共查询到18条相似文献,搜索用时 390 毫秒
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介绍了3×3光纤耦合器输出解调方法的原理,推导出了3×3光纤耦合器输出解调信号的数学表达式,给出了3×3光纤耦合器输出解调算法的解调频率范围,分析了外界干扰信号、耦合器的不对称性、以及信号中存在高次谐波对解调结果的影响。分析结果表明:该方法有比较宽的频率解调范围,能够克服温度变化等外界因素的干扰,能够消除3×3耦合器3个输出端存的偏差对解调结果的影响以及在信号中存在高次谐波的影响。该方法具有性能稳定、不需要载波、不需要稳定的工作点以及抗干扰能力强等优点,具有较强的实用性和可行性,对解调电路的数字化设计具有理论指导意义。 相似文献
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Gd3+,Yb3+和Tm3+共掺杂氟化物纳米晶中Yb3+-Tm3+-Gd3+间的能量传递 总被引:4,自引:4,他引:0
用水热法合成了Y0.8-x-yF3∶Gdx3+,Yb0.23+,Tmy3+纳米晶的上转换发光材料。在典型的Y0.595F3∶Gd0.2003+,Yb0.2003+, Tm0.0053+纳米微晶中,在980 nm激光激发下,观察到了Tm3+的紫外、紫色上转换发射明显增强和来自于Gd3+的6D9/2、6IJ、6P5/2及6P7/2能级到基态8S7/2能级的紫外发射。通过比较Y0.8-x-yF3∶Gdx3+ ,Yb0.23+,Tmy3+纳米晶样品的上转换发光性质以及Tm3+和Gd3+中一些激发态的能级寿命,借助于能级图描述了Yb3+-Tm3+-Ga3+之间的有效的能量传递过程。 相似文献
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GdBO3:Pr3+,Yb3+中Pr3+到Yb3+的能量传递及发光性质 总被引:1,自引:1,他引:0
采用高温固相法制备了一系列单掺或双掺Pr3+和Yb3+的GdBO3材料,分别测试分析了材料的物相结构和发光性质。在446 nm蓝光( Pr3+:3 H4→3 P2)激发下,检测到Yb3+的近红外特征发射,表明样品中存在Pr3+到Yb3+的能量传递。 Pr3+的掺杂浓度一定时,样品的发光会随着Yb3+掺杂浓度的改变而发生变化。通过对比不同掺杂情况下Pr3+:3 P0能级的衰减曲线,发现随着Yb3+的掺杂浓度的增加,该能级的荧光寿命不断缩短;同时利用不同条件下的衰减特性计算得出不同 Yb3+掺杂浓度样品的能量传递效率。用 Inokuti-Hirayama模型分析表明Pr3+-Yb3+能量传递类型为偶极子-偶极子相互作用。 相似文献
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在B3LYP/6-311++G(3df)理论水平,对二元叠氮化合物Al(N3)3和P(N3)3进行密度泛函理论计算研究,获得其稳定分子的几何构型、电子结构、红外光谱以及稳定性.研究结果表明,P(N3)3分子中的磷原子拥有一对孤对电子,给予临近氮原子(Nα)上的孤对电子较大斥力,从而使其表现出三角锥形结构特征,而Al(N3)3表现为平面三角形结构特征.自然键轨道分析表明,Al-Nα和P-Nα键本质上均属于共价键.与叠氮自由基相比较而言,Al(N3)3和P(N3)3的每个叠氮基内部的总成键度显著增大,从而导致N3基的振动频率发生明显蓝移.前线分子轨道能级差和叠氮自由基键离解能的计算结果均表明Al(N3)3比P(N3)3更稳定. 相似文献
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在B3LYP/6-311++G(3df)理论水平,对二元叠氮化合物Al(N3)3和P(N3)3进行密度泛函理论计算研究,获得其稳定分子的几何构型、电子结构、红外光谱以及稳定性。研究结果表明,P(N3)3分子中的磷原子拥有一对孤对电子,给予临近氮原子(Nα)上的孤对电子较大斥力,从而使其表现出三角锥形结构特征,而Al(N3)3表现为平面三角形结构特征。自然键轨道分析表明,Al–Nα和P–Nα键本质上均属于共价键。与叠氮自由基相比较而言,Al(N3)3和P(N3)3的每个叠氮基内部的总成键度显著增大,从而导致N3基的振动频率发生明显蓝移。前线分子轨道能级差和叠氮自由基键离解能的计算结果均表明Al(N3)3比P(N3)3更稳定。 相似文献
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Summary We report the measurements of the3
D(3s4d)-3
P(3s3p)3
D(3s5d)-3
P(3s3p), and3
P(3p
2)-3
P(3s3p) transition frequency of MgI, the fine-structure separation and isotope shift between24Mg and26Mg. The measurements have been performed in a metastable atomic beam; a good agreement is found for data already existing
in the literature. The accuracy of the measurements reported in this paper is mainly limited by the Doppler broadening of
theI
2 transitions used as a reference and by the precision in the knowledge of the related wavelengths. 相似文献
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The systematic application of band contour techniques to account for most of the observed features of the ir spectra of s-triazine and s-triazine-d3 have been made as well as a critique as to the limitations of such methods. The experimental and computer methods used to study the gas phase infrared band contours of s-triazine and s-triazine-d3 are out-lined. Contours of the five E′ fundamentals of s-triazine have been recorded under moderate resolution and analyzed to give the Coriolis constants , i = 6–10. The effects of l-resonance are very apparent for ν8 and ν9, in the form of holes in the Q branches of these bands. Under the highest resolution available, ν6 and ν10 also show l-resonance effects. Values of the l-doubling constants were obtained for these four fundamentals. One of the parallel A2″ fundamentals of C3H3N3 (ν12) has also been studied. It lies close to ν10(E′) and an A × E type of second-order Coriolis resonance may be the cause of the intensity enhancement observed in the inner wings of the ν12 and ν10 bands. Hot bands of the type (νi + nν14 ? nν14) have been observed in the contours of ν8, ν10, and ν12. This is felt to be responsible for the large difference between our observed zeta sum (?1.30) and the theoretical sum (?1.00).The gas phase infrared band contours of the five E′ and 2A2″ fundamentals of C3N3D3 have also been recorded under moderate resolution. From P-R separations and by computer simulation of the contours, values of the Coriolis constants have been obtained for the E′ modes. The effects of l-resonance have been observed for ν8(E′) and ν10(E′) and values of the l-doubling constants have been estimated. An extensive series of hot bands of the type (ν12 + nν14 ? nν14) has been observed in the contour of the ν12 (A2″) fundamental. The mass effect on the Coriolis constants has been discussed.Infrared band contours of the overtone 2ν7 and seven degenerate E′ combination bands of C3N3H3 have been recorded under moderate resolution. Analysis of these contours using the P-R separation method and computer simulation of the contours has given values of for these bands. Fermi resonance between 2ν7 and ν6 has been analyzed. The importance of considering both the observed contour as well as the observed frequency when assigning higher tone bands is illustrated. 相似文献
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P. A. Markovin V. V. Lemanov M. E. Guzhva P. P. Syrnikov T. A. Shaplygina 《Physics of the Solid State》2014,56(5):989-995
The temperature dependences of the dielectric constant and dielectric hysteresis loops in ceramic samples of (1 ? x)SrTiO3?x KNbO3 and (1 ? x)SrTiO3?x KTaO3 (0 ≤ x ≤ 0.3) solid solutions prepared using different heat treatments have been investigated. Phase diagrams of the studied solid solutions have been constructed in the T-x coordinates. It has been shown that, after quenching of samples (spontaneous cooling at room temperature after long-term heating at the sintering temperature of the ceramic samples), the temperature of the induced phase transition increases because of the weakening of random electric fields associated with nonisovalent impurities due to their “frozen” nonequilibrium redistribution. For small concentrations x, strong dielectric relaxation is observed in the temperature range of 150–250 K. A model of relaxing centers, which is based on the local charge compensation of heterovalent impurities, has been proposed. 相似文献
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The infrared spectra of ammonia-borane, BH3NH3, and two of its deuterated isotropic species, BD3ND3 and BH3ND3, isolated in argon matrix at liquid hydrogen temperature have been measured. Well resolved bands for these three isotopic species have been observed for all the fundamentals. A complete frequency assignment based on C3v molecular symmetry has been made. A set of force constants have been calculated from the data for the two isotopes BH3NH3 and BD3ND3 using a valence force field. The agreement between experiment and frequencies calculated from these force constants for the mixed isotopic species, BH3ND3, substantiates the present assignment. 相似文献
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JETP Letters - Films of CH3NH3PbI3 organometallic perovskite, which is currently considered as a promising basic material for new-generation solar cells, as well as films containing CsPbI3... 相似文献
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Knorr K. Loidl A. Stühn B. Buevoz J. L. 《Zeitschrift für Physik B Condensed Matter》1981,41(4):315-320
Neutron diffraction experiments have been carried out on the magnetically ordered phases of ErPb3, HoPb3, ErTl3 and HoTl3. The magnetic moments were found to be sinusoidally modulated with a propagation vector of (0, 0.2, 0.5) for the Pb-compounds and (0.38, 0.38, 0.16) for the Tl-compounds.Work supported by the Bundesministerium für Forschung und Technologie 相似文献
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(LaO)3BO3中Eu^3+和Sm^3+的光致发光 总被引:4,自引:2,他引:2
研究了紫外光激发下,(LaO)3BO3基质中Eu^3+和Sm^3+的光谱性质,Eu^3+和Sm^3+的电荷迁移激发带及发光强度随组成和结构变化的规律性,并探讨了Eu^3+和Sm^3+自身浓度猝灭的机理。 相似文献