Aggregates of chemisorbed copper on the (110) and (100) surfaces of tungsten

• Published in: Surface science 1993, Vol.280 (1), p.91-105
• Main Authors: Gaudin, G.A., Lee, M.J.G.
• Format: Article
• Language: English
• Subjects: Chemistry; Exact sciences and technology; General and physical chemistry; Solid-gas interface; Surface physical chemistry
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/0039-6028(93)90359-R

Aggregates of copper atoms have been observed on the (110) and (100) facets of a thermally annealed tungsten field emitter following chemisorption at 300 K. It is shown that aggregates on the (110) plane form on the bare substrate, while aggregates on the (100) plane form only after an overlayer of copper has been adsorbed. Aggregates on the (110) plane are found to be island-like structures that probably consist of a single layer of copper atoms and grow primarily by atoms binding to the edge. Aggregates on the (100) plane appear to also have a low profile, but the details of the structure are not known. Although sufficiently large copper aggregates are stable at 300 K on both of the tungsten planes studied, a moderate temperature increase causes them to shrink, apparently by diffusion of copper atoms to adjacent facets.