Cu2+:C8N14O6 Zn的局域结构、吸收光谱和电子顺磁共振谱的研究

在晶体场理论的基础上,本文采用半自洽3d轨道模型和3d9电子组态在畸变晶场中的g因子和超精细结构常数A的三阶微扰计算公式,建立了Cu2+:C8N,14O6Zn局域结构与吸收光谱、EPR谱之间的定量关系,统一解释了Cu2+:C8N14O6Zn晶体的吸收光谱和EPR谱,理论结果与实验观测值相符合.     

Fe-P非晶态合金局域结构和电子性质的理论研究

根据Fe-P非晶态合金结构的短程有序、Fe和P之间具较强化学作用和结构中可能存在P-P相互作用的实验事实,选择了单磷原子簇模型FenP(n=1～6,8)和双磷原子簇模型FenP2(n=1～4),用密度泛函理论方法对其进行计算。结果表明,在单磷模型体系中,Fe原子供给P原子电子;而在双磷模型体系中,电子转移方向发生变化,P原子供给Fe原子电子,这与Fe-P非晶态合金的实验结果一致,说明单磷和双磷原子簇模型能较全面反映Fe-P非晶态合金的结构特点。     

石榴石中Cr^3＋的电子结构与晶场强度的关系

本文对掺铬的GGG(Ca,Mg,Zr),GGG,YGG和YAG四种晶体进行了自旋极化的SCC-DV-X_α计算。首次报道了它们的10Dq计算值,与实验值符合得很好,并讨论了中心离子和配位体之间的距离与该计算值的关系。还计算得到了二重态~2E_3的能量值,从而阐明了YAG_2cr~(3+)只能发射窄带荧光,而GGG(Ca,Mg,Zr):Cr~(3+)能发射强的宽带荧光的机理。     

紫外吸收光谱在有机化合物结构解析中的应用

本文总结了紫外吸收光谱在有机化合物结构解析中应用的一些实例,通过这些实例可以使学生理解紫外吸收光谱在有机化合物结构解析中应用的重要性,同时使学生初步了解紫外吸收光谱在有机化合物结构解析中应用的一般方法,通过教学实践表明:利用应用实例进行紫外吸收光谱的教学,其效果是非常好的。     

温火全黑泥中铁赋存状态的研究

利用XRD、XRF、TEM、EPR等分析手段对温火全黑泥进行了铁赋存状态的研究。实验结果表明:温火全黑泥中的铁有两种赋存形式,即结构铁和游离铁。结构铁存在于高岭石晶格中,以Fe~(3+)离子置换八面体层中的Al~(3+)离子;游离铁主要以赤铁矿、针铁矿、磁铁矿等杂质的形式存在。     

光折变缺陷光子晶格的局域光特性研究

以交叉相位法为基础,分别在LiNbO_3:Fe晶体中构造了带有微米量级线缺陷的四方和三角的12μm×12μm光折变光子晶格,并且重点研究了在不同类型和不同的实验条件下的光折变光子晶格中线缺陷的能否局域光的特性。     

基于第一性原理的锐钛矿相EuxTi1-xO2-xNx电子结构及吸收光谱研究

基于第一性原理,采用密度泛函理论平面波超软赝势方法,建立了Eu单掺杂及Eu-N共掺杂的锐钛矿TiO2模型,对各模型的能带分布,态密度及吸收光谱进行计算.结果表明Eu-N共掺杂的锐钛矿TiO2在稳定性、光催化性能、吸收光谱红移等方面均优于Eu单掺杂的锐钛矿TiO2.     

明胶生物大分子中铜离子配位状态初探

本文对明胶生物大分子中铜离子的配位状况进行了初步研究。首先用原子吸收光谱法测定五种国产明胶中铜含量,然后用电子顺磁共振波谱法(EPR)研究明胶中铜的配位状况。结果表明,A、B、E三种胶中含铜量少于5ppm,在EPR谱上反映不出Cu(Ⅱ)的存在;C、D两种胶中含铜大于20ppm,在EPR谱上表现出Cu(Ⅱ)的信号,且信号位置相似,说明二者Cu(Ⅱ)的配位环境存在某些类似;以C胶作为主要研究对象,发现C胶中同时存在顺磁性的Cu(Ⅱ)离于和抗磁性的Cu(Ⅱ)离子的配位结构可能偏离平面四方构型,即不存在D_(4h)对称轴;Cu(Ⅱ)离子属于典型的二型铜,有两个或两个以上组氨酸咪唑基以N原子与Cu(Ⅱ)配位。     

双包覆层局域共振声子晶体带隙特性研究

从理论上提出了一种双包覆层局域共振声子晶体结构,结合有限元对该结构带隙产生的机理、影响因素以及隔声特性进行深入分析。结果表明：带隙上边界频率主要由双包覆层弹性模量大的材料决定;下边界频率主要由基体密度小的材料决定。该声子晶体在低频范围具有良好的隔声特性,为声子晶体的结构设计提供理论指导。     

非晶态合金Co80P20体系局域结构及稳定性的DFT研究

利用含相关校正能的DFT方法在B3LYP/Lan12dz水平下,对原子簇模型Co<,4>P<,30>余种可能存在构型在二、四、六重态下进行全参数优化和频率计算,确定了8种稳定构型.从其能量、结合能、几何参数、过渡态及成键等方面对其稳定构型分析,结果显示,8种稳定构型主要是三角双锥和类螺旋桨两种结构,在二重态和四重态中最...     

Correlation of Photoluminescence and Optical Absorption Spectra of Porous Silicon

Using a quantum confinement based-PL model, PS was modelled as a mixture of Quantum Dots (QDs) and Quantum Wires (QWs) having different concentrations and sizes. It was shown that in the optical absorption edge the PL peak energy and the Optical Absorption (OA) exhibit the same trend, depending on preparation conditions. The spectral behaviours of PL and OA are analysed and correlated throughout the shapes and the size distribution of the nanocrystallites forming PS. Using the quantum confinement formalism, the value of the effective band-gap energy determined from the lowest PL energy almost corresponds to that estimated from the optical absorption coefficient. These results suggest that the lowest radiative transition between the valence band and the conduction band corresponds to the largest luminescent wires, and that the radiative recombination process leading to the PL emission occurs in the c-Si crystallite core.     

Effect of Gamma Radiation on Optical and EPR Absorption Spectra of Phosphate and Fluoride Glasses Containing Lead

The induced optical and EPR absorption spectra of phosphate and fluoride glasses containing lead are investigated. It is revealed that exposure to gamma radiation leads to the formation of radiation-induced defects responsible for the induced absorption band with a maximum at 12500–13500 cm⁻¹ and the EPR signal in the form of an almost symmetric line with a g factor of 1.999 and a linewidth of ≈26 Oe. Analysis of the intensities of the absorption bands and the EPR signals in the spectra of glasses with low terbium, tin, and carbon contents and the study of their thermal bleaching demonstrate that the color centers are electron traps, whereas the paramagnetic centers are hole-trapping centers. Examination of the change in the parameters of the absorption bands in the spectra of glasses with different R ₂O contents (R = Na, K, Rb, Cs) makes it possible to determine the location of the color centers associated with the Pb⁺ ions in the structure. It is established that the glasses under investigation are characterized by the nonlinear absorption of radiation at a wavelength of 1.06 μm. The mechanism of formation of radiation-induced defects is considered. Original Russian Text Copyright ? 2005 by Fizika i Khimiya Stekla, Bocharova, Karapetyan.     

Optical Spectra of Arsenic Chalcogenide Glasses over a Wide Energy Range of Fundamental Absorption

The complete sets of the spectra of optical fundamental functions for vitreous arsenic chalcogenides in the energy range 0–40 eV are compared for the first time. The general features of the spectra and their dependence on the nature of the chalcogen anion are revealed.     

Absorption and Fluorescence Spectra of Nitrobenzanthrones

To identify nitrobenzanthrones (NBAs) such as 3-nitro-7 H -benz[ de ]anthracene-7-one (3-NBA) on the basis of their electronic spectral data, we have synthesized 1-, 2-, 3-, 9-, and 10-NBAs and measured their absorption and emission spectra. The first strong absorption band of the NBAs appeared in the region 350-440 nm; the band of 10-NBA was red-shifted by about 20 nm. The molar absorptivities of 3- and 9-NBA were about two times as large as those of the others. The fluorescence spectra of the NBAs varied more largely with the position of the nitro group compared to the absorption spectra. The quantum yields of fluorescence were very small, ranging from ～10 m 2 for 2- and 10-NBA to ～10 m 4 for 1- and 3-NBA. 3-NBA exhibited a characteristic spectrum with two broad bands at 450 and 530 nm. On excitation causing an n ~ * transition in the NBAs, their fluorescence intensities increased by a factor of 10. Phosphorescence was observed at 77 K for all compounds though that of 1-NBA was very weak. These results give the promise of characterizing individual isomers of NBAs on the basis of their spectroscopic data.     

Optical Spectra of Amorphous and Polycrystalline Beryllium Oxide over a Wide Energy Range of Fundamental Absorption

The complete sets of spectra of the optical fundamental functions for amorphous and polycrystalline beryllium oxides in the energy range 0–40 eV are determined and compared for the first time. The general features of the spectra and their dependence on the long-range order are revealed. The basic parameters of the optical transitions in the range 0–40 eV for amorphous and polycrystalline BeO are obtained for the first time.     

Investigation of Structure of Glasses by Their Infrared Reflection Spectra

Infrared reflection spectra of a number of glasses are presented. It is apparent that in some cases such a method may be a useful tool in determining the atomic arrangement in glasses, especially when combined with quantitative measurements of the refractive index and extinction coefficient. The dispersion curves of barium-containing silicate glasses show that the network of these glasses contains metals in at least two different types of coordination. One is obviously the silica tetrahedron and the other is probably a octahedrally coordinated barium. The latter is concluded by comparison with the reflection spectrum of benitoite. Reflection spectra of boric oxide glasses are presented. These indicate that pure boric oxide glass is not 100% triangularly coordinated and that the pure glass contains much more tetrahedral coordination than was previously concluded from X-ray-scattering data.     

Steric and Electronic Effects in Basic Dyes. I—Electronic Absorption Spectra of Derivatives of Malachite Green Containing Trifluoromethyl Groups in the Phenyl Ring

Absorption spectra of derivatives of Malachite Green containing trifluoromethyl groups in the phenyl ring have been examined. As anticipated, substituents in the 3- or 4-position have little effect on the maximum intensity of the first-frequency band but they modify the position of the band to an extent linearly related to the appropriate Hammett substituent constant. Although a substituent in the 2-position markedly increases the intensity of the first band, the expected bathochromic shift relative to that of the 4-substituted isomer is not observed. Steric hindrance of the central carbon atom in the 2-trifluoromethyl and 2,6-di-(trifluoromethyl) derivatives facilitates replacement of a terminal dimethylamino group by a hydroxyl group, with formation of a fuchsone. The hindrance is sufficient to permit replacement of a dimethylamino group in the corresponding dye-bases.     

Steric and Electronic Effects in Basic Dyes. II—Electronic Absorption Spectra of Derivatives of Malachite Green Containing Electron-withdrawing Substituents in the Phenyl Ring

Absorption spectra of several derivatives of Malachite Green containing electron-withdrawing groups in the phenyl ring have been examined. Substituents in the 3- or 4-position modify the position of the first-frequency band to an extent approximately linearly related to the appropriate Hammett substituent constant. Although substituents in the 2-position show an ortho effect, the intensities of the first bands are generally lower than those of derivatives containing electron-donating groups.     

The Fading of Nitrodiphenylamine Disperse Dyes in Relation to their Structure and Ultraviolet Absorption Spectra

Previous investigations of the stability of simple nitrodiphenylamine dyes have been extended to include dinitrodiphenylamine dyes. Comments are made on the dyeing propertiesand other properties of these dyes. Theories of the relationships between structure and fastness to light developed for the mononitrodiphenylamines are tested for the dinitrodiphenylamines. The relationships between structure and fastness to light of these dyes agreereasonably with previous findings.