The adsorption and desorption of ethanol ices from a model grain surface.
The adsorption and desorption of ethanol ices from a model grain surface.
复制标题
乙醇冰从模型颗粒表面的吸附和解吸。
DOI：
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发表时间：
2008
影响因子：
4.4
通讯作者：
Wendy A. Brown
中科院分区：
文献类型：
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作者：
D. J. Burke;Angela J. Wolff;J. L. Edridge;Wendy A. Brown
用反射吸收红外光谱(RAIR)和程序升温脱附(TPD)研究了98K乙醇在高有序热解石墨(HOPG)上的吸附和脱附过程。RAIR光谱表明，98K时乙醇在表面形成物理吸附的多层膜，超过120K的多层乙醇冰(暴露物>；50 L)在冰内结晶之前会引起形态变化。TPD表明乙醇在HOPG表面以分子形式吸附和解吸，并表现出四种不同的脱附状态。在低覆盖度下，观察到单层乙醇的脱附，并用一级动力学描述。随着覆盖率的增加，在较低的温度下观察到第二个TPD峰，该峰被指定为乙醇双层。当覆盖率进一步增加时，观察到第二个多层，其与下面的乙醇冰膜的结合强度较小。随着覆盖度的增加，该峰在TPD谱中占据主导地位，并具有分数级动力学特征，其脱附能为56.3+/-1.7kJ摩尔(-1)。当曝光量超过50 L时，在160K的TPD谱上也观察到结晶乙醇的形成是一个高温肩。
Reflection absorption infrared spectroscopy (RAIRS) and temperature programed desorption (TPD) have been used to probe the adsorption and desorption of ethanol on highly ordered pyrolytic graphite (HOPG) at 98 K. RAIR spectra for ethanol show that it forms physisorbed multilayers on the surface at 98 K. Annealing multilayer ethanol ices (exposures >50 L) beyond 120 K gives rise to a change in morphology before crystallization within the ice occurs. TPD shows that ethanol adsorbs and desorbs molecularly on the HOPG surface and shows four different species in desorption. At low coverage, desorption of monolayer ethanol is observed and is described by first-order kinetics. With increasing coverage, a second TPD peak is observed at a lower temperature, which is assigned to an ethanol bilayer. When the coverage is further increased, a second multilayer, less strongly bound to the underlying ethanol ice film, is observed. This peak dominates the TPD spectra with increasing coverage and is characterized by fractional-order kinetics and a desorption energy of 56.3+/-1.7 kJ mol(-1). At exposures exceeding 50 L, formation of crystalline ethanol is also observed as a high temperature shoulder on the TPD spectrum at 160 K.