Field Desorption Processes of Pd Adlayer and Adatom on W(011), (112) and (111)

Field desorption of Pd on W(011),(112) and (111) has been studied to determine the characteristic behavior of adsorbed Pd by field emission and field ion microscopies. The results indicate that the field emission current variations at room temperature in the field desorption process can be classified into three regions: (1) the field desorption of the Pd overlayer atFdes=10–28 V/nm, (2) a region where further field desorption does not occur atFdes=30–37 V/nm and finally, (3) a region where the monolayer of Pd suddenly startes to be desorbed in the critical fieldFdes>∼38 V/nm. Binding energies for the overlayer and the monolayer of Pd were found to be 2.9–4.8 eV and 5.72 eV, respectively. Adsorbed Pd at various stages of the field desorption processes was also observed with a field ion microscopy.