Synthesis,Crystal Structure and Magnetic Properties of a Co(Ⅱ) Complex Containing 2′-(l′-Methyl)benzimidazolyl-substituted Nitronyl Nitroxide

A new complex [Co(NIT-1′-MeBzIm)2Cl2](NIT-1′-MeBzIm = 2-{2′-[(l′-methyl)-benzimidazolyl]}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide) has been prepared and structurally characterized by X-ray diffraction method.The complex crystallizes in the monoclinic system,space group C2/c,Z = 4.Crystal data:C30H38Cl2CoN8O4,Mr = 704.51,a = 17.074(3),b = 21.350(3),c = 11.6962(19),β = 108.879(2)°,V = 4034.3(11)3,Dc = 1.160 g/cm3,μ(MoKα) = 0.597 mm-1,F(000) = 1468,R = 0.0422 and wR = 0.1141 for 2577 observed reflections with I > 2σ(I).X-ray analysis reveals that the Co(Ⅱ) ion is six-coordinated with a distorted octahedral geometry.Temperature dependence of susceptibility measurements shows the existence of antiferromagnetic interactions between the Co(Ⅱ) ion and the radicals(J =-52.88 cm-1).     

多孔硅材料光学Anderson局域的研究

本文基于Anderson局域效应和有限时域差分(FDTD)计算方法,对具有一定无序性的多孔硅材料内光的横向局域进行了理论分析,考察了不同无序度、孔洞排列的不同方式对硅材料光学性质的影响。计算结果表明,多孔硅内光的行为和多孔硅的结构参数有很大关系。当结构参数合适时,光束可以呈现比较明显的横向局域效果。适当改变材料中孔道的排列方式,可以有效的调节光在材料中的传播方式与局域效果。设计了具有"边墙"效果的孔洞排列方式,不仅能够固定光斑的位置,而且还可实现光束的局域增强效果。     

Synthesis,Crystal Structure and Magnetic Properties of an Oxalato-bridged Dinickel(Ⅱ) Complex with Nitronyl Nitroxide Radicals

A new oxalato-bridged dinickel(Ⅱ) complex [Ni2(NIT-MeImz)4(C2O4)](Ac)2·8H2O has been synthesized and characterized structurally as well as magnetically.It crystallizes in monoclinic,space group C2/c with a=24.608(4),b=21.399(3),c=17.992(3),β=131.680(2)°,V=7076(2)3,C50H86N16Ni2O24,Mr=1412.77,Z=4,Dc=1.326 g/cm3,μ(MoKα)=0.614 mm-1,F(000)=2984,R=0.0751 and wR=0.1791 for 2956 observed reflections with Ⅰ2σ(Ⅰ).X-ray analysis reveals that the crystal structure consists of [Ni2(NIT-MeImz)4(C2O4)]2+ moiety and two Ac-anions.Each nickel(Ⅱ) ion is six-coordinated with a distorted octahedral geometry:two nitrogen atoms and two oxygen atoms from NIT-MeImz together with two other oxygen atoms from the oxalato ion.The 2-D net structure is formed and arranged through intermolecular H-bonding interactions.Magnetic measurements show antiferromagnetic interactions for this complex.     

扶手椅型碳化硅纳米管电子结构和光学性质的研究

本文基于密度泛函理论研究了扶手椅型碳化硅纳米管(SiCNT)的电子结构、成键机制以及其光学性质。研究结果表明:当碳和硅的原子比为1∶1时,SiCNT的结构最为稳定,并且表现出诸多的优良性质。通过分析计算结果我们发现,SiCNT是间接带隙材料,并且管子的带隙随着直径的增加而增加。从SiCNT的轨道图谱中我们看到碳和硅原子之间属于sp2杂化,同时硅原子周围的电子密度明显要低于碳原子周围的电子密度。对能态密度的计算我们得知碳原子和硅原子分别主导价带和导带。与其它纳米管(BN)有所不同,SiCNT的光学性质更接近于各向同性材料。     

碳纳米管晶格振动模及拉曼光谱的研究进展

本文介绍了碳纳米管的结构特征和晶格振动模的理论研究 ,综述了不同方法生长的多壁碳纳米管和单壁碳纳米管拉曼光谱的研究进展。另外 ,还简单描述了单壁碳纳米管的应用前景     

Synthesis and Crystal Structure of a Novel Co(Ⅱ)-Nitronyl Nitroxide Complex [Co(IM2-Py)(PCA)(N3)2]

The title compound [Co(IM2-Py)(PCA)(N3)2] (IM2-Py = 2-(2'-pyridyl)-4,4,5,5-te- tramethylimidazoline-1-oxyl, PCA = 2-pyridine carboxylic acid) has been prepared and structurally characterized by elemental analysis, IR spectra and X-ray diffraction. It crystallizes in monoclinic, space group P21/c with a = 13.169(3), b = 11.235(2), c = 15.596(3) (A), β = 104.70(3)°, V = 2232.0(8) (A)3, C18H21CoN1oO3, Mr = 484.38, Z = 4, Dc = 1.441 g/cm3,μ(MoKα) = 0.811 mm-1, F(000) = 1000,the final R = 0.0563 and wR = 0.1010. The nitronyl nitroxide (NIT2Py) was reduced to IM2-Py, and another NIT2Py oxidated to PCA. The self-redox reaction between the radicals was observed. The cobalt(Ⅱ) ion is six-coordinated into a distorted octahedral geometry. Meanwhile, the intermolecular hydrogen bonds result in the dimer.     

银纳米三棱柱二聚体的光学性质研究

本文利用离散偶极子近似方法研究了银纳米三棱柱二聚体的光学性质, 考察了粒子相对位置、粒子间隔和入射光偏振方向对消光谱和电场的影响。入射光偏振对二聚体的消光谱和表面电场均有较大的影响。纳米粒子间隔较小时, 粒子间存在较强的耦合; 粒子间隔较大时, 二聚体的消光谱更接近两个相互独立的粒子情形。另外二聚体的表面电场分布和平均电场强度还受到粒子相对位置和间隔的影响, 随着粒子间隔的增大, 表面平均电场值振荡上升达到最大值后减小。     

单壁碳纳米扶手椅、锯齿管声子色散关系的计算

引用石墨经验力常数计算碳纳米管声子色散关系时，必须处理由二维平面卷曲形成三维实体纳米管所引入的问题. 报道对一系列扶手椅和锯齿单壁碳纳米管计及卷曲效应的声子色散关系的计算结果. 基于实际的数值计算结果，以及对单壁碳纳米扶手椅、锯齿管结构的对称性分析，讨论了Brillouin区中心Γ点晶格振动模的分类. 关键词： 碳纳米管 声子色散关系     

非共振条件下单壁碳纳米管拉曼散射强度的计算

利用非共振情况下的键极化模型理论，对单壁碳纳米管的拉曼光谱强度进行了研究.考察了碳纳米管结构、入射光和散射光的偏振方向以及管轴的取向对散射光强度的影响.计算结果表明，光的偏振方向对拉曼散射强度影响较大，而手性对拉曼光谱的影响较小.针对碳管样品的实际情况，给出了无规取向碳管的拉曼散射光谱. 关键词： 碳纳米管 拉曼散射 声子 键极化     

单壁手性碳纳米管Γ点E1和E2振动模式

在卷曲法计算得到的单壁碳纳米管12个非简并的本征频率与手性和管径关系的基础上,继续讨论了简并的本征频率中E1和E2的振动模式,以及其频率与手性和管径的关系.