Ligand polarization contributions to lanthanide 4f → 4f magnetic dipole transition moments and rotatory strengths

Radiation-induced (dynamic) polarizations of electronic charge distributions on ligands may contribute to both the electric- and magnetic-dipole moments of 4f → 4f transitions in lanthanide complexes. These ligand-polarization effects on magnetic-dipole transition moments are examined in the present study, and their possible influence on the rotatory strengths of 4f → 4f transitions in chiral lanthanide systems is given special attention. The ligand-polarization mechanism for magnetic-dipole transition moments is not likely to contribute significantly to the total dipole strengths of 4f → 4f transitions in noncentrosymmetric lanthanide systems. However, this mechanism may contribute significantly (or detectably) to the rotatory strengths of certain 4f → 4f transitions in chiral lanthanide systems. The relative importance of these contributions will be greatest for transitions with predominantly |ΔJ| ≥ 2 character and with relatively large U ^λ(λ = 2, 4, and 6) matrix elements.     

4f滤波系统抑制混淆

光电成像系统欠抽样时 ,将产生混淆。使用 4f 系统预先滤除超出 Nyquist带宽的高频成分 ,不仅能够有效抑制混淆 ,而且还能够体现出预滤波方法抑制混淆的极限形式。分别设计了在单色光和白光照明时的滤波器 ,给出了几个方向上的 4f 预滤波成像结果     

4f轨道的成键性质

本文介绍了目前国内外关于镧系配合物４ｆ轨道成键行为研究的现状与进展,对其理论和研究方法进行了系统的总结,归纳了４ｆ轨道的成键规律。     

L＞4f′的简单证明

固定物、像屏法(或二次成像法)测量凸透镜焦距的前提是物、像屏之距L必须大于四倍的待测透镜的焦距。但是为什么?学生往往说不清楚。笔者从高斯物像公式出发,证明了在二次成像法中为什么必须要求L>4f′。具体证明如下: 由高斯物象公式可知     

Pu和Au原子4f5/2和4f7/2的结合能计算

基于Koopmans定理,应用MCDF方法计算了Pu和Au原子4f5/2和4f 7/2的结合能以及PuO2所引起的化学位移,一般大于固体的相应值.     

基于4f结构平面集成相关器系统优化

在基于4f结构的平面集成光电混合相关器系统中,由于采用折叠光路结构,增大了像差,降低了系统的识别能力。通过对平面集成光学相关器的结构分析,利用斜入射坐标理论,确定系统中微光学透镜的相位调制函数。对微光学透镜元件的相位函数进行分析,用Zemax软件优化系统以降低系统的像差,从而提高识别能力。通过分析像质评价图,得到优化后的系统最大光程差小于λ/4,达到了衍射极限。用Matlab软件对优化前后的系统进对比量化分析,优化后系统的识别能力提高了约0.8倍。表明优化后的像差得到了很好的改善,系统的识别能力有了明显的提高。     

Structural properties and 4f → 5d absorptions in Ce-doped LuAlO?: a first-principles study

The structural properties and the 4f → 5d absorptions of Ce-doped LuAlO(3) have been studied using the density functional theory-based generalized gradient approximation PBE + U (PBE: Perdew, Burke and Ernzerhof) and wavefunction-based embedded cluster calculations, respectively. The PBE or PBE + U calculations reveal that the substitution of Ce for Lu induces a strongly anisotropic distortion of the local atomic structure around the dopant site, which is largely insensitive to the value of U for the Ce 4f states. The calculated electronic structures depend explicitly on the value of U, and a value of U ≈ 6 eV is determined by comparison with experimental x-ray photoelectron data for CeAlO(3). On the basis of the PBE-optimized structure, CASSCF/CASPT2 (complete-active-space self-consistent-field/second-order perturbation theory) embedded cluster calculations for the Ce(3+) 4f → 5d transitions yield energy and intensity patterns in fairly good agreement with those estimated from the experimental absorption spectrum. A Mulliken spin population analysis for the 5d(1) states shows that the origins of the states are significantly different from being caused by the cubic crystal field, confirming an earlier conclusion as regards the origin of the 5d(1) states based on semiempirical molecular orbital calculations. The importance of spin-orbit effects on the energies and wavefunctions of the Ce 5d(1) states is highlighted.     

基于4f系统的光学图像加密与解密

本文利用阿贝成像及对称-非对称混合加密原理,实现了基于4f光路的光学图像加密与解密.首先,本文利用Lee型迂回相位编码方法制作了加密函数对应的相位掩膜,作为密钥,并通过空间滤波的方法完成了光学图像的频域加密.其次,本文结合自行编写的程序实现了加密图像的计算机解密,解决了光学图像解密时相位掩膜难以精准对齐的困难,大幅度提升了解密效率和质量.最后,通过一个验证实例直观地揭示了该加密方法具有较高的安全性,并且证明该方案在较低噪声情况下具有较好的鲁棒性.     

On the Experimental Determination of 4f–4f Intensity Parameters from the Emission Spectra of Europium (III) Compounds

Optics and Spectroscopy - Eu3+ complexes and specially β-diketonate compounds are well known and studied in several areas due to their luminescence properties, such as sensors and lightning...     

SrAl12O19:Pr3+中4f2→4f2电偶极跃迁强度参量化

对SrAl12O19:Pr3+中4f2→4f2电偶极跃迁强度的参量化进行了研究.考虑明确的4f5d组态成分与4f2跃迁能级混杂对4f2组态内跃迁的影响.引入新的强度参数Tkq,参数值由3P0能级的相关实验数据拟合.利用拟合的参数T33和T53计算1S0向下各能级发射的跃迁强度,计算值与实验及Judd-Ofelt理论的结果进行了比较.     

稀土元素Ce的特性与4f电子局域磁矩

本文考虑到电声子相互作用以及4f电子与传导电子相互作用的贡献,对稀土Ce中伴随γ-α相变时所发生的变价现象与磁性等物理特性的关系作了研究,分析了当温度、压强、化合价等变化时稀土金属中的电子行为。     

Hypersensitivity in the 4f–4f absorption spectra of tris (acetylacetonato) neodymium(III) complexes with imidazole and pyrazole in non-aqueous solutions. Effect of environment on hypersensitive transitions

The optical absorption spectra of [Nd(acac)₃(H₂O)₂]·H₂O, [Nd(acac)₃(im)₂] and [Nd(acac)₃(pz)₂] (where acac is the anion of acetylacetone, im is imidazole and pz is pyrazole) complexes in the visible region have been analyzed. The transition ⁴G_5/2←⁴I_9/2 located near the middle of the visible region (17,500 cm^?1) is hypersensitive. Its behavior is in sharp contrast to many other typically weak and consistently unvaried, normal 4f–4f transitions. It is overlapped by a less intense transition ²G_7/2←⁴I_9/2. The band shapes of the hypersensitive transition show remarkable changes on passing from aqueous solution to various non-aqueous solutions, which is the result of changes in the environment about the Nd(III) ion in the various solutions and suggests coordination of a solvent molecules. Pyridine has been found especially effective in promoting 4f–4f electric-dipole intensity. The DMSO invades the complexes and replaces the water molecules and heterocyclic amines from the coordination sphere. Two DMSO molecules coordinate and the complexes acquire similar structure, [Nd(acac)₃(DMSO)₂] in solution. The oscillator strength and the band shape of the hypersensitive transition of all the complexes remains the same in this solvent. The IR spectra and the NMR spectra of the complexes have also discussed.     

Laser Spectroscopy of Cerium Monofluoride: Ligand Field Assignments of Some 4f5d6p← 4f5d6sTransitions

The techniques of selectively detected fluorescence excitation, dispersed fluorescence, and magnetic rotation spectroscopy have been applied to the CeF molecule and used to characterize one [17.6]4.5 electronic state in the ∼2 eV region and three electronic states withT₀< 2000 cm⁻¹:X(1)3.5 and (2)3.5 with Ω = 3.5 and (1)4.5 with Ω = 4.5. Two of these states, the [17.6]4.5 andX(1)3.5 states, had been observed previously [R. M. Clements and R. F. Barrow,J. Mol. Spectrosc.107,119 (1984); Y. Azuma, W. J. Childs, and K. L. Menningen,J. Mol. Spectrosc.145,413 (1991)]. Based on the pattern of Ω-values and the value of ΔG_1/2≈ 550 cm⁻¹, the three low-lying states are assigned to the Ce⁺(4f5d(³H)6s)F⁻superconfiguration. The upper state is assigned to the Ce⁺(4f5d(³H)6p)F⁻superconfiguration on the basis of computed ligand field monopoleB⁰₀(nl,nl) orbital destabilization energies and one-electron transition propensity rules.     

Dilaton Dark Energy Model in f(R), f(T) and Ho?ava-Lifshitz Gravities

In this work, we have considered dilaton dark energy model in Weyl-scaled induced gravitational theory in presence of barotropic fluid. It is to be noted that the dilaton field behaves as a quintessence. Here we have discussed the role of dilaton dark energy in modified gravity theories, namely f(R),f(T) and Hořava-Lifshitz gravities and analyzed the behavior of the dilaton field and the corresponding potential in respect to these modified gravity theories instead of Einstein’s gravity. In f(R) and f(T) gravities, we have considered some particular forms of f(R) and f(T) and we have shown that the potentials always increase with the dilaton fields. But in Hořava-Lifshitz gravity, it has been seen that the potential always decreases as dilation field increases.     

Study of f 0(980) and f 0(1500) from B s →f 0(980)π,f 0(1500)π decays

In this paper, we analyze the scalar mesons f ₀(980) and f ₀(1500) from the decays $\bar{B}^{0}_{s}\to f_{0}(980)\pi^{0},\allowbreak f_{0}(1500)\pi^{0}$ within Perturbative QCD approach. From the leading-order calculations, we find that (a) in the allowed mixing angle ranges, the branching ratio of $\bar{B}^{0}_{s}\to f_{0}(980)\pi^{0}$ is about (1.0～1.6)×10^?7, which is smaller than that of $\bar{B}^{0}_{s}\to f_{0}(980)K^{0}$ (the difference is a few times even one order); (b) the decay $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ is better to distinguish between the lowest lying state or the first excited state for f ₀(1500), because the branching ratios for two scenarios have about one-order difference in most of the mixing angle ranges; and (c) the direct CP asymmetries of $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ for two scenarios also exists great difference. In scenario II, the variation range of the value ${\mathcal{A}}^{\mathrm{dir}}_{CP}(\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0})$ according to the mixing angle in scenario II is very small, except for the values for mixing angles near 90° or 270°, while the variation range of ${\mathcal{A}}^{\mathrm{dir}}_{CP}(\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0})$ in scenario I is very large. Compared with the future data for the decay $\bar{B}^{0}_{s}\to f_{0}(1500)\pi^{0}$ , it is easy to determine the nature of the scalar meson f ₀(1500).     

基于4f的大视角剪切散斑干涉系统设计

数字剪切散斑干涉技术在工业无损检测领域有广阔的应用前景,传统的迈克尔逊型数字剪切散斑干涉仪由于结构的限制,视场角很小,这限制了其在工程上的应用。介绍一种新型的大视角剪切散斑干涉系统,通过在成像镜头和CCD传感器之间嵌入4f光学系统来扩大其视场角,并实现镜头的外置。理论分析证明,视场角不再受到迈克尔逊结构的限制,仅仅取决于镜头的焦距和CCD传感器的靶面尺寸。设计并组建了一个大视场角迈克尔逊剪切散斑干涉系统,对比实验表明,在短的工作距离下实现了大视场的全场检测,在1 m的测距下,新系统测量面积可达800 mm600 mm,而传统的系统测量面积只有250 mm200 mm。