| 1. |
- Xing, K. Z., et al.
(författare)
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The electronic and geometric structures of neutral and potassium-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy
- 1996
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 76:1-3, s. 263-267
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Tidskriftsartikel (refereegranskat)abstract
- The electronic and geometric structures of poly [3-(4-octylphenyl)thiophene] have been studied by X-ray and ultraviolet photoelectron spectroscopy (XPS and UPS, respectively). Thermochromic effects, and new charge induced states generated by potassium doping, have been observed by direct UPS measurements. The experimental results are in very good agreement with the results of theoretical quantum chemical calculations performed with the Austin Model 1 semi-empirical model and the valence-effective Hamiltonian pseudo-potential model.
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| 2. |
- Xing, K. Z., et al.
(författare)
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The electronic structure of neutral and alkali metal-doped poly[3-(4-octylphenyl)thiophene] studied by photoelectron spectroscopy
- 1996
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 80:1, s. 59-66
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Tidskriftsartikel (refereegranskat)abstract
- The electronic structure of poly [3-(4-octylphenyl)thiophene] (POPT) has been studied by ultraviolet photoelectron spectroscopy (UPS) and X-ray photoelectron spectroscopy (XPS), as well as by quantum chemical calculations. Both temperature-dependent effects on the electronic structure of the neutral system, as well as the generation of new electronic states induced by doping with alkaline metals, have been observed. The experimental results are in good agreement with the results of the quantum chemical calculations.
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| 6. |
- Carlsson, Bengt, et al.
(författare)
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Generous and greedy strategies
- 1999
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Ingår i: Complexity International. - 1320-0682. ; 6
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Tidskriftsartikel (refereegranskat)abstract
- We introduce generous, even-matched, and greedy strategies ÊÊas concepts for analyzing games. A two person prisoner's dilemma Êgame is described by the four outcomes (C,D), (C,C), (D,C), and (D,D). In a generous strategy the proportion of (C,D) is larger than that of (D,C), i.e. the probability of facing a defecting agent is larger than the probability of defecting. An even-matched strategy has the (C,D) proportion approximately equal to that of (D,C). A greedy strategy is an inverted generous strategy. The basis of the partition is that it is a zero-sum game given that the sum of the proportions of strategies (C,D) must equal that of (D,C). In a population simulation, we compare the prisoner's dilemma (PD) game with the chicken game Ê(CG), given complete as well as partial knowledge of the rules for moves in the other strategies. In a traffic intersection example, we expected a co-operating generous strategy to be successful when the cost for collision was high in addition to the presence of uncertainty. The simulation indeed showed that a generous strategy was successful in the CG part, in which agents faced uncertainty about the outcome. If the resulting zero-sum game is changed from a PD game to a CG, or if the noise level is increased, it will favor generous strategies rather than an even-matched or greedy strategies.
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| 7. |
- Dannetun, Per, et al.
(författare)
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Proceedings of the International Conference on Science and Technology of Synthetic Metals The chemical and electronic structure of the interface between aluminum and conjugated polymers or molecules
- 1993
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Ingår i: Synthetic metals. - : Elsevier. - 0379-6779 .- 1879-3290. ; 55:1, s. 212-217
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Tidskriftsartikel (refereegranskat)abstract
- The interaction between aluminum and α-ω-diphenyltetradecaheptaenee (DP7), α-sexithienyl (6T), and poly(p-phenylenevinylene) (PPV), respectively have been studied using both X-ray Photoelectron Spectroscopy (XPS) and Ultraviolet Photoelectron Spectroscopy (UPS). The UPS valence band spectra, are interpreted with the help of quantum chemical calculations based upon Modified Neglect of Diatomic Overlap (MNDO), Valence Effective Hamitonian (VEH) and ab initio Hartree-Fock methods. DP7 is a model molecule for polyacetylene, while 6T is a model molecule (an oligomer) of polythiophene. The results indicate that aluminum reacts strongly with the surfaces of all of the materials studied. The π-electronic structure of each material was strongly modified. Furthermore, aluminum reacts preferentially with the polyene partof DP7, with the vinylene part of PPV, and with the α-carbons of the thiophene nits of 6T.
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| 8. |
- Dannetun, Per, et al.
(författare)
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The chemical and electronic structure of the interface between aluminum and polythiophene semiconductors
- 1993
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 99:1, s. 664-672
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Tidskriftsartikel (refereegranskat)abstract
- We have investigated the chemical nature and the electronic structure of the interface between a low work function metal,aluminum, and a conjugated polymersemiconductor, polythiophene. We have studied the initial stages of the interface formation by depositing the metal onto the surface of a polymer film. Charge transfer processes between the metal and the polymer are analyzed using core‐level x‐ray photoelectron spectroscopy (XPS); the evolution upon metallization of the valence electronic levels directly related to the polymerelectronic structure is followed with ultraviolet photoelectron spectroscopy (UPS). With these techniques, we investigate the deposition of aluminum on two polythiophene systems (i) the alkyl‐substituted poly‐3‐octylthiophene and (ii) the α‐sexithiophene oligomer. The experimental data are compared to the results of a recent quantum chemical study on model systems consisting of thiophene oligomers (up to sexithiophene) interacting with a few Al atoms. The interaction of polythiophene with Al atoms is found to modify dramatically the structure of the conjugated backbone, as strong carbon–aluminum bonds are formed in the α positions of the thiophene rings. A large charge transfer takes place from the Al atoms to the polymer chain, and the upper π levels of the polymer are strongly affected. The metallization is contrasted to the doping of conjugated polymers with alkali metals
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