Observation of two reaction pathways for water formation from hydroxyl radical covered Pt(111)

Intense molecular beams of hydroxyl radicals produced in a supersonic corona discharge source were focused and state-selected by an electrostatic hexapole. Thermal desorption spectra from a Pt(111) surface dosed with the resulting pure beam of OD radicals showed features corresponding to D2O and O2 desorption. Two distinct types of adsorbed OD were observed depending on the dosing temperature. Dosing at 215 K generated a low temperature (215 K) D2O desorption feature. Dosing at 275 K generated a high temperature (400 K) D2O desorption feature. Possible origins of these two features are discussed.