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| 2. |
- Fauquet, C., et al.
(författare)
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Electronic structure of trimethylamine alane in the solid state
- 1995
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Ingår i: Chemical Physics Letters. - : Elsevier. - 0009-2614 .- 1873-4448. ; 235:5-6, s. 528-534
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Tidskriftsartikel (refereegranskat)abstract
- The chemical and electronic structure of ultrathin molecular films of trimethylamine alane (TMAA), condensed in UHV at − 100°C, have been studied in the solid state, using both X-ray and ultraviolet photoelectron spectroscopy. The results are analyzed with the help of quantum chemical calculations at the ab initio Hartree-Fock 6-31G∗ level. Based upon the good agreement between theory and experimental, it is determined that clean, oxygen-free, condensed molecular solid films consist of the 2:1 adduct of TMAA, which was previously uncertain. In addition, based upon the electronic structure results, it is clear that the mechanism of the photodecomposition of TMAA can be explained in terms of the wavefunction of electrons photoexcited into the first unoccupied molecular orbital.
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| 3. |
- Lazzaroni, R., et al.
(författare)
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Chemical and electronic aspects of metal/conjugated polymer interfaces : Implications for electronic devices
- 1995
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 71:1-3, s. 2159-2162
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Tidskriftsartikel (refereegranskat)abstract
- The chemical nature and the electronic structure of metal/conjugated polymer interfaces are investigated in the context of polymer-based light-emitting diodes. We consider the interaction of low-workfunction metals (Al, Ca) with the surface of conjugated polymers or model oligomer molecules with a combined experimental and theoretical approach. The early stages of the interface formation are followed with X-ray and ultraviolet photoelectron spectroscopies and the experimental data are compared to the results of quantum chemical calculations. The reactions of Al and Ca with the organic surface are found to be fundamentally different: while the former forms new covalent bonds onto the polymer backbone, the latter tends to dope the conjugated system. Both types of reaction are expected to modify drastically the electronic properties of the polymer semiconductor.
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| 4. |
- Almqvist, Nils, et al.
(författare)
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Scanning probe microscopy and thermo-mechanical characterization of silicon carbide composites
- 1995
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Ingår i: Fourth Euro-Ceramics. - : Gruppo Ed. Faenza Ed.. - 8881380072 ; , s. 361-368
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Konferensbidrag (refereegranskat)abstract
- series of SiC-based composites was obtained by sintering. Since such materials are considered for fusion applications, their thermal shock resistance and behaviour under deuterium irradiation are of primary interest. Extensive bulk and surface characterisation of pure and doped (AlN, TiB2, graphite) silicon carbides treated by a deuterium plasma was carried out. The change in surface structure following irradiation is addressed, and major factors influencing deuterium retention are discussed.
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| 7. |
- Lögdlund, Michael, et al.
(författare)
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Theoretical and experimental studies of the interaction between sodium and oligothiophenes
- 1996
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Ingår i: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 53:24, s. 16327-16333
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Tidskriftsartikel (refereegranskat)abstract
- Quantum-chemical calculations and ultraviolet photoelectron spectroscopy (UPS) measurements have been performed in order to study the interaction between sodium and oligothiophenes, with a focus on the origin of experimentally observed relaxation energy effects in alkali-metal-doped conjugated molecules. Upon doping of a -sexithienylene (α-6T) with sodium atoms, (1) a broad feature appears in the valence band, in an energy region corresponding to the band gap in pristine α-6T, and (2) certain structural features in the valence band shift towards lower binding energies in the doped material. In particular, upon doping, a structural peak related to electronic levels mainly localized to the sulfur and b-carbon atoms destabilizes to an energy corresponding to that of the valence-band edge in pristine α-6T. The results of ab initio Hartree-Fock and local-spin-density calculations on α-trithienylene and bithiophene are consistent with the experimental data, and allow for an assignment of these destabilization effects in terms of initial-state relaxations. We stress that similar destabi-lization effects, reported for other alkali-metal-doped conjugated systems, had previously been proposed to be associated with final-state electronic screening, i.e., a dynamic artifact within the UPS measurements; this is in contradiction to the results of our ab initio theoretical studies. Our present results show that all structural features in the UPS data are contained in the results of sufficiently complete quantum chemical calculations.
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