Ab initio Study of Electronic Structure and Properties in Crystalline 1,1,3,3,5,5‐Hexaazidocyclotriphosphazene

The banding and electronic structures of crystalline 1,1,3,3,5,5‐hexaazidocyclotriphosphazene (P₃N₂₁) have been investigated at DFT‐B3LYP/6‐31G(d) level. Relaxed crystal structure compares well with experimental data. The energy gap is 5.57 eV, indicating that P₃N₂₁ is an insulator. The frontier orbital is mainly formed by atomic orbitals of azido group, so it is the most reactive part of the molecule. The intermolecular interaction is strong along the direction that is nearly perpendicular to the phosphazene ring. The distribution of electrostatic potential is quite uneven, so P₃N₂₁ has a very high impact sensitivity. The point charge electrostatic potential is very high between the azido groups of the neighboring molecules, which indicates that the crystal lattice in this position may easily be broken and becomes the explosion center when P₃N₂₁ is impacted. The overlap populations of P–N_α bonds are much less than those of other bonds, therefore the P–N_α bonds first rupture by external stimuli, which agrees well with the experimental study of mass spectrum.     

Fe/Cr超晶格的电子结构和磁性质

应用密度泛函全势线性缀加平面波(FLAPW)方法研究了Fem/Crn (m=3, 4; n=1, 3, 4)超晶格的电子结构和磁性质. 结果表明, Fe3/Cr1和Fe3/Cr3体系的基态中, Fe层间存在铁磁耦合; 而Fe4/Cr4体系基态中, 存在反铁磁耦合; Cr层的磁矩方向交替变化, 交界面上的Fe和Cr间存在反铁磁耦合.     

C76Si2异构体的分子设计和光谱研究

用INDO系列方法对C76Si2的17种可能异构体进行系统理论研究, 表明最稳定异构体是由C78(C2V)沿X方向椭球长轴所穿过的六元环上的2个C原子(29, 30)被Si取代所形成, 异构体稳定性随2个Si原子沿Z方向距离增加而降低, 且取代场所附近易成为进一步反应中心; C76Si2(29, 30)电子光谱吸收峰与C78相比发生红移, 主要是由于其对称性降低和LUMO- HOMO能隙变小。     

Fe/RE多层膜磁性及其变化机制

研究了Ｆｅ／ＲＥ多层膜（Ｆｅ单层厚度〈２．０ｎｍ）沉积态退火过程中（温度≥４７３Ｋ）的结构与磁性，分析了磁性变化的原因。沉积态的Ｆｅ单层由分离的Ｆｅ岛组成，小尺寸的Ｆｅ岛呈超顺磁性导致了整个膜显示顺磁性，退火时Ｆｅ岛合并长大，膜由超顺磁转变为铁磁，同时磁化强度和妖顽力增加。     

铀氮化物晶体结构及电子结构

铀氮化物因其独特的物理化学性质及优良的性能而成为核燃料循环系统中重要的燃料材料,是核领域的研究热点材料之一。此外,铀氮化物也被用作抗腐蚀涂层材料,在金属铀的表面腐蚀防护领域具有重要的应用价值。在铀-氮体系中,五种结构铀氮化物,包括NaCl型UN、HgIn型UN、Mn₂O₃型α-U₂N₃、La₂O₃型β-U₂N₃和CaF₂型UN₂,已经被确认并进行了广泛研究。但是到目前为止,由于铀氮化物复杂的非化学计量比问题,导致对上述物相之间的转化关系的认识仍不清楚;而不同化学计量比的铀氮化物由于其电子结构的差异,使得其基本物理化学性质发生了根本的变化。有关铀氮化物晶体结构和电子结构方面的研究是探讨其优异性能起因的第一步,因此引起研究者的广泛关注。本文在归纳和分析大量文献的基础上,结合本课题组在铀氮化物相关方面的研究成果,着重介绍铀氮化物晶体结构和电子结构方面的主要进展,并对铀氮化物相结构的转化规律以及电子结构的演化规律进行总结,以期为铀氮化物的实验研究和功能应用提供参考。     

Synthesis,Crystal and Electronic Structure of Ba_3ZnSb_2O_9 with the 6H-perovskite-type Structure

Crystals of Ba3ZnSb2O9 have been grown by a high-temperature solid-state reaction and characterized by single-crystal X-ray diffraction.Ba3ZnSb2O9 crystallizes in the hexagonal P63/mmc space group with a = 5.8663(4),c = 14.478(2) ,V = 431.49(8) 3,Z = 2 and R(all data) = 0.0167.The structure of Ba3ZnSb2O9 consists of pairs of face-sharing Sb2O9 bi-octahedra connected via corners with two single layers of mutually isolated ZnO6 octahedra.Each Ba2+ ion is bonded to 12 oxygen atoms.The UV-vis absorption spectrum of the compound has been investigated.Additionally,the calculations of band structure and density of states have also been performed with density functional theory method.The obtained results tend to support the experimental data of the absorption spectrum.     

[M(phen)3][Ni(mnt)2](M2+=Ni2+，Fe2+；phen=1，10-菲咯啉，mnt2-=马来二腈二硫烯)离子对配合物的合成、晶体结构、电子光谱和磁性质

本文制备了2种新的离子对配合物[M(phen)3][Ni(mnt)2](phen=1,10-菲咯啉,mnt2-=马来二腈二硫烯;M2+=Ni2+,1;Fe2+,2),并进行了结构表征。2种离子对配合物晶体的空间群都为P21/n,具有类似的晶胞参数和堆积结构。紫外可见-近红外光谱显示在近红外区域没有出现明显的吸收峰。在2到400 K的温度范围内,化合物1表现居里-外斯型的顺磁性行为,并在磁性[Ni(phen)3]2+离子之间存在弱的反铁磁作用,而且在八面体配位环境下Ni2+离子自旋基态S=1。化合物2在40 K向上显示抗磁性,意味[Fe(phen)3]2+离子处于低自旋态。低于40 K时,弱居里尾巴可能是由于小部分顺磁性[Ni(mnt)2]-杂质导致的。     

X-Ray Study of the Electronic Structure of Copper(II) Acetylacetonate

The Cu(acac)₂ complex was investigated by X-ray emission and XANES spectroscopy using synchrotron radiation. Structural data for the complex were obtained in chloroform solution and C₂F matrix. The experimental spectra and their fitting on a single scale of binding energies point to possible relaxation effects. As shown by model quantum-chemical calculations, the structure and energy position of the LUMOs constructed from the vacant metal 4p, 5p AOs strongly depends on the nature of the nearest environment.Original Russian Text Copyright © 2004 by L. N. Mazalov, S. V. Trubina, E. S. Fomin, I. M. Oglezneva, G. K. Parygina, N. V. Bausk, and I. K. Igumenov__________Translated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 5, pp. 844–851, September–October, 2004.     

Electronic Structure and Magnetic Properties of Rh13 Cluster with Three Possible Symmetries

1 INTRODUCTION Transition-metal (TM) clusters have been the sub- ject of widespread investigations in recent years be- cause of their promising practical applications in de- veloping new magnetic materials with large moment. As is well known that all 3d, 4d and 5d TM atoms have a finite magnetic moment due to the Hund’s- rule coupling in their unfilled d shells, but only 3d Fe, Co and Ni atoms are able to retain these mo- ments at a much reduced level in the bulk environ- ment. On the…     

电结晶制Co/Pt多层膜的结构及磁性研究

以单晶Si(111)为基底, 在以P盐[主要成分Pt(NO₂)₂(NH₃)₂]和CoSO₄为主盐的硼酸体系中电结晶Co/Pt多层膜. SEM观察多层膜的断面形貌, 证实多层膜具有周期结构. 经XRD测试, 首次证实了Co-Pt界面上有CoPt₃化合物的存在. 用PPMS测试了多层膜的磁滞回线, 平行于外磁场时膜的矫顽力约为165 Oe, 垂直于外磁场时的矫顽力随Co含量的增加而增加, 最大达到396 Oe. 首次用电结晶方法制得了易磁化轴垂直于膜面的Co/Pt多层膜.     

Electronic Structure, Aromaticity, and Physicochemical Characteristics of Carbene, Radical, and Ionic Forms of Compounds of the Imidazole Series, and their Oxo and Thio Analogs

The effects of benzannellation, phenyl substitution at the nitrogen atom, protonation at the carbene carbon, ionization, and the state of the carbene center (² or ²) on the electronic structure, diamagnetic susceptibility, induced -electron ring currents, the ¹H, ¹³C, and ¹⁴N chemical shifts, and the energies of the lowest electronic transitions of imidazol-2-ylidenes and their oxo and thio analogs were examined in the bound version of -electron perturbation theory. The calculated and experimental data are compared.     

单金属锰、铁卟啉对空气氧化α-蒎烯的催化作用及取代基效应

以α-蒎烯为底物,空气作氧化剂,研究了苯环上带有不同取代基团的单锰卟啉和单铁卟啉对空气氧化α-蒎烯的催化作用及反应中的取代基效应.结果表明,单锰卟啉及单铁卟啉催化氧化α-蒎烯得到双键和烯丙位一、二级碳氢键的氧化产物,没有烯丙位三级碳氢键的氧化产物.环氧化合物是主要产物,而且氧化产物的产率随时间的变化呈较好的线性关系.随着苯环上meso位取代基Cl,CH3,OCH3和OH的供电子能力的增强,锰卟啉和铁卟啉对α-蒎烯的催化活性逐渐减弱,α-蒎烯的转化率逐渐降低.锰卟啉和铁卟啉的催化反应表观速率常数k与环外苯基上的取代基特性常数σ均呈良好的线性关系,Hammett关系式分别为lnk=1.2168σ-7.9968,lnk=0.6251σ-8.2426;线性相关系数分别为0.9507和0.9715.     

A Probe of Valence and Conduction Band Electronic Structure of Lead Oxide Films for Photodetectors

We investigate how the electronic structure of amorphous lead oxide (a-PbO) films deposited on ITO substrate is changed after annealing at various temperatures. Both experimental soft X-ray spectroscopic and density functional theory (DFT) based computational techniques are used to explore the electronic structure of this material. X-ray emission, resonant X-ray inelastic scattering, and X-ray absorption spectroscopic techniques are employed to directly probe the valence and conduction bands. We discover that the films are very stable and remain amorphous when exposed to temperatures below 300 °C. An amorphous-to-polycrystalline (α-PbO phase) transformation occurs during annealing at 400 °C. At 500 °C, an alpha to beta phase change is observed. These structural modifications are accompanied by the band gap value changing from 1.4±0.2 eV to 2.0±0.2 eV upon annealing at 400 °C and to 2.6±0.2 eV upon annealing at 500 °C. A difference between surface and bulk structural properties is found for all samples annealed at 500 °C and above; these samples also exhibit an unexpected suppression of O : 2p density of states (DOS) near the bottom of the conduction band, whereas additional electronic states appear well within the valence band. This study provides a significant step forward to understanding the electronic properties of two polymorphic forms of PbO needed for optimization of this material for use in X-ray sensors.     

聚硅烷研究进展：（Ⅱ）聚硅烷的电子结构与电子光谱特性

聚硅烷的独特性质与其电子在主链上离域有密切关系，本文就聚硅烷的电子结构及电子光谱特性的研究作一综述。     

Electronic Structure of Cu(II) Complexes with N,N′-Disalicylidene-1,2-cyclohexanediamine and N,N′-Disalicylidenetrimethylenediamine

Summary.  The electronic absorption and X-ray photoelectron spectra of N,N′-disalicylidenetrimethylenediaminatocopper(II) ([Cu(saltn)]) and N,N′-disalicylidene-trans-1,2-cyclohexanediaminatocopper(II) ([Cu(salchx)]) were measured. From these results and from informations derived from MO calculations the electronic structure of the complexes was clarified. Each electronic absorption band which can be assigned to the ππ^ast; or ML/LMCT transition of [Cu(saltn)] or [Cu(salchx)] observed in the wavelength region of 450–200 nm appears at the almost same frequency as the corresponding band of N,N′-disalicylideneethylenediaminatocopper(II) ([Cu(salen)]) in solution. The LLCT bands (the intramolecular CT band between two π-electronic systems separated by saturated hydrocarbon chains such as ) also appear at nearly the same positions (ca. 245 nm) for [Cu(salchx)], [Cu(saltn)], and [Cu(salen)]. The locations of the dd transition and the intensity of the ML/LMCT transition of [Cu(saltn)] are significantly different from those of [Cu(salen)] and [Cu(salchx)]. These differences may arise from the strengths of the interaction between metal and ligand. Received August 21, 2001. Accepted (revised) October 20, 2001     

碳纤维微晶结构的形成与生长

碳纤维的微晶结构是影响其性能的决定性因素,本论文采用广角X-射线衍射法研究了聚丙烯腈预氧纤维在碳化阶段中微晶结构的形成、生长与转变过程。研究结果表明:在1000℃以下,经预氧化反应形成的不连续多环芳香平面结构沿平行于纤维轴的方向堆积并逐渐靠近,形成类似于晶核的微晶结构生长中心,表现为类石墨片层间距的减小而晶粒增长缓慢;当温度高于1000℃时,晶粒的生长速度明显加快,形成三维有序的微晶结构;在温度高于1500℃的石墨化阶段,类石墨微晶结构进行重排,晶粒尺寸迅速增加。根据这一规律,可以通过控制晶核生成和晶粒生长速度的匹配,进行碳纤维的结构设计和调控。     

Electronic structure and conformational study of thiobiurets

Quantum mechanical calculations at all valence complete neglect of differential overlap (CNDO/2) and self-consistent charge extend Huckel (SCC-EH) and the Pi electron Pariser-Parr-Pople with limited configuration interaction (PPP-LCI) levels of approximation have been accomplished for monothiobiuret and dithiobiuret. From the calculated results, a discussion of the electronic structure, photoelectron and electronic spectra and the conformational stability are given. The electronic and¹H nmr spectra are also reported. A trans-cis-CONHCS-structure is found to be the stable conformation for monothiobiuret consistent with other evidences.     

Spectroscopic Determination of the Electronic Structure of a Uranium Single-Ion Magnet

Early actinide ions have large spin-orbit couplings and crystal field interactions, leading to large anisotropies. The success in using actinides as single-molecule magnets has so far been modest, underlining the need for rational strategies. Indeed, the electronic structure of actinide single-molecule magnets and its relation to their magnetic properties remains largely unexplored. A uranium(III) single-molecule magnet, [U^III{SiMe₂NPh}₃-tacn)(OPPh₃)] (tacn=1,4,7-triazacyclononane), has been investigated by means of a combination of magnetic, spectroscopic and theoretical methods to elucidate the origin of its static and dynamic magnetic properties.