| 1. |
- Guimond, S., et al.
(författare)
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Vanadium oxide surfaces and supported vanadium oxide nanoparticles
- 2006
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Ingår i: Topics in catalysis. - : Springer Science and Business Media LLC. - 1022-5528 .- 1572-9028. ; 38:1-3, s. 117-125
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Tidskriftsartikel (refereegranskat)abstract
- The information obtained from the characterization of vanadium oxide single crystal surfaces is related to the study of vanadia nanoparticles supported on silica and alumina thin films, model systems for the so-called “supported monolayer vanadia catalysts”. It is found that these particles have properties similar to V2O3 surfaces, where the topmost V ions are involved in vanadyl groups and have a 5+ oxidation state. A vibrational spectroscopy investigation combined with DFT calculations show that the accepted interpretation of vibrational spectra from vanadia catalysts must be revised.
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| 2. |
- Liu, Y., et al.
(författare)
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Surface Action Spectroscopy : A review and a Perspective on a New Technique to Study Vibrations at Surfaces
- 2021
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Ingår i: The chemical record. - : Wiley. - 1527-8999 .- 1528-0691. ; 21:6, s. 1270-1283
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Tidskriftsartikel (refereegranskat)abstract
- A new vibrational spectroscopy method aimed at the investigation of solid surfaces in ultrahigh vacuum, called “Surface Action Spectroscopy (SAS)”, is described and the first results are reviewed. This technique is based on ideas and experiments performed in the gas phase. A surface is exposed to a messenger species at low temperature. This messenger species is desorbed via absorption of tunable infrared light from a free-electron laser and the desorption rate of the messenger species is recorded via mass spectrometry. It is shown that the technique is extremely surface sensitive and we discuss the basic mechanisms of the technique. We show a feasibility study on a V2O3(0001) surface, where we know the surface structure. We then proceed to the example of iron oxide films to study the surface structure in parallel with calculations of the surface phonons, which allow us to confirm the surface structure of Fe3O4(111) to be Fetet terminated. It also provides evidence for the so-called biphase structure. To conclude, we discuss possibilities to apply the technique to interesting questions in model and real catalysis, since the technique may provide interesting information independent of long-range order of the sample.
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| 3. |
- Sandell, A., et al.
(författare)
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Observation of a low-energy adsorbate core-level satellite for CO bonded to palladium : Coordination-dependent effects
- 1998
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Ingår i: Physical Review B (Condensed Matter). - 0163-1829. ; 57:20, s. 13199-13208
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Tidskriftsartikel (refereegranskat)abstract
- A strong low-energy shake-up satellite for CO adsorbed on Pd is observed. The occurrence of the satellite is established for the CO/1 ML Pd/Mo(110) system at a coverage where CO adsorbs exclusively on-top. Comparisons with CO adsorbed on Pd single-crystal surfaces and small supported Pd particles indicate that the strongly increased satellite intensity is due to the decreased CO-Pd interaction strength for on-top adsorbed CO. This can be used to get further insight into the structure and bonding properties of the adsorbate system. Since a low-energy shake-up feature may be misinterpreted as a chemically shifted component, the conclusion is that great care has to be taken in the evaluation of adsorbate core-level spectra for systems with large variations in adsorption strength depending on the adsorbate sites. Large variations in the CO site distribution may furthermore occur depending on the nature of the Pd substrate: Adsorption of CO on 1 ML Pd/Mo(110) leads to an overlayer dominated by an on-top species and, likewise, the CO overlayer formed on small Pd particles after large doses has a large fraction of on-top bonded species. This is in strong contrast to Pd single-crystal surfaces, where CO adsorbed in more highly coordinated sites is abundant.
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| 4. |
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