ACTIVATION-ENERGIES FOR THERMAL-DESORPTION OF HYDROXYL RADICALS FROM SINGLE-CRYSTAL PLATINUM(111) AND POLYCRYSTALLINE PLATINUM FOIL SURFACES

Apparent desorption energies were obtained for OH radicals formed in the associative reaction of chemisorbed O and H atoms on single-crystal Pt(111) and polycrystalline Pt foil surfaces by using the laser-induced fluorescence (LIF) technique coupled to an UHV surface science apparatus. As the reactant O/H gas mixture ratio is decreased from 10 to 0. 1, the OH desorption energies increase from 27 to 36 kcal/mol for the Pt(111) crystal and from 32 to 42 kcal/mol for the polycrystalline Pt foil.