ZnSe∶Fe~(2+)中的动态Jahn-Teller效应和远红外光谱的研究

推导了 3d4 / 3d6离子基态 5D在立方晶体场、自旋 轨道耦合和动态Jahn Teller效应作用下的哈密顿矩阵 ,并用对角化该哈密顿矩阵的方法研究了Fe2 + 在ZnSe中的远红外光谱 ,理论计算与实验符合得好 .研究表明 ,在ZnSe∶Fe2 + 中 ,比晶体场理论分析多出的分裂谱线是Fe2 + 与ZnSe晶格间的动态Jahn Teller效应引起的 .还预测了其它Jahn Teller效应分裂谱 .所推导的哈密顿矩阵对研究 3d4 / 3d6离子在立方晶体中的精细光谱、电子顺磁共振谱和动态Jahn Teller分裂都是有用的 .     

掺入Mg2+对CsNiCl3晶体的基态能级、零场分裂参量及Jahn-Teller效应的影响

应用不可约张量理论构造了三角对称晶场中3d2/3d8态离子的45阶可完全对角化的微扰哈密顿矩阵,在考虑了以前工作中被忽略的自旋-自旋耦合作用的基础上计算了CsNiCl3晶体和CsNiCl3:Mg2+晶体的基态能级、晶体结构、零场分裂参量和Jahn-Teller效应,研究了掺入Mg2+对CsNiCl3晶体的光谱、零场分裂参量及Jahn-Teller效应的影响和自旋单重态对基态能级的贡献,发现掺杂使得晶体结构产生畸变,从而改变晶体光谱的精细结构和零场分裂参量,不改变Jahn-Teller效应的分裂规律但改变分裂的大小.     

掺入Mg2+对CsNiCl3晶体的基态能级、零场分裂参量及Jahn-Teller效应的影响

应用不可约张量理论构造了三角对称晶场中3d²/3d^８态离子的45阶可完全对角化的微扰哈密顿矩阵，在考虑了以前工作中被忽略的自旋-自旋耦合作用的基础上计算了CsNiCl₃晶体和CsNiCl₃:Mg²⁺晶体的基态能级、晶体结构、零场分裂参量和Jahn-Teller效应，研究了掺入Mg²⁺对CsNiCl₃晶体的光谱、零场分裂参量及Jahn-Teller效应的影响和自旋单重态对基态能级的贡献，发现掺杂使得晶体结构产生畸变，从而改变晶体光谱的精细结构和零场分裂参量，不改变Jahn-Teller效应的分裂规律但改变分裂的大小. 关键词： 基态能级 掺杂 零场分裂 自旋-自旋耦合     

ZnSe∶Fe2+的基态精细分裂和磁的各向异性理论研究

用双SO耦合模型推导了立方晶场中3d⁴/3d⁶离子⁵D态的哈密顿矩阵公式(25×25阶).用该公式计算了晶体ZnSe∶Fe²⁺的基态精细结构分裂，研究了在外磁砀为0—30T范围以及在［100］和［111］方向的Zeeman分裂、Raman移动和磁化强度.理论计算与实验符合很好. 关键词：     

MnFe204晶体的基态能级和零场分裂参量

由不可约张量理论构成一个3d^4／3d^6离子三角(C3v)对称的晶体场和自放—轨道相互作用哈密顿矩阵，由这个晶体场和自放—轨道相互作用哈密顿矩阵被完全对角化后能够求出MnFe204晶体中的Fe^2 离子的电子顺磁共振零场分裂参量D和F—a，计算了低自旋态(^3L态)对电子顺磁共银零场分裂参量(D，F—a)的贡献。结果显示低自放^3L态对电子顺磁共振的零场分裂参量的贡献是较强的。理论计算的结果与实验值是相符的。     

掺有Ni~(2+)的α-Al_2O_3晶体的基态精细光谱、晶体局域结构和Jahn-Teller效应

应用晶体场理论和不可约张量算符方法构造了3d2/3d8态离子在C3v对称晶场中包含自旋-轨道相互作用、自旋-自旋相互作用、自旋-其它轨道相互作用和其它轨道-其它轨道相互作用四种微观磁效应的45阶可完全对角化的能量哈密顿矩阵.利用该矩阵,计算了Ni2+∶α-Al2O3晶体的光谱精细结构和晶体局域结构,深入研究了Ni2+∶α-Al2O3晶体的自旋-轨道相互作用、自旋-自旋相互作用、自旋-其它轨道相互作用和其它轨道-其它轨道相互作用和它们对光谱精细结构的影响及Jahn-Teller效应.理论计算值和实验值相符合.研究发现,掺杂没有改变晶体的对称性、同时发现并合理解释了Ni2+对α-Al2O3晶体基态精细光谱中Jahn-Teller效应的存在机理.     

掺有Ni2+的α-Al2O3晶体的基态精细光谱、晶体局域结构和Jahn-Teller效应

应用晶体场理论和不可约张量算符方法构造了3d2/3d8态离子在C3v对称晶场中包含自旋-轨道相互作用、自旋-自旋相互作用、自旋-其它轨道相互作用和其它轨道-其它轨道相互作用四种微观磁效应的45阶可完全对角化的能量哈密顿矩阵.利用该矩阵,计算了Ni2+∶α-Al2O3晶体的光谱精细结构和晶体局域结构,深入研究了Ni2+∶α-Al2O3晶体的自旋-轨道相互作用、自旋-自旋相互作用、自旋-其它轨道相互作用和其它轨道-其它轨道相互作用和它们对光谱精细结构的影响及Jahn-Teller效应.理论计算值和实验值相符合.研究发现,掺杂没有改变晶体的对称性、同时发现并合理解释了Ni2+对α-Al2O3晶体基态精细光谱中Jahn-Teller效应的存在机理.     

Cr3+∶MgAl2O4晶体的基态能级分裂及Jahn-Teller效应*

构造了3d3/3d7离子在三角对称晶场中考虑自旋-轨道相互作用,自旋-自旋相互作用和自旋-其它轨道相互作用的120阶微扰哈密顿矩阵.利用完全对角化该矩阵的方法计算了Cr3+∶MgAl2O4晶体的基态能级、零场分裂参量,理论计算值与实验值相符合.定量研究了自旋二重态对基态能级的贡献,证明该贡献是不可忽略的.定量研究了自旋-轨道相互作用、自旋-自旋相互作用和自旋-其它轨道相互作用对Cr3+∶MgAl2O4晶体的光谱精细结构和零场分裂参量的影响,发现自旋-轨道和自旋-自旋相互作用对基态能级和零场分裂参量的影响的程度和方式是不同的,自旋-其它轨道相互作用的影响也是不可忽略的.通过理论计算值和实验值的比较,证实了在Cr3+∶MgAl2O4晶体中Jahn-Teller效应的存在,解释了该晶体的光谱精细结构的成因.     

Ni2+：CsMgCl3晶体的光谱精细结构、零场分裂参量及Jahn-Teller效应

应用不可约张量理论构造了三角对称晶场中3d2/3d8态离子的45阶可完全对角化的微扰哈密顿矩阵,研究了CsNiCl3单晶掺入CsMgCl3晶体后光谱精细结构、晶体结构、零场分裂参量、Jahn-Teller效应以及自旋单重态对Ni2+离子基态能级的影响,理论与实验相符合.研究了自旋-自旋耦合作用和Trees修正对Ni2+:CsMgCl3晶体的光谱精细结构和零场分裂参量的影响,发现有五种机理会影响零场分裂参量:(1)自旋-轨道耦合机理;(2)自旋-自旋耦合机理;(3)自旋-轨道与自旋-自旋联合耦合机理;(4)自旋-轨道与Trees修正联合耦合机理,(5)自旋-自旋作用与Trees联合耦合机理.其中自旋-轨道耦合机理是最主要的,其它几种机理也是不可忽略的.     

掺入V3+离子α-Al2O3晶体的基态精细光谱和晶体局域结构及J-T效应的研究

应用晶体场理论和不可约张量算符方法构造了3d2/3d8态离子在C3v对称晶场中包含自旋-轨道相互作用、自旋-自旋相互作用、自旋-其它轨道相互作用和其它轨道-其它轨道相互作用四种微观磁效应的完全能量哈密顿矩阵。利用该矩阵,计算了V3+:α-Al2O3晶体的光谱精细结构和晶体局域结构,进一步研究了V3+:α-Al2O3晶体的自旋-轨道相互作用、自旋-自旋相互作用、自旋-其它轨道相互作用和其它轨道-其它轨道相互作用和它们对光谱精细结构影响及Jahn-Teller效应。理论计算值和实验值相符合。结果发现,掺杂没有改变晶体的对称性、同时发现并合理解释了V3+对α-Al2O3晶体基态精细光谱中J-T效应的存在机理。     

Self-organization of five species in a cyclic competition game

Cyclic competition game models, particularly the “rock–paper–scissors” model, play important roles in exploring the problem of multi-species coexistence in spatially ecological systems. We propose an extended “rock–paper–scissors” game to model cyclic interactions among five species, and find that two of the five can coexistent when biodiversity disappears, which is different from the “rock–paper–scissors” game. As the number of fingers is five, we named the new model the “fingers” game, where the thumb, forefinger, middle finger, ring finger, and little finger cyclically dominate their subsequent species and are dominated by their former species. We investigate the “fingers” model in two ways: direct simulations and nonlinear partial differential equations. An important finding is that the number of species in a cyclic competition game has an influence on the emergence of biodiversity. To be specific, the “rock–paper–scissors” model is in favor of maintaining biodiversity in comparison with the “fingers” model when the variables (population size, reproduction rate, selection rate, and migration rate) are the same. It is also shown that the mobility and reproduction rate can promote or jeopardize biodiversity.     

Experimental study on downstep in Chinese intonation

Downstep in pitch contour of Chinese Putonghua is examined using subtly designed sentences by controlling tone combinations. The results show both automatic and nonautomatic downstep phenomena exist in Chinese. In non-automatic downstep, low tones compress downwards the pitch range of the following syllables. and the main influence of downstep is on topline. Low tone not only lower the topline behind it, but also raise the high tones before it, the effects are compatible with each other. In automatic downstep, the topline of pitch contour in intonational phrase is presented as a linear downtrend, but it differs among speakers due to the effect of personal stress practice. In comparison with downstep phenomenon in other tone or non-tone languages, the downstep ratio in Chinese is not constant, and the domain of downstep is not limited within the adjacent tones.     

Contrastive analysis on tone between Putonghua and Taiwan Mandarin

The differences of the pitch and duration of Chinese syllables between Putonghua （PTH） and Taiwan Mandarin （TM） were studied. The speech materials to be used are not only isolated syllables, but also sentences. The results reveal that： For the isolated syllables, T1 and T2 in TM are influenced by Minnan dialect, therefore their pitch are lower than those in PTH. T3 is fall-rise in PTH, while it is fall in TM. Moreover, the syllable duration sequence for different tone is T3〉T2〉T1〉T4 in PTH, while it is T1〉T2〉T3〉T4 in TM. For the syllables in sentences, T2 is mid-rise in PTH, while it is mid-level in TM. And the T3 is longer than T4 but shorter than T1 or T2 in PTH, while it is the shortest in TM. Furthermore the effects of prosodic phrase boundary on duration for different tones are almost the same in PTH, but the lengthening part of T1 or T2 is longer than that of T3 or T4 in TM.     

Abelian-Higgs phase of SU(2) QCD and glueball energy

It is shown that SU(2) QCD admits an dual Abelian-Higgs phase, with a Higgs vacuum of a type-Ⅱ superconductor. This is done by using a connection decomposition for the gluon field and the random-direction approximation. Using a bag picture with soft wall, we presented a calculational procedure for the glueball energy based on the recent proof for wall-vortices [Nucl. Phys. B 741(2006)1].     

High efficiency filtering using two-dimensional photonic crystal coupled cavity structures

Transmission spectra of coupled cavity structures (CCSs) in two-dimensional (2D) photonic crystals (PCs) are investigated using a coupled mode theory, and an optical filter based on CCS is proposed. The performance of the filter is investigated using finite-difference time-domain (FDTD) method, and the results show that within a very short coupling distance of about 3λ, where λ is the wavelength of signal in vacuum, the incident signals with different frequencies are separated into different channels with a contrast ratio of 20 dB. The advantages of this kind of filter are small size and easily tunable operation frequencies.     

Signal generation in an isotropic medium in scanning electron acoustic microscope

Based on the research in Ref. [5][Materials Science and Engineering, 1989; A122： 57 63], an improved model of heat source is set up, the different modes of Lamb wave in an isotropic sample generated by a chopped electron beam at frequency f are obtained with integral transform and normal function expansion method, and the output signal of PZT coupled at the back surface of the sample is found out. The generation mechanism of SEAM （Scanning Electron Acoustic Microscopy） signal is discussed. It shows that the SEAM is a near field imaging technique with high spatial resolution and its best lateral spatial resolution is about 2√2α （α is the radius of the focused electron beam）. Some of experimental results of SEAM images are presented in the paper and it shows that the spatial resolution of SEAM is better than 0.5 μm and smaller than the thermal diffusion length of the sample. Therefore the character of near field imaging in SEAM is also proved experimentally.     

Real-time restoration of rotational blurred image using gradient-loading

The key to the restoration of rotational motion blurred image is how to restore the image under a low cost and to correct the irreversibility of the degradation function matrix.Based on the special qualities of degradation function matrix and precise deduction in space-domain, we present a new approach using gradient-loading for restoration of rotational blurred image.By easily adding a gradient operator, the irreversibility of the original matrix is corrected and can be applied for inverse filtering then.Gradientloading is the optimized approach which combines the advantages of both the approaches using constrained least square filtering and traditional diagonal-loading.Compared with the approach using least square filtering, its peak signal-to-noise ratio (PSNR) is improved from 3.18 to 6.46dB, while the computing time is reduced to 1/2-1/3.Experimental results demonstrate the effectiveness, noise-resistibility, robustness, and low complexity of this approach, which make it more suitable for real-time environment.     

All-Optical Logic Device Using Bent Nonlinear Tapered Y-Junction Waveguide Structure

We propose an all-optical logic device made of a bent tapered Y-junction waveguide with a Kerr-type nonlinear interface. It could provide an AND gate, OR gate, and exclusive-OR (XOR) gate. We could obtain different transmission results by adjusting the bending angle. The numerical simulation results show that the device functions as AND, OR, and XOR gates.     

Real-time, continuous-wave terahertz imaging by a pyroelectric camera

Real-time, continuous-wave terahertz (THz) imaging is demonstrated. A 1.89-THz optically-pumped farinfrared laser is used as the illumination source, and a 124 × 124 element room-temperature pyroelectric camera is adopted as the detector. With this setup, THz images through various wrapping materials are shown. The results show that this imaging system has the potential applications in real-time mail and security inspection.