Department of Chemical and Biological Physics, Weizmann Institute of Science, 234 Herzl Street, 76100 Rehovot, Israel.
J Phys Chem Lett. 2023 Mar 16;14(10):2644-2650. doi: 10.1021/acs.jpclett.3c00161. Epub 2023 Mar 8.
The interaction between submonolayers of methanol and water on Cu(111) is studied at 95-160 K temperature range with surface-sensitive infrared spectroscopy using isotopically labeled molecules. The initial interaction of methanol with the preadsorbed amorphous solid water at 95 K is through hydrogen-bonding with the dangling hydroxyl groups of water. Upon increasing the temperature up to 140 K, methanol and deuterated water form H-bonded structures which allow hydrogen-deuterium exchange between the hydroxyl group of methanol and the deuterated water. The evolution of the O-D and O-H stretching bands indicate that the hydrogen transfer is dominant at around 120-130 K, slightly below the desorption temperature of methanol. Above 140 K, methanol desorbs and a mixture of hydrogen-related water isotopologues remains on the surface. The isotopic composition of this mixture versus the initial DO:CHOH ratio supports a potential exchange mechanism via hydrogen hopping between alternating methanol and water molecules in a hydrogen-bonded network.
在 95-160 K 的温度范围内，使用表面敏感的红外光谱法，用同位素标记的分子研究了甲醇亚单层与 Cu(111)上预吸附非晶态水之间的相互作用。甲醇与 95 K 下预先吸附的无定形固态水的初始相互作用是通过与水的悬空羟基形成氢键。当温度升高到 140 K 时，甲醇和氘化水形成氢键结构，允许甲醇的羟基和氘化水之间进行氢-氘交换。O-D 和 O-H 伸缩带的演化表明，在 120-130 K 左右，氢转移占主导地位，略低于甲醇的脱附温度。高于 140 K 时，甲醇脱附，表面上仍残留有与氢相关的水同位素混合物。该混合物的同位素组成与初始 DO:CHOH 比值相对应，支持了一种通过氢键网络中交替的甲醇和水分子之间的氢跳跃的潜在交换机制。
