-condensed gas on cryodeposited frosts in microscopic view. Local density profile of molecules in a slit at various pressure has been studied. The ad- sorption isotherms of helium on argon frost with different slit width have been studied at different tempera- ture. The simulation results indicate that local density increases as pressure rises at the given temperature, but the position of maximal value doesn＇ t change with it. The interaction between helium and frost decrea- ses as the width rises when the system temperature maintains at 4.2 K. The adsorption isotherms are almost the same when the pore width is larger than 1.5 nm. The lower the system temperature was, the smaller the starting adsorption pressure.