Regensburg 2002 – wissenschaftliches Programm

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O: Oberflächenphysik

O 32: Adsorption an Oberfl
ächen (IV)

O 32.10: Vortrag

Donnerstag, 14. März 2002, 17:45–18:00, H43

Quantitative determination of the adsorption structure of carbonate on Ag(110) — •D.I. Sayago¹, M. Kittel¹, J.T. Hoeft¹, M. Polcik¹, M. Pascal², C.L.A. Lamont², R.L. Toomes³, and D.P. Woodruff^3,1 — ¹Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin, DE — ²University of Huddersfield, Huddersfield HD1 3DH, UK — ³University of Warwick, Coventry CV4 7AL, UK

The formation of carbonate (CO₃) on Ag(110) by the reaction of CO₂ with preadsorbed oxygen has been investigated by various techniques, but there has not been a full quantitative structural determination of the system until now. We have used C 1s photoelectron diffraction in scanned-energy mode to determine the adsorption geometry of the (1x2) phase of CO₃ on Ag(110). The experiments have been performed at the storage ring Bessy II on the UE-56/2 beamline. Our results confirm the added-row model proposed by Guo and Madix [1]. The carbonate adsorbs parallel to the surface and bonds through at least one of the oxygen atoms to silver adatoms in agreement with quantum-chemical calculations [2]. The distance between this oxygen and its next neighbour Ag atom in the added row is 1.9(±0.2) Å. The average C-O distance is 1.3(±0.07) Å. The very large separation of the carbon from its nearest neighbour Ag atom (2.64(±0.09) Å) contradicts [3] in which the carbonate is supposed to bond via its carbon atom .

[1] X.-C. Guo and R. J. Madix, Surface Science, 489:37, 2001

[2] J. A. Rodriguez and C. T. Campbell, Surface Science, 206:426, 1988

[3] B. Krenzer, L. Constant and H. Conrad, Surface Science, 443:116, 1999