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1.
《原子与分子物理学报》2016,(4)
利用密度泛函理论研究锂原子修饰线型碳原子链团簇Li2Cm(m=2-8)的结构及其储氢性能.结果表明,Li原子可键合于碳链团簇的两端,Li原子本身不发生团聚,氢在Li2Cm(m=2-8)中能以分子形式吸附,每一个Li原子最多可吸附5个氢分子,氢分子的平均吸附能为0.460~2.276 kcal·mol-1.其中Li原子修饰C2团簇的质量储氢分数最大,为34.72 wt%,表明了它在常温常压条件下作为储氢材料的可行性. 相似文献
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Ruan Wen 《原子与分子物理学报》2017,34(6)
采用密度泛函方法对锂原子修饰线型硼原子链团簇Li2Bn(n=2~8)的结构及其储氢性能进行理论研究. 结果显示, Li原子可键合于硼链团簇的两端,氢能以分子形式吸附在Li原子周围, 每一个Li原子最多可吸附4个氢分子, 氢分子的平均吸附能为2.020 ~ 2.832 kcal.mol-1. 其中Li原子修饰B2小团簇的质量储氢分数最大,为31.24 wt%,表明在常温常压条件下它有可能成为一种潜在的储氢媒介. 相似文献
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采用密度泛函方法对锂原子修饰线型硼原子链团簇Li_2B_n(n=2~8)的结构及其储氢性能进行理论研究.结果显示,Li原子可键合于硼链团簇的两端,氢能以分子形式吸附在Li原子周围,每一个Li原子最多可吸附4个氢分子,氢分子的平均吸附能为2.020~2.832 kcal.mol~(-1).其中Li原子修饰B2小团簇的质量储氢分数最大,为31.24 wt%,表明在常温常压条件下它有可能成为一种潜在的储氢媒介. 相似文献
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本文采用密度泛函理论中的广义梯度近似系统地研究了钴原子修饰的(5,5)单壁氮化铝纳米管(SWANNT)的几何结构、电子性质以及储氢性能.研究结果表明:钴原子倾向于以顶位的形式吸附于(5,5) SWANNT表面N原子上.在钴原子周围可以吸附4个完整的H分子,平均吸附能为0.624 e V,表明钴原子修饰的SWANNT材料有望在温和环境中实现对H分子的快速吸附和脱附. 相似文献
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利用密度泛函理论研究锂原子修饰线型碳原子链团簇Li2Cm(m=2—8)的结构及其储氢性能. 结果表明, Li原子可键合于碳链团簇的两端,Li原子本身不发生团聚,氢在Li2Cm (m=2—8)中能以分子形式吸附,每一个Li原子最多可吸附5个氢分子,氢分子的平均吸附能为0.460 ~ 2.276 kcal.mol-1. 其中Li原子修饰C2团簇的质量储氢分数最大,为34.72 wt%,表明了它在常温常压条件下作为储氢材料的可行性. 相似文献
7.
为了研究Co对单层MoS_2电子结构和磁性的影响,本文基于第一性原理,采用数值基组的方法计算了Co吸附式掺杂、Co替代式掺杂单层MoS_2的能带结构、态密度以及分析了其结构的稳定性.结果发现:Co替换式掺杂体系的形成能较低,实验上容易实现;Co在Mo位吸附的稳定性强于在S位吸附;Mo位吸附体系的总磁矩为0.999μB,其磁矩的主要来源于Co原子的吸附所贡献的0.984μB,Co原子的掺杂体系总磁矩为1.029μB,其磁矩的主要由Co原子替代掉一个Mo原子所贡献的磁矩为0.9444μB,相比于吸附体系,Co原子对磁矩的贡献率有所降低;无论是Co吸附在单层MoS_2表面还是Co直接替代掉Mo原子的掺杂体系,Co原子3d轨道的引入是引起单层MoS_2体系磁性的主要原因. 相似文献
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阮文罗文浪余晓光谢安东伍冬兰金仕显 《原子与分子物理学报》2016,(4):615-620
利用密度泛函理论研究锂原子修饰线型碳原子链团簇Li2Cm(m=2-8)的结构及其储氢性能.结果表明, Li原子可键合于碳链团簇的两端,Li原子本身不发生团聚,氢在Li2 Cm ( m=2-8)中能以分子形式吸附,每一个Li原子最多可吸附5个氢分子,氢分子的平均吸附能为0.460~2.276 kcal·mol^-1.其中Li原子修饰C2团簇的质量储氢分数最大,为34.72 wt%,表明了它在常温常压条件下作为储氢材料的可行性. 相似文献
10.
《原子与分子物理学报》2017,(3)
采用包含色散力校正的密度泛函理论(DFT-D)方法系统地研究了气体分子(O_2,H_2,NO,CO,CO_2,SO_2,H_2S,H_2O)在Co掺杂单层BN(Co-BN)表面的吸附,分析了吸附小分子的几何结构,吸附能,电荷转移等情况.结果表明:1)CO等气体分子主要吸附在Co及其近邻六元环的顶位,吸附结构的电荷转移表明掺杂原子Co对BN衬底的气敏特性有较好的调制作用;2)在Co-BN表面吸附的O_2和CO较易被活化,表明Co-BN可能是一种对CO氧化有较好催化活性的新型催化材料. 相似文献
11.
Guided-Wave Two-Dimensional Acousto-Optic Scanner Using Proton-Exchanged Lithium Niobate Waveguide 总被引:1,自引:0,他引:1
Two-dimensional scanning of a 0.6328 mum guided-light beam has been realized using noncolinear acousto-optic (AO) coplanar Bragg diffraction together with colinear AO guided-mode to substrate radiation-mode conversion in a Z-cut Xpropagation LiNbO3 proton-exchanged (PE) waveguide. The two surface acoustic (SAW) waves utilized are at the center frequencies of 500 and 200 MHz, propagating in the Y and X axes, respectively. Two-dimensional scanning of approximately 720 resolvable light beam spots, namely, 18 40 (horizontal vertical) scanning, has been demonstrated using a light beam of 1.0 mm aperture. The total number of resolvable beam spots can be greatly increased from 720 by simply utilizing SAW transducers of larger bandwidth and a light beam of greater aperture. It should also be possible to significantly increase the diffraction efficiency from 3 % by optimizing the parameters of the PE waveguide and the SAWs. 相似文献
12.
S. G. Nedel’ko M. A. Krysyuk A. L. Apanasenko L. N. Lymarenko Z. T. Moroz 《Journal of Applied Spectroscopy》1997,64(1):55-61
Results of a study of the effect of γ-radiation on the spectral luminescence properties of cadmium tungstate crystals doped
with silver, bismuth, and molybdenum cations are presented. Spectral characteristics of the nondnnnoped crystals are briefly
described. Absorption and photo and X-ray luminescence spectra of the crystals taken before and after exposure to γ-radiation
(5.5·104 Gy) are compared. It is found that the spectral characteristics of the crystals doped with silver, bismuth, and molybdenum
cations do not change markedly after the exposure. The relation between the type of impurity-induced defects, individual characteristics
of the impurity cations, and the character of the effect of γ-radiation on the spectral luminescence properties of impure
crystals is analyzed (preliminarily).
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 1, pp. 55–60, January–February, 1997. 相似文献
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A multi-conjugate adaptive optics (MCAO) can offer a possibility of widening field of view (FOV) characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle's expressions of two deformable mirrors (DMs) MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance. 相似文献
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Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use. 相似文献
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40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm. 相似文献
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A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands. 相似文献
18.
References: 《声学学报:英文版》2008,27(1):85-96
Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation. 相似文献
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Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser. 相似文献
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Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored. 相似文献