Formation of chemisorbed H 2 in the Ni(100)-H-CO coadsorption system

Using EELS and LEED, we have investigated the vibrational motion and structure of H and CO coadsorbed on Ni(100). The initial structure, Ni(100)p(1×1)Hc(2×2)CO, formed at 80 K by first adsorbing a p(1×1)H overlayer and subsequently a c(2×2)CO overlayer is metastable. At ≈150 K the system transforms structurally. The CO molecules change adsorption sites and most notably chemisorbed H ₂ is formed.