| 1. |
- Sandell, A., et al.
(author)
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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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In: Physical Review B (Condensed Matter). - 0163-1829. ; 57:20, s. 13199-13208
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Journal article (peer-reviewed)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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| 2. |
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| 3. |
- Sun, L C, et al.
(author)
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Binuclear ruthenium-manganese complexes as simple artificial models for photosystem II in green plants
- 1997
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 119:30, s. 6996-7004
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Journal article (peer-reviewed)abstract
- As part of a project aimed at developing models for photosystem II (PSII) in green plants, we have prepared a series of model compounds (7, 8, and 13). In these compounds, a photosensitizer, ruthenium(II) tris(bipyridyl) complex (to mimic the function of P-680 in PSII), was covalently linked to a manganese(II) ion through different bridging ligands. The structures of the compounds were characterized by electron paramagnetic resonance measurements and electrospray ionization mass spectrometry. The interaction between the ruthenium and manganese moieties within the complex was probed by steady-state and time-resolved emission measurements. When the binuclear complexes are exposed to flash photolysis in the presence of an electron acceptor such as methylviologen (MV2+), it could be shown that after the initial electron transfer from the excited state of Ru(II) in compound 7, forming Ru(III) and MV+., an intramolecular electron transfer from coordinated Mn(II) to the photogenerated Ru(III) occurred with a first-order rate constant of 1.8 x 10(5) s(-1), regenerating Ru(II). This is believed to be the first supramolecular system where a manganese complex has been used as an electron donor to a photo-oxidized photosensitizer, Possible extensions to develop the manganese donor, and thus to approach the function of reaction center in PSII, are indicated.
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| 4. |
- Tobias, Peter, et al.
(author)
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Influence of gas consumption on the response of metal oxide silicon carbide sensors to exhaust gases
- 1998
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In: EUROSENSORS XII, VOLS 1 AND 2. - : Institute of Physics Publishing (IOPP). - 0750305363 ; , s. 249-252
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Conference paper (other academic/artistic)abstract
- Silicon carbide based Schottky diodes w th catalytic gate metals are promising for diagnosis of exhaust gas from combustion engines. The forward voltage measured at a constant current changes from a low level in reducing gases to a high level in oxidising gases. Factorial design in two levels on synthetic exhausts reveal interesting details of the influence of the different components on the sensor signal. Contrary to earlier experiments, an increase of the concentration of hydrocarbons and carbon monoxide increases the signal level. Hydrogen gas behaves as expected, an increased concentration increases the signal level. The total area of catalytic metal was much smaller in the new experiment and the different behavior of the sensor signal can probably be explained by consumption cf gases on catalytic metal surfaces.
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