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991.
MoTe2是一种非空间反演对称性半导体,由线性偏振光照射,在无偏压条件下可以直接产生光电流,但是非常微弱.掺杂可以改变电子能带结构和降低空间反演对称性,从而有效的增强光电流.本文基于非平衡格林函数-密度泛函理论,采用第一性原理,计算了本征、Nb掺杂、Ti掺杂和W掺杂2H-MoTe2的能带结构、透射谱和光电流.能带结构表明:Nb掺杂使半导体2H-MoTe2能带穿越费米能级,转变为金属特性;Ti和W掺杂减小了2H-MoTe2的带隙,能带没有穿越费米能级,依然为半导体.掺杂都降低2H-MoTe2的反演对称对称性,从本征的D3h转变为Cs.从而在线偏振光的照射下可以有效的提高2H-MoTe2的光电流.同时,发现掺杂可以提高单层2H-MoTe2在低光子能量下的消光比,如Nb和Ti掺杂单层2H-MoTe2分别在光子能量1.1 eV和1.2 eV处取得39.48和28.48的高消光比... 相似文献
992.
Lijun Cai Sarina Macfadyen Baozhen Hua Haochuan Zhang Wei Xu Yonglin Ren 《Molecules (Basel, Switzerland)》2022,27(6)
Monitoring and early detection of stored-grain insect infestation is essential to implement timely and effective pest management decisions to protect stored grains. We report a reliable analytical procedure based on headspace solid-phase microextraction coupled with gas chromatography–mass spectrometry (HS-SPME-GC-MS) to assess stored-grain infestation through the detection of volatile compounds emitted by insects. Four different fibre coatings were assessed; 85 µm CAR/PDMS had optimal efficiency in the extraction of analytes from wheat. The headspace profiles of volatile compounds produced by Tribolium castaneum (Herbst), Rhyzopertha dominica (Fabricius), and Sitophilus granarius (Linnaeus), either alone or with wheat, were compared with those of non-infested wheat grains. Qualitative analysis of chromatograms showed the presence of different volatile compound profiles in wheat with pest infestation compared with the wheat controls. Wheat-specific and insect-specific volatile compounds were identified, including the aggregation pheromones, dominicalure-1 and dominicalure-2, from R. dominica, and benzoquinones homologs from T. castaneum. For the first time, the presence of 3-hydroxy-2-butanone was reported from S. granarius, which might function as an alarm pheromone. These identified candidate biomarker compounds can be utilized in insect surveillance and monitoring in stored grain to safeguard our grain products in future. 相似文献
993.
介绍了电子设备方舱基本总体设计流程及其相关的基本原则.论述了电气总体设计与电源选择、电磁兼容以及电缆布线设计、布线施工一致性的关系.提出了电子设备方舱总体设计的基本方法,并举例说明通过电缆布线设计解决电磁兼容问题的方法. 相似文献
994.
995.
On the basis of liquid crystal model with the electric dipole moment of cell membrane,the microscopic mechanism of the electricity and thermology effects of interaction of laser with cell membrane is researched by electromagnetic, quantum mechanics and quantum statistics. We derive the formulas on the polarization effects and "temperature-rising effect" of laser-cell membrane interaction. The results of the theoretical research can explain some experiments. 相似文献
996.
LIN Guo-ping ZHANG Lei MALe SUN Ming-hao XU Hui-ying CAI Zhi-ping 《光电子快报》2007,3(3):231-233
We report the observation of the splitting of whispering-gallery mode in the silica spherical resonator. To characterize the fused-silica spherical resonator,an evanescent fiber taper coupling technique is employed. The coupling system consists of a fiber taper with a diameter of about 2.8 microns and a fused-silica spherical resonator with a diameter of about 143 microns. By injecting the laser power into the fiber taper,a number of narrow absorption peaks with equal peak spacing of 3.7 nm are observed in a wide spectral range. After replacing the resonator by the other one with the shape being slightly modified,whispering-gallery mode splitting in the spherical resonator is observed. The wavelength spacing between adja-cent peaks is 0.32 nm,much smaller than that of the previous one. 相似文献
997.
CHANG Min PENG Dan XU Ke-xin 《光电子快报》2007,3(3):211-214
A double beam near-infrared spectrometer is developed to compensate the water absorption and instrumental drift in intensity. The spectrometer may be used for both single and double beam measurements,and the two operation modes are compared. The results show that the double beam technique eliminates instrumental drift in the single beam measurement and therefore the stability of the system increases by more than 20%. The compensation of the double beam system on water absorption is verified by the measurement of fat content in milk. The results show that the spectrum data based on double beam mode get better calibration model and lower prediction error than traditional single beam mode. 相似文献
998.
Diffraction efficiency of grating plays an important role in output power of incoherent fiber laser beam combination. Through theoretic analysis and numerical simulations it has been proved that the diffraction efficiency would increase with the decrease of grating frequency and wavelength bandwidth. On the condition that the width of a fiber array is fixed at W=10 cm, an optimum grating frequency were numerically simulated as f=230 mm-1. Also an unequal interval method was proposed to improve the system efficiency of diffraction into 0.4293, which is higher than 0.3824 under the equal interval condition. 相似文献
999.
Enhancement of signal-noise-ratio in a distributed polarization mode coupling detection system 总被引:1,自引:0,他引:1
JING Wen-cai LI Xiao-jingi LIU Kun XU Tian-hua ZHANG Yi-mo ZHANG Hong-xia JIA Da-gong PENG Gang-Ding 《光电子快报》2007,3(1):57-61
White-light interferometry (WLI) is an efficient method for measurement of strain, twist, temperature, and many other physical parameters in fiber-optic measurement systems. [1-10]. It can provide large dynamic range and high accuracy for absolute measurements of displacement and strain. Meanwhile, it is not sensitive to optical power fluctuation [6]. WLI based on optic sensors are immune to electromagnetic interference, suitable for harsh environments and compat- ible with optical fiber dat… 相似文献
1000.