The first observation of Mo5+ in the passivation layer of Mo2N

Molybdenum nitride powder with S_g of 115 m² · g¹ (passivated) has been prepared by a temperature programmed reaction of MoO₃in H₂/N₂ mixture. It exhibited high catalytic activity in CO oxidation at low temperature. XPS, EPR and LRS studies have shown the existence of mixed valence states of Mo ions, especially Mo⁵⁺ ion (g(tT=1.932,g||=1.892) observed for the first time, in the passivation layer of molybdenum nitride. A surface Superoxide species, O₂ (g = 2.001, Raman band 1 124 cm¹), was found to be produced accompanying the transformation of Mo⁵⁺/Mo⁴⁺ redox pair. Evidence has been given to suggest that this surface superoxide might be responsible for CO oxidation over Mo₂N catalyst.     

MoSe2电子结构和光学性质的理论研究

基于密度泛函理论第一性原理,计算了MoSe2的能带结构、态密度和光学性质,再根据相关参数分析了该材料的半导体特性和光学性质.能带结构结果表明MoSe2具有间接带隙宽度为0.853 eV的半导体材料,从态密度图可看出价带由Mo的5s4d价电子和Se的4s4p价电子起主要作用,其它价电子作用较少导带主要是Mo的4d和Se的...     

理论研究半金属TiB2的电子结构和光学特性

为了系统地分析半金属TiB₂的能带结构及光学特性，采用密度泛函理论的第一性原理平面波赝势方法，计算分析了TiB₂的电子结构及光学特性。能带结构表明TiB₂具有直接带隙宽度为0.388 eV的半金属材料，在费米能级附近，态密度的价带主要由Ti的3p价电子和B的2p价电子起作用，导带由Ti的3d价电子起主要贡献。从获得的光学特性参数发现在光子能量为0.73 eV处，Ti的4s3p和B的2p电子发生共振，复介电函数的峰值主要出现在低能区，材料对紫外光的最大吸收系数为4.03×10⁵cm^-1。本研究得到的光学特性参数在光电子器件、微电子和紫外探测器等制作方面有着较好的参考作用。     

Sb掺SnO2的光电性质研究

基于密度泛函理论,我们研究了掺杂浓度为12.5%时Sb掺杂SnO₂的电子结构和光学性质,包括能带结构、态密度、介电函数和光学吸收谱。掺杂后的SnO₂材料的导电性得到了明显的增强,具有了半金属的性质;费米能级处能带细化,介电常数和光学吸收谱具有对应关系,光学吸收谱峰值发生了蓝移。     

VUV threshold photoelectron spectroscopy of the C2H3Cl molecule

The threshold photoelectron spectrum of the C₂H₃Cl molecule is studied by using synchrotron radiation light source and supersonic molecular beam. The vertical ionization potentials of different orbital electrons and some vibrational structures are obtained. The observed Rydberg autoionization peaks are assigned by A²A¹ state of C₂H₃Cl₊.     

Expression, purification and characterization of the soluble CuA domain of cytochrome c oxidase ofParacoccus versutus

The key subunit Ⅱ of cytochrome c oxidase (CcO) contains a soluble binuclear copper center (Cu_A) domain. The Cu_A domain of Paracoccus versutus was cloned, expressed, purified and characterized. The gene encoding the Cu_A domain in pET11d vector was expressed in E. coli BL21 (DE3). The results showed that the Cu_A domain was expressed mostly in inclusion bodies and the Cu_A domain protein synthesized in E. coli cells represents approximately 10 percent of the total cellular proteins. Dissolved in urea, dialyzed and recombined with Cu⁺/Cu²⁺ and purified by the Q-sepharose fast flow anion-exchange column and Sephadex G-75 gel filtration column, the soluble purple-colored protein, which shows a single band in electrophoresis, was obtained. The UV-visible absorption spectrum of Cu_A domain showed that there are intense band at 478 nm and a shoulder peak at 530 nm, and two weak bands at 360 and 806 nm respectively, which can be assigned to the charge transfer and the interactions of obitals of Cu—S and Cu——Cu in the mixed-valence binuclear metal center (Cu₂S₂R₂). The far-UV CD spectrum indicated that this domain is predominantly in β-sheet structure. The fluorescence spectra showed that its maximal excitation wavelength and maximal emission wavelength are at 280 and 345 nm, respectively.     

The evolution of local structure of Mo6S8 during Li+ electrochemical storage studied by in-situ tender X-ray absorption spectroscopy

Chevrel phase Mo₆S₈ has attracted great interest because of its capability to accommodate different types of small cations through reversible topotactic redox reactions.However,the intercalation mechanism of Mo₆S₈ is still far from being fully understood owing to the complexity of the crystal structure and limitation of the probe tools.In our study,the reaction mechanism of Li⁺ intercalation into Mo₆S₈ was studied as a ...     

MoTe2的电子结构及光学性质的理论研究

利用密度泛函理论第一性原理方法对MoTe_2的能带结构、能态密度和光学性质进行了理论计算,得到能带结构、态密度、光吸收谱、能量损失谱和介电函数等光学性质。结果表明:MoTe_2具有间接带隙宽度为1.066 eV的半导体材料,价带主要由Mo的5s4p价电子和Te的5s5p价电子起主要作用;导带由Mo和Te的4d价电子起主要作用。由获得的光学性质可知,介电函数的实部和虚部的峰值都出现在低能区;位于可见到紫外区域的光子具有很强的吸收,最大吸收系数为2.84×10~5cm~(-1);同时在光子能量为16.40 eV处出现了共振现象,其它区域内电子之间共振非常微弱。这些光学性质奠定了该材料在制作微电子和光电子器件方面的作用。     

A multiphoton ionization study of acetone using time-of-flight mass spectrometry

The 3p Rydberg states of acetone and photodissociation of the acetone cation were studied using time-of-flight (TOF) mass spectrometry. The 3p Rydberg state spectroscopy of acetone was investigated with linearly polarized two-photon resonance enhanced multiphoton ionization (REMPI) from 320 to 337 nm. Several new transition bands were observed in the spectra. In addition to the CH₃COCH₃ ⁺ ion, CH₃CO⁺ and CH₃ ⁺ fragments were observed. The laser power dependences suggest that the CH₃COCH₃ ⁺, CH₃CO⁺ and CH₃ ⁺ ions are produced in three-, four-, and four-photon processes, respectively. Production of CH₃CO⁺ and CH₃ ⁺involves excitation of the ground state acetone cation by an additional photon and subsequent decomposition of the excited acetone ion. The average translational energies of CH₃CO⁺ and CH₃ ⁺ from dissociation in CH₃COCH₃ ⁺(X) + hv → CH₃CO⁺ + CH₃ and CH₃COCH₃ ⁺(X) + hv → CH₃ ⁺ + CH₃CO, respectively, were derived from the ion TOF peak profiles.     

Bi~(3+)/Yb~(3+)共掺GdVO_4近红外发光性能研究

使用高温固相法制备了一种新的Bi3+,Yb3+共掺杂GdVO4量子裁剪近红外发光材料,该材料在波长为250~400nm的紫外光激发下发射出很强的近红外光(900~1100nm).由于体系中Bi3+离子的引入,相对于Gd0.9Yb0.1VO4,Gd0.87Yb0.1Bi0.03VO4在989nm处的近红外发光强度提高近120%,且其激发峰也从323nm红移至341nm,整个激发谱带更宽,更有利于实际应用.由于Yb3+离子既可以利用基质中的VO3-4电荷迁移态跃迁的能量,也可以同时利用Bi3+的1S0-3P1能级跃迁传递能量,相对于目前报道的理论量子裁剪效率最高的YVO4:Bi3+,Yb3+,GdVO4:Bi3+,Yb3+无论其近红外发光强度还是可见光发光强度强度皆有提升,是一种很有希望的紫外宽带激发近红外发光材料.     

EPR and UV—vis studies of biomimetic complexes of molybdoenzyme and tungstoenzyme

The biomimetic synthesis and the study of the ca-talysis mechanism of molybdenum and tungsten oxotransfer enzyme have been attracted considerable at-tention for a long time, because the oxotransfer enzymes play an important part in the nitrogen, sulfur and carbon cycles in the biological system[1—4]. With the development of the X-ray crystallography, it is possible to determine the structure of molybdenum and tungsten enzymes. However, due to the complexity and dedicated nature of the protein…     

Effect on membrane transport in the erythrocytes by band 3 cross-linking

Band 3 and glucose transport protein (GluT1) are two kinds of important proteins in the human erythrocyte membranes. Bis(sulfosuccinimidyl)suberate (BS³), an impermeable cross-linker of band 3, inhibited NO₂ ⁻ transport, showing that anion exchange is affected by the association state of band 3 in the intact erythrocyte membranes. At the same time, the rates of glucose transport of both exit and entry declined. The amount of monomers of band 3 was decreased after treatment of the erythrocytes with BS³, but there was no change in GluT1 according to the SDS-PAGE patterns. This demonstrates that band 3 and GluT1 would be linkaged together in the erythrocyte membranes for the requirement of rapid and cooperative performance of physiological functions of the membrane proteins.     

Theoretical study of partial oxidation of ethylene by vanadium trioxide cluster cation

Density functional theory （DFT） study of reaction between vanadium trioxide cluster cation （VO3^＋） and ethylene （C2H4） to yield VO2^＋ ＋ CH3CHO （acetaldehyde） and VO2CH2^＋ ＋ HCHO （formaldehyde） is carried out. Structures of all reactants, products, intermediates, and transition state in the reaction have been optimized and characterized. The results show unexpected barriers in the reaction due to the existence of a η^2-O2 moiety in the ground state structure of VO3^＋. The initial reaction steps combining ethylene adsorption, C=C activation and O-O cleavage are proposed as rate limiting processes. Comparison of reactions of VO3^＋ ＋ C2H4 with VO3 ＋ C2H4 and VO2^＋ ＋ C2H4 in the previous studies is made in detail. The results of this work may shed light on the understanding of C=C bond cleavage in related heterogeneous catalysis.     

Measurement of the absorption spectrum of H2O+ in the visible region

Together with the 74 lines belonging to (0,9,0)- (0,0,0) band, the high-resolution absorption spectrum of H₂O⁺ A²A₁-X²B₁ system was observed in the visible region of 16680 — 17300 cm^-1 using optical heterodyne magnetic rotation enhanced velocity modulation spectroscopy for the first time, which verifies the high sensitivity and high signal to noise ratio (S/N) of this technique.     

混合配体构筑的钌-铀酰异金属配位聚合物的合成和晶体结构及荧光性能

利用钌金属络合物离子和芳香有机二羧酸配体与铀酰离子在水热条件下反应，合成了一例新的异金属有机配位聚合物，也即[Ru(bipy)₃][(UO₂)₂(BDC)₃]·2H₂O，利用单晶X-射线衍射方法、粉末X-射线衍射方法、红外光谱对该配位聚合物结构进行了基本表征。该配合物是由金属配合物阳离子客体[Ru(bipy)₃]²⁺ 、二维蜂窝状平面结构的聚阴离子主体框架[(UO₂)₂(BDC)₃]_n^2-之间通过分子内和分子间C-H···O氢键的相互作用形成准三维超分子结构。此外，固体紫外-可见漫反射光谱测试表明此配合物具有半导体性质，是潜在的光电材料。固体荧光测量表明配合物表现出强烈的发光性能。     

Enhancement of magnetism of Zn0.95Co0.05O films by p-type Cu+ doping

Organic solar cells withμ-oxo-bridged gallium phthalocyanine dimer(GaPc dimer) and fullerene were produced by an evaporation method.A device based on the GaPc dimer provided a conversion efficiency of 4.2×10~(-3)%,which is better compared to a device based on phthalocyanine monomer.Dimerization effect was discussed with a molecular orbital calculation,and the crystalline phases of the present solar cells were investigated by X-ray diffraction.Further improvement of the efficiency was discussed on the bas...     

V掺杂CrSi2能带结构的第1性原理计算

 采用基于第1性原理的密度泛函理论(DFT)赝势平面波方法和广义梯度近似,计算了V掺杂CrSi₂体系的能带结构和态密度,计算结果表明,本体CrSi₂是具有ΔE_g=0.35eV狭窄能隙的间接带隙半导体,其费米面附近的态密度主要由Cr的3d层电子和Si的3p层电子的态密度决定;V替代Cr掺杂后,费米能级进入价带,费米面插在价带的中间,带隙变窄,且间接带隙宽度ΔE_g=0.25eV;掺杂后费米面附近的电子能态密度则由Cr的3d层电子、V的3d层电子和Si的3p层电子的态密度共同决定,掺杂后V原子成为受主,在价带顶附近贡献了一定数量的空穴,使掺杂后CrSi₂的导电类型变为p型,提高了材料的电导率.     

Surface state of molybdenum cations in MoO3/CeO2

Conclusion  

广西伊岭岩岩石(CaCO3)晶体结构、德拜温度以及硬度研究

本文从微观角度研究碳酸钙矿石的晶体结构与物理性能,为碳酸钙矿石的应用提供理论依据。利用X射线衍射(XRD)技术分析广西伊岭岩岩石2个样品(A_1、A_2)的相组成及其晶体结构,并利用带能谱仪的电子显微镜(SEM/EDS)测试这2个样品的各相成分。结果表明:广西伊岭岩岩石的主要成分为CaCO_3,其中A_1样品含有少量的K~+,A_2样品含有少量Na~+。通过Rietveld全谱图拟合晶体结构精修可知,K~+替代样品A_1主要物相CaCO_3中的Ca~(2+),使其点阵参数变大,单胞体积变大。同样A_2样品中的Na~+替代了样品中CaCO_3的Ca~(2+)位置,造成A_2中的CaCO_3点阵参数变小,单胞体积变小。德拜温度近似模型计算出2个样品的德拜温度分别为318.86K、324.82K。维氏硬度测试法测试出2个样品的硬度大小分别为132.6HV、148.9HV。