Instituto de Estructura de la Materia, CSIC, Serrano 123, 28006 Madrid, Spain.
Phys Chem Chem Phys. 2010 Apr 7;12(13):3164-70. doi: 10.1039/b922598f. Epub 2010 Feb 18.
Ice mixtures of methane and water are investigated by means of IR spectroscopy in the 14-60 K range. The spectroscopic research is focused on the symmetry-forbidden nu(1) band of CH(4) and the dangling bond bands of water. The nu(1) band is visible in the spectra of the mixtures, revealing a distorted methane structure which co-exists with the normal crystalline methane. The water dangling bond bands are found to increase their intensity and appear at red-shifted frequency when distorted methane is present. Methane adsorbed on water micropores or trapped inside the amorphous solid water structure is assumed to be responsible for these effects. CH(4) mobility in water ice depends on the deposition method used to prepare the samples and on the temperature. After warming the samples to 60 K, above the methane sublimation point, a fraction of CH(4) is retained in the water ice. An adsorption isotherm analysis is performed yielding the estimation of the desorption energy of CH(4) on H(2)O amorphous surfaces.
通过在 14-60 K 范围内的红外光谱法研究了甲烷和水的冰混合物。光谱研究集中在甲烷的对称禁阻 ν(1)带和水的悬挂键带。混合物的光谱中可见 ν(1)带，表明存在与正常结晶甲烷共存的扭曲甲烷结构。当存在扭曲甲烷时，发现水悬挂键带增加其强度并出现在红移频率处。假定吸附在水微孔上或被困在无定形固态水结构内的甲烷对此类效应负责。甲烷在水冰中的迁移率取决于用于制备样品的沉积方法和温度。在将样品升温至 60 K 以上的甲烷升华点后，一部分 CH4 保留在水冰中。进行了吸附等温线分析，得出了 CH4 在 H2O 非晶表面解吸的能量估计。
