Effect of inorganic metal ion impurities on lyoluminescence

It is observed that the intensity of lyoluminescence (LL) (the emission during the dissolution of irradiated crystals) is considerably enhanced in the presence of certain transition metal ions in low concentration, while the LL is quenched due to the presence of certain other transition metal ions. A detailed investigation is carried out to understand the effect of these metal ions and probable mechanisms are proposed.     

Positron trapping and annihilation rates in some inorganic compounds

Summary The disappearance rates of positrons annihilated in some inorganic compounds were measured. The observed correlation between these rates is discussed on the basis of a two-state trapping model.

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Riassunto Sono state misurate le costanti di decadimento di positroni che annichilano in alcuni composti inorganici. Si pone in evidenza una correlazione tra queste costanti e la si discute sulla base di un modello a transizione tra due stati aventi differente densità elettronica.

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Резюме Измеряются постоянные распада позитронов, которые аннигилируют в некоторых неорганических соединениях. Обсуждается наблюденная корреляция между интенсивностями аннигиляции на основе модели перехода между двумя состояниями, имеющими различные электронные плотности.

     

Field ion and field desorption mass spectrometry of inorganic compounds

The review on recent developments in field ionization mass spectrometry of inorganic compounds concerns the different mechanisms of ion formation at surfaces and under the influence of extremely high electric fields, field dependent chemical reactivity at surfaces and ion desorption from surfaces for mass spectrometric analysis. Applications in various areas are discussed, where this method has been used to identify surface compounds or to study kinetic phenomena at interfaces.     

Ga primary ion ToF-SIMS fragment pattern of inorganic compounds and metals

Regularity of Ga⁺ primary ion ToF-SIMS fragment pattern of inorganic compounds is discussed. For an inorganic compound as formulated M–A, where the valence of cation M is +n and that of anion A is −p, the chemical composition of appeared ToF-SIMS fragment are M_xA_y, which satisfy the rule nx≥py+1 for positive ion fragments and nx≤py+1 for negative ones. For example, for oxide fragment of chemical composition, M_xA_y (valence of M is +n), the fragment obeys the rule nx≥2y+1 for positive ions and nx≤2y+1 for negative ones, respectively. The regularity of ToF-SIMS fragment patterns of sulfides, nitrates, sulfates etc. is discussed.     

Enthalpy of activation for self-diffusion of inorganic substances having the NaCl structure

Conclusions A relation has been derived between the activation energy for self-diffusion and the characteristic temperature near the melting point for inorganic crystals having the NaCl structure, on the basis of a vacancy diffusion mechanism.A simplified relation, (10), has been found for determining E_A from a melting point. Carbon diffusion in carbides on the basis of structural vacancies has been discussed.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 147–150, September, 1969.     

Effect of hydrostatic pressure on self-diffusion in metal nanoparticles

The thermodynamics approach has been developed to describe the self-diffusion in nano-sized solids. It has been established that identical homologous temperatures of metal nanoparticles with their fixed characteristic size give the identical coefficients of diffusion under different pressures. The dependence of the activation enthalpy of diffusion on pressure and on the characteristic size of nanoparticles is first obtained.     

Effect of hydrostatic pressure on self-diffusion in metal nanoparticles

The thermodynamics approach has been developed to describe the self-diffusion in nano-sized solids. It has been established that identical homologous temperatures of metal nanoparticles with their fixed characteristic size give the identical coefficients of diffusion under different pressures. The dependence of the activation enthalpy of diffusion on pressure and on the characteristic size of nanoparticles is first obtained.     

Stability of divalent/trivalent oxidation state of europium in some Sr-based inorganic compounds

This work investigates the stability of Eu²⁺ and Eu³⁺ in some Sr-based inorganic compounds. Generally reducing condition is adopted in order to obtain Eu²⁺, however, the Eu doped SrAl₂O₄/SrLaAlO₄ case indicates that for some compounds Eu³⁺ is stabilized even in reducing atmosphere. Bond valence method is applied to explain this phenomenon and it reveals that crystal structure also determines the valence state of europium cations along with reducing/oxidizing condition. An analysis of other Eu doped Sr-based materials is performed which shows the relationship between Eu²⁺/Eu³⁺ stability and the Global Instability Index (GII). This research provides a guideline for synthesizing specific novel Eu²⁺/Eu³⁺ phosphors.     

Charge ordering in inorganic compounds

A theory is presented for the charge ordering observed in many inorganic compounds; equations have been derived for the Vervey temperatures of binary and ternary compounds with the CdI₂ structure. The temperature dependence of the electronic-order parameter has been related to the composition, the temperature, and the deformation parameter. The theoretical calculations agree qualitatively with experiment for TiSe₂, Ti_1–cV_cSe₂, Ti_1–cZr_cSe₂.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 12, pp. 42–48, December, 1990.     

A New method for studying ion beam mixing

A new method of ion beam mixing is presented. Using the metallic superlattice as a target,-2 X-ray diffraction measurements, and the computer program SLFOR for detailed calculations of X-ray diffraction spectra, it was possible to investigate the spread of mixed regions with an accuracy of a few angstroms. This method has been applied to Bi-Sb and Ag-Cu targets mixed by the use of 250–300 keV Ar²⁺ ions. The mixing parameterD*t/ was estimated to be 43×10³ Å⁴ and 23×10² Å⁴ for Bi-Sb and Ag-Cu superlattices, respectively.     

A new method for studying ion injection in liquid benzene

Ion-exchange membranes prepared by soaking into convenient solutions of salts in benzene, act afterwards as strong ion injectors in the pure liquid. Unipolar injection is used to measure, with precision, mobilities of known ions and to study electrohydrodynamic phenomena.     

Spin-echo measurements of the conduction electrons self-diffusion coefficient in a metal

The principle possibility of spin echo measurements of conduction electron orbital motion parameters is experimentally demonstrated, using metallic lithium as an example.     

Application of random walk concept to the cyclic diffusion mechanisms for self-diffusion in intermetallic compounds

Huntington–Elcock–McCombie (HEM) mechanism involving six consecutive and correlated jumps, a triple-defect mechanism (TDM) involving three correlated jumps and an anti-structure bridge (ASB) mechanism invoking the migration of an anti-structure atom are the three mechanisms currently in vogue to explain the self- and solute diffusion in intermetallic compounds. Among them, HEM and TDM are cyclic in nature. The HEM and TDM constitute the theme of the present article. The concept of random walk is applied to them and appropriate expressions for the diffusion coefficient are derived. These equations are then employed to estimate activation energies for self-diffusion via HEM and TDM processes and compared with the available experimental data on activation energy for self-diffusion in intermetallic compounds. The resulting activation energies do not favour HEM and TDM for the self-diffusion in intermetallic compounds. A comparison of the sum of experimentally determined activation energies for vacancy formation and migration with the activation energies for self-diffusion determined from radioactive tracer method favours the conventional monovacancy-mediated process for self-diffusion in intermetallic compounds.     

Reflectometry technique for studying metal nanolayers on a substrate

A new noncontact technique is proposed for determining the parameters of nanosized metal coatings (absorption coefficients, refractive indices, and thicknesses). It is based on processing the measured angular dependence of the energy reflection coefficient of a polarized laser beam reflected by a thin-film structure surface. Features of determining the parameters of films on silicon substrates have been considered.     

Quantum yield and photometric parameters of some transition metal ion schiff base complexes

In the present studies, a series of transition metal Ni(II), Mn(II), Co(II) and Cu(II) complexes were synthesized using a Schiff base ligand formed by condensation reaction of p-phenylenediamine with 2-hydroxy-1-naphthaldehyde. The prepared ligand and complexes were characterized by FTIR, HNMR, UV–Vis and fluorescence techniques. The peak in the HNMR spectra as well as important band in the FTIR spectra is discussed in relation to the molecular structure. Quantum yield of the prepared samples was calculated by taking quinine sulphate as a reference solvent. The quantum yield and fluorescence intensity of Ni(II), Mn(II) and Co(II) complexes were found to be more compared to Cu (II) complex and ligand. The photometric parameters were also calculated for ligand and complexes.     

Lasing properties of some metal complexes of compounds containing the methyleneiminobisacetic acid group

Aqueous solutions of some fluorescent metal complexes of three compounds containing the methyleneiminobisacetic acid group have been found to show lasing when tested on a pulsed nitrogen laser. Degradation constants for lasing of one of the complexes and of the corresponding uncomplexed dye have been determined by coaxial flashlamp pumping.     

The x-ray LIII absorption discontinuity of ytterbium in the metal and in some of its compounds

The shape and fine structure of the x-ray L_III absorption discontinuity of ytterbium (Z=70) has been studied in the pure metal and in several of its compounds. The shape and the near edge structure of the discontinuity in the metal reflects the band structure. A molecular orbital interpretation for the fine structure near the absorption edge has been proposed for the spectrum of the sesqui-oxide. The average bond lengths for the systems studied have been determined from the measurements on the fine structure employing Lytle’s and Levy’s methods and are compared with the available crystallographic data in the case of the metal, oxide and fluoride.     

A generalized Langevin algorithm for studying permeation across biological ion channels

We present a new leapfrog algorithm for the numerical solution of the generalized Langevin equation (GLE) in the case where the friction kernel is exponentially decaying. Like other leapfrog and Verlet algorithms, our algorithm is second order in velocity and third order in position. It is relatively easy to implement compared with other available algorithms, and would therefore make a good candidate for exploring the effects of finite memory time-scales in situations where modelling the precise functional form of the memory kernel was not important. We have tested this algorithm on a one-dimensional barrier crossing model, and found good asymptotic agreement with limits obtained using Brownian dynamics (BD) simulations, as well as with a theoretical asymptotic limit. We have also used the algorithm to perform a more sophisticated simulation of ion conduction through a KcsA channel. The results are a close match to corresponding results obtained using the Langevin equation, thereby helping to justify the use of Brownian dynamics in KcsA and other similar ion channels.     

Long-life bismuth liquid metal ion source for focussed ion beam micromachining application

Liquid metal ion sources (LMISs) with Ga as ion species are widely used in focused ion beam (FIB) technology for micromachining and surface treatment on the sub-micron and nano-scale. Key features of a LMIS for investigating mechanical properties and 3D-microfabrication of materials are long life-time, high brightness, stable ion current and a highly effective milling ability for the material to be modified. In order to increase the material removal rate, heavier ions than Ga and their clusters should be applied. Bismuth (Bi) is the heaviest, non-radio-active element in the periodic table, is non-toxic and exhibits a low melting point. We have thus produced a long-life (about 1000 h) Bi LMIS with a good beam performance, applicable in any FIB system. Since Bi is the only element in this source, it is not necessary to separate it from other ions by a mass filter. Investigation of the sputtering rate of NiTi shape memory alloys using Ga and Bi LMIS showed that, for the same experimental conditions, the material removal rate with using of Bi_n^k+ ions in a standard FIB machine without a mass separator is about five times larger compared to Ga⁺ ions. This use of Bi as LMIS-species is the ultimate breakthrough in sputtering applications.