活化液中稀土离子Ce3+对铜粉化学法镀银的促进作用

通过化学镀活化液中添加微量稀土元素Ce3+,采用电化学在Cu粉表面化学镀银,用电化学法和扫描电子显微镜测试技术分别研究了含稀土活化液的极化曲线、镀银层的表面形貌、银包覆率。结果表明,稀土以适宜比例添加到Pd2+活化液中,能使静止电极电位正移,极化度减小,过电位绝对值增大,活化液中的反应易于进行。适量稀土介入活化液中有助于提高镀银铜粉表面银在铜粉表面的沉积速度和包覆率,逐渐增加稀土含量,使镀层晶粒和组织逐渐细化且致密。 最佳加入值为0.32 g/L     

电活性铁氰化镍膜电极对稀土钇的电控离子分离

通过电沉积方法分别在镀铂石英晶片和铂基底上制备了电活性铁氰化镍膜,并考察了膜电极在含钇离子溶液中的电控离子交换性能. 在0.1 mol·L^-1的硝酸钇溶液中,使用循环伏安法及石英晶体微天平技术测试考察了铁氰化镍膜对钇离子的置入释放性能及对应的质量变化,同时比较了铁氰化镍膜电极在Y(NO₃)₃和Sr(NO₃)₂溶液中的电化学性能. 在0.1 mol·L^-1 [Y(NO₃)₃ + Sr(NO₃)₂]混合溶液中,通过循环伏安法分析了薄膜对Y³⁺/Sr²⁺离子的选择性. 用扫描电子显微镜观察了铁氰化镍膜的表面形貌,并通过X射线光电子能谱仪测定了膜在氧化和还原状态下的元素组成. 结果表明,铁氰化镍膜在含Y³⁺溶液中具有良好的离子交换行为,其中氧化过程薄膜质量减少,对应着钇离子的释放;还原过程薄膜质量增加,对应钇离子的置入;在0.0 V或0.9 V调控膜电极的氧化还原状态实现对钇离子的有效分离.     

Effect of Condensed Media on the Luminescent Characteristics of Lanthanide Complexes

The effect condensed media based on water-soluble polymers (WSPs) have on the luminescence of Eu³⁺ and Tb³⁺ complexes with derivatives of benzoic acid and β-diketones is investigated. The effect of WSPs is found to depend on the ratio between the triplet energy levels of polymers and ligands. The most intense luminescence is observed in WSP films. The possibility of a proportional increase in the intensity of Ln³⁺ luminescence in WSP solutions over a wider range of concentrations than in an aqueous solution, and of a considerable increase in Ln³⁺ luminescence in WSP solutions and films in the presence of d- and f-element quenchers, is established.     

Tb3+ as Fluorescent Probe in the Study of the Interaction of Other Lanthanide Ions with Trichosanthin

The interaction of lanthanide (Ln³⁺)ions with trchosanthin(TCS)was investi-gated using Tb³⁺ as fluorescent probe.The metal-binding sites of the protein were probed by means of adding the Tb³⁺ into the protein solutions.If other Ln³⁺ ions exist in the Tb³⁺ protein complex system, they would compete against Tb³⁺ in the binding sites of the protein, and so the fluorescence intensity of Tb³⁺ decreased,which is called quenching effect.The quencliing effect is related to the ionic radii of the Ln³⁺ ions and energy transfer from Tb³⁺ protein to Ln³⁺ ions.Based on the ex-perimental results,a schematic of the energy transfer from protein-Tb³⁺ complex to protein-Ln³⁺ complex is suggested.     

Reduction of Cd(II) and Mn(II) at the Dropping Mercury Electrode in the Presence of 1,3,5-Trihydroxybenzene in Aqueous Sodium Perchlorate

Reduction of Cd²⁺ at the dropping mercury electrode in solutions of 1, 3, 5-trihydroxybenzene was carried out in nonbuffer solutions of 0.1 M NaClO₄. The polarogram consists of two waves, the first wave can be taken in quantitative determination of Cd²⁺ in solutions containing 3.5 mM 1, 3, 5-trihydroxybenzene in 0.1 M NaClO₄. Mn²⁺ produces single well-defined diffusion controlled irreversible wave whose half-wave potential shifts to a more negative value with increasing 1, 3, 5-trihydroxybenzene. Me(II) forms two weak complexes, MX₁ and MX₂ at 25°. The behaviour of this metal ions is summarized.     

Control of the contaminant level for determination of Al3+ using 8-quinolinol by high-performance liquid chromatography with fluorescence detection

We developed a technique controlling contaminant Al3+ level using a combination of kinetics and thermodynamics at a pre-column derivatizing step in HPLC. The technique involves modifying a conventional HPLC of 8-quinolinol (Ox) complex with Al3+. The contaminant suppressing reagents, dihydroxyazobenzene (DHAB) and 1,2,3-trihydroxybenzene (pyrogallol) were added to the Ox and pH buffer solutions to convert contaminant Al3+ in these solutions to inactive complexes. The Al3+ in the sample selectively formed Ox complexes with fast kinetics. After that, the labeled fluorescent complexes in the resultant metastable state were separated in the HPLC. This technique successfully suppressed contamination by a factor of 17. This method allowed for an improvement in the detection limits and also provided a stable blank.     

Evidence of different stoichiometries for the limiting carbonate complexes across the lanthanide(III) series: a capillary electrophoresis-mass spectrometry study

The electrophoretic mobilities (mu ep,Ln) of twelve lanthanides (not Ce, Pr and Yb) were measured by CE-ICP-MS in 0.15 and 0.5 mol L(-1) Alk2 CO3 aqueous solutions for Alk+ = Li+, Na+, K+ and Cs+. In 0.5 mol L(-1) solutions, two different mu ep,Ln values were found for the light (La to Nd) and the heavy (Dy to Tm) lanthanides, which suggests two different stoichiometries for the carbonate limiting complexes. These results are consistent with a solubility study that attests the Ln(CO3)3(3-) and Ln(CO3)4(5-) stoichiometries for the heavy (small) and the light (big) lanthanides, respectively. The Alk+ counterions influence the mu ep,Ln Alk2 CO3 values, but not the overall shape of the mu ep,Ln Alk2 CO3 plots as a function of the lanthanide atomic numbers: the counterions do not modify the stoichiometries of the inner sphere complexes. The influence of the Alk+ counterions decreases in the Li+ > Na+ > K+ > Cs+ series. The K3,Ln stepwise formation constants of the Ln(CO3)3(3-) complexes slightly increase with the atomic numbers of the lanthanides while K4,Ln, the stepwise formation constants of Ln(CO3)4(5-) complexes, slightly decrease from La to Tb, and is no longer measurable for heavier lanthanides.     

A Role of the Plating Regime in the Deposition of Bismuth Films onto a Carbon Paste Electrode. Microscopic Study

A microscopic study is presented based on observations of bismuth films deposited from various plating solutions and under different experimental conditions onto the carbon paste surface. Electrolytic plating of bismuth films was performed either as simulation of preconcentration in‐situ from a 0.2 M acetate buffer containing 5×10^?5 M Bi³⁺ (pH 4.25), or as external deposition from various plating solutions: 0.1 M acetate buffer with 5×10^?4 M Bi³⁺ (pH 4.50), 0.5 M HCl with either 0.001 M BiCl₃ or 0.005 M BiCl₃ , 0.5 M HCl+0.5 M KBr+0.005 M BiCl₃ , and 0.5 M HCl+0.5 M KI+0.005 M BiCl₃ (all pH≈0.5). Scanning electron microscopic images of the bismuth films showed a considerable variability in structure and compactness of the deposited layer in dependence on experimental conditions chosen such as the concentration of Bi(III) species, the total acidity of plating media, the stability of complexes of Bi(III) with halogenide anions or the deposition potential applied.     

硫酸溶液中Ce3+在铂电极上阳极氧化动力学

用分解极化曲线法研究了铂电极上Ce（Ⅳ）阳极形成动力学与机理．实验结果表明，电位在1．7—1．9V（vs．SCE）的高极化区，分解得到的O2和Ce（Ⅳ）的极化曲线Tafel斜率分别为2．303RT／βF和2×2．303RT／βF，两者的动力学方程可分别用下式表示：
i(O2)=k1aw4exp(βφF/RT)
i(Ce4+)=k2aw2[Ce3+]exp(βφF/2RT)
假设了Ce3＋是通过反应中间基MCe（OH）3•Oad氧化的机理．由此所导出的动力学方程与实验结果相符．     

钒化合物对酸性镀锡溶液的稳定作用

研究了钒化合物稳定剂对酸性SnSO4 溶液稳定性的影响 .可见光谱分析表明稳定剂中主要含有VO2 + 和少量的V3+ ,循环伏安实验显示在 - 0 .2 0～ - 0 .55V(vs .SCE)电位范围内VO2 + 能够在阴极上还原为V3+ ,在更负的电位下V3+ 能进一步还原到V2 + .实验结果说明稳定剂中的低价钒离子有效地清除了镀液中的溶解氧 ,因而防止了Sn2 + 离子的氧化 ,显著地提高了酸性锡镀液的稳定性 .     

Thermal properties of ternary systems: The calculation of the standard enthalpy of solution for compounds in binary mixtures

An equation free of fitting parameters is proposed for calculating the standard heats of solution for compounds in nonaqueous binary mixtures. The parameters of the equation are the standard heats of solution of a compound in the components of the mixed solvent. Nonlinear ΔH ⁰(x) trends are reconstructed for solutions of water in i-PrOH + MeOH and MeCN + MeOH, t-BuOH in MeCN + MeOH, squalane in CHCl₃ + CCl₄ and C₆H₆ + CHCl₃, and hexadecane in MeOH + i-Pr₂O and in mixtures of butyl acetate, ethyl acetate, and 1,4-dioxane with 1-octanol. The standard heats of solutions are calculated for water in alcohol + alcohol, alcohol + aprotic solvent, and aprotic solvent + aprotic solvent mixtures     

Effects of Temperature Raising Speed on the Growth of BN Crystals in Hydrothermal Solutions

Cubic boron nitride (cBN) and orthorhombic boron nitride (oBN) crystals have been prepared in hydrothermal solutions by reacting H3BO3 NaN3 P and H3BO3 NaN3 N2H4 respectively. The experimental results indicated that, if the temperature was increased rapidly, both the yield and perfectness of BN crystals became poor. On the contrast, the yield and perfectness of BN crystals can be improved very much by slowly increasing the temperature of the reaction mixture. The results of X-ray powder diffraction (XRD), Fourier transform infrared spectrum (FTIR) and high resolution transmission electron microscopy (HRTEM) proved that the samples were composed of oBN and cBN.     

Parametric analysis of the energy levels of Nd3+ in frozen dilute aqueous solutions of neodymium chloride

A parametric analysis of the Stark-split spectra of Nd³⁺ in frozen dilute aqueous solutions of neodymium chloride has been carried out.The similarity of the spectra of Nd³⁺ in frozen dilute solutions and in crystals, where the ion is nine-fold coordinated and of approximate D_3h symmetry (Nd³⁺: LaCl₃, neodymium ethylsulfate and bromate), was used to obtain initial parameter values. Simultaneous diagonalization of the free ion and crystal field hamiltonians resulted in a r.m.s. deviation σ of 11 cm^?1 for 50 levels. The resulting crystal field parameters are B²₀ = 278 ± 19, B⁴₀ = ?201 ± 39, B^b₀ = ?946 ± 55 and B⁶₆ = 663 ± 43 cm^?1. Selection rules for D_3h are approximately obeyed. The small value of σ, the number of levels accounted for and the fact that the final parameters are not very different from those in the crystals indicate a nine-fold coordination of approximate D_3h symmetry for Nd³⁺ in frozen aqueous solutions. The spectra of liquid solutions show by their similarity to the spectra of frozen solutions that the same surroundings exist in the liquid.     

Electrochemistry of catechol terminated monolayers with Cu(II), Ni(II) and Fe(III) cations: a model for the marine adhesive interface

The redox electrochemistry of hydroquinone and Cu2+-, Ni2+-, and Fe3+-hydroquinone complexes immobilized at the SAM interface has been studied in aqueous solutions with pH 5 to 12 using cyclic voltammetry. Self-assembled monolayers were constructed with terminal hydroquinone residues designed to model marine adhesive proteins that use the DOPA (3,4-dihydroxyphenylalanine) moiety. Coordination of metal to the hydroquinone group results in a shift to the ligand oxidation potential, with the value for Delta E p,a dependent on the solution pH and identity of the metal. Cu2+ shifts the hydroquinone oxidation by -285 mV (pH 8.8), and Ni2+ by -194 mV (pH 9.16). The hydroquinone oxidation was shifted by -440 mV at pH 5 for Fe3+ solutions examined up to pH 7. By contrast, reduction of the quinone is unperturbed by the presence of Cu2+, Ni2+, and Fe3+ ions. Implications of these results to the mechanism of marine adhesion are discussed.     

利用荧光浓度指示剂fura-2研究稀土离子的跨膜行为

本文提出了利用fura-2测量细胞内游离稀土离子浓度的定量方法。实验结果表明, 在模拟细胞内离子组成的条件下, 稀土离子La^3^+和Y^3^+与fura-2形成1:1的配合物。其配合物的表观离解常数分别为161nmol.dm^-^3和404nmol.dm^-^3,pH7.05, 有未配对f电子的Nd^3^+, Ho^3^+, Sm^3^+, Dy^3^+,Ce^3^+, Yb^3^+等稀土离子对荧光起萃灭作用。此性质使我们能够定性鉴定它们是否进入了细胞。我们使用如上性质, 利用单细胞阳离子测试系统, 以小鼠骨髓瘤细胞为模式细胞, 研究了上游离稀土离子的跨膜行为及部分体内小分子对稀土离子跨膜行为的影响。实验结果支持游离稀土离子不能通过细胞膜的假设, 而且所研究的体内小分子在生理浓度下对稀土离子的跨膜也无明显作用。     

Effect of the nature and concentration of salting-out agents on the extraction of cobalt(II) from chloride solutions with trialkylamine

The effect of chlorides of Ca²⁺, Ni²⁺, Mg²⁺, Al³⁺, Li⁺, Fe²⁺, Cr³⁺, Na⁺, NH ₄ ⁺ , La³⁺, Nd³⁺ on the extraction recovery of cobalt from chloride solutions with mixtures based on trialkylamine was studied. The series of the salting-out activity of differently charged cations and the degree of their coextraction were determined.     

A comparative study of the adsorption of La and Al at the mercury/aqueous electrolyte interphase

Cationic surface excesses at the mercury/aqueous A1Cl₃, LaCl₃ and AlCl₃ + LaCl₃ interphases have been determined from differential capacity, potential of zero charge and interfacial tension measurements. A comparative analysis of the adsorption of La³⁺ and Al³⁺ at negative potentials has been carried out. No definite support for La³⁺ specific adsorption has been found. On the other hand, a simple combination of ion size effects and the Gouy-Chapman theory was able to give a reasonable account of the experimental surface excesses, obtained from either single-salt or mixed-salt solutions.     

Energy transfer characteristics of the hydrogen peroxide induced Ce3+-Ce4+ mixture

Luminescence of Ce3+ in the hydrogen peroxide induced sulfuric acid solutions was observed to be quenched by Ce4+ ions in the solution by energy transfer due to electric dipole interaction between Ce3+ and Ce4+. A systematic investigation of the energy transfer characteristics of Ce3+-Ce4+ mixture has been made by measuring the absorption, luminescence and excitation spectra at room temperature. The effect of the concentration of Ce3+ on the energy transfer process has been also studied and the critical transfer distance (Ro) has been calculated considering F?rster type interaction between the ions and found to be 8.7 A for the mixture of 1 x 10(-4) mol 1(-1) Ce3+ and 3 x 10(-4) mol l(-1) Ce4+.     

Luminescence properties and water coordination of Eu3+ in the binary solvent mixture water/1-butyl-3-methylimidazolium chloride

The effect of relative water content on the luminescence properties and speciation of Eu3+ ions in solutions of EuCl3 in the binary solvent mixture water/[BMI]Cl is presented, where [BMI]Cl is the ionic liquid (IL) 1-butyl-3-methylimidazolium chloride. Using luminescence techniques, the binding properties of water to Eu3+ are determined for samples with mole ratios of water-to-IL ranging from 0 to 5. Very little water binds to Eu3+ at mole ratios of water-to-IL less than 1, above which binding increases rapidly with increasing water concentration. It is shown that only certain hydration numbers for Eu3+ complexes are stable in the water/IL solutions. The data presented suggest that the Eu3+ species present are [EuClx]3-x, [EuCly(H2O)3-4]3-y, [EuClz(H2O)6]3-z, and [Eu(H2O)8-9]3+ (where x > y > z). Comparison of the positions of the 5D0<--7F0 transitions of the Eu3+ complexes in IL solution with those of model crystal systems provides insight into the extent of Cl- complexation. This study suggests that [BMI]Cl is a promising medium for luminescent lanthanide (Ln) compounds due to the low-energy phonon environment of the [LnClx]3-x complex and to the fact that moderate water contamination does not result in direct binding of water to Ln3+, which would result in luminescence quenching.     

Use of luminescence probing for the study of the interaction of polytitanasiloxane with trivalent rare earth ions

Luminescent probing methods were employed to investigate the interaction of the Ti-O chains of polytitanasiloxane with europium ions in the mixture of ethanol and water. The UV-vis absorption, the luminescence intensity, and the luminescence lifetimes of the Eu3+ ions in PTS solutions were all found to increase with the increase of TBT/TEOS molar ratio. The results indicated that the incorporation of TBT can result in the increase of absorption energy of the Ti-O group by near-UV excitation and in the increase of energy transfer to the metal ion, and that the Ti-O chains due to the site binding of Eu3+ ions can expel six to nine solvent molecules from the first coordination solvation shell of the ion. The investigation of the energy transfer from europium to neodymium ions in polytitanasiloxane solutions revealed the formation of aggregates consisting of seven rare earth ions (together with the polytitanasiloxane countercharges).