Synchrotron Study of the Dynamical Effects in the LVV Auger Transitions in the First-Row Transition Elements

The intensity ratio between L2-M45M45 and L3-M45M45 spectral features for both Fe and Co indicates significant tranfer of intensity from L2- to L3-M45M45 region due to Coster-Kronig L2-M45M45 transition. The L2-L3M45 transition can be suppressed by turning the photon energy between the L2 and L3 thresholds; however, the L3-M45M45 spectral shapes for Fe and Co do not change very significantly even at these photom energies unlike the cases of Ni, Cu and Zn, thus establishing that the M45-hole decays predominantly before the L3-hole Auger decay in the early transition elements in contrast to the late ones.

Embedded Thin Film Resistors on BCB by Low-Cost PWB Compatible Electroless Plating by Direct Foil Lamination Transfer Processes

Benzocyclobutene (BCB) has been proposed as a board level dielectric for advanced system-on-package (SOP) module primarily due to its attractive low-loss (for RF application) and thin film (for high density wiring) properties. Realization of embedded resistors on low loss benzocyclobutene (dielectric loss ~0.0008 at > 40 GHz) has been explored in this study. Two approaches, viz, foil transfer and electroless plating have been attempted for deposition of thin film resistors on benzocyclobutene (BCB). Ni-P alloys were plated using conventional electroless plating, and NiCr and NiCrAlSi foils were used for the foil transfer process. This paper reports NiP and NiWP electroless plated embedded resistors on BCB dielectric for the first time in the literature

Metal-Ion Metathesis in Metal-Organic Frameworks: A Synthetic Route to New Metal-Organic Frameworks

A porous metalorganic framework, Mn(H3O)(Mn4Cl)(3)(hmtt)(8)] (POST-65), was prepared by the reaction of 5,5',10,10',15,15'-hexamethyltruxene-2,7,12-tricarboxylic acid (H(3)hmtt) with MnCl2 under solvothermal conditions. POST-65(Mn) was subjected to post-synthetic modification with Fe, Co, Ni, and Cu according to an ion-exchange method that resulted in the formation of three isomorphous frameworks, POST-65(Co/Ni/Cu), as well as a new framework, POST-65(Fe). The ion-exchanged samples could not be prepared by regular solvothermal reactions. The complete exchange of the metal ions and retention of the framework structure were verified by inductively coupled plasmaatomic emission spectrometry (ICP-AES), powder X-ray diffraction (PXRD), and BrunauerEmmettTeller (BET) surface-area analysis. Single-crystal X-ray diffractions studies revealed a single-crystal-to-single-crystal (SCSC)-transformation nature of the ion-exchange process. Hydrogen-sorption and magnetization measurements showed metal-specific properties of POST-65.

Phase Evolution in the AuCu/Sn System by Solid-State Reactive Diffusion

The interfacial reactions between several Au(Cu) alloys and pure Sn were studied experimentally at 200A degrees C. Amounts of Cu in the AuSn4 and AuSn2 phases were as low as 1 at.%. On the basis of these experimental results there is no continuous solid solution between (Au,Cu)Sn and (Cu,Au)(6)Sn-5. The copper content of (Au,Cu)Sn was determined to be approximately 7-8 at.%. Substantial amounts of Au were present in the (Cu,Au)(6)Sn-5 and (Cu,Au)(3)Sn phases. Two ternary compounds were formed, one with stoichiometry varying from (Au40.5Cu39)Sn-20.5 to (Au20.2Cu59.3)Sn-20.5 (ternary ``B''), the other with the composition Au34Cu33Sn33 (ternary ``C''). The measured phase boundary compositions of the product phases are plotted on the available Au-Cu-Sn isotherm and the phase equilibria are discussed. The complexity and average thickness of the diffusion zone decreases with increasing Cu content except for the Au(40 at.%Cu) couple.

Microstructural features of an iron-based laser coating

A high toughness wear resistant coating is produced by laser clad Fe-Cr-W-Ni-C alloys. The microstructural and compositional features of the laser-solidified microstructures and phase evolutions occurring during high temperature tempering at 963 K were investigated by using analytical electron microscopy with energy dispersive X-ray analysis. The clad coating possesses the hypereutectic microstructure consisted of M7C3 + (Y + M7C3) Du ring high temperature aging, the precipitation of M23C6 and M2C in austenite and in situ transformation of dendritic M7C3 to M23C6 and eutectic M7C3 to M6C occurred. The laser clad coating reveals an evident secondary hardening and superior impact wear resistance.

Homo- and Heteronuclear Transition Metal Complexes Supported by Multinucleating Ligands

This dissertation is mainly divided into two sub-parts: organometallic and bioinorganic/materials projects. The approach for the projects involves the use of two different multinucleating ligands to synthesize mono- and multinuclear complexes. Chapter 2 describes the synthesis of a multinucleating tris(phosphinoaryl)benzene ligand used to support mono-nickel and palladium complexes. The isolated mononuclear complexes were observed to undergo intramolecular arene C¬–H to C–P functionalization. The transformation was studied by nuclear magnetic resonance spectroscopy and X-ray crystallography, and represents a rare type of C–H functionalization mechanism, facilitated by the interactions of the group 10 metal with the arene π–system.

Chapter 3 describes the construction of multinickel complexes supported by the same triphosphine ligand from Chapter 2. This chapter shows how the central arene in the ligand’s triarylbenzene framework can interact with dinickel and trinickel moieties in various binding modes. X-ray diffraction studies indicated that all compounds display strong metal–arene interactions. A cofacial triangulo nickel(0) complex supported by this ligand scaffold was also isolated and characterized. This chapter demonstrates the use of an arene as versatile ligand design element for small molecular clusters.

Chapter 4 presents the syntheses of a series of discrete mixed transition metal Mn oxido clusters and their characterization. The synthesis of these oxide clusters displaying two types of transition metals were targeted for systematic metal composition-property studies relevant to mixed transition metal oxides employed in electrocatalysis. A series of heterometallic trimanganese tetraoxido cubanes capped with a redox-active metal [MMn₃O₄] (M = Fe, Co, Ni, Cu) was synthesized starting from a [CaMn₃O₄] precursor and structurally characterized by X-ray crystallography and anomalous diffraction to conclusively determine that M is incorporated at a single position in the cluster. The electrochemical properties of these complexes were studied via cyclic voltammetry. The redox chemistry of the series of complexes was investigated by the addition of a reductant and oxidant. X-ray absorption and electron paramagnetic resonance spectroscopies were also employed to evaluate the product of the oxidation/reduction reaction to determine the site of electron transfer given the presence of two types of redox-active metals. Additional studies on oxygen atom transfer reactivities of [MMn₃O₄] and [MMn₃O₂] series were performed to investigate the effect of the heterometal M in the reaction rates.

Chapter 5 focuses on the use of [CoMn₃O₄] and [NiMn₃O₄] cubane complexes discussed in Chapter 4 as precursors to heterogeneous oxygen evolution reaction (OER) electrocatalysts. These well-defined complexes were dropcasted on electrodes with/without heat treatment, and the OER activities of the resulting films were evaluated. Multiple spectroscopic techniques were performed on the surface of the electrocatalysts to gain insight into the structure-function relationships based on the heterometallic composition. Depending on film preparation, the Co-Mn-oxide was found to change metal composition during catalysis, while the Ni-Mn oxide maintained the NiMn3 ratio. These studies represent the use of discrete heterometallic-oxide clusters as precursors for heterogeneous water oxidation catalysts.

Appendix A describes the ongoing effort to synthesize a series of heteromultimetallic [MMn₃X] clusters (X = O, S, F). Complexes such as [ZnMn₃O], [CoMn₃O], [Mn₃S], and [Mn₄F] have been synthesized and structurally characterized. An amino-bis-oxime ligand (PRABO) has been installed on the [ZnMn₃O] cluster. Upon the addition of O₂, the desymmetrized [ZnMn₃O] cluster only underwent an outer-sphere, one-electron oxidation. Efforts to build and manipulate other heterometallic [MMn₃X] clusters are still ongoing, targeting O₂ binding and reduction. Appendix B summarizes the multiple synthetic approaches to build a [Co₄O₄]-cubane complex relevant to heterogeneous OER electrocatalysis. Starting with the tricobalt cluster [LCo₃(O₂CR)₃] and treatment various strong oxidants that can serve as oxygen atom source in the presence Co²⁺ salt only yielded tricobalt mono–oxo complexes. Appendix C presents the efforts to model the H-cluster framework of [FeFe]-hydrogenase by incorporating a synthetic diiron complex onto a protein-supported or a synthetic ligand-supported [Fe₄S₄]-cluster. The mutant ferredoxin with a [Fe₄S₄]-cluster and triscarbene ligand have been characterized by multiple spectroscopic techniques. The reconstruction of an H-cluster mimic has not yet been achieved, due to the difficulty of obtaining crystallographic evidence and the ambiguity of the EPR results.

Metrologia de instrumentos endodônticos por microscopia eletrônica de varredura e análise digital de imagens: uma proposta metodológica

A padronização para a fabricação de instrumentos endodônticos em aço inoxidável contribuiu para o desenvolvimento de novos aspectos geométricos. Surgiram propostas de alterações no desenho da haste helicoidal, da seção reta transversal, da ponta, da conicidade e do diâmetro na extremidade (D0). Concomitantemente, o emprego de ligas em Níquel-Titânio possibilitou a produção de instrumentos acionados a motor, largamente empregados hoje. A cada ano a indústria lança instrumentos com diversas modificações, sem, contudo, disponibilizar informações suficientes quanto às implicações clínicas destas modificações. Existe um crescente interesse no estudo dos diferentes aspectos geométricos e sua precisa metrologia. Tradicionalmente, a aferição de aspectos geométricos de instrumentos endodônticos é realizada visualmente através de microscopia ótica. Entretanto, esse procedimento visual é lento e subjetivo. Este trabalho propõe um novo método para a metrologia de instrumentos endodônticos baseado no microscópio eletrônico de varredura e na análise digital das imagens. A profundidade de campo do MEV permite obter a imagem de todo o relevo do instrumento endodôntico a uma distância de trabalho constante. Além disso, as imagens obtidas pelo detector de elétrons retro-espalhados possuem menos artefatos e sombras, tornando a obtenção e análise das imagens mais fáceis. Adicionalmente a análise das imagens permite formas de mensuração mais eficientes, com maior velocidade e qualidade. Um porta-amostras específico foi adaptado para obtenção das imagens dos instrumentos endodônticos. Ele é composto de um conector elétrico múltiplo com terminais parafusados de 12 pólos com 4 mm de diâmetro, numa base de alumínio coberta por discos de ouro. Os nichos do conector (terminais fêmeas) têm diâmetro apropriado (2,5 mm) para o encaixe dos instrumentos endodônticos. Outrossim, o posicionamento ordenado dos referidos instrumentos no conector elétrico permite a aquisição automatizada das imagens no MEV. Os alvos de ouro produzem, nas imagens de elétrons retro-espalhados, melhor contraste de número atômico entre o fundo em ouro e os instrumentos. No porta-amostras desenvolvido, os discos que compõem o fundo em ouro são na verdade, alvos do aparelho metalizador, comumente encontrados em laboratórios de MEV. Para cada instrumento, imagens de quatro a seis campos adjacentes de 100X de aumento são automaticamente obtidas para cobrir todo o comprimento do instrumento com a magnificação e resolução requeridas (3,12 m/pixel). As imagens obtidas são processadas e analisadas pelos programas Axiovision e KS400. Primeiro elas são dispostas num campo único estendido de cada instrumento por um procedimento de alinhamento semi-automático baseado na inter-relação com o Axiovision. Então a imagem de cada instrumento passa por uma rotina automatizada de análise de imagens no KS400. A rotina segue uma sequência padrão: pré-processamento, segmentação, pós-processamento e mensuração dos aspectos geométricos.

Spin wave resonance in ferromagnetic films

The objective of this investigation has been a theoretical and experimental understanding of ferromagnetic resonance phenomena in ferromagnetic thin films, and a consequent understanding of several important physical properties of these films. Significant results have been obtained by ferromagnetic resonance, hysteresis, torque magnetometer, He ion backscattering, and X-ray fluorescence measurements for nickel-iron alloy films.

Taking into account all relevant magnetic fields, including the applied, demagnetizing, effective anisotropy and exchange fields, the spin wave resonance condition applicable to the thin film geometry is presented. On the basis of the simple exchange interaction model it is concluded that the normal resonance modes of an ideal film are expected to be unpinned. The possibility of nonideality near the surface of a real film was considered by means of surface anisotropy field, inhomogeneity in demagnetizing field and inhomogeneity of magnetization models. Numerical results obtained for reasonable parameters in all cases show that they negligibly perturb the resonance fields and the higher order mode shapes from those of the unpinned modes of ideal films for thicknesses greater than 1000 Å. On the other hand for films thinner than 1000 Å the resonance field deviations can be significant even though the modes are very nearly unpinned. A previously unnoticed but important feature of all three models is that the interpretation of the first resonance mode as the uniform mode of an ideal film allows an accurate measurement of the average effective demagnetizing field over the film volume. Furthermore, it is demonstrated that it is possible to choose parameters which give indistinguishable predictions for all three models, making it difficult to uniquely ascertain the source of spin pinning in real films from resonance measurements alone.

Spin wave resonance measurements of 81% Ni-19% Fe coevaporated films 30 to 9000 Å thick, at frequencies from 1 to 8 GHz, at room temperature, and with the static magnetic field parallel and perpendicular to the film plane have been performed. A self-consistent analysis of the results for films thicker than 1000 Å, in which multiple excitations can be observed, shows for the first time that a unique value of exchange constant A can only be obtained by the use of unpinned mode assignments. This evidence and the resonance behavior of films thinner than 1000 Å strongly imply that the magnetization at the surfaces of permalloy films is very weakly pinned. However, resonance measurements alone cannot determine whether this pinning is due to a surface anisotropy, an inhomogeneous demagnetizing field or an inhomogeneous magnetization. The above analysis yields a value of 4πM=10,100 Oe and A = (1.03 ± .05) x 10^-6 erg/cm for this alloy. The ability to obtain a unique value of A suggests that spin wave resonance can be used to accurately characterize the exchange interaction in a ferromagnet.

In an effort to resolve the ambiguity of the source of pinning of the magnetization, a correlation of the ratio of magnetic moment and X-ray film thickness with the value of effective demagnetizing field 4πNM as determined from resonance, for films 45 to 300 Å has been performed. The remarkable agreement of both quantities and a comparison with the predictions of five distinct models, strongly imply that the thickness dependence of both quantities is related to a thickness dependent average saturation magnetization, which is far below 10,100 Oe for very thin films. However, a series of complementary experiments shows that this large decrease of average saturation magnetization cannot be simply explained by either oxidation or interdiffusion processes. It can only be satisfactorily explained by an intrinsic decrease of the average saturation magnetization for very thin films, an effect which cannot be justified by any simple physical considerations.

Recognizing that this decrease of average saturation magnetization could be due to an oxidation process, a correlation of resonance measurements, He ion backscattering, X-ray fluorescence and torque magnetometer measurements, for films 40 to 3500 Å thick has been performed. On basis of these measurements it is unambiguously established that the oxide layer on the surface of purposefully oxidized 81% Ni-19% Fe evaporated films is predominantly Fe-oxide, and that in the oxidation process Fe atoms are removed from the bulk of the film to depths of thousands of angstroms. Extrapolation of results for pure Fe films indicates that the oxide is most likely α-Fe₂O₃. These conclusions are in agreement with results from old metallurgical studies of high temperature oxidation of bulk Fe and Ni-Fe alloys. However, X-ray fluorescence results for films oxidized at room temperature, show that although the preferential oxidation of Fe also takes place in these films, the extent of this process is by far too small to explain the large variation of their average saturation magnetization with film thickness.

Major and trace element analytical methods of the National Status and Trends Program: 2000-2006

This document contains analytical methods that detail the procedures for determining major and trace element concentrations in bivalve tissue and sediment samples collected as part of the National Status and Trends Program (NS&T) for the years 2000-2006. Previously published NOAA Technical Memoranda NOS ORCA 71 and 130 (Lauenstein and Cantillo, 1993; Lauenstein and Cantillo, 1998) detail trace element analyses for the years 1984-1992 and 1993-1996, respectively, and include ancillary, histopathology, and contaminant (organic and trace element) analytical methods. The methods presented in this document for trace element analysis were utilized by the NS&T Mussel Watch and Bioeffects Projects. The Mussel Watch Project has been monitoring contaminants in bivalves and sediment for over 20 years, and is the longest active contaminant monitoring program operating in U.S. costal waters. Approximately 280 Mussel Watch sites are monitored on biennial and decadal timescales using bivalve tissue and sediment, respectively. The Bioeffects Project applies the sediment quality approach, which uses sediment contamination measurements, toxicity tests and benthic macroinfauna quantification to characterize pollution in selected estuaries and coastal embayments. Contaminant assessment is a core function of both projects. Although only one contract laboratory was used by the NS&T Program during the specified time period, several analytical methods and instruments were employed. The specific analytical method, including instrumentation and detection limit, is noted for each measurement taken and can be found at http://NSandT.noaa.gov. The major and trace elements measured by the NS&T Program include: Al, Si, Cr, Mn, Fe, Ni, Cu, Zn, As, Se, Sn, Sb, Ag, Cd, Hg, Tl and Pb.

催化消除NO_x复合氧化物催化剂的研究

氮的氧化物(NOx)是大气中的一种重要的污染物，是酸雨的主要来源，目前氮氧化物的无毒处理已经是国际环保研究中最关键的课题之一。本论文选择了两种复合氧化物：一种是钙钛石结构的含Cu的层状复合氧化物；另一种是以水滑石为前体经焙烧后得的复合氧化物为催化剂对它们的物化性质和对催化消除NOx的活性进行了系统的研究，得到了一些有意义的结果。第一部分：钙钛石型结构的含Cu层状复合氧化物钙钛石复合氧化物由于具有独特的物理化学性质，长期以来一直受到固态物理、固体化学和催化领域的科技工作者的重视。尤其近年来对它们在催化消除NOx反应中的活性的研究引起了催化工作者的极大兴趣，这是由于，一方面，钙钛石类复合氧化物对处理NOx的反应活性比较高，有希望取代贵金属催化剂；另一方面，探讨复合氧化物的固态物理、化学性质与处理NOx反应催化性能的关系，有利于揭示处理NOx反应的催化作用本质，为寻找高效实用的催化剂提供理论依据。本论文系统研究了三个系列含Cu钙钛石型复合氧化物的固态物理化学性质和对NO-CO反应的催化性能，并讨论了二者的关系。主要的工作和结论如下：1) 以La_2CuO_4为模型化合物研究了制备方法对它的性质的影响：用四种制备方法：柠檬酸络合爆炸法，聚乙二醇凝胶法，聚丙烯酰胺凝胶法，DTPA络合法合成了La_2CuO_4。比较了四种方法的特点，和制备方法对La_2Cu0_4的结构的影响，并对所得La_2CuO_4在NO-CO反应中的催化活性的影响进行了研究。结果发现聚乙二醇凝胶法和DTPA络合法有利于形成好的晶形，而聚乙二醇凝胶法和聚丙烯酰胺凝胶法对NO-CO反应有较好的活性，这是由于由不同制备方法得到的样品中的缺陷的种类和含量不I司所致。2) La_(1-x)Ba_xCuO_(3-λ)系列中Ba含量对它的性质的影响：用柠檬酸络合法合成了LaBa_2Cu_3O_(7-λ)，LaBaCu_2O_(5-λ)，La_2BaCu_3O_(7-λ) La_4BaCu_5O_(13-λ)及YBa_2Cu_3O_(7-λ)五种钙钛石结构的复合氧化物。XRD分析表明此系列样品均为层状ABO_3结构（分别为二，三，五层）。用XPS和O_2-TPD对样品中的氧种进行了研究，结果显示样品中存在着两种活性氧种：α氧种和β氧种。在O_2-TPD中低温脱附的是α氧种，它可归属于化学吸附氧与样品中的氧空位的浓度有关。β氧种的脱附温度较高，它归属于晶格氧。利用H_2-TPR和化学分析的手段对样品中的金属离子和活性氧的稳定性进行了表征。结果显示大量的氧空位和Cu~(3+)存在于样品中，并且它们的浓度受Ba离子浓度的影响。此系列样品对CO还原NO的活性研究表明：它们的活性远远高于结构类似的Ln_2CuO_4和Ln_2NiO_4等复合氧化物，在低于300 ℃时N0转化率已接近100％．分析结果表明Cu~(3+)和氧空位对活性起很重要的作用。Ba离子的作用是：一方面使含Cu的ABO_3结构稳定；另一方面使样品更容易吸附NO。3) La_4BaCu_5O_(13-λ)中Mn或C0逐步取代Cu对样品性质的影响合成了两系列分别由Mn或Co逐步取代Cu的样品，XRD分析表明它们仍旧是钙钛石结构。通过XPS，O_2-TPD和化学分析方法对样品中的活性氧种进行了表征，结果表明，当Mn逐步取代Cu离子时，晶格氧增加，而吸附氧开始变化较小，当Mn含量大于Cu含量时，吸附氧迅速减少。在Co取代样品的O_(1s)的XPS谱中，氧种变化较Mn取代的小，这表明Co离子对样品中的氧空位含量的影响较Mn离子的小。氧化还原性能的研究表明当Cu离子被Mn或Co离子部分取代后，Cu离子变得更容易被还原，这表明Cu-M(Mn或CO)之间发生了协同作用，使Cu离子更活泼。当Mn或Co部分取代Cu离子之后，样品对CO还原NO反应的催化活性明显提高，当取代含量达到一定程度时（即X ≥ 3），催化活性迅速降低，这表明Cu离子在反应中起着很重要的作用，经过分析我们认为反应机理如下：Cu~(3+)-O~=-Cu~(3+) + CO → Cu~(2+)-□-Cu~(2+)+CO_2 Cu~(2+)-□-Cu~(2+) → Cu~(3+)-□-Cu~(2+) Cu~(3+)-□-Cu~(2+) + NO~-Cu~(3+)-NO-Cu~(2+) 2Cu~(3+)-NO-Cu~(2+) → 2Cu~(3+)-O~=-Cu~(3+) + N_2 式中□是氧空位，Cu~(3+)-□ 是F心。掺杂部分Mn或Co后，催化活性的提高可以归属于Cu-M之间发生的协同作用使Cu离子更活泼，表征结果表明Cu-Co之间的协同作用较Cu-Mn之间的弱（这可能是由于Co，Cu之间化学性质相似），但掺杂Co的样品的活性较掺杂Mn的要高，同时我们在反应中发现，Co含量较高的样品中反应产物中N_2O比掺杂Mn的样品高出许多，因此我们认为Co离子对反应中反应中间产物N_2O的生成比Mn离子要活性。第二部分以水滑石化合物为前体的复合氧化物水滑石类化合物属于一种阴离子粘土，由带正电荷的金属氧化物／氢氧化物和层间阴离子及水分子组成。以水滑石为母体经焙烧制得的氧化物催化剂用于氧化反应的实例尚不多，且大多用于液相催化反应。最近有文献报道含Co，Cu，Ni水滑石经焙烧后对N_2O分解有很好的活性，但还没有关于此类化合物应用于NO还原和分解的文献报道。我们首次将以水滑石为母体经焙烧制得的尖晶石催化剂用于催化消除NO_x的反应中，考察和表征了变更过渡金属离子时Co-M-Al系列和Mg-M-Al系列催化剂在CO还原NO，NO吸附和NO分解反应中的活性。1) 以Mg-M-Al水滑石为前体的催化剂用共沉淀法合成了一系列Mg-M-Al水滑石（M = Cr，Fe，Mn，Co，Ni，Cu；Mg/M/A1 = 3/1/1）。XRD表征表明所有化合物均为典型的水滑石化合物。通过TG-DTA考察了焙烧对样品的结构和组成的影响。450 ℃焙烧后所有样品的XRD图中仅能发现MgO相，表明过渡金属氧化物均匀地分散在MgO-Al_2O_3中，换句话说，所得样品焙烧后是过渡金属氧化物负载在MgO-Al_2O_3载体上。H_2-TPR研究进一步证实过渡金属氧化物在载体上得到了稳定。此系列样品对C0还原N0反应活性的测定表明Mg-Al-Cu样品表现出远远高于其它样品的活性，而Mg-Al和Mg-Ni-Al在550 ℃以下对反应几乎没有活性，其它样品表现出一定的活性。2) 以Co-M-Al水滑石为前体的催化剂体系经共沉淀法合成了Co-M-Al水滑石（M = 过渡金属），经焙烧后发现样品中有尖晶石相出现。比表面研究表明，在500-700 ℃之间比表面变化较小大约在80m~2/g左右，在更高温度焙烧后比表面迅速下降。此系列样品对NO的吸附性能研究表明Co-Al，C0-Ni-Al，Co-Cr-Al，Co-Fe-Al表现出较高的吸附性能，尤其是Co-Ni-Al在100 ℃对NO表现出100％的吸附；其它样品对NO的吸附较低。用过渡金属离子中d轨道电子在吸附前后的晶体场稳定化能的变化可以很好地解释此系列样品对NO的吸附性能。对NO分解的活性测定表明Co-Ni-A1，Co-Cr-A1和Co-Al表现出了较好的活性，其中Co-Ni-Al的活性最高。其它样品在600 ℃以下几乎没有活性。分析结果表明样品对NO分解有活性的催化剂必须具备两个条件：1：对NO有较好的吸附性能；2: NO分解后产生的氧可以容易的脱附。除Co-Al外，所有样品对CO还原NO表现出很高的活性：在150 ℃即有较高的NO转化率，在180 ℃NO转化率即可达到100％。催化剂的氧化还原性能在反应中起着很重要的作用，H_2-TPR研究发现掺杂其它过渡金属后Co离子的还原温度明显降低，表明Co离子得到了活化。3) 以Co-Cu-Al水滑石为前体的样品用共沉淀法合成了一系列Co/Cu/Al含量不同的水滑石化合物，包括Co/Cu/Al分别为7/1/1，3/1/1及1/1/1和仅含Co或Cu的Co/Al = 3/1，Cu/Al = 3/1等一系列样品。XRD结果表明除Cu-Al外其它样品经焙烧后均出现了尖晶石相。Cu-Al样品经焙烧后出现了CuO相表明样品为CuO负载于Al_2O_3上。NO和CO的TPD研究表明三组份样品对NO和CO的吸附明显高于二组份样品，而且含CO量高的样品对NO和CO的吸附能力更好，表明Co起较强的作用。在三组份样品的NO-TPD脱出物中发现有N_2O和N_2，表明NO在样品表面的吸附为活化吸附。对CO还原NO反应活性的研究表明，三组份样品的活性远远高于二组份样品，且含Co量高的样品活性较高，表明在此系列样品中Co离子起决定性作用，而Cu离子起助催化作用。通过对反应中各组份含量的变化分析，我们认为反应机理如下：CO + O-Cat → CO_2 + □-Cat NO + □-Cat → NO-Cat 2(NO-Cat) → N_2O + O-Cat + □-Cat N_2O + □-Cat → N_2O-Cat N_2_O-Cat → N_2 + O-Cat 2(N_2O-Cat) → N_2 + 2(O-Cat) O-Cat是样品中的晶格氧，在Co-Al中加入其它过渡金属离子使样品中的晶格氧得到活化，因此，催化活性得到提高。用以水滑石为前体，共沉淀法和固相反应法等三种制备方法合成了一系列Co-Cu-Al催化剂，发现以水滑石为前体的样品不论是对NO，CO的吸附性能还是对NO-CO反应的催化活性都远远高于其它方法制备的样品，这可能是由于水滑石可以起到一个模版作用，使Cu, Co离子分散的更均匀，以及使催化剂表面的含氧基团丰富。

杂多化合物的氧化还原性质、自组装和应用

1．利用电化学和现场紫外-可见-近红外光谱电化学的方法，系统研究了一系列过渡金属取代杂多化合物ZnW_(11)M(M = Cr，Mn，Fe，Co，Ni，Cu，Zn)的电化学行为。所有的这些化合物都在相近的电位处表现出四对连续的基于W中心的氧化还原反应。研究表明，ZnW_(11)M中基于W中心的氧化还原反应可能反映了它那个未知的缺位阴离子ZnW_(11)的氧化还原反应。此外，电活性过渡会属取代杂多化合物ZnW_(11)M(M = Cu，Fe，Mn)还表现了过渡金属M的氧化还原反应。例如：ZnW_(11)Cu~(11)表现出Cu的沉积和溶出，ZnW_(11)Fe~(III)在正电位处有一特殊的源于Fe的氧化还原反应，ZnW_(11)Mn则发生一个氧化反应和两个还原反应。根据实验结果我们提出了一些基本的反应机理。选取HNO_2为底物考察了这一系列过渡金属取代杂多化合物的电催化性能。通过比较电催化还原电流的大小，我们可以定性地排出这一系列过渡金属取代杂多化合物对HNO_2还原反应的电催化性能的顺序（由高到低）：ZnW_(11)Cu > ZnW_(11)Co > ZnW_(11)Cr和ZnW_(11)Fe > ZnW_(11)Zn、ZnW_(11)Mn和ZnW_(11)Ni。这一系列过渡金属取代杂多化合物的电催化性能的差别，可能主要是来自于它们分子结构中所取代的过渡金属元素的影响。实验证明ZnW_(11)M对HNO_2还原反应的电催化过程中产生NO气体。2．采用末端带有电荷的烷基硫醇首先自组装在金电极表面形成前体膜，在此前体膜上成功地沉积出杂多阴离子和一种阳离子聚合物的多层膜。利用多种技术对这种多层膜进行了表征，包括紫外可见光谱法、X射线光电子能谱法、反射-吸收红外光谱法、电化学石英晶体微天平法等。而且我们把这种修饰方法推广应用于不同结构类型、不同组成的杂多阴离子和同多阴离子中去，制备了它们的多层膜。利用原位EQCM技术研究了杂多酸分子的吸附动力学行为及电化学反应过程中的离子传输特性。实验结果表明，在修饰膜的电化学反应过程中，HSO_4~-离子的迁移在膜的电荷补偿中是必不可少的。修正并发展了依据原位EQCM技术考察迁移物种特性的方法，并基于此详细分析了HPA分子在各种修饰条件下电化学反应中正常及反常的频率响应及离子迁移行为。3．首次开发出来一种新颖的多层膜成膜方法-电化学生长法，并应用于制备含杂多化合物的多层膜中。通过多种技术表征，证明了电化学生长法比文献中通用的浸泡法更优越，可以在含有支持电解质的溶液里成膜而没有其它离子竞争吸附的缺点，制备出的自组装多层膜生长更均匀、超薄且功能良好。电化学生长法可望在制备其它种类的多层膜中会有广泛的应用。同时，我们也比较了这两种多层膜对于底物BrO_3~-和HNO_2还原反应的电催化作用。特别地，我们详细考察了多层膜厚度和最外层种类对电催化反应的影响。我们发现电催化性能随着多层膜层数（厚度）的增加而增长，这意味着我们可以通过调节多层膜的层数来达到最有效的催化性能，这一点是多层膜修饰电极优越于其它类型修饰电极最突出的优点之一。此外，我们还发现QPVP-Os最外层对催化反应有着一定的阻碍作用。这些影响作用可以从多层膜中电催化剂沉积量的多少和QPVP-Os最外层的屏蔽作用得以解释。4．尽管SiW_(l2)O_(40)~(4-)不能直接吸附在裸金电极的表面形成单层膜，我们成功地在预先自组装有半胱氨的金电极上制备出来了SiW_(12)O_(40)~(4-)单层膜。但是，这种SiW_(12)O_(40)~(4-)单层膜化学修饰电极的稳定性较差。基于同阳离子聚合物QPVP-Os的静电相互作用，我们成功地制备了均匀的SiW_(l2)O_(40)~(4-)多层膜。SiW_(l2)O_(40)~(4-)多层膜CMEs对BrO_3~-，H_2O_2和HNO_2的还原表现出显著的催化效应。对HNO，还原的催化效应随着层数由l到3的增加而增强，而这种催化效应的增强却随着层数由3到7而趋于平缓。由于多层膜结构是建立在同QPVP-Os的强烈的静电作用上的，因此SiW_(12)O_(40)~(4-)多层膜CMEs比单层膜CMEs有更好的稳定性。我们主要利用电化学方法（循环伏安法，CV）、紫外可见光谱法(UV-vis)、X-射线光电子能谱法(XPS)、X-射线反射法(XR)和电化学交流阻抗法(EIS)，对这种杂多阴离子自组装多层膜的成膜过程、多层膜结构和组成进行了进一步地表征。5．通过氨阳离子自由基修饰方法，把4-氨基苯甲酸修饰到玻碳电极表面。研究了该单层膜对多种电活性分子的影响，膜的阻滞行为主要是由于静电相互作用所导致的。利用循环伏安和电化学交流阻抗法考察了4-氨基苯甲酸修饰电极对不同酸度条件下铁氰化钾的电子传递情况，并测得了它的表面pKa值大约为3.1。以修饰在玻碳电极表面的4-氨基苯甲酸单层膜为前体膜，成功地静电沉积了阳离 子聚合物QPVP-Os和多种杂多化合物组成的多层膜。采用循环伏安法详细研究了这种杂多化合物单层膜和多层膜的电化学行为，并且考察了这种复合膜对三种底物BrO_3~-,HNO_2及H_2O_2的还原反应的电催化性能。6．类似地，在4-氨基苯甲酸修饰的玻碳电极表面上，我们也成功地制备了SiW_(12)的多层膜。循环伏安、X-射线光电子能谱和X-射线反射的实验结果证明多层膜的生长非常均匀而且稳定。X-射线反射实验测定了多层膜中每个SiW_(12)/QPVP-Os双层的平均厚度为30.3A。这种复合膜对Br0_3~-，HNO_2和H_2O_2还原有明显的催化活性，并且在较大的浓度范围内催化电流与浓度具有良好的线性关系。更有意义的是，随着SiW_(12)多层膜层数的增加（固定在多层膜中催化剂量的增加），多层膜的催化能力具较大程度地提高。因此，我们可以通过合理地控制多层膜的厚度来改善其催化活性及分析测定的灵敏度，从而达到最佳的催化效能和优化出最适宜的实验条件。由于电极的稳定性较好，期望可以实际用于Br0_3~-，HNO_2和H_20_2的检测。7．采用电化学生长方法在4-氨基硫酚自组装膜修饰的金电极上，制备了包含杂多阴离子（SiMo_(11)VO_(40)~(5-)和Pr(SiMo_7W_4)O_(40)~(5-)）和阳离子聚合物PDDA的多层膜修饰电极。用循环伏安法研究了多层膜修饰电极的电化学行为。在多层膜生长过程中，我们发现Mo的第三个氧化还原峰随多层膜层数的增加显著增长，而前两个氧化还原峰增长缓慢甚至不增长，这可能是由于PDDA对Mo的前两个还原峰有一定的阻碍作用所导致的。多层膜修饰电极的峰电位随pH的增加而线性负移，表明有氢离子参与到杂多阴离子的氧化还原反应中。多层膜修饰电极对BrO_3~-和HNO_2的还原反应有良好的电催化作用，Mo的第三个还原峰峰电流与BrO_3~-的浓度都有良好的线性关系，并且催化电流随着多层膜层数的增加而增长。8．我们考察了首先通过静电沉积技术（离子键组装）成膜，然后经过后续光化学反应来制备一类含聚苯胺的基于共价键结合的多层膜。通过紫外光的辐照，膜的交联结构可由离子键型转变为共价键型。溶剂刻蚀的结果表明此种共价键合多层膜有更好的稳定性。电化学实验表明，以此种方式组装在多层膜中的聚苯胺仍保留了其电化学性质。

金属酞菁作为苯及其衍生物羟化授反应的催化剂-第五配位体作用的探讨

按文献方法合成了一些过渡金属的酞菁络合物（MPc,其中：M = Fe、Co、Ni、Cu），并对已合成的金属酞菁进行了提纯、鉴定（IR、UV。元素分析）。为了研究第五配位体对酞菁铁催化性能的影响，我们从以下几个方面探讨了第五配位体的作用：（1）测定了不同轴向配体L存在时FePc(L)_2型络合物的电子光谱，考察了随轴向配体L变化电子光谱的改变，为尚无定论的外加谱带（Extra banol）II的归属提供了一定的证据。根据位子谱带β和Q_（0-0）之间的吸收II的位置和强度随L的变化趋势，将吸收峰II归为Q_(1g)（dZ~2）→ b_(1u) (π~*）跃迁。轴向配体对FePc的相互作用可分为σ-作用和π-作用，轴向配位体的自由碱碱度P_(Ka)可作为σ-作用大小的量度。我们发现：PK_a与Q_(0-0)吸收峰的能量存在着线性关系。根据FePc(L)_2络合物的结构特点和配位场理论，阐明了Q_(0-0)的红移程度只与轴向配体的σ-作用有关，而II的能量要受到轴向配体的σ-作用和π-作用影响的规律。根据上述结论，探讨了配位原子分别为O、N、S等元素的轴向配体对FePc的相互作用规律。对于配位原子为O和N的轴向配位体，配体对中心离子的作用以σ-作用为主，其强度为：DMSO < DMF < THF Py < Im < Pi_P < ButNH_2 < NH_3 < CN~-配位原子为S的轴向配体容易与中心离子形成具有电子授受作用的反馈π键（M<->~п_σL)，因此具有较强的π作用。（2）为了进一步讨论轴向配体的作用对FePc氧分活化性能的影响，借助于电子光谱的变化对FePc/DMSO、FePc/DMF、FePc/THF体系的与O_2作用动力学进行了跟踪，提出了相应的反应动力学和机理，理论动力学机理通过计算得到的动力学曲线与实验结果一致，从而验证了所提出的反应机理。实验结果表明：不同的第五配位体可改变FePc与O_2反应动力学的控制步骤，反位配体（第五配体）的σ-作用越大，配位O_2分子中O-O键断裂的趋势增大，同时生成桥氧（μ-oxo）二聚物的趋势也增大。（3）以半胱氨酸（Cystecine）为第五配体，研究了FePc-Cysteine模拟体系对苯胺的羟化学反应，提出了相应的催化反应机理，解释了羟化反应中所观察到了一些实验事实。实验表明：在此体系中苯胺的羟化需要在半胱氨酸过量的条件下进行，并且弱酸性和非极性条件对苯胺的羟化反应有利。这说明RS~-在反应中不仅是一个第五配体，而且也起到电子授与体的作用。羟化反应条件与细胞色素P-450生物体系所需条件基本一致，因此，FePc-Cysteine体系是一个比较好的P-450模拟体系。实验还表明σ-作用可以使不可逆的自动氧化过程加速，单纯的σ-作用对羟化反应并不十分有利，π-作用可以使活性中间体得到稳定，因而在生物化学上有重要意义的半胱氨酸是一个比较理想的第五配位体。

典型沉积物组分结合的重金属对芦苇的植物有效性研究

沉积物中的重金属，与无机、有机胶体通过吸附、配位体交换、络合、共沉淀等作用与沉积物中不同组分结合，由于污染来源、环境条件、赋存时间的不同，重金属可以有不同的化学形态。不同赋存形态的重金属具有不同的生物环境地球化学过程及生物有效性规律。 5种氧化物矿物吸附态Cd的富集实验表明，芦苇对吸附在含铝矿物表面的Cd吸收最多，其次为铁锰矿物。比表面积较大、等电点较低的矿物与Cd的吸附强度和稳定性较强，进而造成Cd的植物有效性较低。可能对Cd的吸附解吸产生影响的是植物根系分泌的有机酸，有机酸对不同矿物吸附Cd的解吸规律与芦苇对Cd的吸收规律一致。有机酸本身性质，如羧基数量、电离常数等影响Cd解吸量。 环境中与水合氧化物结合（吸附和共沉淀）的Cd生物有效性研究表明，两种结合形式的Cd均被芦苇富集，不同处理体系中富集强度不同，根中富集量9.1 ~ 37.8 mg/kg；地上部分富集量为0 ~ 10.0 mg/kg。由于共沉淀处理增加了矿物的比表面积和吸附位点密度，并且在预先混合的过程中Cd进入氧化物内部使结合了Cd的水合氧化物更加稳定，因此吸附态Cd的植物有效性大于共沉淀。老化处理可使Cd向水合氧化物晶格内部扩散，因而显著地降低吸附态Cd的富集。由于Fe(OH)3的等电点较低、阳离子交换容量较大，因此与Fe(OH)3 结合的Cd有效性较低。采用2种低分子量有机酸对Cd进行解吸，Cd的解吸规律与芦苇对镉的富集规律一致。 与无定形铁氧化物结合（吸附和共沉淀）的多金属富集实验表明，芦苇对不同金属的富集强度不同。金属离子与铁氧化物的亲合力由金属阳离子水合半径和水化数决定，本研究中金属与铁矿物结合亲合力遵循：Pb > Cd > Cu > Ni，因此芦苇对金属的富集规律大致为Ni > Cu > Cd > Pb。在多金属处理体系中，金属之间往往竞争相同的吸附位点，形成相似络合物，从而改变吸附强度和稳定性。Ni和Cd在根中富集量较少，可能是体系中Pb的投加产生了竞争作用。此外，植物对金属的选择性吸收也影响金属的植物有效性。解吸实验表明，吸附处理的金属解吸量大于共沉淀，单一金属投加体系中，重金属的解吸量：Ni > Cu > Cd > Pb；多种金属投加体系中，Pb的解吸量增加，Cd的解吸量下降。根系分泌的低分子量有机酸对沉积物中的重金属有重要的活化作用，这可能是植物吸收污染沉积物或土壤中重金属的重要因素之一。 针铁矿和不溶性腐殖酸吸附态Cd的富集实验表明，水溶态金属的有效性最大，其次为针铁矿吸附态，最难被植物吸收的是腐殖酸吸附态金属。由于腐殖酸结构复杂、表面多官能团和吸附位点，因此与金属的亲合力较大，结合牢固，不易被芦苇吸收富集。解吸实验验证了相同条件下，柠檬酸对腐殖酸吸附态金属的解吸量小于针铁矿结合态。pH值是影响金属与沉积物中活性组分结合强度和稳定性的重要因素。较低的pH值，水相中H+浓度较高，与金属离子竞争吸附位点，降低针铁矿或腐殖酸对金属离子的吸附容量和稳定性。另外，环境pH值较低（低于矿物等电点）时，矿物表面趋于带正电，增加了金属离子吸附的难度。 水体－沉积物体系中，可溶性腐殖酸影响重金属的迁移和生物有效性。不同的腐殖酸浓度和投加顺序对金属的生物有效性影响研究表明，单一金属投加体系中，金属在芦苇体内的富集规律为：Cu > Cd > Ni > Pb，金属在植物不同部位的分布遵循：根 > 叶 > 茎 > DCB，腐殖酸浓度的增加降低了金属的富集（除Ni外）。混合金属投加体系中，金属的富集遵循：Ni > Cu > Cd > Pb（HA 5 ppm）；Cd > Ni > Cu > Pb（HA 20 ppm）。与单一金属投加相比，金属的富集量降低，DCB提取态金属含量增加。腐殖酸浓度的增加降低了金属的生物有效性。腐殖酸加入顺序显著影响的金属与针铁矿的吸附，进而影响金属的生物有效性。

Analytical intercomparison results from the 1990 Intergovernmental Oceanographic Commission open-ocean baseline survey for trace metals: Atlantic Ocean

“Dissolved” (< 0.4 μm filtered) and “total dissolvable” (unfiltered) trace element samples were collected using “clean” sampling techniques from four vertical profiles in the eastern Atlantic Ocean on the first IOC Trace Metals Baseline expedition. The analytical results obtained by 9 participating laboratories for Mn, Fe, Co, Ni, Cu, Zn, Cd, Pb, and Se on samples from station 4 in the northeast Atlantic have been evaluated with respect to accuracy and precision (intercomparability). The data variability among the reporting laboratories was expressed as 2 × SD for a given element and depth, and was comparable to the 95% confidence interval reported for the NASS seawater reference standards (representing analytical variability only). The discrepancies between reporting laboratories appear to be due to inaccuracies in standardization (analytical calibration), blank correction, and/or extraction efficiency corrections.Several of the sampling bottles used at this station were not adequately pre-cleaned (anomalous Pb results). The sample filtration process did not appear to have been a source of contamination for either dissolved or particulate trace elements. The trace metal profiles agree in general with previously reported profiles from the Atlantic Ocean. We conclude that the sampling and analytical methods we have employed for this effort, while still in need of improvement, are sufficient for obtaining accurate concentration data on most trace metals in the major water masses of the oceans, and to enable some evaluation of the biogeochemical cycling of the metals.

Effect of substitution of chromium for nickel on structure and electrochemical characteristic of Ti0.26Zr0.07V0.24Mn0.1Ni0.33 multi-phase hydrogen storage alloy

Ti-Zr-V-Mn-Ni-based multi-component alloys demonstrate high discharge capacity in KOH electrolyte. However, the drastic decrease in their discharge capacities makes them unsuitable for use as negative electrode material in the Ni/MH battery. In present work, Ni is partially replaced by Cr in the Ti-Zr-V-Mn-Ni-based alloys to improve their cycle life. The effects of Cr substitution on microstructures and the electrochemical characteristics of the alloys are investigated. It is found that Cr substitution is very effective to improve the cyclic durability of the alloys although the discharge capacity decreases with changing x from 0.05 to 0.20. Some kinetic performances have been also investigated using electrochemical impedance spectroscopy (EIS) and potentiostatic discharge technique.