Bonding and adsorption structure of CO on W(100)-(5×1)–C
1987; American Institute of Physics; Volume: 87; Issue: 3 Linguagem: Inglês
10.1063/1.453198
ISSN1520-9032
AutoresC. M. Friend, Jarosław Serafin, E. K. Baldwin, Paul A. Stevens, R. J. Madix,
Tópico(s)Electron and X-Ray Spectroscopy Techniques
ResumoThe adsorption structure of carbon monoxide on W(100)-(5×1)–C has been characterized using high-resolution electron energy loss spectroscopy and near edge x-ray absorption fine structure measurements. A single C–O stretch of 2100 cm−1 is observed at a surface temperature of 130 K. The C–O bond vector is determined to be normal to the surface on the basis of near edge x-ray absorption fine structure measurements. The position in energy of the C(1s)→σ* resonance in CO was measured to be 304.2 eV. The empirical relation between the σ* resonance energy and bond length yields a bond length of 1.12 Å. All spectroscopic results are consistent with CO bound atop a single tungsten atom, normal to the surface plane with minimal C–O bond weakening. These results correlate with the known difference in the reactivity of the W(100)-(5×1)–C surface compared to clean W(100). The increased barrier for CO dissociation on the W(100)-(5×1)–C surface is explained on the basis of reduced backdonation of electron density from the tungsten d band to the CO 2π* orbitals. Tight-binding slab calculations for CO on W(100) and W(100)-(5×1)–C which support this contention are discussed.
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