Paper SS-TuP18
Exploring the Extent of Hydrogen/Deuterium Exchange on Au(111) between Molecularly-bound Surface Species

Tuesday, October 22, 2019, 6:30 pm, Room Union Station B

The exchange between hydrogen and deuterium atoms in molecularly-bound surface species can occur at low temperatures on Au(111). The hypothesized mechanism for the hydrogen/deuterium exchange in ethanol-OD and water is by the Grotthuss mechanism facilitated by hydrogen-bonded molecular networks on Au(111). Therefore, the molecular orientation and packing is central to this exchange. In an effort to rationalize the hypothesized mechanism and realize the extent of hydrogen/deuterium exchange at low temperatures, the co–adsorption of fully deuterated ethanol (EtOD₆) and water were investigated. The fragmentation pattern for EtOD₆ was first monitored using temperature programmed desorption (TPD), before increasing amounts of water were added to Au(111). A broad range of masses distinct to EtOD₆ were monitored using a mass spectrometer and desorption areas were quantified from TPD spectra. Comparing fractional coverages for hydrogen-exchanged EtOD₆ products suggest that hydrogen/deuterium exchange predominantly occurs through the hydrogen-bonded network.