Adsorption of CO on Ni(100): a FTIRAS - TDS Study
Engineering, Chemical Engineering, Membrane Science
The adsorption of CO at Ni(100) surfaces was studied in the temperature range 125–350 K using TDS, FTIRAS and LEED. With TDS, three desorption states, β2, β1 and α were observed at 450, 350 and 280 K corresponding to completion of coverages θ = 0.25, θ = 0.5, and θ = 0.67 (± 0.03), respectively. At coverages below θ = 0.5 CO adsorbs at terminal and bridge sites with coverage dependent C-O stretch frequencies of 2016 (low θ) to 2048 cm−1 (high θ) and 1885 to 1924 cm−1, respectively. The population of the sites is temperature dependent, bridge sites are favored over top sites at low temperature and vice versa. At θ = 0.5 both, terminal and bridge sites are occupied, top site occupation exceeding bridge site occupation. Above θ = 0.5 FTIRA spectra exhibit in the terminal region a broad band from 2000 to 2100 cm−1, which contains at least 3 components and suggests that a distinct terminal site does not exist at these coverages. On the contrary, in the bridge site region a single peak at 1968 cm−1, with a width of 25 cm−1, signals that bridge type or almost bridge type adsorption sites are still present at the CO covered surface. The results are in accordance with the assumption that CO molecules are arranged in incommensurate or weakly incommensurate adsorbate layers above half monolayer coverage.
Digital Object Identifier (DOI)
Published in Surface Science, Volume 279, 1992, pages 287-296.
© Surface Science, 1992, Elsevier
Lauterbach, A.J., Wittmann, M., Kuppers, J. (1992). Adsorption of CO on Ni(100): a FTIRAS - TDS study. Surface Science, 279, 287-296.