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61.
The cyclization reactions of the 4-pentenyl, 5-hexenyl, 6-heptenyl, and 7-octenyl fluorinated and ether radicals have been studied by a hybrid Hartree-Fock density functional method. The reliability of this approach has been confirmed in agreement with experimental data and post-Hartree-Fock projected M?ller-Plesset second-order method. The analysis of the theoretical results shows that two factors are crucial for the determination of the regiochemistry and the reactivity of these reactions. The first factor is the ability of the starting radical to have a stable conformation in position to form the transition state, and the second one is the enthalpic effect of the reaction through the stability of the resulting cyclized radical. It should be pointed out that these factors are not linked to the polarity of the radicals due to the presence of CF2 groups. 相似文献
62.
P. Billaud J.-R. Huntzinger E. Cottancin J. Lermé M. Pellarin L. Arnaud M. Broyer N. Del Fatti F. Vallée 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2007,43(1-3):271-274
The extinction spectrum of single silver nanoparticles
with size ranging from 20 to 80 nm is investigated with the spatial
modulation spectroscopy technique using either a tunable laser or a white
lamp as the broadband source. Results are in good agreement with the
prediction of the Mie theory, permitting to extract the nanoparticle size
from the measured absolute value of the optical extinction cross-section. In
contrast, the deduced refractive index of the nanoparticle environment and
the reduction of the electron mean free path show a large dependence on the
precise value of the bulk silver dielectric function. 相似文献
63.
We address the problem of degree of polarization (DOP) estimation in images limited by additive Gaussian detector noise. We derive and analyze the probability density function (PDF) of the pixelwise DOP estimate, which is shown to have significantly different statistical properties than when noise is Gamma distributed (speckle). We then determine the Cramer-Rao Lower Bound and the maximum likelihood estimator of the DOP. We deduce from this study practical solutions for characterizing and reducing the noise in these images. 相似文献
64.
Sébastien DegorceFrédéric H. Jung Craig S. Harris Patrice KozaJonathan Lecoq Arnaud Stevenin 《Tetrahedron letters》2011,52(50):6719-6722
The synthesis of differentially-substituted 3,5-bis(arylamino)pyrazoles has not yet been documented. During our investigation, we managed to develop a novel, entirely combinatorial synthesis of 3,5-bis(arylamino)pyrazoles relying on a simple one-pot two-step operation. 相似文献
65.
Julien Amalric Claude Poleunis Arnaud Delcorte Jacqueline Marchand-Brynaert 《Surface science》2012,606(13-14):1071-1077
Chalcogenide glasses are useful optic materials that find applications in infrared spectroscopy, sensors and thermal imaging. A route for direct surface modification of such glasses with organic layers has been investigated by static Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). The GAS (germanium–arsenic–selenium) glasses are modified by deposition followed by UV-irradiation of disulfide- or/and silane-functionalized organic molecules. SIMS analysis shows the characteristic fragments of the grafted molecules and organic–inorganic fragments which prove unambiguously the binding mode to the surface: disulfides, after S–S cleavage, are linked to arsenic and selenium; triethoxysilanes bind exclusively to oxidized germanium. The successive grafting of disulfide and silane compounds on the same substrate (IG2 glass with 33% of Ge) affords a “mixed” organic layer on the glass surface. From water contact angle measurements and X-ray Photo-electron Spectroscopy (XPS), the coverage density is not significantly improved comparatively to the “non-mixed” layers. However, the grafting of both types of molecules allows to reach a more homogeneous coverage. 相似文献
66.
Lionel Santinacci Anne-Marie Gonçalves Muriel Bouttemy Arnaud Etcheberry 《Journal of Solid State Electrochemistry》2010,14(7):1177-1184
In this paper, we investigate the properties of porous structures anodically grown onto n-InP (100) in HCl. In situ electrochemical
characterizations show the pore morphology strongly influences the properties of the InP surfaces. Both dc- and ac-electrochemical
measurements reveal an enhancement of the capacitive current and a modification of the electronic distribution at the interface.
Photocurrent spectra performed during the pore growth are also strongly modified. For low anodic charges, an increase of the
photocurrent with a redshift of the absorption edge is measured. These evolutions can be respectively ascribed (i) to a reflection decrease due to a surface roughening and (ii) to the creation of surface states within the band gap. For higher anodic charges, the photocurrent drops with a narrowing
of the spectrum. Using a model based on the “dead” layer, the porous layer is considered as an absorbent film that progressively
attenuates the photocurrent of the bulk semiconductor. 相似文献
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70.
Véronique Dupuis Nils Blanc Luis E. Diaz-Sanchez Arnaud Hillion Alexandre Tamion Florent Tournus Gustavo M. Pastor Andrei Rogalev Fabrice Wilhelm 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2013,67(2):1-4
In this paper, the one-way absorption property in one-dimensional dielectric/metal photonic crystal structure with a dielectric defect layer is studied. The effects of incident angle and state of polarization on one-way absorption behaviour of the anti-resonant (AR) mode are investigated. The normally incident wave from left to right propagation is totally allowed to penetrate to the structure but right to left propagation totally reflected at the same wavelength. It is found that, with increasing of the incident angle, the AR mode shifts to the lower wavelengths and its intensity decreases. Simultaneously, another AR mode with reversed one-way property appears at higher wavelength. The one-way behaviour on absorption is observed at the both states of polarizations but is localized on different wavelengths. Those effects, are suggesting that the proposed structure can be used as a direction sense polarization splitter or reflector/antireflector device. 相似文献