IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Semiconductors Thursday Sessions
       Session SC+SS-ThA

Paper SC+SS-ThA9
Adsorption of C@sub 2@H@sub 2@ on Si(100) - New High Resolution Core-level Photoemission and Photoelectron Diffraction Results

Thursday, November 1, 2001, 4:40 pm, Room 111

Session: Semiconductor Surface Structure
Presenter: M. Polcik, Fritz-Haber-Institut der MPG, Germany
Authors: M. Kittel, Fritz-Haber-Institut der MPG, Germany
M. Polcik, Fritz-Haber-Institut der MPG, Germany
J.-T. Hoeft, Fritz-Haber-Institut der MPG, Germany
D.I. Sayago, Fritz-Haber-Institut der MPG, Germany
R.L. Toomes, University of Warwick, UK
D.P. Woodruff, University of Warwick, UK
Correspondent: Click to Email
The adsorption of acetylene and ethylene on Si(100) has been subject of a large number of experimental and theoretical studies. Most theoretical studies have favoured a 'di-@sigma@' bonding character for both species, in which the C-C axis lies parallel to the Si dimers with the molecules symmetrically placed atop the dimers. Two independent experimental scanned-energy mode photoelectron diffraction (PhD) studies of the structure of the ethylene adsorption system have provided confirmation of this idea,@footnote 1,2@ but in the case of acetylene adsorption, one such study@footnote 3@ found this atop dimer configuration, but another found a totally different site between two dimers@footnote 2@. In an attempt to resolve this discrepancy we have carried out further experimental studies of the Si(100)/acetylene system at different temperatures and coverages, using high-resolution C 1s photoemission and C 1s PhD. Our new measurements confirm the dominance of the aligned atop-dimer geometry under all conditions studied. We find no direct evidence for a second species, except under conditions associated with fragmentation of the molecular adlayer by the incident soft X-ray beam, although the PhD data could be reconciled with some fractional occupation of other lower-symmetry sites which may contribute only very weak PhD modulations. @FootnoteText@ @footnote 1@ P.Baumgärtel et al, New.J.Phys 1 (1999) 20.1 @footnote 2@ S.H.Xu et al., Phys. Rev. Lett. 84, 939 (2000) @footnote 3@ R. Terborg et al., Phys.Rev.B 61, 16697 (2000).