原子分辨显微分析技术研究进展

非接触原子力显微技术(NC-AFM)近年来发展迅速. NC-AFM对单个分子的成像和谱学实现了原子分辨和单个化学键分辨. NC-AFM自身功能的拓展及其与不同探针技术的联用将为材料、物理、化学和生命科学有关的研究提供崭新的思路. 本文首先介绍NC-AFM和qPlus 传感器的基本原理, 然后讨论原子尺度的相互作用力和短程力的精确测量, 总结近年来NC-AFM在原子尺度的化学结构成像、化学识别、电子结构性质分析以及原子操纵技术中的研究进展, 并讨论了开尔文探针力显微技术(KPFM)在局域接触势差(LCPD)测量方面的应用. 最后展望了NC-AFM面临的挑战和发展机遇.     

石墨炉内石墨探针表面上的原子化机理研究——Ⅷ 锡的原子化机理

利用探针原子化技术,研究了在普通石墨管中锡化合物的原子化过程中所发生的化学反应,阐述了锡的原子化机理。结果表明,锡试样首先转化成为氧化物,氧化物发生石墨碳还原而生成气态原子。     

石墨炉内石墨探针表面上的原子化机理研究(Ⅴ)——锰的原子化机理

在石墨炉原子吸收光谱(GFAAS)法中,反应前后的化合物形态可以借助于X射线衍射(XRD)、俄歇电子能谱(AES)及化学分析光电子能谱(ESCA)等现代分析仪器来鉴定,本文综合利用上述分析方法,对锰化合物在石墨探针表面上于不同温度下的化学形态进行鉴定,结合元素的灰化和原子化曲线,详细地研究和阐述了锰的原子化机理。     

Comparative Studies on Chemical Modification by Diethyldithiocarbamate for ETV-ICP-OES and ETAAS Determination of Chromium and Nickel

The chemical modification of diethyldithiocarbamate (DDTC) in electrothermal vaporization inductively coupled plasma optical emission spectrometry (ETV-ICP-OES) and in electrothermal atomic absorption spectrometry (ETAAS) was comparatively investigated. The experimental results indicated that the formation of Cr- and Ni-DDTC chelates enhanced significantly the emission signals of Cr and Ni in ETV-ICP-OES, but decreased the absorption signal of Cr and Ni in ETAAS. The different role of DDTC in ETV-ICP-OES and ETAAS was attributed to the different functions of the graphite furnace in the two techniques. The graphite furnace was used as both a vaporizer and an atom-vessel for analytes in ETAAS, but only used as a vaporizer for the sample in ETV-ICP-OES. Thermal gravimetric analysis of Cr- and Ni-DDTC chelates and UV-Vis analysis of the sample vapor collected in CHCl₃ after vaporization of their chelates from the graphite furnace indicated that the analytes were vaporized and transported into ICP as their chelates. In addition, the vaporization mechanism of Cr and Ni was also briefly discussed.     

Determination of mercury in environmental samples by cold vapour generation and atomic-absorption spectrometry with a gold-coated graphite furnace

Mercury is determined at below the pg/ml level by a combination of cold vapour generation, trapping in a gold-coated graphite furnace and atomic-absorption detection. The mercury is reduced to the element by stannous chloride, stripped from solution by a stream of nitrogen and collected on a gold-coated porous graphite disk in a graphite furnace. It is then atomized by increasing the graphite furnace temperature and detected by an atomic-absorption spectrophotometer. The absolute detection limit and the characteristic mass were found to be 5 and 20 pg for 0.0044 absorbance, respectively. The concentration limit of detection was 0.1 pg/ml for a 50-ml sample, and the linear dynamic range covered three orders of magnitude. The precisions of the measurements were 2.7% for 0.1 ng and 2.6% for 2 ng of mercury. Analyses of NBS and NIES reference materials showed quantitative recovery. Analytical results obtained by the technique are presented for natural waters, marine biota and sediments.     

Atom probe tomography: a technique for nanoscale characterization.

Atom probe tomography is a technique for the nanoscale characterization of microstructural features. Analytical techniques have been developed to estimate the size, composition, and other parameters of features as small as 1 nm from the atom probe tomography data. These methods are outlined and illustrated with examples of yttrium-, titanium-, and oxygen-enriched particles in a mechanically alloyed, oxide-dispersion-strengthened steel.     

Trends in Preconcentration Procedures for Metal Determination Using Atomic Spectrometry Techniques

 Methods for metal preconcentration are often described in the literature. However, purposes are often different, depending on whether the methods are applied in environmental, clinical or technological fields. The respective method needs to be efficient, give high sensitivity, and ideally also is selective which is useful when used in combination with atomic spectroscopy. This review presents the actual tendencies in metal preconcentration using techniques such as Flame Atomic Absorption Spectrometry (FAAS), Electrothermal Atomic Absorption Spectrometry (ETAAS), Hydride Generation Atomic Absorption Spectrometry (HGAAS), Inductively Coupled Plasma Optical Emission Spectrometry (ICP OES) and Inductively Coupled Plasma Mass Spectrometry (ICP-MS). Procedures based on related to electrochemical, coprecipitation/precipitation, liquid–liquid and solid–liquid extraction and atom trapping mechanisms are presented. Correspondence: Department of Analytical Chemistry, Universidade Estadual de Campinas – UNICAMP, P.O. Box 6154, 13083-970 Campinas, Brazil. e-mail: zezzi@iqm.unicamp.br Received December 20, 2001; accepted October 11, 2002     

Electrothermal atomic absorption spectrometric determination of arsenic in essential lavender and rose oils

Analytical procedures for electrothermal atomic absorption spectrometric (ETAAS) determination of arsenic in essential oils from lavender (Lavendula angustifolia) and rose (Rosa damascena) are described. For direct ETAAS analysis, oil samples are diluted with ethanol or i-propanol for lavender and rose oil, respectively. Leveling off responses of four different arsenic species (arsenite, arsenate, monomethylarsonate and dimethylarsinate) is achieved by using a composite chemical modifier: l-cysteine (0.05 g l⁻¹) in combination with palladium (2.5 μg) and citric acid (100 μg). Transverse-heated graphite atomizer (THGA) with longitudinal Zeeman-effect background correction and ‘end-capped’ graphite tubes with integrated pyrolytic graphite platforms, pre-treated with Zr-Ir for permanent modification are employed as most appropriate atomizer. Calibration with solvent-matched standard solutions of As(III) is used for four- and five-fold diluted samples of lavender and rose oil, respectively. Lower dilution factors required standard addition calibration by using aqueous (for lavender oil) or i-propanol (for rose oil) solutions of As(III). The limits of detection (LOD) for the whole analytical procedure are 4.4 and 4.7 ng g⁻¹ As in levender and rose oil, respectively. The relative standard deviation (R.S.D.) for As at 6-30 ng g⁻¹ levels is between 8 and 17% for both oils. As an alternative, procedure based on low temperature plasma ashing in oxygen with ETAAS, providing LODs of 2.5 and 2.7 ng g⁻¹ As in levender and rose oil, respectively, and R.S.D. within 8-12% for both oils has been elaborated. Results obtained by both procedures are in good agreement.     

Understanding and Manipulating Inorganic Materials with Scanning Probe Microscopes

Scanning probe microscopies, such as scanning tunneling microscopy and atomic force microscopy, are uniquely powerful tools for probing the microscopic properties of surfaces. If these microscopies are used to study low-dimensional materials, from two-dimensional solids such as graphite to zero-dimensional nanostructures, it is possible to elucidate atomic-scale structural and electronic properties characteristic of the bulk of a material and not simply the surface. By combining such measurements with chemical synthesis or direct manipulation it is further possible to elucidate relationships between composition, structure, and physical properties, thus promoting an understanding of the chemical basis of material properties. This article illustrates that the combination of scanning probe microscopies and chemical synthesis has advanced our understanding of charge density waves, high-temperature superconductivity, and nanofabrication in low-dimensional materials. This new approach to studying materials has directly contributed to our knowledge of how metal dopants interact with charge density waves and elucidated the local crystal chemistry of complex copper oxides, microscopic details of the superconducting states in materials with a high superconducting transition I_c, and new approaches to the fabrication of multi-component nanostructures. Coupling scanning probe microscopy measurement and manipulation with chemical synthesis should provide an approach to understanding material properties and creating complex nanostructures in general.     

异种金属焊接接头的电子探针分析

用电子探针对异种金属摩擦焊接接头进行了扩散组元含量分布和成分定量分析。结果表明电子探针能有效地分析出固体中的微观传质现象,同时可方便地测出接头处扩散层的宽度和微观组织结构变化情况。     

Ultratrace and microdistribution analysis in material sciences

Summary All-rounders and experts are two basic types of scientists. A harmonic cooperation between these two groups is essential for today's large study groups engaged in materials development. Materials development programmes in many high-tech countries are major fields of research supported by special financial arrangements (e.g. COST, EURAM or BRITE-programmes in Europe). Modern materials development is not possible without analytical guidance. This is not always realized by all engaged partners and it is a main obligation of analytical chemists to make aware of the role of a potent materials characterization in relevant development programmes. This should be demonstrated in two essential relevant areas: a) Bulk trace and ultra trace analysis of metals. Many important metal properties are directly or indirectly influenced by trace elements. In complex systems like fusion reactors or microelectronic components, trace contents of even minor metal parts might decisively influence system properties. As refractory metals and their silicides gain rising importance in VLSI microelectronic applications, their ultratrace characterization becomes a major challenge. Essential progress was possible by the complementary application of mass-spectrometric methods. Latest results and a critical survey will be given, including GDMS, SIMS, SSMS, IDMS and ICP-MS.Surprisingly, however, highest sensitivities and best detection limits were recently achieved by a combination of trace-matrix separation procedures and final end determination with ICP-MS. This combination also proved to be the most economic and safest approach from the view point of accuracy and precision. b) The analytical characterization of discontinuities and heterogeneities in solid matter. Practical examples are again taken from the study of refractory and hard metals and ceramics. A survey is given as to the manifold effects, heterogeneities and discontinuities exert on modern high-tech materials: as a function of their average diameter, they can either strengthen the material (dispersion strengthening), or they can cause deterioration of material properties e.g. as points of crack initiation, by grain boundary embrittlement etc. Together with most important methods for detection and characterization of heterogeneities and discontinuities, their evaluation and possible prevention during materials fabrication are discussed and pertinent examples are given. The phenomena of heterogeneous particles and pores are elucidated in more detail.

Acronyms used

1 Abbreviations for European research programmes AGATA Advanced Gas Turbines for Automobiles - BRITE Basic Research for Industrial Technologies for Europe - COST Cooperation in Science and Technology - EURAM European Research Activities Programme on Materials 2 Abbreviations in the field of refractory metals technology ADM Ammonium-Di-Molybdate - APT Ammonium-Para-Tungstate - HP High Purity - MHC Molybdenum-based alloy containing 1.2% Hf and 0.1% C - NS Non-sag (tungsten, used for lamp filaments and evaporative metallization techniques) - ODS Oxide Dispersion Strengthened - RM Refractory Metal - TZM Molybdenum-base alloy containing 0.5% Ti, 0.08% Zr and 0.025% C - UHP Ultra High Purity - VLSI Very large scale integration - ZHM Molybdenum-base alloy containing 0.40% Zr, 1.2% Hf and 0.15% C 3 Analytical technique names AA Activation Analysis - AAS Atomic Absorption Spectrophotometry - AES Auger Electron Spectrometry or Atomic Emission Spectrometry (only used in this work where it is clear that Auger Electron Spectrometry is not meant) - EDX(RS) Energy Dispersive X-Ray Spectrometry - EELS Electron Energy Loss Spectrometry - EP(X)MA Electron Probe X-Ray Microanalysis - GDMS Glow Discharge Mass Spectrometry - GFAAS Graphite Furnace Atomic Absorption Spectrometry - ICP-OES, MS Inductively Coupled Plasma — Optical Emission Spectrometry, Mass Spectrometry - ID-MS Isotope Dilution — Mass Spectrometry - LAS Classical photometry (Liquid Absorption — Spectrophotometry) - LEED Low Energy Electron Diffraction - MS Mass Spectrometry - NAA Neutron Activation Analysis - OES Optical Emission Spectrometry - SEM Scanning Electron Microscopy - SIMS Secondary Ion Mass Spectrometry - SSMS Spark Source Mass Spectrometry - TEM Transmission Electron Microscopy - TMS Trace-Matrix Separation (procedure) - WLD(-XRS) Wave Length Dispersive — XRS - XR(F)S X-Ray (Fluorescence) Spectrometry     

Comparative study on the use of Ir, W and Zr-coated graphite tubes for the determination of chromium in slurries of human scalp hair by electrothermal atomic absorption spectrometry

The use of Ir, W and Zr-coated graphite tubes, as permanent chemical modifiers, was studied for the determination of chromium in human scalp hair by ETAAS using the slurry sampling technique. The use of Mg(NO₃)₂ and Pd, as aqueous chemical modifiers, was also investigated and compared to the use of the permanent chemical modifiers. Scalp hair samples were pulverized using a Zr vibrational ball mill, (mean particle diameter of 0.8 μm) and suspended in ultrapure water. The lowest limit of detection, 44.5 μg kg^–1,was achieved for the use of W-coated graphite tubes. The repeatability of the overall procedures (slurry preparation and ETAAS determination) were 15.7, 14.5 and 16.7% for W- and Zr-coated graphite tubes and Mg(NO₃)₂, respectively. The methods were applied to several reference materials, CRM 397 (human hair), DOLT-1 (dogfish liver) and DORM-1 (dogfish muscle), and the results obtained were in agreement to the certified values. Finally, the methods were applied to several human scalp hair samples from healthy adults.     

X射线晶体学结合电子晶体学在复杂无机晶体结构解析中的应用

自然界中的材料,比如无机材料,有机材料,生物材料等等,均有其独特的物理和化学性质。而材料的性能又与材料的结构息息相关,只有充分了解了材料的结构,才能更加深入的研究材料性质。因此,材料结构的确定在化学、物理、生物等学科中的显得尤为重要。X射线晶体学作为传统的结构解析技术仍然是目前最重要的结构解析手段,但是对于复杂结构,X射线衍射晶体学解析结构也存在一些不足,往往需要其他技术手段相补充才能完成复杂结构的结构解析。电子晶体学虽然起步比X射线晶体学晚,但是,经过近几十年的发展,已经是结构解析领域一个非常重要的手段。本文将主要介绍X射线晶体学结合电子晶体学在复杂无机晶体结构解析中的应用。     

Pure graphite as a reference material for the determination of trace elements — an interlaboratory collaborative study

Seven synthetic graphite powders of different grade of purity were analyzed by means of INAA, WDXRF, EDXRF, DC-OES directly and using ICP-MS, ICP-OES, ETAAS and FAAS in combination with various sample preparation techniques. On the basis of a statistical evaluation of the results obtained, for the trace elements Al, Ca, Cr, Cu, Fe, Mn and Ni, reference values were established and, for the elements As, Co, Mg, Mo, Pb, Sb, Si, Sr, Ti, V, Zn and Zr, informative values are given. The analyzed reference materials are commercially available.     

The role of atomic scale investigation in the development of nanoscale materials for information storage applications.

It is well established that the response of devices based on the giant magnetoresistance (GMR) effect depends critically on film microstructure, with parameters such as interfacial abruptness, the roughness and waviness of the layers, and grain size being crucial. Such devices have applications in information storage systems, and are therefore of great technological interest as well as being of fundamental scientific interest. The layers must be studied at high spatial resolution if the microstructural parameters are to be characterized with sufficient detail to enable the effects of fabrication conditions on properties to be understood, and the techniques of high resolution electron microscopy, transmission electron microscopy chemical mapping, and atom probe microanalysis are ideally suited. This article describes the application of these techniques to a range of materials including spin valves, spin tunnel junctions, and GMR multilayers.     

Determination of vanadium in water by electrothermal atomisation atomic absorption spectrometry after extraction with 8-hydroxyquinoline in isobutyl methyl ketone

A sensitive method for the determination of vanadium in water by electrothermal atomisation atomic absorption spectrometry (ETAAS) is described. The vanadium is chelated with 8-hydroxyquinoline in isobutyl methyl ketone and determined by ETAAS after pre-heating the pyrolytic graphite coated graphite tube of a graphite furnace atomiser before injection. The effects of the pH and amount of reagent required for the extraction were studied. The precision, accuracy and interferences of the method were also investigated. The proposed method allows concentrations of vanadium of 0.16 microgram l-1 to be detected.     

Determination of ultratrace elements in natural waters by solid-phase extraction and atomic spectrometry methods

A study was carried out on the preconcentration of ultratrace amounts of cadmium, lead, manganese, copper and iron from high-salinity aqueous samples and determination by atomic spectrometry methods. Sample volume, amount of resin, loading flow rate, and elution volume were optimized in order to obtain the simultaneous preconcentration of all the analytes. Quantitative recoveries were obtained by using 200 mg of iminodiacetic resin with a loading flow rate of 2 mL min(-1), elution volume of 3 mL and sample volume of 50-450 mL. Only copper in seawater samples was not completely retained by the resin (60-70% recovery), due to unfavorable competition of iminodiacetic-active groups with organically bound metal.To quantify the metals in the eluates, two atomic spectrometry techniques were compared: electrothermal atomization atomic absorption spectrometry (ETAAS) and inductively coupled plasma-optical emission spectrometry (ICP-OES) with simultaneous CCD detection system. Both techniques are suitable for sample analysis with detection limits of 1.0, 4.7, 3.3, 6.8, and 53 ng L(-1) using ETAAS and 12, 122, 3.4, 17, and 21 ng L(-1) using ICP-OES for Cd, Pb, Mn, Cu, and Fe, respectively. Relative standard deviations of the procedures ranged from 1.7 to 14% at the sub-microg L(-1) concentration level. The accuracy of both methods was verified by analyzing various certified reference materials (river water, estuarine water, coastal and off-shore seawater).     

Application of Nanocrystalline Graphite‐like Pyrolytic Carbon Film Electrode in the Electroanalytical Determination of Famotidine

Direct electro‐oxidation of famotidine at different graphitic carbon‐based electrode materials was evaluated. These materials included conventional electrodes of edge‐plane pyrolytic graphite, basal‐plane pyrolytic graphite, carbon paste, and glassy carbon as well as nano‐structured carbon‐based materials such as pyrolytic carbon film, carbon nanotube, and nano‐graphene. Raman spectroscopy and scanning electron microscopy were employed to analyze their structural and morphological features. It was found that the pyrolytic carbon film electrode, after a simple and fast anodic activation, shows superior electroanalytical performance. The method was successfully applied for the electroanalytical determination of famotidine in tablet dosage forms and urine samples.     

含Fe、Co、Ni的层状双金属氢氧化物为催化剂前体生长碳纳米管

分别以具有相似Fe、Co、Ni含量的层状双金属氢氧化物(LDHs)为催化剂前体,用化学气相沉积的方法生长碳纳米管(CNTs).催化剂由LDHs焙烧还原得到.通过X射线衍射(XRD)、扫描电子显微镜(SEM)、透射电子显微镜(TEM)及拉曼光谱(Raman)测试技术对LDHs及其焙烧产物的结构、CNTs的形貌和结构进行了研究.结果表明,3种催化剂生长的CNTs均为多壁结构;其中Co催化剂活性较低,生长CNTs的管径较细、石墨化程度较高;Ni催化剂的活性较高,生长CNTs的密度较大、管壁较厚、石墨化程度较差;Fe催化剂的活性介于Co和Ni之间.催化剂活性及CNTs的密度可以由生长CNTs的结构来解释.