| 1. |
- Adebahr, J, et al.
(author)
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Ion and solvent dynamics in gel electrolytes based on ethylene oxide grafted acrylate polymers
- 2002
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In: The Journal of Physical Chemistry Part B. - : American Chemical Society (ACS). - 1520-5207 .- 1520-6106 .- 1089-5647. ; 106:47, s. 12119-12123
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Journal article (peer-reviewed)abstract
- Multinuclear pulsed field gradient NMR measurements and theological viscosity measurements were performed on three series of polymer gel electrolytes. The gels were based on a lithium salt electrolyte swollen into a copolymer matrix comprising an acrylate backbone and ethylene oxide side chains. In each series the side chains differed in length and number, but the acrylate-to-ethylene oxide ratio was kept constant. It was found that the self-diffusion coefficient of the cations was much lower than that of the anions, and that it decreased rapidly when the side chains got longer. In contrast, the self-diffusion coefficient of the anions was found to be independent of chain length. In the gel electrolytes, the diffusion coefficients of the solvent molecules are relatively constant despite an increased viscosity with increasing length of the side chains. However, in saltfree gels made for comparison, the diffusion coefficients of the solvent molecules decreased with, increasing length of the side chains, which is consistent with an increased viscosity.
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| 2. |
- Cohen, David, et al.
(author)
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Modulated Fourier expansions of highly oscillatory differential equations
- 2003
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In: Foundations of Computational Mathematics. - : Springer Science and Business Media LLC. - 1615-3375 .- 1615-3383. ; 3:4, s. 327-345
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Journal article (peer-reviewed)abstract
- Modulated Fourier expansions are developed as a tool for gaining insight into the long-time behavior of Hamiltonian systems with highly oscillatory solutions. Particle systems of Fermi-Pasta-Ulam type with light and heavy masses are considered as an example. It is shown that the harmonic energy of the highly oscillatory part is nearly conserved over times that are exponentially long in the high frequency. Unlike previous approaches to such problems, the technique used here does not employ nonlinear coordinate transforms and can therefore be extended to the analysis of numerical discrelizations.
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| 3. |
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| 4. |
- Kilså, Kristine, et al.
(author)
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Enhanced Intersystem Crossing in Donor/Acceptor Systems Based on Zinc/Iron or Free-Base/Iron Porphyrins
- 2001
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In: Chemistry, A European Journal. - 1521-3765 .- 0947-6539. ; 7:10, s. 2122-33
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Journal article (peer-reviewed)abstract
- The deactivation pathways of the singlet excited state of a series of zinc or free-base donor porphyrins covalently linked by a bridge to a paramagnetic iron(iii) chloride porphyrin acceptor have been studied. These donor-bridge-acceptor systems all share a similar geometry (25 Å donor-acceptor center-to-center distance), but the bridges vary in electronic structure. In previously reported investigations of zinc/iron porphyrin systems, the fluorescence quenching of the donor has predominantly been assigned to electron transfer. However, for the porphyrin systems studied in this paper, we show that the dominant deactivation channels are enhanced intersystem crossing and singlet energy transfer. In both series, the intersystem crossing rate (S1T1) of the donor moiety is almost doubled in the presence of a paramagnetic high-spin metal-porphyrin acceptor. The significant spectral overlap of the donor fluorescence and acceptor absorption in both series allows for efficient singlet energy transfer (Förster mechanism). Furthermore, the bridging chromophores mediate energy transfer and the enhancement is inversely dependent upon the energy gap between the donor and bridge excited states. Although Marcus theory predicts thermodynamically favorable electron transfer to occur in the systems investigated, the quenching rate constants were found to be independent of solvent polarity, and no charge-separated state could be detected, indicating very small electronic coupling for electron transfer.Supporting information for this article is available on the WWW under http://www.wiley-vch.de/contents/jc_2111/2001/f2779_s.pdf or from the author. 1H NMR spectra of FeP, FeP-OB, FeP-BB, FeP-NB, FeP-AB, ZnP-OB-FeP, ZnP-BB-FeP, ZnP-NB-FeP, and ZnP-AB-FeP.
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| 5. |
- McRae, Edward, et al.
(author)
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Raman light scattering and c-axis resistivity evidence for a pressure-induced stage transformation in PdAl2Cl8 intercalated graphite.
- 2000
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In: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 62:20, s. 13757-13766
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Journal article (peer-reviewed)abstract
- We have examined several samples of first- to third-stage PdAl2Cl8-intercalated graphite under hydrostatic pressures up to 1 GPa. In stage-1 highly oriented pyrolytic graphite–(HOPG) and single-crystal-graphite-based materials, the c-axis resistivity decreases sharply above a few kilobars; pressure release induces a reversible return to the initial value only in the case of the latter sample. Raman spectra taken in situ under pressure on a HOPG-based material show similarly irreversible effects. Analysis of the spectra taken on higher-stage samples leads to the conclusion that hydrostatic pressure beyond a few kilobars increases the density of the intercalate within the graphitic galleries, transforming the initial sample to a higher-stage material. Since there is no loss of intercalate, the overall intercalate-to-host charge transfer remains constant so that the Raman frequency is approximately the same for both first- and second-stage products. This is an unusual situation in which there is thus an apparent lack of Raman signature in spite of the stage change.
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| 6. |
- Isaksson, Anders, 1965
(author)
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Venture Capital - begrepp och definitioner
- 2000
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In: Svenska Riskkapitalföreningens medlemsmatrikel 2000/2001. - Stockhom : Svenska Riskkapitalföreningen. ; , s. 28-32
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Book chapter (other academic/artistic)abstract
- Venture capital som begrepp är relativt nytt i Sverige. Som så mycket annat inom det finansiella området har begreppsapparaten även färgats starkt av USA där venture capital, som en definierad investeringsform, funnits sedan 50-talet. Svenska begrepp blandas friskt med engelska eller ”svengelska” begrepp. Snarlika engelska ord som venture capital och riskcapital har i många svenska översättningar blivit synonymer. Kombinationen av branschens ungdom i det svenska språket och svåröversatta uttryck och facktermer har därför inneburit en viss begreppsförvirring. Denna artikel syftar därför att reda ut en del av de begrepp och definitioner förekommer inom området.
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| 7. |
- Kilså, Kristine, 1972, et al.
(author)
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Bridge-dependent electron transfer in porphyrin-based donor-bridge-acceptor systems
- 2001
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In: Journal of the American Chemical Society. - : American Chemical Society (ACS). - 1520-5126 .- 0002-7863. ; 123:13, s. 3069-3080
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Journal article (peer-reviewed)abstract
- Photoinduced electron transfer in donor-bridge-acceptor systems with zinc porphyrin (or its pyridine complex) as the donor and gold(III) porphyrin as the acceptor has been studied. The porphyrin moieties were covalently linked with geometrically similar bridging chromophores which vary only in electronic structure. Three of the bridges are fully conjugated pi -systems and in a fourth, the conjugation is broken. For systems with this bridge, the quenching rate of the singlet excited state of the donor was independent of solvent and corresponded to the rate of singlet energy transfer expected for a Forster mechanism. In contrast, systems with a rr-conjugated bridging chromophore show a solvent-dependent quenching rate that suggests electron transfer in the Marcus normal region. This is supported by picosecond transient absorption measurements, which showed formation of the zinc porphyrin radical cation only in systems with pi -conjugated bridging chromophores. On the basis of the Marcus and Rehm-Weller equations, an electronic coupling of 5-20 cm(-1) between the donor and acceptor is estimated for these systems. The largest coupling is found for the systems with the smallest energy gap between the donor and bridge singlet excited states. This is in good agreement with the coupling calculated with quantum mechanical methods, as is the prediction of an almost zero coupling in the systems with a nonconjugated bridging chromophore.
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