排序方式: 共有27条查询结果,搜索用时 16 毫秒
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Figliozzi P Sun L Jiang Y Matlis N Mattern B Downer MC Withrow SP White CW Mochán WL Mendoza BS 《Physical review letters》2005,94(4):047401
Optical second-harmonic generation (SHG) is used as a noninvasive probe of the interfaces of Si nanocrystals (NCs) embedded uniformly in an SiO2 matrix. Measurements of the generated SH mode verify that the second-harmonic polarization has a nonlocal dipole form proportional to (E x Delta inverted) E that depends on inhomogeneities in the incident field E, as proposed in recent models based on a locally noncentrosymmetric dipolar response averaged over the spherical NC interfaces. A two-beam SHG geometry is found to enhance this polarization greatly compared to single-beam SHG, yielding strong signals useful for scanning, spectroscopy, and real-time monitoring. This configuration provides a general strategy for enhancing the second-order nonlinear response of centrosymmetric samples, as demonstrated here for both Si nanocomposites and their glass substrates. 相似文献
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S. Bodforss A. Holmgvist B. B. Malvea und J. R. Withrow 《Fresenius' Journal of Analytical Chemistry》1932,90(7-8):280-281
Ohne Zusammenfassung 相似文献
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P. Wenger Ch. Cimerman M. Wyszewianska F. Hecht R. Reissner M. Möller G. Schlegel M. W. Gaptschenko C. Sumuleanu G. Ghimieeseu L. Wolf W. Düsing A. Martos A. Stock A. Friedrich S. Rapoport J. S. Hughes und J. R. Withrow 《Fresenius' Journal of Analytical Chemistry》1937,109(5-6):204-209
Ohne Zusammenfassung 相似文献
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C.-M. Chan S.L. Cunningham M.A. Van Hove W.H. Weinberg S.P. Withrow 《Surface science》1977,66(2):394-404
Elastic low-energy electron diffraction (LEED) intensity versus voltage (I-V) measurements for the clean Ir(111) surface have been obtained. Seven specular I-V spectra were measured from 15 to 975 eV at incident angles from 7° to 62.5° relative to the surface normal. The outermost atomic layer spacing of the unreconstructed Ir(111) surface was determined both by the convolution-transform method we have presented previously (including certain convenient modifications) and by dynamical calculations. Results from the analysis of the I-V spectra by the convolution-transform method indicate that the outermost Ir(111) layer spacing is either unrelaxed or contracts by 4% of its bulk value depending upon whether the θ=7° data or the θ = 25° data are used. In agreement with this, the dynamical calculations show that the outermost Ir(111) layer spacing contracts by 2.5± 5% and, in addition, that the registry of the first layer of the crystal surface is not shifted, maintaining the fcc structure. 相似文献
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Katz CE Ribelin T Withrow D Basseri Y Manukyan AK Bermudez A Nuera CG Day VW Powell DR Poutsma JL Aubé J 《The Journal of organic chemistry》2008,73(9):3318-3327
The influence of attractive, nonbonded interactions on the reactions of 1,2- and 1,3-hydroxyalkyl azides with ketones has been investigated through experimental and computational means. A series of 1,3-hydroxyalkyl azides bearing electronically tuned aromatic groups at the 2 position were prepared and reacted along with several derivatives designed to conformationally restrict the rotational orientation of the aromatic substituent. These studies showed that a cation-pi interaction between an aryl moiety and an N2(+) leaving group plays a role in determining the stereoselectivity of these reactions. A series of ab initio calculations supported this hypothesis. A computational and experimental analysis suggested a primarily steric model for the analogous reactions of substituted 2-azido-1-ethanol analogues. 相似文献
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J. H. Stansbie E. Gilchrist A. Ch. Cumming J. R. Withrow Arthur J. White R. Belasio M. Marchionneschi Ch. Lind W. D. Treadwell A. Sieverts W. Wippelmann H. Graefe Geo Kemerer E. B. Spear S. S. Strahan C. B. Spear E. E. Tainton A. Mazzuchelli B. L. Murray E. P. Schoch F. M. Crawford John H. Reedy 《Analytical and bioanalytical chemistry》1917,56(5):246-253
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