| Abstract
| - Large-angle X-ray scattering (LAXS) measurements over a temperature range from 223 to 298 K have beenmade on methanol confined in mesoporous silica MCM-41 with two different pore diameters, 28 Å (C14)and 21 Å (C10), under both monolayer and capillary-condensed adsorption conditions. To compare the structureof methanol in the MCM-41 pores with that of bulk methanol, X-ray scattering intensities for bulk methanolin the same temperature range have also been measured. The radial distribution functions (RDFs) for themonolayer methanol samples showed that methanol molecules are strongly hydrogen bonded to the silanolgroups on the MCM-41 surface, resulting in no significant change in the structure of adsorbed methanol withrespect to the pore size and temperature. On the other hand, the RDFs for the capillary-condensed methanolsamples showed that hydrogen-bonded chains of methanol molecules are formed in both pores. However, thedistance and number of hydrogen bonds estimated from the RDFs suggested that hydrogen bonds betweenmethanol molecules in the pores are significantly distorted or partly disrupted. It has been found that thehydrogen bonds are more distorted in the smaller pores of MCM-41. With decreasing temperature, however,the hydrogen-bonded chains of methanol in the pores were gradually ordered. A comparison of the presentresults on methanol in MCM-41 pores with those on water in the same pores revealed that the structuralchange with temperature is less significant for confined methanol than for confined water.
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