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61.
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Based on the analysis of the near-field evanescent wave in total internal reflection, the flip-chip light-emitting diode (LED) structure was proposed by placing a plasmonic Ag grating and a perforated sapphire grating in the substrate. The finite difference time domain (FDTD) method has been applied to study the spectral properties of the hybrid structure and the enhancement factor of light extraction efficiency of the LED model. From the computation examples, the effects of structure parameters on the extraction enhancement have been investigated. The results indicate that the plasmonic grating can enhance the near-field evanescent wave and couple it to propagation wave in the specific wavelength bands, which leads to the photons emitting out of the LED chip with high extraction efficiency. Due to the combined gratings used, the enhancement factor of the light extraction efficiency can reach approximately 4 times at a relatively longer wavelength. 相似文献
63.
Asymmetric 1,4‐conjugation addition of dialkylzinc (diethylzinc and dimethylzinc) to cyclic enones, chalcone and nitroalkenes was achieved by a 25 mol% (R)‐6,6′‐Br2‐BINOL( 1f ), 25 mol% CuSPh and 100 mol% dicyclohexylmethylamin(Cy2NMe) catalyst system. The Cu(I) catalyst system enables the cyclic enone, chalcone and nitroalkene generality with high enantioselectivity (up to 84% ee) and isolated yield (up to 94%) under mild reaction conditions. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献
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α-Trifluoromethyl alkenes can be used as peptide isosteres, moreover, the pre-installed vinyl group make it possible that transformation to diverse fluorine-containing unities. However, the cross-coupling of benzyl group with α-trifluoromethyl alkenes has yet to be developed. In this report, we describe a general method for the cross-coupling of benzylzinc reagents with 2-bromo-3,3,3-trifluoropropene (BTP) to afford diverse α-trifluoromethylalkene derivatives by using Pd(TFA)2 as catalyst. This method takes advantage of cheap industrial available fluorine building blocks and easily prepared benzylzinc reagents to generate α-trifluoromethylalkene derivatives, which features with mild reaction conditions, wide substrate scope and feasibility of product transformations. 相似文献
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Enantioselective addition of diethylzinc to a series of aromatic aldehydes was developed using a modular amino acid amide chiral ligand (2S)‐3‐phenyl‐N‐((R)‐1‐phenyl‐ethyl)‐2‐(tosylamino)propanamide without using titanium complex. The catalytic system employing 10 mol% of 1g was found to promote the addition of diethylzinc (ZnEt2) to a wide range of aromatic aldehydes with electron‐donating and electron‐withdrawing substituents, giving up to 82% ee of the corresponding secondary alcohol under mild conditions. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
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Compact laser system for atom interferometry 总被引:1,自引:0,他引:1
P. Cheinet F. Pereira Dos Santos T. Petelski J. Le Gouët J. Kim K.T. Therkildsen A. Clairon A. Landragin 《Applied physics. B, Lasers and optics》2006,84(4):643-646
We describe an optical bench in which we lock the relative frequencies or phases of a set of three lasers in order to use them in a cold atom interferometry experiment. As a new feature, the same two lasers serve alternately to cool atoms and to realize the atomic interferometer. This requires a fast change of the optical frequencies over a few GHz. The number of required independent laser sources is then only three, which enables the construction of the whole laser system on a single transportable optical bench. Recent results obtained with this optical setup are also presented. PACS 32.80.Pj; 42.50.Vk; 39.20.+q 相似文献
70.
勾秉聪 《原子与分子物理学报》1997,14(4):505-510
采用马鞍点变分方法和复数转动技术,计算了类锂离子2s2p2p2S三激发共振态的能量,并运用截断变分方法得到能量改进量,以及计算了相对论效应、质量极化效应,从而获得了高精度的能量计算值。还计算了该系统的Auger宽度,位移和辐射跃迁率。 相似文献