Temperature effects on the coadsorption of K-CO on Ni(100)

High-resolution electron energy-loss spectra of the coadsorption of potassium and CO on the Ni(100) surface show the role of temperature in driving chemical species along the surface towards the formation of ordered islands made of alkali atoms and CO species. At low potassium precoverages, the formation of K-CO islands occurs by heating the sample to 420 K. On the contrary, for a potassium coverage near 0.38 ML, K-CO patches of ordered phases grow spontaneously even at 220 K. The interpretation of the present data relies essentially on two literature works on the K-CO/Ni(100) system, one of them presenting calorimetric measurements and the other reporting the theoretical temperature behaviour of the chemical species on the nickel surface. (C) 2000 Elsevier Science B.V. All rights reserved.