Hamburg 2001 – wissenschaftliches Programm
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O: Oberflächenphysik
O 10: Adsorption an Oberfl
ächen (I)
O 10.5: Vortrag
Montag, 26. März 2001, 17:15–17:30, C
CO ADSORPTION ON Pt(110) INVESTIGATED BY X-RAY PHOTOELECTRON DIFFRACTION — •Marek Nowicki, Arndt Emundts, Gerd Pirug, and Hans Bonzel — IGV, Forschungszentrum Jülich, D-52425 Jülich
The adsorption of CO on a Pt(110) surface was investigated by LEED, angle-resolved x-ray photoelectron spectroscopy (XPS) and diffraction (XPD). For a CO coverage of 0.5 ML, achieved by slowly cooling the crystal during exposure from 600 till 410 K, polar and large solid angle intensity distributions of C 1s photoelectrons show a perpendicular orientation of CO molecules on the unreconstructed (1x1) surface. For higher coverages of 0.8 and 1 ML, obtained by cooling the sample during CO exposure from 600 till 350 and 80 K respectively, a (2x1)p2mg LEED pattern was observed. C 1s intensity angular distribution from the saturated CO adlayer exhibits well distinguished intra- and inter-molecular forward scattering maxima which reveal a 22o tilt of the adsorbed CO molecules along the [001] azimuth, supporting the space group symmetry p2mg. Adsorption below 240 K leads to a CO c(8x4) structure on a reconstructed Pt(110)-(1x2) surface with on-top and bridge adsorption sites. Single scattering cluster calculations performed for (2x1)p2mg and c(8x4) real space models of CO molecules show good consistency with the experimental C 1s angular intensity distributions.