Effect of Implantation of Ba+ Ions on the Composition, Electronic and Crystal Structure of W(111) and WO2 Surfaces

It is shown that upon the implantation of Ba+ ions in W, a mechanical mixture of [Ba + W] atoms is formed in the surface layer. At an ion energy of E0 = 0.5 keV, the thickness of this layer is ~25–30 Å. Due to a decrease in the work function and an increase in the atomic density of ion-implanted layers, the maximum coefficient of secondary-electron emission σmax and the photoelectron quantum yield Y increase significantly. When the [Ba + W] system is heated to T = 900 K, the formation of a chemical bond between Ba and W atoms is not observed. In the case of the implantation of Ba+ ions in WO2, compounds of the W–O, Ba–O, and Ba–O–W types are formed in the surface layer. In this case, the growth of σm and Y is explained only by a decrease in the work function of the surface.

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