Molybdenum,Platinum, and Tantalum Metal Atomizers or Vaporizers in Analytical Atomic Spectrometry

Abstract

The application of metal (tantalum, molybdenum, and platinum) devices in analytical atomic spectrometry is reviewed in this article. These metal devices have been employed in various analytical atomic spectrometric techniques for more than three decades, mainly as electrothermal atomizers or electrothermal vaporizers, in various physical shapes, such as tubes, platforms, loops, and wires (or coils/filaments). Their application spans from atomic absorption spectrometry (AAS), atomic emission spectrometry (AES) atomic fluorescence spectrometry (AFS), inductively coupled plasma atomic emission spectrometry (ICP‐AES) to inductively coupled plasma mass spectrometry (ICP‐MS). The analytical figures of merit and the practical applications reported for these metal devices are reviewed, and the atomization mechanism on these metal atomizers is briefly summarized, too. In addition, other applications of the metal devices are discussed, including analyte preconcentration by electrodeposition and sequential metal vapor elution analysis (SMVEA). Furthermore, the application of these metals in graphite furnaces encompasses the schemes with the metals in the form of furnace linings, platforms, or impregnated salts.     

Spin dynamics of the muon in muonium in normal metals

The question of the charge state of the proton (the positive muon) in metals is of fundamental importance for the theory of metal hydrides. The theory developed here permits determination of the charge state of μ ⁺ in normal metals. The experimental possibilities of the observation of Mu atoms in metals at various strengths of the external magnetic field and various temperatures are analyzed. Zh. éksp. Teor. Fiz. 111, 730–736 (February 1997)     

Fourier Transform Infrared Spectroscopy: Probing the Structure of Multicomponent Polymer Blends

Abstract

Polymer blends may be defined a s physical mixtures of two or more polymers [1]. Conceptually, polymer blends are analogous to metal alloys, materials which date back to the dawn of civilization. In much the same way as the metallurgists sought to improve the chemical and physical properties of metallic materials by mixing various metals, polymer scientists have also employed this technique to produce a wide variety of useful polymeric materials. However, we must be careful not to push this analogy too far. There are many fundamental differences between these two classes of materials.     

Determination of Metals in Seafood and Fish in Southwest Louisiana

Abstract

This review presents results of concentrations of various metals in seafood such as shrimp, oysters, alligators, crayfish, and crabs. The majority of results are presented from the authors' area of interest, namely southwest Louisiana. This area is typical and fairly representative of many areas around the world where the seafood industry and industrial chemical plants co‐exist. Inclusion of organics and near by areas of southwest Louisiana as well as selected results from around the world are presented for completeness. Heavy and toxic metals including Hg, Pb, and Cd have attracted the most interest. Concentrations of metals in seafood are often higher than expected. Studies on soil and sediments have allowed extrapolation of toxicity in seafood.     

Electronic structure of Y and Pr in Laves phases with Mg, Al, Fe, Co, and Ni

The electronic structure (population of the valence d and s shells) of Y and Pr in the RM₂ Laves phases with Mg, Al, Fe, Co, and Ni has been determined experimentally by the x-ray K-line shift method. It was found that the Y and Pr electronic structures in RM₂ with Mg and Al are practically the same as in metals, but the distribution of the three outer electrons between the d and s shells in Y is essentially different from that in Pr. In the Laves phases with 3d metals (Fe, Co, or Ni), the outer-electron distributions between the d and s shells in Y and Pr are practically identical and do not depend on the d metal. Fiz. Tverd. Tela (St. Petersburg) 41, 1721–1723 (October 1999)     

Research and development of metal powder for magnetic recording

Since its first application within the compact cassette in 1978, magnetic recording media using metal powder have been improved at a rate of roughly 1 dB per year as a result of advances in such fields as tape materials, tape-making technologies, etc. Today, metal tapes have a widely expanded application area, including video and data-information applications. Dowa Mining Co., Ltd., began its research regarding magnetic powder for recording media in 1978. The Company successfully developed metal powder for 8 mm video tape. Since then, Dowa has endeavored to improve the magnetic properties and reduce the particle size of metal powder. It accomplishes these goals through the full use of the Company's unique Al doping method. Especially, during the past several years, significant improvements of the magnetic properties of metal powder have been achieved. These improvements have resulted from the introduction of new technologies, including Fe–Co alloying, sintering prevention, new reaction processes, and many other new techniques. Currently, Dowa Mining is supplying a new type of metal powder for the most technologically advanced high-density recording media. Dowa's new metal powder has an axis length of 0.1 μm, H_c of 2400 Oe, and σ_s of 155 emu/g.     

Extinction coefficient and skin depth of alkali metals from 10 to 1000 nm

The alkali metals have often been characterized as being transparent to optical radiation in the ultraviolet. An investigation was performed to evaluate the feasibility of exploiting this so-called transparency phenomenon for laser doppler velocimetry in these metals. The extinction coefficient, skin depth and skin depth divided by wavelength were determined from the literature for wavelengths between 10 and 1000 nm. Data is included for lithium, sodium, potassium, rubidium, cesium, and a sodium-75% potassium alloy. The results show that the skin depths are less than 3 μm, and the prospects for perfoming liquid metal laser doppler velocimetry are poor. The compilation of the data in one document and in a common format may be useful to other researchers.     

Ion-induced sputtering of a metal in the form of large clusters

A model is proposed for the ion-induced sputtering of a metal in the form of large clusters with a number of atoms N⩾5. The model is based on simple physical assumptions and is consistent with experiment. As an example, calculations are made of the relative cluster yield as a function of the number of atoms in the cluster as a result of the bombardment of various metals by singly charged 5 keV argon ions. A comparison is made with experimental data. Zh. Tekh. Fiz. 69, 64–68 (March 1999)     

Positron annihilation in polycrystalline metals

The empirical relation θ _p ⁶ /I _p=aK (where θ _p is the limiting angle of the parabolic component in the angular distributions of annihilation photons in metals, I _p is the integrated contribution of this component, K=1, 2, 3, ... is an integer, and a is a constant independent of the type of metal) observed earlier has been tested on magnesium, aluminum, copper, zinc, lead, and bismuth samples. The validity of this relation has been substantiated. The value of the dimensionless constant a has been determined and was found to coincide within experimental error with the result obtained in previous measurements. It is shown that the value of K for the same metal but for different samples may be different. It is conjectured that this may be due to different defect concentrations in samples. Fiz. Tverd. Tela (St. Petersburg) 40, 600–602 (April 1998)     

Phytoremediation of Arsenic: Fundamental Studies,Practical Applications,and Future Prospects

Abstract

Arsenic is a toxic element that is naturally present but is also introduced through a variety of anthropogenic activities. Phytoremediation, which is the use of green plants to minimize the impact of toxic substances, has been widely used for arsenic. Phytoextraction employs plants to accumulate toxins into aboveground biomass. Pteris vittata, commonly known as the brake fern, was the first species used for phytoextraction and the most widely investigated, although other Pteris plants have been successfully employed. Several studies have investigated the accumulation of arsenic in food plants to assess possible impact upon human health. Phytostabilization, which involves the use of contaminant-immobilizing soil amendments with plants to reduce contaminant availability, has been successfully employed for arsenic. It is expected that phytoremediation will be employed in the future as a low-cost alternative for the remediation of arsenic in soil.     

New scientific opportunities for high pressure research by energy-dispersive XMCD

ABSTRACT

XMCD under pressure is used to study the magnetic properties of the transition metal (TM) systems for over 15 years. We present the technique and how it has been developed. The energy dispersive XAS spectrometer is particularly suited for these studies. The effect of pressure on TM magnetism is discussed. Recent studies performed at different edges illustrate the information that can be obtained through XMCD. Finally, some results obtained on TMs are presented, either at the L_II,III edges of 5d metals or at the K edge of 3d metals, which correspond to the energy ranges that can be probed when using diamond anvil cells for high pressure. Different cases are treated: pure 3d metals, alloys, magnetic insulator and inorganic compounds.     

Influence of 3d metal atoms on the geometry,electronic structure,and stability of a Mg13H26 cluster

This paper reports on the results of the theoretical investigation of magnesium hydride nanoclusters doped with 3d metals (from Sc to Zn). The influence of transition metal atoms on the geometry, electronic structure, and energy characteristics of the clusters has been analyzed. The results of the performed calculations have been compared with the available experimental data. This comparison has made it possible to predict which 3d transition elements can serve as the most effective catalysts for the improvement of the thermodynamic characteristics of MgH₂.     

Properties of positron annihilation in metals

Positron annihilation in bulk metals has been studied by examining the angular distribution of the annihilation photons in polycrystalline samples of magnesium, aluminum, copper, zinc, indium, tin, lead, and bismuth. It has been shown that conduction electrons as well as core electrons take part in this process. The conduction electron densities and Fermi energies have been determined. It is found that the electron density in the vicinity of a positron is significantly higher than the density of the free electron gas. We believe that this is due to the formation of Wheeler complexes and we estimate its charge. We have analyzed various means of measuring the conduction electron density and conclude that the positron method gives the most reliable information. Fiz. Tverd. Tela (St. Petersburg) 41, 929–934 (June 1999)     

Determination of Heavy Metal Accumulation in Plant Samples by Spectrometric Techniques in Turkey

Abstract:

Heavy metals are significant and extremely persistent environmental pollutants and their toxicity is a problem of increasing significance for ecological, nutritional, and environmental reasons. Biomonitoring methods are gaining more importance because they allow for prediction, detection, and control of potential environmental hazards caused by heavy metal pollution. The objective of the present study was to collect and analyze research on heavy metal accumulation in plant samples using spectrometric detection techniques in Turkey published between 2003 and 2013. Five main criteria were predetermined to limit the study and better portray the studies on heavy metal accumulation using plant samples in Turkey. These criteria were as follows: studies aiming to determine heavy metal accumulation levels, studies sampling plant species growing at various localities in Turkey, studies using spectrometric detection techniques, studies published as journal articles, and studies undertaken between 2003 and 2013. Consequently, 47 studies that satisfied all criteria were considered and selected for this investigation. A content analysis method was used for the review and analysis of the selected studies. The results of the review analysis were grouped under three categories and the findings obtained in this scope were presented.     

Determination of the polaron shift in titanium diselenide-based intercalation compounds

A study is reported of the dependence of the TiSe₂ lattice constants on the concentration of an intercalated metal in various valence states and external pressure. The strain energy and the polaron shift created in the intercalation of TiSe₂ with metals in various valence states have been determined. The position of the polaron band is shown to decrease linearly with the increasing intercalant ionization potential.     

A new route for the synthesis of nitrides: The solvothermal preparation of GaN

Abstract

A new solvothermal route for the synthesis of nitrides is proposed using liquid NH3 as solvent in supercritical conditions, Such a preparation method was applied to the synthesis of GaN using gallium metal as starting material.

GaN is a wide band-gap semi-conductor (3.4eV). It is a very attractive nitride due to its various applications in micro- and opto-electronics [1,2]. Consequently, many research groups are interested in synthesising GaN. Two methods have been principally developed:

(i) synthesis of thin films by epitaxy [3,4]

(ii) synthesis of bulk GaN by high pressure method [5,6].

The new proposed process leads to fine microcrystallites of GaN with the wurtzite-type structure. The chemical purity can be optimised versus the synthesis mechanism. The size and shape of the crystallites would be influenced by the nature of the nitriding additive and the thermodynamical conditions (pressure and temperature) used for the synthesis.     

On the relationship between the ionization potential and the work function: Metals

A relationship is analyzed between the ionization energy of atoms I and the work function φ of a metal composed of these atoms. The transition energy ∑=I?φ is assumed to be the sum of kinetic K and coulombic C contributions. Contribution K is calculated in the framework of a model of uniform gas of quasi-free electrons, and C is determined from experimental values of Σ. Calculations performed for a wide range of metals have shown that the dimensionless coefficients determining the Coulombic contribution C differ insignificantly between various groups of metals. The relationships obtained have been used for determining the work function of binary alloys.     

Studies on the effect of titanium addition on LiCoO2

The lithiated transition metal oxide has been used as the cathode materials for lithium ion rechargeable batteries. Among the various cathode materials, LiCoO₂ has been widely used. There are lot of reports on the substituted LiCoO₂ replacing small amount of Cobalt with other transition and nontransitional metals. Here, we focus on to a tetravalent transition metal atom such as titanium, as an addition in LiCoO₂ and studied its performance. The titled cathode material was synthesized by solid-state reaction method. Thermogravimetric/differential thermal analysis, X-ray diffraction, X-ray fluorescence, scanning electron microscopy, and particle size analysis were carried out to assess the effect of addition of titanium on LiCoO₂. Electrochemical studies were carried out by cyclic voltammetry and life cycle analyzer.     

The determination of the lifetime of hot electrons in metals by time-resolved two-photon photoemission: the role of transport effects, virtual states, and transient excitons

Experience has shown that theoretically determined lifetimes of bulk states of hot electrons in real metals agree quantitatively with the experimental ones, if theory fully takes into account the crystal structure and many-body effects of the investigated metal, i.e., if the Dyson equation is solved at the ab initio level and the effective electron–electron interaction is determined beyond the plasmon-pole approximation. Therefore the hitherto invoked transport effect [Knoesel et al.: Phys. Rev. B 57, 12812 (1998)] does not seem to exist. In this paper we show that likewise neither virtual states [Hertel: et al. Phys. Rev. Lett. 76, 535 (1996)] nor damped band-gap states [Ogawa: et al.: Phys. Rev. B 55, 10869 (1997)] exist, but that the hitherto unexplained d-band catastrophe in Cu [Cu(111), Cu(110)] can be naturally resolved by the concept of the transient exciton. This is a new quasiparticle in metals, which owes its existence to the dynamical character of dielectric screening at the microscopic level. This means that excitons, though they do not exist under stationary conditions, can be observed under ultrafast experimental conditions. Received: 30 March 2000 / Accepted: 2 September 2000 / Published online: 12 October 2000