排序方式: 共有59条查询结果,搜索用时 46 毫秒
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椅型碳纳米管电子结构与长度效应 总被引:8,自引:2,他引:8
采用PM3方法对含帽结构的三种(5,5)椅型有限长碳纳米管的构型和电子结构进行了系统研究,结果表明,随着管长度的增加,除了最高占据轨道(HOMO)和最低空轨道(LUMO)之间的能隙(Eg)出现周期性的变化外,纳米管端“表面”(管的末端和管帽)构型也出现周期振荡现象,通过研究同种类型纳米管三组不同的长度效应,发现属于同一组的纳米管具有相似的构型和电子结构变化规律,此外,研究表明纳米管帽的尺寸效应可以看成为一定长度管壁的简单延伸,揭示了含帽与不含帽纳米管电子结构之间的相似性。本文还对处在管末端以及管帽上的表面态及其化学反应性进行了探讨。 相似文献
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Yong-Hong Ma Rong Zhao Xing-Wang Hou Jia-Wei Liu Ming-Xin Li Xinyu Zhao 《Annalen der Physik》2023,535(4):2200470
Chaos is important in nonlinear science and promotes the development of fundamental studies, such as neural networks, extreme event statistics, and electron transport. In this paper, a theoretical scheme for generating dynamical chaos in a Fabry–Perot cavity with two-level atoms is investigated. Through the injection of atoms, controllable chaos of the cavity and mechanical oscillator is achieved simultaneously by the external laser field. The trajectory and the maximal Lyapunov exponent that characterize the properties of the chaos could be optimized by adjusting the coupling constant, driving field, injection of atoms, the frequency of the cavity, and the frequency of the mechanical oscillator. This study provides a new idea to manipulate the cavity and mechanical chaos assisted by two level atoms. It is hoped that the results presented can benefit controllable chaos generation and its applications. 相似文献
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Qin-Pei Wu Ming-Xin Zhou Di Song Hai-Xia Liu Qing-Shan Zhang 《Tetrahedron letters》2008,49(17):2714-2718
The transformation of acetonides into the corresponding diacetates is often required in the synthetic chemistry. An efficient procedure for direct conversion of acetonides into diacetates in the presence of Bi(OTf)3·xH2O under mild conditions has been developed. Primary hydroxyl-acetonides could be selectively transformed into diacetates in the presence of anomeric acetonides and the anomeric acetonides could be tunably converted into 2-acetoxyisopropyl or diacetate groups. 相似文献
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芳基伯胺与芳基溴在Pd(dba)2/P(t-Bu)3催化下于80 ℃甲苯溶液中反应生成芳基仲胺, 芳基仲胺再与3-溴苯并[de]蒽-7-酮在Pd(OAc)2/P(t-Bu)3催化下于120 ℃邻二甲苯溶液中反应生成苯并[de]蒽-7-酮类叔芳胺有机电致发光材料; 3-二苯基氨基苯并[de]蒽-7-酮与丙二腈反应生成2-(3-二苯基氨基)苯并[de]蒽-7-基亚基丙二腈. 产物的结构经1H NMR, 13C NMR, 13C (DEPT), HRMS光谱所证实. 用UV-Vis, PL, DSC测定了化合物的发光性能. 相似文献
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MANG Chao-Yong ZHANG Ming-Xin WU Ke-Chen ② 《结构化学》2006,25(5):517-522
1 INTRODUCTION Triangular close shell d10 complexes of Cu, Ag and Au have attractive luminescent properties. The weakly metal-metal interactions, which are inter- or intra-molecular interactions, will notably affect their photophysical properties. It was until recently that Balch et al reported an Au3 complex exhibiting “sol- voluminescence”[1], although several triangular Au3 compounds have been synthesized as early as 1970s. Whereafter, some unusual phenomena, such as “tibo- lumine… 相似文献
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Design of a compact polarization beam splitter based on a deformed photonic crystal directional coupler
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In this paper a compact polarization beam splitter based on a deformed photonic crystal directional coupler is designed and simulated. The transverse-electric (TE) guided mode and transverse-magnetic (TM) guided mode are split due to different guiding mechanisms. The effect of the shape deformation of the air holes on the coupler is studied. It discovered that the coupling strength of the coupled waveguldes is strongly enhanced by introducing elliptical airholes, which reduce the device length to less than 18.Sttm. A finite-difference tlme-domain simulation is performed to evaluate the performance of the device, and the extinction ratios for both TE and TM polarized light are higher than 20 dB. 相似文献
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通过电纺丝法结合原位还原及原位氧化反应, 成功制备了均匀负载Ag/AgCl复合纳米粒子/聚丙烯腈(PAN)复合纳米纤维膜. 首先利用电纺丝技术制备了PAN/AgNO3复合纳米纤维, 然后用乙二醇将硝酸银还原成银纳米粒子, 最后采用三氯化铁溶液对材料进行原位氧化. 所得纤维膜材料可以作为高效的可见光催化剂, 具有高可见光利用率, 优异的柔性和高光催化动力学等特性. 相似文献
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研究了慢光模式在SOI(silicon-on-insulator)材料光子晶体线缺陷弯折波导中的传输特性. 通过优化波导弯折处的结构参数,慢光模式在光子晶体60°与120°弯折波导中的透射率提高10倍以上,归一化透射率分别达到80%和60%以上. 为了进一步减慢光速,设计了新颖的高Q值耦合腔弯折波导结构,在归一化透射率达到75%的基础上,光波群速度低至c/170(c为真空光速). 研究结果对于增强光子晶体的慢光效应,提高光子晶体慢光器件的微型化和集成化都有一定的积
关键词:
光子晶体
慢光
弯折波导
透射率 相似文献