The adsorption of ammonia on zirconium surfaces: effect of adsorption temperature on the thermal desorption of water

Ammonia adsorption on Zr(0 0 0 1) under ultra-high vacuum conditions has been studied using temperature programmed desorption (TPD) and low energy electron diffraction (LEED) methods. Data from TPD measurements indicate that water accompanies the thermal desorption of ammonia and that relative yields and desorption profiles depend on adsorption temperature. Subsequent to desorption, recovery of clean-surface LEED patterns requires various amounts of sputtering and annealing depending on adsorption conditions. The implications are that ammonia dissociation occurs in this system leaving residual nitrogen at or near the surface and that the formation of water may involve oxygen from the bulk. (C) 2001 Elsevier Science Ltd. All rights reserved.