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991.
992.
黎新 《武汉大学学报(理学版)》2007,53(2):160-164
用 Onsager 模型和密度泛函B3LYP方法在6-31G^*基组水平上对邻二甲苯分子的几何构型进行了全优化,计算了最优构型的红外光谱.将计算所得的邻二甲苯的红外频率与其Sadtler标准红外光谱进行了比较,确定了邻二甲苯的分子结构,并对红外光谱进行了归属.同时,对 Onsager 模型的适用性进行了讨论,进而得出了 Onsager 模型适于研究纯液态的邻二甲苯分子结构和红外光谱的结论. 相似文献
993.
994.
Radioactive decay of super heavy nuclei via the emission of α-particles has been studied theoretically in the preformed cluster model (PCM). The nucleus-nucleus (NN) potential is obtained by double folding the density distributions of the α-particle and the daughter nucleus with a realistic effective interaction. The M3Y effective interaction, supplemented by a zero-range pseudo-potential for exchange term, is used to calculate the NN potential. The α decay half-lives for 317 nuclei at Z=102 120 are performed in the PCM framework with the theoretical Q values extracted from the MSller-Nix-Kratz and Liran-Marinov-Zeldes mass tables and are compared with the experimental data. The calculated results are also compared with those obtained by using Q values from the Muntian-Hofmann-Patyk-Sobiczewski and Myers-Swiatecki mass estimates. 相似文献
995.
The cross sections of the fragments produced in the projectile fragmentation reactions of the even calcium isotopes from A=36 to A=52 are calculated using the statistical abrasion ablation model.The neutron skin thickness are studied by investigating the fragments isotopic cross section distributions.The neutron-skin thicknesses of the calcium isotopes have a good linear correlation to the peak positions of their fragment isotopic cross section distributions.The correlation between the neutron skin thickness and the neutron density distributions of 48 Ca is investigated by introducing a parameter to adjust the diffuseness parameter in the fermi-type density distribution. 相似文献
996.
Stable Narrow Linewidth 689nm Diode Laser for the Second Stage Cooling and Trapping of Strontium Atoms 下载免费PDF全文
We report stable narrow linewidth laser systems based on self-developed Littman configuration external cavity diode lasers (ECDLs). The frequency of the ECDL is stabilized to a high fineness ultralow-expansion glass reference cavity with the Pound-Drever-Hall technique. By heterodyne beating of two identical systems, we conclude that the linewidth 4.3× 10^-14 at an averaging measurement time. of each ECDL is reduced to lower than 150 Hz and its frequency stability reaches time of 1 s, the averaged long-term frequency drift is less than 0.2 Hz/s over 30 h 相似文献
997.
We report observations of the enhancement and suppression of four-wave mixing (FWM) in an electromagnetically induced transparency window in a Y-type ^85 Rb atomic system. The results show the evolution of the dressed effects (from pure enhancement to partial enhancement/suppression, and finally into pure suppression) in the degenerate-FWM processes. Moreover, we use the perturbation chain method to describe the FWM process. Finally, we observe the polarization dependence of the enhancement and suppression of the FWM signal. 相似文献
998.
We perform a first-principles calculation based on density functional theory to investigate the interface between single layer graphene and metal oxides. Our study reveals that the monolayer graphene becomes semiconducting by single crystal SiO2 and Al2O3 contact, with energy gaps to - 0.9 and - 1.8 eV, respectively. We find the gap originates from the breakage of π bond integrity, whose extent is related to the interface atom configuration. We believe that our results highlight a promising direction for the feasibility to apply large scale graphene layers as building blocks in future electronics devices. 相似文献
999.
Narrow Linewidth Tm^3+-Doped Large Core Fiber Laser Based on a Femtosecond Written Fiber Bragg Grating 下载免费PDF全文
A diode laser (LD) clad-pumped narrow linewidth all-fiber Tm^3+-doped fiber laser is reported with a maximal output power of 27W at 1.947μm. By successively splicing an LD pigtail fiber, a single-mode Tm^3+-doped fiber, and a multi-mode Tm^3+-doped fiber, the fiber laser has 70pm narrow linewidth output, and a high slope efficiency of nearly 47.5% with respect to the launched pump power. The high reflectivity fiber Bragg gratings, which are directly written into the single-mode Tm^3+-doped fiber core by the 800nm femtosecond pulsed laser, act as the high reflectivity coupler. The output laser has diffraction-limited beam quality with a factor M^2 of 1.29, when the output laser power is nearly 27W. 相似文献
1000.
We present a comparison between intracavity cooling and external cavity cooling for optical refrigeration. The results show that the intracavity scheme is preferred at low optical densities (〈 0.008), while the external cavity scheme is preferred at higher optical densities (〉 0.01). We can choose the proper scheme for different eases in experiments. Moreover, under the same conditions, taking Yb^3+-doped ZBLAN (ZrF4-BaF2-LaF3-AlFa-NaF) film as an example, the cooling processes of the two scheme are obtained. The calculated results show that intracavity cooling will achieve a larger temperature drop for a thin film sample. Finally, the diode laser may become a candidate for the intraeavity model briefly discussed. 相似文献