用ICP-AES内标法测定铝酸钇(YAP)激光晶体中单掺或双掺稀土元素钕镥铒钬铈的研究

本文采用磷酸溶解样品,在不分离基体的情况下,用ICP-AES内标法直接、快速测定YAP激光晶体中单掺或双掺钕、镥、铒、钬、铈的含量;同时研究了溶液的磷酸浓度、基体浓度以及被测双掺稀土元素相互之间的影响。确定了分析的最佳工作条件和选择了欲测稀土元素的相应内标元素。方法回收率98～105%,相对标准偏差±5%以内,对于样品的分析取得满意的结果。     

铕(Ⅲ)-二苯甲酰甲烷-聚丙烯酸/聚(苯乙烯-丙烯酸)配合物及其性质研究

研究了铕(Ⅲ)和二苯甲酰甲烷(HDBM)形成的有机配体NaEu(DBM)4与聚丙烯酸(PPA)(Mr=5000)、聚(苯乙烯-丙烯酸)(PSAA)(Mr=3000)发生配位反应分别得到配合物Eu(Ⅲ)-DBM-PAA和NaEu(Ⅲ)-DBM-PSAA,得率分别为89.7％和87.3％。红外光谱、紫外光谱、X光电子能谱的测试表明了Eu3 分别与PAA,PSAA和DBM-发生配位。元素分析和电导率测定结果证明了一个Eu3 分别与PAA中二个链节或PSAA中三个链节的羧基和一个DBM-发生配位。Eu3 离子在配合物Eu(Ⅲ)-DBM-PAA和NaEu(Ⅲ)-DBM-PSAA中的质量分数分别为28.46％和12.23％。荧光光谱表明,常温下配合物在紫外光下发出强的红光,主要是Eu3 离子的5D0→7F2的能级跃迁。     

OXIDATIVE COUPLING OF METHANE OVER Ba-La-O CATALYSTS PROMOTED WITH FLUORINE ANION

Oxidative coupling reaction of methane (OCM) was studied over Ba-La-O-F catalysts. F-anions exhibited apparent promoting effects on Ba-La-O-F catalysts for OCM reaction. Over BaF2/La2O3, C2 yield was 1 to 4 percent higher than that over BaO/La2O3 catalysts.     

过渡金属原子簇中的协同效应

以铁硫、铁钼硫簇合物为例对过渡金属簇合物中的协同效应进行了讨论。利用结构谱学数据,从簇骼转化、电子加入对簇骼的影响,端基、桥基、非邻近基团的作用等几个方面讨论了铁硫、铁钼硫簇合物中各种基团之间的相互作用。     

The band structures of some transition metals and their NaCl-type compounds

The band structures of Group IVB (Ti,Zr,Hf),VB (V,Nb,Ta) and VIB (Cr,Mo,W) transition metals and some of their carbides and nitrides (TiN,ZrN,HfN,VC,NbC,TaC,VN,NbN,TaN) with NaCl-type (Bl-type) structure have been calculated by using the tight-binding method within the Extended Hiickel approximation (EHT).The energy bands,densities of states and crystal orbital overlap populations are given.The relationship between the bonding properties and the superconducting transition temperatures (Tc) of them is discussed.The influences of various kinds of metallic atoms and changes of bond lengths on Tc are also discussed.     

用ICP-AES法测定首饰金的成分

本文报道采用ICP-AES法直接同时测定首饰金中合金无素及主要杂质元素含量,通过计算求得金含量。确定了仪器的最佳工作条件,进行了干扰试验。方法适用于18k～99.99%成色的首饰金。测定的RSD为<0.01%(对于高纯度金祥n=10)～0.2%(对于10k金样n=10)之间,分析结果表明,方法准确、快速、简便且样品消耗量少。     

Theoretical study on tetranuclear boron clusters: B4X4 (X = H, F, Cl, Br, I)

The molecular orbitals for B4H4, B4F4, B4Cl4, B4Br4 and B4I4 have been calculated by using all-electron or effective core potential ab initio method at the self-consistent field level using basis sets with diffuse and polarization functions. The boron-boron and boron-halide (-hydrogen) distances of these cage compounds are optimized with three kinds of basis sets constrained to a tetrahedral symmetry. According to the localization scheme of Boys, four three-centered two-electron (3c2e) B-B-B bonds localized on each of the faces of the B4 tetrahedron are derived for B4X4 clusters. The HOMO-LUMO energy gaps, atomization energies and Mulliken overlap populations of these compounds indicate that the stabilities of the clusters decrease in the sequence of B4F4 > B4Cl4, B4H4 > B4Br4 > B4I4.     

Scanning electrochemical microscopy-development of instrumentation utilizing piezo-bimorph X-Y scanners

The development of the instrumentation of a scanning electrochemical microscopy (SECM) is presented. The core of the SECM sensing system is constructed based on piezobimorph scanners, a mechanical micropositioner of multi-dimensional adjustment and ultramicroelectrodes. The control of the electrochemical cell and the SECM system is realized by a battery powered bipoteniostat and analog control circuits respectively with the control of a microcomputer work station. The demonstrations of SECM experiments are given on both a standard IDA sample and a silver electrode. Discussions on the resolution and quality of SECM image are made.     

Conversion of N2O to N2 on MgO （001） Surface with Vacancy： A DFT Study

The adsorption and decomposition of NzO at regular and defect sites of MgO (001) surface have been studied using cluster models embedded in a large array of point charges (PCs) by DFT/B3LYP method. The results indicate that the MgO (001)surface with oxygen vacancies exhibits high catalytic reactivity toward N2O adsorptive-decomposition. It is different from the regular MgO surface or the surface with magnesium vacancies.Much elongation of O—N bond of N2O after adsorption at oxy-gen vacancy site with O end down shows that O—N bond has been broken with concurrent production of N2, leaving a regu-lar site instead of the original oxygen vacancy site (F center ).The MgO (001) surface with magnesium vacancies hardly ex-hibits catalytic reactivity. It can be concluded that N2O dissoci-ation likely occurs at oxygen vacancy sites of MgO (001) sur-face, which is consistent with the generally accepted viewpoint in the experiments. The potential energy surface (PES) reflects that the dissociation process of N2O does not virtually need to surmount a given energy barrier.     

TDDFT Studies of Electronic Structure and First Hyperpolarizability of Tetra-nuclear Cubane-like Transition Metal Clusters

A series of tri-nuclear transition metal clusters with incomplete cubane-like configurations have been studied by TDDFT method. The calculations show that they have enormously large second-order polarizabilities () and are potential nonlinear optical materials for infrared double frequency conversion1. In this paper some tetra-nuclear transition metal clusters with cubane-like configurations, MCu3X4 (PPh3)3 (M=W, Mo; X= S, O, Cl, Se, Br), were studied by TDDFT method for a reference…