Hydrogen Exchange through Hydrogen Bonding between Methanol and Water in the Adsorbed State on Cu(111)
Roey Ben David, Adva Ben Yaacov, Baran Eren
Abstract
High Resolution Image Download MS PowerPoint Slide 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 D 2 O:CH 3 OH ratio supports a potential exchange mechanism via hydrogen hopping between alternating methanol and water molecules in a hydrogen-bonded network.