Local Structures of Methanol鈥揥ater Binary Solutions Studied by Soft X-ray Absorption Spectroscopy

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• 作者：Masanari Nagasaka ; Kenji Mochizuki ; Valentin Leloup ; Nobuhiro Kosugi
• 刊名：Journal of Physical Chemistry B
• 出版年：2014
• 出版时间：April 24, 2014
• 年：2014
• 卷：118
• 期：16
• 页码：4388-4396
• 全文大小：464K
• 年卷期：v.118,no.16(April 24, 2014)
• ISSN：1520-5207

文摘

Liquid methanol shows one- and two-dimensional (1D/2D) hydrogen bond (HB) networks, and liquid water shows three-dimensional (3D) HB networks. We have clearly found three different local structures around the methyl group of methanol鈥搘ater binary solutions (CH₃OH)_X(H₂O)_1鈥?i>X at different concentrations in C K-edge soft X-ray absorption spectroscopy (XAS). With the help of molecular dynamics simulations, we have discussed the concentration dependence of the hydrophobic interaction at the methyl group in the C K-edge XAS spectra. In the methanol-rich region I (1.0 > X > 0.7), a small amount of water molecules exists separately around dominant 1D/2D HB networks of methanol clusters. In the region II (0.7 > X > 0.3), the hydrophobic interaction of the methyl group is dominant due to the increase of mixed methanol鈥搘ater 3D network structures. In the water-rich region III (0.3 > X > 0.05), methanol molecules are separately embedded in dominant 3D HB networks of water. On the other hand, the pre-edge feature in the O K-edge XAS shows almost linear concentration dependence. It means the HB interaction between methanol and water is almost the same as that of water鈥搘ater and of methanol鈥搈ethanol.