The Interaction of Platinum with W[111] Tip: Diffusion, Desorption and Changes of Tip Morphology

Summary form only given. Adsorption, diffusion and desorption of platinum on W[111] oriented tip has been studied using field electron microscopy technique. The diffusion of platinum in submonolayer range on clean W tip was studied at temperatures 630-750 K. Mean activation energy for diffusion was established for Ediff=112plusmn7 kJ/mol. The layer equilibrated in diffusion process was stable at temperatures up to 1150-1200 K where some changes of tip morphology, likely due to alloying of Pt with W, started to be visible. Submonolayer of platinum started to desorb from the tip at temperatures as high as 1850-1900 K. The measurements of activation energy for desorption of Pt from W were carried out at temperatures 2050-2150 K and yield the value of Edes=425plusmn40 kJ/mol