排序方式: 共有13条查询结果,搜索用时 31 毫秒
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采用密度泛函理论对CO在阴离子团簇Aun+1-1、AunCr-1(n=1-10))表面的吸附做了系统研究.结果表明,团簇Aun+1CO-1、AunCrCO-1的基态结构是在团簇Aun+1-1、AunCr-1最低能量结构的基础上吸附CO形成; 吸附后的CO键长变长,振动频率减小,表明CO分子被活化;取值相同时,AunCrCO-1的平均结合能高,表明团簇Aun+1CO-1掺杂Cr后稳定性升高.HOMO-LOMO能隙结果表明Aun+1CO-1替代掺杂Cr原子后团簇的化学活性得到了提升,AunCrCO-1、Aun+1CO-1团簇能隙具有奇偶振荡的现象;轨道电荷分析表明CO与团簇相互作用实质是C原子与成键Au原子或Cr原子间转移电荷,CO在与团簇相互作用过程中O原子轨道电荷分布几乎没有发生变化. 相似文献
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研究了利用光辐照法制作光折变波导时LiNbO3:Fe晶体中折射率变化的规律.分别采用波长为6328nm和532nm的寻常偏振和非常偏振的细激光束和片状激光束,在LiNbO3:Fe晶体中进行了写入波导实验.研究表明,制作波导的写入光宜采用寻常偏振光.在利用由光束辐照LiNbO3:Fe晶体形成的正折射率变化区域作为波导结构时,必须严格控制辐照时间.否则,由于长时间光辐照会带来较强的噪音栅以及折射率变化区域会发生扩展,而难以形成优 质波导.利用片光在“三明治”方式辐照下,以小曝光量制作波导时,可以避免噪音栅的
关键词:
光致折射率变化
光折变波导
光辐照法
LiNbO3:Fe晶体 相似文献
4.
Slide-away discharges are achieved by decreasing the plasma density or ramping down the plasma current in runaway discharges in the HT-7 tokamak. In the case of plasma current ramp down, the ratio of the electron plasma frequency to the electron cyclotron frequency is higher than in the stationary pulses when the discharge goes into a slide-away regime. The instability regime is characterized by relaxations in the electron cyclotron emission due to relativistic anomalous Doppler effect which transfers energy from parallel to perpendicular motion. The triggering of relativistic anomalous Doppler effect at higher density by ramping down of plasma current may provide a alternative runaway energy control scenario. 相似文献
5.
The effects of relativistic broadening and frequency down-shift on electronben cyclotron emission measurements in EAST 下载免费PDF全文
Liu Yong Han Xiang Ti Ang Wang Yu-Min Ling Bi-Li Hu Li-Qun Gao Xiang 《中国物理 B》2012,21(4):45201-045201
This paper presents a theoretical calculation of the effects of relativistic broadening and frequency down-shift on the electron cyclotron emission measurements for a wide range of plasma parameters in the Experimental Advanced Superconducting Tokamak (EAST). The calculation is based on the radiation transfer equation, with the reabsorption and reemission processes taken into account. The broadening effect contributes to the radial resolution of the measurement, and the calculation results indicate that it is ~2 cm in the case of the central electron temperature 10 keV. A pseudo radial displacement of the obtained electron temperature profile occurs if the relativistic frequency down-shift effect is not taken into account in the determination of the emission layer position. The shift could be a few centimeters as the electron temperature increases, and this effect should be taken into account. 相似文献
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本文采用密度泛函理论对NO在阴离子团簇AunMg-1、Aun-1 (n=1-8)表面的吸附做了系统研究.结果表明, 团簇AunMgNO-1、AunNO-1的基态与亚稳定结构是在团簇AunMg-1、Aun-1最低能量结构的基础上吸附NO形成,NO的吸附没有改变团簇AunMg-1、Aun-1的最低能量结构;吸附后的NO键长变长, 表明NO分子被活化,此外吸附后的NO均带负电;计算表明团簇AunMgNO-1、AunNO-1吸附能都具有奇偶振荡的现象,取值相同时,AunMgNO-1的吸附能较低,表明团簇AunNO-1掺杂Mg后稳定性降低;HOMO-LOMO能隙结果表明AuMgNO-1活性最低、总体上AunNO-1掺杂Mg原子后团簇的化学活性降低. 相似文献
7.
利用扩展的准直He-Ne激光束通过菲涅耳双棱镜所形成的干涉光场辐照SBN:Cr晶体, 同时沿晶体光轴方向施加适当的直流电场,可在晶体中形成类似于体相位光栅结构的阵列平 面光波导. 采用马赫-曾德干涉仪光路实时测量了所写入阵列平面光波导的横向折射率分布 ,其峰值接近10-4. 初步的导光测试结果表明,利用周期结构光辐照并辅以适当的外加电场在SBN:Cr晶体中写入阵列平面光波导是可行的. 并且由于SBN:Cr晶体的快速响应特性,所写入的光波导是动态的,可随着写入光的撤除而快速消失,或通过改变双光束夹角
关键词:
SBN:Cr晶体
结构光辐照
阵列平面光波导
折射率分布
外电场 相似文献
8.
借助第一性原理计算,对VOBr2单层的结构、磁性以及铁电性进行了系统研究.计算结果表明低温下VOBr2会产生自发铁电极化,从高对称顺电相转变为铁电相结构.与同族姊妹材料VOI2不同的是,V的二聚化现象不仅无法在VOBr2中稳定存在,还会导致局域磁矩淬灭.此外,VOBr2易磁化轴在面内a轴方向,面内a,b轴上近邻磁矩均为反铁磁耦合.VOBr2中的铁电极化主要由V在a轴方向V—O—V链上的铁电位移产生,大小约为40μC/cm~2.与铁电同步翻转相比,通过分步翻转不同链上的铁电极化,可以有效降低铁电翻转能垒,从而有望通过低能外场实现部分或个别链上的铁电翻转,为低能耗高密度铁电存储器件设计提供新的思路和方向. 相似文献
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Anatase phase visible-light-driven TiO2 yolk-shell spheres with the size of ca. 1-2 μm have been synthesized with the combination of solvothermal and heat treatment method. XRD, SEM, TEM, XPS, and PL analysis were used to examine structure and properties of the photocatalyst. The N species and Ti3+ centers introduced into the as-prepared photocatalyst can enhance the visible light absorption significantly. The mesoporous shell of the prepared photocatalyst, which promotes the pollutant adsorption ability, consists of the high-reactive {0 0 1} facets dominated nanocrystals. Due to the unique structure, it is also observed that the as-prepared visible-light-driven TiO2 yolk-shell spheres exhibit a superior photocatalytic activity for organic dyes decomposition than the well-known P25. 相似文献
10.
Operation of HT-7 tokamak in a multicycle alternating
square wave plasma current regime is reported. A set of AC operation
experiments, including LHW heating to enhance plasma ionization
during the current transition and current sustainment, is described.
The behaviour of runaway electrons is analysed by four HXR detectors
tangentially viewing the plasma in the equatorial plane, within
energy ranges 0.3--1.2~MeV and 0.3--7~MeV, separately. High energy
runaway electrons (\sim MeV) are found to circulate predominantly
in the opposite direction to the plasma current, while the number of
low energy runaway electrons (\sim tens to hundreds of keV)
circulating along the plasma current is comparable to that in the
direction opposite to the plasma current. AC operation with lower
hybrid current drive (LHCD) is observed to have an additional
benefit of suppressing the runaway electrons if the drop of the loop
voltage is large enough. 相似文献