Adsorption of CO on Cu layers adsorbed on a W(110) surface

• Published in: Surface science 1987-08, Vol.186 (3), p.412-446
• Main Authors: Chelvayohan, M., Gomer, R.
• Format: Article
• Language: English
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(87)80385-0

Changes in work functionas function of absolute CO coverage, sticking coefficients as function of coverage and surface temperature, as well as LEED structures and equilibrium isobars were determined for CO adsorption on W(110)/Cu 1. Isothermal desorption measurements were also made. Δ versus CO flux was also determined on thicker Cu deposits and isobars were taken on W(110)/Cu 6. For W(110)/Cu 1 Δ increases monotonically reaching 390 meV for CO/Cu∼0.75 the maximum coverage. There is also some CO adsorption on tungsten sites, and this can be increased by exposure at T>250 K and finite CO pressure. For two or more Cu layersdecreases initially, goes through a minimum and then increases. There are significant differences between annealed and unannealed Cu deposits. For W(110)/Cu 1 sticking coefficients are nearly unity at low coverage up to T s=250 K but fall rapidly with increasing coverage. On this surface isobars show a plateau at CO/Cu=0.5, corresponding to completion of a binding state, with increased adsorption occurring only when T is lowered below 210–170 K depending on pressure (in the range 10 −8 to 10 −6 Torr). For CO/Cu