| 1. |
- 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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| 2. |
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| 3. |
- Denecke, R., et al.
(author)
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Beamline 1511 at MAX II, capabilities and performance
- 1999
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In: Journal of Electron Spectroscopy and Related Phenomena. - 0368-2048. ; 101-103, s. 971-977
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Journal article (peer-reviewed)abstract
- The new undulator beamline 1511 at MAX-lab, now under commissioning, has been optimized for X-ray emission and photoelectron spectroscopies. Using an SX-700 high flux monochromator the accessible photon energy range is from 90 eV to about 1500 eV. The performance of the undulator agrees very well with the specifications, as shown by measurements using a photodiode. The energy resolution of the monochromator has been checked using absorption measurements in a gas cell. It was found to meet the expectations and exceeds a resolving power of 10 000 at 244 eV. The photon flux as a function of energy has been recorded as well and gives a maximum flux of 3×1013 photons/s/100 mA/0.1% BW. Beamlines 1511 and 1411 will be the first synchrotron beamlines making use of a so-called beam waist phenomenon, known from laser physics. We show results of ray-tracing calculations to determine the ultimate spot size on the sample location. The endstations to be used at this new beamline and their capabilities will be discussed as an example of the future use of this facility.
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| 4. |
- Johansson, L.I., et al.
(author)
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Electronic structure of 6H-SiC(0001)
- 1996
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In: Physical Review B (Condensed Matter). - 0163-1829. ; 53:20, s. 13803-13807
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Journal article (peer-reviewed)
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| 5. |
- Mårtensson, P, et al.
(author)
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HALIDE CHEMICAL-VAPOR-DEPOSITION OF BI2SR2CACU2O8+X - ASPECTS OF EPITAXY
- 1995
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In: Journal of Crystal Growth. - Elsevier Science BV. ; 156, s. 1-267
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Journal article (other academic/artistic)abstract
- The superconducting Bi2Sr2CaCu2O8+x phase has been deposited bg halide chemical vapour deposition (CVD) on three different substrate materials, MgO(001), SrTiO3(001) and LaAlO3(001). Metal iodides and oxygen were used as precursors. The films were found
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| 6. |
- Puglia, Carla, et al.
(author)
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Core level spectroscopy study of N-2 adsorbed on (2x2)K/graphite
- 1998
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In: SURFACE SCIENCE. - 0039-6028. ; 414:1-2, s. 118-130
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Journal article (other academic/artistic)abstract
- We report a study of N-2/(2 x 2)K/graphite at 25 K using X-ray photoemission, X-ray absorption (XAS), ultraviolet photoemission, autoionization and Auger spectroscopies. At this temperature me found that N-2 physisorbs. Comparisons with the physisorbed sy
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| 7. |
- 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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| 8. |
- 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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| 9. |
- Tobias, Peter, et al.
(author)
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Electrical characterization of chemical sensors based on catalytic metal gate - Silicon carbide Schottky diodes
- 1998
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In: Silicon Carbide, III-Nitrides and Related Materials, Part 1-2. - : Trans Tech Publications. - 0878497900 ; , s. 1097-1100
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Conference paper (peer-reviewed)abstract
- The IV-characteristics of platinum gate Schottky diodes with an interfacial layer of TaSix or Ta depends on gas ambient and they are therefore used as gas sensors, e.g. for combustion engine monitoring. Ideality factors and barrier heights depend on interfacial layers and temperature and are further investigated here. Gas sensitive Schottky diodes on both p-and n-type SIC are shown.
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| 10. |
- Tobias, Peter, et al.
(author)
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Studies of the ambient dependent inversion capacitance of catalytic metal oxide silicon carbide devices based on 6H- and 4H-SiC material
- 1998
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In: Silicon Carbide, III-Nitrides and Related Materials, Part 1-2. - : Trans Tech Publications. - 0878497900 ; , s. 1089-1092
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Conference paper (peer-reviewed)abstract
- Platinum-oxide-silicon carbide structures change their capacitance upon gas exposure and are used as gas sensors. The decrease of the inversion capacitance within 750 to 900 degrees C due to hydrogen exposure is studied for 4H- and 6H-SiC,:both n- and p-type. A mechanism for the capacitance decrease is suggested which explains also the large change in the conductance of the structures.
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