LiNbO3∶Fe3+晶体的光谱精细结构、零场分裂参量及Jahn-Teller效应

应用不可约张量方法和群的理论构造了三角对称晶场中3d5组态离子的252阶可完全对角化的微扰哈密顿矩阵,利用该矩阵计算了LiNbO3∶Fe3+晶体的光谱精细结构、零场分裂、晶体结构、Jahn-Teller(J-T)效应,其理论计算值与实验值相符合,并研究了自旋四重态、自旋二重态分别对基态能级的影响,证明了自旋四重态对基态能级的贡献是主要的,自旋二重态对基态能级的贡献虽很小,但却是不可忽略的.在此基础上,进一步研究了自旋-轨道耦合作用、自旋-自旋耦合作用对LiNbO3∶Fe3+晶体的光谱精细结构和零场分裂参量的影响,发现自旋-轨道耦合作用是最主要的,自旋-自旋耦合作用也是不可忽略的. 研究表明,该种物质的四重态光谱结构中含有J-T效应. 其产生原因是自旋-轨道耦合及三角畸变的共同作用的结果,两者缺一不可.     

Instantaneous coherent polarization and coherent polarimetric spectra

The statistics of polarization in electromagnetic waves or target vector has been studied deeply, generally using Stokes parameters. Unfortunately, all the data-processing includes the assumption that the sampling data are independent of time, without a consideration of the time coherence of the polarization data, such as instantaneous Stokes parameters. In this paper, the definitions of the instantaneous coherent polarization function and polarimetric spectrum are presented for the first time, which shows the coherences of the instantaneous Stokes parameters in both time and frequency domain, even in spatial coherence. The new formula of definition can be extended to spatial propagation coherence, both in free space or any linear medium.     

Trace Formulae of Characteristic Polynomial and Cayley-Hamilton＇s Theorem, and Applications to Chiral Perturbation Theory and General Relativity

By using combinatorics, we give a new proof for the recurrence relations of the characteristic polynomial coefficients, and we further obtain an explicit expression for the generic term of the coefficient sequence, which yields the trace formulae of the Cayley-Hamilton＇s theorem with all coefficients explicitly given. This implies a byproduct, a complete expression for the determinant of any finite-dimensional matrix in terms of the traces of its successive powers. And we discuss some of their applications to ehiral perturbation theory and general relativity.     

竹红菌甲素与血红蛋白相互作用光谱

竹红菌甲素与血红蛋白相互作用光谱;马心血红蛋白;竹红菌甲素;相互作用;UV-Vis吸收光谱;荧光光谱;荧光猝灭动力学常数     

活性粒子吸附对ZnO纳米粒子表面光伏特性的影响

作为一种传统的半导体,氧化锌在压电陶瓷、光电化学、光催化、发光器件以及气体传感器等方面具有广阔的应用前景,特别是氧化锌纳米粒子,由于其比表面积大、表面活性较高和对周围环境的敏感性,使其成为传感器研究领域中最有前途的材料,有关生物氧传感器和激光器的光电功能特性以及其能带结构的研究已有报道,     

High-temperature current conduction through three kinds of Schottky diodes

Fundamentals of the Schottky contacts and the high-temperature current conduction through three kinds of Schottky diodes are studied. N-Si Schottky diodes, GaN Schottky diodes and AlGaN/GaN Schottky diodes are investigated by I--V--T measurements ranging from 300 to 523~K. For these Schottky diodes, a rise in temperature is accompanied with an increase in barrier height and a reduction in ideality factor. Mechanisms are suggested, including thermionic emission, field emission, trap-assisted tunnelling and so on. The most remarkable finding in the present paper is that these three kinds of Schottky diodes are revealed to have different behaviours of high-temperature reverse currents. For the n-Si Schottky diode, a rise in temperature is accompanied by an increase in reverse current. The reverse current of the GaN Schottky diode decreases first and then increases with rising temperature. The AlGaN/GaN Schottky diode has a trend opposite to that of the GaN Schottky diode, and the dominant mechanisms are the effects of the piezoelectric polarization field and variation of two-dimensional electron gas charge density.     

Steroids and triterpenoids from <Emphasis Type="Italic">Cucumis sativus</Emphasis> roots

Investigations on the EtOH extract of Cucumis sativus roots led to the isolation of 15 compounds (1–15). Their structures were identified using spectroscopic methods. Among these compounds, compound 1, stigmasta-8(14),22-diene-7α-methoxy-3β-ol, is a new steroid, and 2, 4–15 were isolated from this plant for the first time.     

Aryl-to-Vinyl 1,4-Nickel Migration/Reductive Cross-Coupling Reaction for the Stereoselective Synthesis of Multisubstituted Olefins

The aryl-to-vinyl nickel 1,4-migration (1,4-Ni migration) reaction has been reported for the first time. The generated alkenyl Ni species undergo a reductive coupling reaction with unactivated brominated alkanes affording a series of trisubstituted olefins. This tandem reaction exhibits mild conditions, a broad substrate scope, high regioselectivity, and excellent Z/E stereoselectivity. A series of controlled experiments have shown that the critical 1,4-Ni migration process is reversible. In addition, the alkenyl nickel intermediates obtained after migration are highly Z/E stereoselective and do not undergo Z/E isomerization. The obtained trace isomerization products are caused by the instability of the product.     

Two new Co(II) and Ni(II) complexes with 3-(2-Pyridyl)pyrazole-based ligand: synthesis, crystal structures, and bioactivities

Two new Co(II) and Ni(II) complexes exhibiting DNA cytotoxic activities with 3-(2-pyridyl)pyrazole-based ligand, [Co(L)(3)](ClO(4))(2) (1) and [Ni(L)(3)](ClO(4))(2) (2) (L=1-[3-(2-pyridyl)-pyrazol-1-ylmethyl]-naphthalene) were synthesized and structurally characterized. Both 1 and 2 crystallized in the monoclinic system, space group P2(1)/c, for 1, a=12.8324(8), b=12.1205(8), c=33.27(2) A, beta=93.92(3) degrees and Z=4; for 2, a=12.8764(3), b=12.1015(3), c=33.2415(9) A, beta=93.998(1) degrees and Z=4. Among them, the Co(II) and Ni(II) ions were all coordinated by six N donors from three distinct L ligands. In addition, the cytotoxic activities of 1, 2 and L in vitro were evaluated against three different cancer cell lines HL-60 (human leukemia), BGC-823 (stomach cancer) and MDA-MB-435 (mammary cancer), respectively. The results showed that 1 exhibited significantly high cytotoxic activities against HL-60 and moderate activities against BGC-823 and MDA-MB-435. In order to further investigate the relationships between structures and DNA-binding behaviors of these complexes, the interactions of 1, 2 and L with calf thymus DNA (CT-DNA) were then subjected to thermal denaturation, viscosity measurements and spectrophotometric methods. The results indicated that 1 and 2 intercalated with DNA via L ligand. The intrinsic binding constants of 1, 2 and L with DNA were 1.6x10(4), 5.6x10(3) and 2.76x10(3) M(-1), respectively.