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61.
An analysis is made on the absorption distribution within a cylindrical active medium lamp pumped by means of fused silica light-guides. The performances of the proposed pump cavities are analysed through a non-sequential 3D ray-trace program and are compared to those of three reflective chambers: an elliptical cavity, a close-coupled cavity and a diffusive close-wrap cavity. Two light-guides cavities with eight and nine guides, respectively, were built and tested. High coupling efficiency and a reasonable uniform absorption distribution were registered. An overall laser efficiency of 1% was measured. The proposed cavities have permitted the tailoring of the absorption distribution within the laser rod. 相似文献
62.
Haohai Yu Dawei Hu Huaijin Zhang Zhengping Wang Wenwei Ge Xinguang Xu Jiyang Wang Zongshu Shao Minhua Jiang 《Optics & Laser Technology》2007,39(6):1239-1242
In single-pass configuration, a picosecond pulse laser was used to investigate the stimulated Raman scattering in different BaWO4 crystals. Using the thresholds for the first Stokes line along the a- and c-axis, the Raman gain coefficients of the BaWO4 crystals were calculated along their respective direction. The higher Stokes (fourth) and anti-Stokes (third) lines were observed. Compared with other well-known Raman crystals, such as KGd(WO4)2 and Ba(NO3)2, BaWO4 has favorable properties for scattering the pump radiation with picosecond pulse duration. The Raman gain coefficients of BaWO4 are different, but do not vary for different transmission directions, which means that this Raman material can be selected more freely. 相似文献
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65.
本文用红外光致发光方法研究了InP中与C带有关的深能级的性质和起源。峰值位于价带上0.34eV(77K)附近的宽谱带普遍存在于不同方式生长的InP外延层和掺Sn与不掺杂的衬底中,且与P空位引起的复合缺陷有关。 通过红外光致发光强度对温度的依赖关系得到C带的热激活能为0.17eV。这刚好与采用σ函数来描述深能级的Locovsky模型相吻合,光谱线型与温度猝灭的量子力学位形坐标模型拟合,得到与C带有关的深能级hv=0.02eV,S=8。 相似文献
66.
Renhua Qiu Guoping Zhang Xinhua Xu Kangbin Zou Lingling Shao Dawei Fang Yinhui Li Akihiro Orita Ryosuke Saijo Hidetaka Mineyama Tomoyoshi Suenobu Shunichi Fukuzumi Delie An Junzo Otera 《Journal of organometallic chemistry》2009,694(9-10):1524-1528
Zirconocene and titanocene bis(perfluorooctanesulfonate)s were synthesized. In contrast to the corresponding triflates and perchlorates, these compounds are air- and water-stable. They were proved to be ionic on the basis of conductivity measurements and X-ray analysis, allowing these complexes to be stored for months. The strong Lewis acidity of these cationic metallocene species, which was proved by ESR study, enabled catalytic glycosylation. 相似文献
67.
Zhiguo Liu Dawei Dong Milan Liu Yu Sui Wenhui Su Zhengnan Qian Zhe Li 《Hyperfine Interactions》2005,163(1-4):13-27
The quadrupole splitting distributions (QSDs) from the Mössbauer spectra of triphylite, ferrisicklerite and purpurite at 298 K and 80 K were obtained by the use of the Voigt-based quadrupole splitting distribution (QSD) method for the first time. QSDs of Fe2+ and Fe3+ are attributed to Fe2+ and Fe3+ at the corresponding octahedrally coordinated sites in the crystal structures of the three phosphate minerals. The influence on the distortion of the M2 site by different next-nearest neighbor (NNN) configurations was discussed based on the Jahn–Teller effect in purpurite, and the authors propose two M2 subsites with different distortions in purpurite. Two QSDs of Fe3+ in the Mössbauer spectra of purpurite are tentatively assigned to Fe3+ at the two M2 subsites, and next-nearest neighbor (NNN) effects were used to interpret the Mössbauer spectra of purpurite. 相似文献
68.
We investigate how the barb of bird feathers is changed along both the rachis and barb.To investigate the microstructures and the mechanical behaviors of barbs,a series of barbs are manually cut from an eagle’s primary feather to observe the cross sections.Aλ-like cross section with a tiny hook is observed at the right feet at each section.Afterwards,a measurement of the setup system is developed to evaluate the leakage ratio of a feather followed by a numerical predicting approach based on the CFD method.It is found that the air leakage increases linearly against the pressure,and the predicted results coincide well with the experimental results.Finally,the influences of leakage of the flight feather on both steady and unsteady aerodynamics are studied. 相似文献
69.
First-principles analysis of phonon thermal transport properties of two-dimensional WS_2/WSe_2 heterostructures
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The van der Waals(vdW)heterostructures of bilayer transition metal dichalcogenide obtained by vertically stacking have drawn increasing attention for their enormous potential applications in semiconductors and insulators.Here,by using the first-principles calculations and the phonon Boltzmann transport equation(BTE),we studied the phonon transport properties of WS2/WSe2 bilayer heterostructures(WS2/WSe2-BHs).The lattice thermal conductivity of the ideal WS2/WSe2-BHs crystals at room temperature(RT)was 62.98 W/mK,which was clearly lower than the average lattice thermal conductivity of WS2 and WSe2 single layers.Another interesting finding is that the optical branches below 4.73 THz and acoustic branches have powerful coupling,mainly dominating the lattice thermal conductivity.Further,we also noticed that the phonon mean free path(MFP)of the WS2/WSe2-BHs(233 nm)was remarkably attenuated by the free-standing monolayer WS2(526 nm)and WSe2(1720 nm),leading to a small significant size effect of the WS2/WSe2-BHs.Our results systematically demonstrate the low optical and acoustic phonon modes-dominated phonon thermal transport in heterostructures and give a few important guidelines for the synthesis of van der Waals heterostructures with excellent phonon transport properties. 相似文献
70.
Boutaka Rabeh Liang Dawei Bouadjemine Rochdi Traiche Mohammed Kellou Abdelhamid 《Journal of Russian Laser Research》2021,42(4):453-461
Journal of Russian Laser Research - Laser side-pumping approach is an extremely attractive configuration for many laser applications. Through this approach, the laser beam can be generated in the... 相似文献