Interaction of hydrogen with solid surfaces

The chemisorption of carbon monoxide on palladium single crystal surfaces: IR spectroscopic evidence for localised site adsorption

On the adsorption of CO on Pt(111)

Publisher Summary Catalytic oxidation of carbon monoxide over catalysts from the platinum group metals has been investigated. Apart from its enormous practical importance, this reaction is considered to proceed through a relatively simple mechanism because only diatomic molecules are involved and product formation occurs presumably only over a very few steps. This chapter discusses the adsorptive properties of the reactants, their mutual interaction, and the mechanism and kinetics of product formation as well as the investigations with well defined single-crystal surfaces. The activity of a catalyst for a particular reaction is strongly dependent on the surface structure. Directive investigation of the influence of the surface structure on the catalytic activity was performed by using a platinum single crystal whose surface was curved in such a way that not only the plane but also vicinals with varying step density of two different crystallographic directions were present.

Elementary Steps in the Catalytic Oxidation of Carbon Monoxide on Platinum Metals

High resolution vibrational spectroscopy of CO on Ru(001): The importance of lateral interactions

The surface vibrations of CO adsorbed on Pt(111) single crystal surfaces at 320 K have been studied by electron-energy-loss spectroscopy. At low coverages two vibration modes at 58 and ∼260 meV are observed. For exposures >0.2 Langmuir two additional modes at 45 and 232 meV develop. Considering also the observed LEED structures these vibrations are attributed to CO molecules being adsorbed upright in on-top and bridge sites, respectively.

Adsorption sites of CO on Pt (111)

The localized surface vibrations of oxygen adsorbed on a clean W (100) surface were studied by high-resolution electron-energy-loss spectroscopy. At low coverages $\ensuremath{\theta}l0.25$ a single surface vibration of the dissociated oxygen atoms is observed, while a rather complicated loss spectrum develops at higher coverages. Spectra of oxygen-covered annealed surfaces are also reported. Rather detailed models are presented for both surfaces, which are consistent with the number and frequency of the observed vibrations as well as with previous results on the same system. It is argued that the driving forces for the formation of the adsorbate superlattice are Coulomb repulsion and the energy gain in a surface disproportionation reaction.

Surface vibrations of oxygen on W(100)

The surface vibrations of H adsorbed on W(100) at 300 K have been studied by electron-energy-loss spectroscopy. Two vibration modes corresponding to atomic hydrogen in two different sites have been found with the relative occupation depending on the total coverage. The single mode observed at high coverages is attributed to the occupation of bridge sites (${\ensuremath{\beta}}_{1}$ hydrogen) while the mode observed at low coverages is associated with on-top sites (${\ensuremath{\beta}}_{2}$ hydrogen).

Surface Sites of H on W(100)

Electron spectrometers working with electrostatic deflection are characterized by a typical background structure. Experimental investigations and model calculations for a 127° analyzer show that the major part of this background is caused by specular reflections of the electrons from the deflection plates towards the exit slits. The background is reduced by a factor ≳10 when the deflection plates are appropriately corrugated. In a comparison with the most rational general CFF available, that of Ermer and Lifson, the most significant discrepancies found to occur are those for certain stretch–bend couplings assumed to be zero in the CFF, but shown to be appreciable by quantum calculation. It is observed that these couplings, but not the stretch–stretch couplings, are well accounted for by a steric interaction model. The ab initio cubic constants examined display the same pattern of conformity with a steric model. Bend–bend–bend and bend–bend–stretch but not all stretch–stretch–stretch interactions agree wit...

H. Ibach

Papers

Adsorption sites of CO on Pt (111)

Surface vibrations of oxygen on W(100)

Surface Sites of H on W(100)

Reduction of spurious background peaks in electron spectrometers

Surface vibrations of CO on W(100)