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991.
The influence of the well width fluctuations on the dependence of the binding energy of excitonic complexes in quantum wells is studied by using the path-integral Monte-Carlo technique. The results are compared with available experimental data and a good agreement is found.Postdoctoral researcher of FWO-Vlaanderen 相似文献
992.
Th. Münzel A. Wynter Blyth Kützing Ch. Girard 《Analytical and bioanalytical chemistry》1882,21(1):436-438
993.
Electron spin resonance (ESR) study was done on calcite encrustation on Fili neotectonic fault surface, Greece. Normally such
calcite encrustations on fault surfaces are not observed. Significantly, the ESR study has detected the presence of nitrate
NO32− radical in this calcite encrustation, havingg
⊥=2.0063±0.0001 and hyperfine coupling constantA
⊥=3.44 mT, the second such detection of nitrate NO32− radical following a sample from Scott Glacier, Antarctica. From isochronal thermal annealing measurement the NO32− radical was found to be quite stable, only fully annealed at 475°C. This study also shows that the ESR, as a tool, can be
suitably applied to date the age of formation of the calcite encrustation with SO3− as an ESR dating signal by additive γ-ray irradiation. A preliminary estimation indicates the age of formation of calcite
precipitation at Fili fault, Greece to be about 5600 years. 相似文献
994.
995.
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997.
C. Mattea N. Fatkullin E. Fischer U. Beginn E. Anoardo M. Kroutieva R. Kimmich 《Applied magnetic resonance》2004,27(3-4):371-381
Linear polyethylene oxides with molecular weightsM w of 1665 and 10170 confined in pores with variable diameters in a solid methacrylate matrix were studied by proton field-cycling nuclear magnetic resonance relaxometry. The pore diameter was varied in the range of 9–57 nm. In all cases, the spin-lattice relaxation time shows a frequency dependence close toT 1∞ v3/4 in the range ofv=3·10?1-2·101 MHz as predicted by the tube-reptation model. This protonT 1 dispersion essentially reproduces that found in a previous deuteron study (R. Kimmich, R.-O. Seitter, U. Beginn, M. Möller, N. Fatkullin: Chem. Phys. Lett. 307, 147, 1999). As a feature particularly characteristic for reptation, this finding suggests that reptation is the dominating chain dynamics mechanism under pore confinement in the corresponding time range. The absolute values of the spin-lattice relaxation times indicate that the diameter of the effective tubes in which reptation occurs is much smaller than the pore diameters on the time scale of spin-lattice relaxation experimens. An estimation leads to a valued *~0.5 nm. The impenetrability of the solid pore walls, the uncrossability of polymer chains (“excluded volume”) and the low value of the compressibility in polymer melts create the “corset effect” which reduces the lateral motions of polymer chains to a microscopic scale of only a few tenths of a nanometer. 相似文献
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999.
C. A. M. Balling 《Analytical and bioanalytical chemistry》1880,19(1):200-202
1000.