石墨炉原子吸收光谱中海水的背景吸收研究

由于海水的成分复杂,含盐量高,给用石墨炉直接测定其中的痕量杂质带来许多困难^[1]。Sturgeon等用预先分离的方法来克服干扰^[2]。为了进行直接测定,研究海水背景吸收的来源、特点和消除方法是重要的。海水背景吸收的波长特性和在石墨管内蒸发行为的研究表明,海水的背景吸收主要来自氯化钠。时间特性的研究表明,背景吸收的时间分布及背景峰高与原子化阶段的加热方式和原子化温度有关。作者还研究了基体改进。剂和其它减小背景吸收的方法。     

恒温炉中加热管材料对灵敏度的影响

恒温炉中加热管石墨表面结构和物理性质,直接影响分析试样的原子化行为。目前,利用热解涂层石墨管改善原子吸收分析灵敏度,已被人们重视并广泛应用^[1-2]。本文采用Woodriff炉做原子化器,对Al、K、Ag、Cd在普通石墨管和玻璃碳管中的原子化行为进行了研究,结果四种元素在玻璃碳管中的灵敏度均获得提高。     

炸药爆轰合成纳米石墨的红外光谱研究

石墨是碳材料中最常见的结晶状态,它具有耐高温、抗腐蚀、自润滑、无毒及价格低廉等特点,广泛应用于润滑剂和添加剂等方面^[1].由于高纯纳米石墨粉在某些高新技术领域中有较好的应用前景,近些年来得到开发和应用,如制成复合导电材料、吸波材料及储氢材料等^[2].以前有学者用纳米金刚石粉加热相转变^[3]和高能球磨^[4,5]的方法制备了纳米石墨,在制备碳纳米管时也有石墨的纳米粒子生成^[6].但用这几种方法制备纳米石墨,既费时又消耗较大能量,成本非常高.     

ETV-ICP-AES联用技术的蒸发器研究

ETV-ICP-AES是样品电热气化/电感耦合等离子体激发的联用技术^[1～7],具有进样效率高并可进行微升级样品分析的特点.ETV-ICP-AES多采用石墨炉或石墨棒蒸发器.因此,蒸发器的结构、形状、升温速率以及温度分布等对分析信号有很大的影响^[3,4].本文研究了蒸发器的接口、形状、结构的影响;自行设计了插入式平台,减小死体积,还研究了在载气单向连续流动的情况下,石墨炉内部温度的大致分布,讨论了平台蒸发和管壁蒸发.     

氢化物发生石墨炉原子吸收进展

在氢化物发生原子吸收光谱中,石英管是使用较为广泛的原子化器,但由于其气相干扰比较严重,石英管表面性质对分析灵敏度影响较大,因而又发展了石墨炉原子化器。自提出涂钯石墨管原位富集氢化物以后,氢化物发生石墨炉原子吸收受到人们的重视。现将氢化物发生石墨炉原于吸收的主要方法分述如下: 1 石墨炉在线原子化法 所谓石墨炉在线原子化法,是将生成的氢化物直接通入已经达到原子化温度的石墨管里的方法。氢化物可以从石墨炉内气路通入石墨管,也可以从石墨管进样孔进入石墨管。由于石墨炉原子化的温度较高,因而能大大减小可以形成氢化物元素的气相干扰。文献[1]比较了石英管和石墨管两种原子化器的抗干扰能力,其中有关砷和硒的干扰情况见表1。     

火焰原子吸收光谱法测定铋渣中银的含量

<正>铋渣是有色金属冶炼工业生产中的一种中间产品，是回收铋的重要原料^[1-2],其含有多种贵金属以及其他一些有价金属^[3-5]。采用合适的方法快速、准确地测定铋渣中银的含量，对企业工业生产过程具有较为重要的指导意义。目前测定银含量的主要方法有火试金富集重量法^[6-9]、电位滴定法^[10-11]、火焰原子吸收光谱法^[12-17]、电感耦合等离子体原子发射光谱法(ICP-AES)^[18-20]以及电感耦合等离子体质谱法(ICP-MS)^[21-22]等。火试金富集重量法存在灰吹时银损失的问题，对灰吹温度的控制要求较高，且基体铋对测定结果有较大干扰^[23];电位滴定法在滴定溶液标定、滴定终点判定等步骤要求精准；ICP-AES则存在样品光谱干扰较多，对于进样基体浓度水平、酸度的要求苛刻等问题；ICP-MS更多应用于高纯材料痕量杂质元素分析领域。利用火焰原子吸收光谱法具有较好的分析精度、检出限低，以及仪器长期稳定...     

石墨炉原子化器中原子化过程的研究(Ⅲ)——石墨炉中锗的原子化机理

有关锗的石墨炉原子吸收光谱分析,文献报道较少,对锗的原子化机理,亦有不同的看法^[1~3].本文基于右墨炉中锗原孚化行为的观察,对锗原子形成的过程进行了讨论,认为原子化过程中,并存着二种还原反应:GeO₂(s)+C→GeO(g)+CO(g),GeO₂(s)+CO→GeO(g)+CO₂,而锗原子的形成是GeO(g)热分解的结果。     

两种卟啉化合物在Ag溶胶表面的紫外-可见吸收光谱和表面增强拉曼散射光谱研究

表面增强拉曼散射(SERS)自1974年被Fleischmann等^[1]发现以来,日益受到人们的重视.通过SERS谱图分析,可以获得物质结构及其与基体作用的信息.由于SERS可使拉曼信号增强10⁵~10⁶倍^[2],并且在某些情况下银胶还能使表面吸附质的荧光猝灭^[3,4], SERS常用来检测一些普通拉曼光谱难以检测的样品和考察界面络合物的形成.     

焦磷酸络锰三价离子引发淀粉-丙烯酰胺的接枝共聚合

将带有极性基团的乙烯类单体通过化学接枝到淀粉或纤维素之类的天然多糖上,可作为絮凝剂、脱除剂和粘接剂^[1～3],近来已发展为高吸水性材料和石油分离剂^[4]。用Ce⁴⁺引发乙烯类单体接枝到淀粉和纤维素类已有报道^[5]。Rayonier用Mn³⁺的焦磷酸盐络合物引发接枝乙烯类单体至纤维素及其衍生物上^[6];Cenita等用Mn³⁺引发MMA、AN接枝淀粉^[7]。本文以焦磷酸络锰离子(Mn³⁺)作引发剂、丙烯酰胺(AM)为单体、淀粉为接枝基体进行接枝共聚,这一工作目前在国内外尚未见报道。     

二苯并噻吩及其氧化物与离子液体相互作用的理论研究

采用密度泛函理论方法比较了DBT/DBTO₂和[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-的相互作用。对最稳定的[BMIM]⁺[PF₆]^-、[BMIM]⁺[PF₆]^--DBT、[BMIM]⁺[PF₆]^--DBTO₂、[BMIM]⁺[BF₄]^-、[BMIM]⁺[BF₄]^--DBT、[BMIM]⁺[BF₄]^--DBTO₂进行了NBO和AIM分析。结果表明,DBT和[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-中的咪唑环彼此相互平行,NBO和AIM分析表明它们之间发生了π-π相互作用。H1'和H9'形成的F…H氢键有利于π-π堆积作用的形成。DBTO₂倾向于趋近C2-H2和甲基基团形成O…H相互作用;DBTO₂优先吸附在[BMIM]⁺[PF₆]^-/[BMIM]⁺[BF₄]^-。在模拟油中,[BMIM]⁺[PF₆]^-和[BMIM]⁺[BF₄]^-离子液体对DBTO₂的萃取能力大于DBT,其原因是可能是DBTO₂具有较大的极性和O…H与F…H的氢键作用。     

Binary modifiers for the determination of zinc in pure copper and nickel-based alloy by longitudinal Zeeman electrothermal atomic absorption spectrometry

The determination of zinc in pure copper and nickel-based alloy was successfully accomplished with a longitudinal Zeeman-effect correction and end-capped transversely heated graphite atomizer. Since aqua regia (an acid mixture of nitric acid and hydrochloric acid, 1:3, v/v) was used as the dissolving reagent, volatile ZnCl₂ was formed. Consequently, less Zn was found in the sample. EDTA could improve the atomic absorption profiles. Binary modifiers, EDTA + Pd(NO₃)₂ and EDTA + Mg(NO₃)₂, were effective for eliminating the chloride interference and the spectral interference from Cu I 213.853 nm. The experimental results obtained with and without the modifiers were compared. Increase of 200 °C in the pyrolysis temperature resulted from the addition of binary modifiers for both pure copper and nickel-based alloys. For pure copper, the atomization temperature increased from 1400 to 1600 °C whereas the atomization temperature increased from 1100 to 1600 °C for nickel-based alloys. The analytical performance of the proposed method was evaluated. Zinc contents in the pure copper and nickel-based alloy standards determined with both binary modifiers agreed closely with the certified values. The recovery ranged from 93 ± 2 to 104 ± 6% at 95% confidence level. The detection limits obtained by the binary modifiers of EDTA + Pd(NO₃)₂ and EDTA + Mg(NO₃)₂ were 0.77 and 0.31 pg, respectively.     

电解质对非离子型微乳液的影响

本文通过测定微乳液的电导率和相图,研究了电解质(硝酸镍)对非离子型微乳液Triton X-100/正己醇/环己烷/水或硝酸镍水溶液系统稳定性的影响.发现分散相为水的微乳液体系中,表面活性剂的含量越大微乳液的电导率越大;分散相为盐溶液的微乳液体系中,微乳液的电导率随着盐溶液浓度的增大而减小;而且盐溶液浓度越大微乳液的含水量越小.     

Solvothermal Syntheses and Characterization of Three One-dimension Cadmium Selenidoarsenates [Ni(1,2-dap)3][As2CdSe4],[Zn(1,2-dap)3][As2CdSe4] and [Ni(en)3][As2CdSe4]

Three new cadmium selenidoarsenates,[Ni(1,2-dap)3][As2CdSe4](1)(1,2-dap=l,2-diaminopropane),[Zn( 1,2-dap)3][As2CdSe4](2) and [Ni(en)3][As2CdSe4](3)(en=ethylenediamine), were synthesized under solvothermal conditions. And they are isostnictural and monoclinic crystalls. As seen from their structures, they exhibited one-dimensional(1D) chains composed of [As2CdSe4]^2- anions and [TM(amine)3]^2+(TM=Ni,Zn;amine=1,2-dap, en) cations. Their absorption edges are 2.32, 1.84 and 2.38 eV and they show the properties of the semiconductor. These compounds were also characterized by means of single-crystal X-ray ditlraction(XRD), powder X-ray diflraction (PXRD), solid-state optical absorption spectrometry, and so on.     

New Tetraazamacrocyclic Ligand with Neutral Pendent Groups 1,4,7,10-tetrakis (2-cyanoethyl)-l,4,7,10-tetraazacyclododecane (L) and Its Cobalt (Ⅱ), Nickel (Ⅱ) and Copper (Ⅱ) Complexes:Synthesis,Structural Characterization and Antitumor Activities

A new tetraazamacrocyclic ligand (L) with four neutral 2-cyanoethyl pendent groups and its divalent transition-metal complexes:[Co(L)(NO₃)]NO₃·H₂O (1),[Ni(L)(NO₃)]NO₃·3H₂O (2) and[Cu(L)(H₂O)](NO₃)₂ (3) have been synthesized. The crystal structures of (1) and (3) have been determined by X-ray analysis. In complex (1) the cobalt atom is coordinated by four nitrogen atoms and two oxygen atoms of a nitrate anion, which define a distorted octahedron. The other nitrate ion lies in the lattice as a counter ion.     

Tetrakis(triphenylphosphine oxide) complexes of the lanthanide nitrates; synthesis, characterisation and crystal structures of [La(Ph3PO)4(NO3)3]·Me2CO and [Lu(Ph3PO)4(NO3)2]NO3

The reaction of Ln(NO₃)₃·6H₂O (Ln=La, Ce, Pr or Nd) with a sixfold excess of Ph₃PO in acetone formed [Ln(Ph₃PO)₄(NO₃)₃]·Me₂CO. The crystal structure of the La complex shows a nine-coordinate metal centre with four phosphine oxides, two bidentate and one monodentate nitrate groups, and PXRD studies show the same structure is present in the other three complexes. In CH₂Cl₂ or Me₂CO solutions, ³¹P NMR studies show that the complexes are essentially completely decomposed into [Ln(Ph₃PO)₃(NO₃)₃] and Ph₃PO. Similar reactions in ethanol gave [Ln(Ph₃PO)₃(NO₃)₃] only. In contrast for Ln=Sm, Eu or Gd, only the [Ln(Ph₃PO)₃(NO₃)₃] are formed from either acetone or ethanol solutions. For the later lanthanides Ln=Tb–Lu, acetone solutions of Ln(NO₃)₃·6H₂O and Ph₃PO gave [Ln(Ph₃PO)₃(NO₃)₃] only, even with a large excess of Ph₃PO, but from cold ethanol [Ln(Ph₃PO)₄(NO₃)₂]NO₃ (Ln=Tb, Ho–Lu) were obtained. The structure of [Lu(Ph₃PO)₄(NO₃)₂]NO₃ shows an eight-coordinate metal centre with four phosphine oxides and two bidentate nitrate groups. In solution in CH₂Cl₂ or Me₂CO the tetrakis-complexes show varying amounts of decomposition into mixtures of [Ln(Ph₃PO)₃(NO₃)₃], [Ln(Ph₃PO)₄(NO₃)₂]NO₃ and Ph₃PO as judged by ³¹P{¹H} NMR spectroscopy. The [Ln(Ph₃PO)₃(NO₃)₃] also partially decompose in solution for Ln=Dy–Lu, forming some tetrakis(phosphine oxide) species.     

Melting and thermal decomposition of [Ni(H2O)6](NO3)2

The two-stage melting process and the thermal decomposition of [Ni(H₂O)₆](NO₃)₂ was studied by DSC, DTA and TG. The first melting point at 328 K is connected with the small and the second melting point at 362 K with the large enthalpy and entropy changes. The thermal dehydration process starts just above ca. 315 K and continues up to ca. 500 K. It consists of three well-separated stages, but the sample mass loss at each stage depends on the experimental regime. However, irrespective of the chosen regime, the total of registered mass losses in stage one and two amounts to three H₂O molecules per one [Ni(H₂O)₆](NO₃)₂ molecule. The remaining three H₂O molecules are gradually freed in the temperature range of 440–500 K in the third stage of the dehydration. Above 580 K, anhydrous Ni(NO₃)₂ decomposes into NO and NiO. The gaseous products were identified by quadrupole mass spectrometer (QMS), and the solid product was identified by X-ray diffraction (XRD) analysis.     

二维金属-六亚氨基苯框架材料的气体吸附效应

利用密度泛函理论研究了气体分子(NH₃, H₂O, H₂S, NO₂)吸附在二维M₃(HIB)₂(M=Ni, Cu; HIB为六亚氨基苯)薄膜上体系的几何结构和电子结构的变化. 结果表明, 2种薄膜对气体分子的响应不同. 其中NH₃, H₂O和H₂S在M₃(HIB)₂薄膜表面的吸附较弱, 主要与薄膜的亚氨基形成氢键, 吸附能均小于-0.36 eV, 吸附对体系电子性质的影响很小. 但是 NO₂分子在薄膜表面形成化学吸附, 吸附能在-0.65~-1.72 eV范围内. 吸附NO₂分子使其电子结构发生明显改变, 如Cu₃(HIB)₂在费米能级处打开带隙, 由金属性质转变为半导体性质. 这是由于NO₂分子的p_z轨道与金属原子$d_{z}^{2}$ 轨道发生了强烈的轨道杂化. 此外, 研究发现高浓度的NO₂分子吸附能够使Ni₃(HIB)₂薄膜由非磁性变为磁性体系, 由普通金属性质变为半金属性质; 而高浓度的NO₂分子使Cu₃(HIB)₂薄膜由金属性质变为半导体性质, 薄膜电导率降低.     

含稀土的钛系催化剂进行乙烯聚合动力学及ZnCl2调节分子量的研究

以SN-1催化剂进行乙烯常压聚合动力学研究表明,催化剂高效的主要原因是活性中心浓度明显增大、表观活化能△E较低。研究了ZnCl₂对乙烯聚合反应的影响。发现ZnCl₂能有效地降低聚乙烯的分子量,并能显著地提高催化效率,当ZnCl₂浓度过大时,则对聚合反应有抑制作用。     

Copper(II), nickel(II) and cobalt(II) complexes of 4-cyanobenzonic acid: syntheses, crystal structures and spectral properties

Three new metal complexes, Cu(4-Hcba)₂(4-cba)₂(Py)₂ (4-Hcba=4-cyanobenzoic acid) 1 and M[H(4-cba)₂]₂(Py)₂ (M=Ni 2, Co 3), have been prepared by the treatment of 4-Hcba with the respective metal nitrate M(NO₃)₂ (M=Cu, Ni, Co) in the presence of pyridine (Py). Single-crystal X-ray diffraction analyses (3 is isostructural to 2) show that the obtained complexes are of isolated mononuclear and the metal atoms have distorted octahedral coordination environment. Two different types of intramolecular hydrogen bonds exist: asymmetrical O–HO for 1 and symmetrical OHO for 2 and 3. The crystal packing between the molecular complexes is controlled mainly by T-shaped C–Hπ interactions between pyridine and phenyl rings. Preliminary discussions on IR, UV–VIS and fluorescent spectra have also been carried out.     

The ternary system H2O–Fe(NO3)3–Co(NO3)2 isotherms 0 and 15 °C

The solid–liquid equilibria of the ternary system H₂O–Fe(NO₃)₃–Co(NO₃)₂ were studied by using a synthetic method based on conductivity measurements.

Two isotherms were established at 0 and 15 °C, and the stable solid phases which appear are the iron nitrate nonahydrate (Fe(NO₃)₃·9H₂O), the iron nitrate hexahydrate (Fe(NO₃)₃·6H₂O), the cobalt nitrate hexahydrate (Co(NO₃)₂·6H₂O) and the cobalt nitrate trihydrate (Co(NO₃)₂·3H₂O).