Radiation-induced radical ions in calcium sulfite

We have used EPR to study the effect of γ radiation on calcium sulfite. We have observed and identified the radiation-induced radical ions SO ₂ ⁻ (iso) with g = 2.0055 and SO ₂ ⁻ (orth-1) with g₁ = 2.0093, g₂ = 2.0051, g₃ = 2.0020, identical to the initial and thermally induced SO ₂ ⁻ respectively, SO ₃ ⁻ (iso) with g = 2.0031 and SO ₃ ⁻ (axial) with g_⊥ = 2.0040, g_∥ = 2.0023, identical to mechanically induced SO ₃ ⁻ . We have established the participation of radiation-induced radical ions SO ₃ ⁻ in formation of post-radiation SO ₂ ⁻ . __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 4, pp. 467–472, July–August, 2006.     

Optoacoustic gas analyzer based on a13C16O2 laser for multicomponent pollution of air

A computer-aided optoacoustic gas analyzer based on a continuous¹³C¹⁶C₂ laser for multicomponent pollution of atmospheric air is described. The analyzer has the ability to detect absorption of radiation by detected substances at the level of ∼1·10⁻⁹ cm⁻¹ at a time resolution of 30 sec. Results of an experiment on simultaneous detection of H₂O, CO₂, NO₂, NH₃, HNO₃, OCS, and C₂H₄ in the atmospheric air using 40 laser lines are presented. B. I. Stepanov Institute of Physics, National Academy of Sciences of Belarus, 68, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 3, pp. 345–350, May–June, 1999.     

EPR spectra of γ-irradiated hydrated barium dithionate single crystals

EPR spectra of barium dithionate hydrate single crystals γ-irradiated at low (80 Gy) and high (10 kGy) doses are studied. Four lines, the strongest of which is due to the SO₃⁻ radical, are observed in the EPR spectrum of the low-irradiated samples. Another line seems to belong to SO₂⁻. The strong line and weak lines with hyperfine structure and lines for pairs of closely spaced SO₃⁻ centers with a strong angular dependence are observed at high irradiation doses. The main values of the SO₃⁻ hyperfine coupling tensor and the dipole-dipole coupling constants of the SO₃⁻ pairs are determined. A quantum-chemical calculation of the electronic structure of isolated SO₃⁻ and SO₂⁻ radicals is performed. Values of the g tensors and hyperfine couplings are calculated. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 75, No. 1, pp. 18–22, January–February, 2008.     

Stabilization of Ion-Radicals in the Structure of Calcium Sulfite

Using the EPR- and IR-spectroscopy methods, we studied the conditions of formation of stable ion-radicals in the structure of calcium sulfite and determined the limits of their stability. We detected and identified the ion-radicals SO ₂ ⁻ with g(iso) = 2.0055 in the initial substances, two types of thermally induced SO ₂ ⁻ (with g₁ = 2.0093, g₂ = 2.0045, and g₃ = 2.0020, and g₁ = 2.0104, g₂ = 2.0049, and g₃ = 2.0018) when the substance was heated, and three types of mechanically induced SO ₃ ⁻ (with g_⊥ = 2.0036 and g_‖ = 2.0022, with g(iso) = 2.0033 and ΔH = 0.1 mT and with g(iso) = 2.0031 and ΔH = 0.33 mT) when the substance was ground up. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 72, No. 3, pp. 391–396, May–June, 2005.     

Infrared spectra of BeSO4.4H2O and its deuterated analogue in 4000–1200 cm−1 region

IR spectra of BeSO₄.4H₂O and its deuterated analogue at ∼300 K and ∼110 K are reported in the region 4000–1200 cm⁻¹ using thin film and nujol mull techniques. The observed bands have been assigned as the internal modes of the water and the overtones and combinations of various modes using the recently revised assignments of SO₄ ²⁻ and Be(aq)₄ fundamentals in the region 1200–250 cm⁻¹ (Srivastavaet al 1976). The splitting of the internal modes of water has been discussed in the light of the effects of deuteration and cooling and it is shown that all the water molecules in a unit cell are asymmetric but crystallographically equivalent.     

Nature of Thermally Induced Ion-Radicals in γ-Irradiated Barium Dithionate

The physicochemical properties of -irradiated barium dithionate in the temperature range 40-80°C were investigated by EPR and IR spectroscopy methods. It has been revealed that on decomposition of the substance, thermally induced ion-radicals of two types are formed, which are interpreted as SO₃ ^– (g = 2.0049, g = 2.0034) and SO₂ ^– (g ₁ = 2.0107, g ₂ = 2.0066, g ₃ = 2.0034). The conditions of their formation and limits of their stability have been determined. The heterogeneous phase BaSO₃/BaSO₄ is considered as the stabilizing one. The upper limit of applicability of barium dithionate as a dosimeter is 40°C.     

Determination of Trace Mercury by Solid Substrate-Room Temperature Phosphorimetry Quenching Method Based on Catalytic Effect of Hg2+on Formation of the Ion Association Complex [Sn(XO)6]4+·[(Fin)4]

A new method for the determination of trace mercury by solid substrate-room temperature phosphorimetry (SS-RTP) quenching method has been established. In glycine-HCl buffer solution, xylenol orange (XO) can react with Sn⁴⁺ to form the complex [Sn(XO)₆]⁴⁺. [Sn(XO)₆]⁴⁺ can interact with Fin⁻ (fluorescein anion) to form the ion associate [Sn(XO)₆]⁴⁺·[(Fin)₄]⁻, which can emit strong and stable room temperature phosphorescence (RTP) on polyamide membrane (PAM). Hg²⁺ can catalyze H₂O₂ oxidizing the ion association complex [Sn(XO)₆]⁴⁺·[(Fin)₄]⁻, which causes the RTP to quench. The ΔIp value is directly proportional to the concentration of Hg²⁺ in the range of 0.016–1.6 fg spot⁻¹ (corresponding concentration: 0.040–4.0 pg ml⁻¹, 0.40 μl spot⁻¹), and the regression equation of working cure is ΔIp=10.03+83.15 m Hg²⁺ (fg spot⁻¹), (r=0.9987, n=6) and the detection limit (LD) is 3.6 ag spot⁻¹(corresponding concentration: 9.0×10^–15 g ml⁻¹, the sample volume: 0.4 μl). This simple, rapid, accurate method is of high selectivity and good repeatability, and it has been successfully applied to the determination of trace mercury in real samples. The reaction mechanism for catalyzing H₂O₂ oxidizing the ion association complex ([Sn(XO)₆]⁴⁺·[(Fin)₄]⁻) SS-RTP quenching method to determine trace mercury is also discussed.     

Nuclear Spin–Lattice Relaxation of Single Crystal Sr14Cu24O41

Nuclear spin–lattice relaxation rate T ₁ ⁻¹ has been measured for the ladder sites of two single crystals Sr₁₄Cu₂₄O₄₁ (Sr14-A,B) by ⁶³Cu NMR/NQR. The hole localization around 100 K appears as a peak in the T variation of T ₁ ⁻¹(NQR). On the other hand, it is suppressed in the T ₁ ⁻¹ (NMR) data under the magnetic field H ∼ 11 T, and a new peak appears around 20 K. T ₁ ⁻¹(NMR) around the peak is more enlarged for Sr14-B than for Sr14-A. Hence, holes on the ladders of Sr14-B tend to be more localized. This is considered to be an origin for the occurrence of the magnetic order in Sr14-B under H ∼ 11 T.     

Solid polymeric electrolyte of PVC–ENR–LiClO<Subscript>4</Subscript>

The ionic conductivity of PVC–ENR–LiClO₄ (PVC, polyvinyl chloride; ENR, epoxidized natural rubber) as a function of LiClO₄ concentration, ENR concentration, temperature, and radiation dose of electron beam cross-linking has been studied. The electrolyte samples were prepared by solution casting technique. Their ionic conductivities were measured using the impedance spectroscopy technique. It was observed that the relationship between the concentration of salt, as well as temperature, and conductivity were linear. The electrolyte conductivity increases with ENR concentration. This relationship was discussed using the number of charge carrier theory. The conductivity–temperature behaviour of the electrolyte is Arrhenian. The conductivity also varies with the radiation dose of the electron beam cross-linking. The highest room temperature conductivity of the electrolyte of 8.5 × 10⁻⁷ S/cm was obtained at 30% by weight of LiClO₄. The activation energy, E _a and pre-exponential factor, σ _o, are 1.4 × 10⁻² eV and 1.5 × 10⁻¹¹ S/cm, respectively.     

Relation between highT c superconductivity and structure: A study of Ba3+x Cu6O14+δ and YBa2Cu3O7−δ systems

Superconductivity is found in tetragonal La_3−x Ba_3+x Cu₆O_14+δ and La, Ba)_6−x Sr _x Cu₆O_14+δ even though they do not possess Cu-O chains or the K₂NiF₄ structure. Resistivity measurements confirm the occurrence of a transformation from chain-superconductivity to sheet-superconductivity in YBa₂Cu₃O_7−δ as δ is varied in the range 0.0–0.5. Contribution No. 481 from the Solid State and Structural Chemistry Unit     

In situ FTIR study of oxygen adsorption on nanostructured RuO2 thin-film electrode

In situ Fourier transform spectroscopy (FTIR) was used to study interactions of nanostructured ruthenium oxide (RuO₂) thin-film sensing electrode with O₂ at room temperature. RuO₂ nanostructures were pretreated at 1,000 °C for 1 h in order to obtain good crystallinity of amorphous RuO₂ nanoparticles. Morphology and properties of nanostructured RuO₂ were characterized by X-ray diffraction, thermo-gravimetric/differential thermal analysis, scanning electron microscopy, and FTIR. It was shown that pretreated RuO₂ is quite active for O₂ ⁻, O₂ ²⁻, and O²⁻ adsorption with clear 722 cm⁻¹ band for superoxide ions (O₂ ⁻) adsorption for the different oxygen concentrations. The results of in situ FTIR measurements revealed that the active sites for oxygen adsorption are not limited to the triple boundaries, but extended to surfaces of RuO₂ electrodes. Fundamental vibration frequencies of ruthenium–oxygen bond at a temperature of 23 °C as well as region above fundamental frequencies for the nanostructured RuO₂ were identified.     

Superconductivity in Bi2.2Ca2.8−x Sr x Cu2O y system and effect of rare earth substitution

The oxide system Bi_2.2Ca_2.8−x Sr _x Cu₂O _y has been investigated for superconductivity as a function of Ca/Sr ratio withx=0.7, 1.0, 1.4 and 1.8. All these compositions are found to be superconducting with onset temperature in the range of 80–90 K implying a large homogeneity range between Sr and Ca for the superconductivity to occur in this system. Effect of partial replacement of Bi by rare earths has been studied and it is observed that 20% replacement of Bi by Nd and Eu does not significantly affect the superconducting transition temperature.     

Thermal and optical properties of electron beam irradiated cellulose triacetate

Samples from Cellulose triacetate (CTA) sheets were irradiated with electron beam in the dose range 10–200 kGy. Non-isothermal studies were carried out using thermogravimetric analysis (TGA) to obtain the activation energy of thermal decomposition for CTA polymer. The CTA samples decompose in one main break down stage. The results indicate that the irradiation by electron beam in the dose range 80–200 kGy increases the thermal stability of the polymer samples. Also, the variation of melting temperatures with the electron dose has been determined using differential thermal analysis (DTA). The CTA polymer is characterized by the appearance of one endothermic peak due to melting. It is found that the irradiation in the dose range 10–80 kGy causes defects generation that splits the crystals depressing the melting temperature, while at higher doses (80–200 kGy), the thickness of crystalline structure (lamellae) is increased, thus the melting temperature increases. In addition, the transmission of these samples in the wavelength range 200–2500 nm, as well as any color changes, were studied. The color intensity ΔE* was greatly increased on increasing the electron beam dose, and accompanied by a significant increase in the blue color component.      

Infrared spectra of BeSO4.4H2O and its deuterated analogue at 110K in 1200–250 cm−1 region

IR absorption spectra of BeSO₄.4H₂O and its deuterated analogue are reported in the region 1200–250 cm⁻¹ at 110 K. The half-widths and relative integrated intensities of the bands are also reported. The study largely confirms the assignments for thev ₃ andv ₄ modes of SO ₄ ²⁻ ion and thev ₃ mode of Be(aq) ₄ ²⁺ , complex as made by Diemet al. The assignments of the other modes of SO ₄ ²⁻ and Be(aq) ₄ ²⁺ , and the librational modes of water are given a more solid footing as result of the present investigation.     

Structural and electrical characterisation of strontium zirconate proton conductor co-sputter deposited coatings

SrZr_1−x Y _x O₃ coatings were co-sputtered from metallic Zr–Y (84–16 at.%) and Sr targets in the presence of a reactive argon–oxygen gas mixture. The structural and chemical features of the film have been assessed by X-ray diffraction and scanning electron microscopy. The electrical properties have been investigated for different substrates by Complex Impedance Spectroscopy as a function of crystalline state, temperature and atmosphere. The as-deposited coatings are amorphous and crystallise after annealing at 673 K for 2 h under air. The stabilisation of the perovskite structure is a function of the nominal composition. The films are dense and present a good adhesion on different substrates. Crystallisation and mechanical stresses are detected by alternating current (AC) impedance spectroscopy. Significant ionic conductivity in the 473–823 K temperature range is evidenced in air. Two different conduction regimes in the presence of steam are attributed to a modification of the charge carrier nature. In spite of low conductivity values (σ ~10⁻⁶ S.cm⁻¹ at 881 K), the activation energies are in agreement with that of Y-doped strontium zirconate ceramics (~0.7 eV in air).     

Physicochemical properties of LiAl x Mn2 − x O4 and LiAl0.05Mn1.95O4 − y F y cathode material by the citric acid-assisted sol–gel method

LiAl _x Mn_2 − x O₄ and LiAl_0.05Mn_1.95O_4 − y F _y spinel have been successfully synthesized by citric acid-assisted sol–gel method. The structure and physicochemical properties of this as-prepared powder were investigated by electronic conductivity test, powder X-ray diffraction (XRD), scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), and galvanostatic charge–discharge test in detail. The electronic conductivity decreases with increasing of the content of doped Al. XRD patterns show that the diffraction of LiAl_0.05Mn_1.95O_4 − y F _y samples is similar, with all the peaks indexable in the Fd3m space group, and a little impurity appears in the LiAl_0.05Mn_1.95O_3.8F_0.2 sample. SEM reveals that all LiAl_0.05Mn_1.95O_4 − y F _y powders have the uniform, nearly cubic structure morphology with narrow size distribution which is less than 500 nm. Galvanostatic charge–discharge test indicates that LiAl_0.05Mn_1.95O₄ has the highest discharge capacity and electrochemical performance among all LiAl _x Mn_2 − x O₄ samples after 50 cycles, and the initial discharge capacity of LiAl_0.05Mn_1.95O_4 − y F _y (y = 0, 0.02, 0.05, 0.1) is 123.9, 124.6, 124.9, and 125.0 mAh g⁻¹, respectively, and their capacity retention ratios are 94.2%, 94.9%, 91.7%, and 89.9% after 50 cycles, respectively. EIS indicates that LiAl_0.05Mn_1.95O_3.98F_0.02 have smaller charge transfer resistance than that of LiAl_0.05Mn_1.95O₄ corresponding to the extraction of Li⁺ ions.     

Theψ-particles in an SU4 scheme with anomalous currents

The recently discovered narrow peaks (theψ-particles) in e⁺e⁻ system at 3.105 and 3.695 GeV are interpreted as hadrons in a broken SU₄ symmetry scheme. A new additional additive quantum number, parachargeZ, is combined with the usual SU₃ quantum numbers in the group SU₄. Theψ (3.1) is assigned to a near ideally mixed15⊕1 multiplet of vector mesons (containing theρ) as theI=Y=0, charge conjugationC=−combination ofZ=±1.members. Theψ (3.7) is assigned correspondingly to another mixed15⊕1 multiplet containing theρ′ (1600). The hadronic electromagnetic interactions are modified by the addition of (non-minimal) anomalous pieces that can changeZ. The decays of theψ-particles are discussed. New enlarged SU₄ multiplets of other hadrons are proposed. Tests of our scheme are put forward. The most crucial test will be the observation of two rather broad resonances in e⁺ e⁻ collisions with masses around 4.2 GeV and 5.1 GeV. Another prediction is the presence of energetic photons in the decays of theψ-particles. Important results concerning the recently observed phenomena in the process e⁺e⁻→hadrons follow in this scheme.     

1H NMR study of multiply charged anions of Ni-octaethylporphin

An analysis of¹H NMR spectra of reduced Ni-octaethylporphin (NiOEP)ⁿ⁻ n=2,3) complexes has allowed the conclusion that the first and third excess electrons are localized on orbitals of the porphyrin ligand, while the first excess electron is on the d_x ²-y²-orbital of Ni. This is a basis for thinking that in the course of NiOEP reduction the energy of the lowest unoccupied molecular orbital of the ligand becomes smaller than that of the d_x ²-y²-orbital of nickel. Institute of Molecular and Atomic Physics of the Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 4, pp. 513–517, July–August, 1997.     

Modeling the atomic and electronic structure of diamond nanocrystals containing [NV]<Superscript>−</Superscript> centers by the density functional method

We have used the density functional method to model the atomic and electronic structure of diamond nanocrystals passivated by hydrogen atoms and either not containing defects or containing a single [NV]⁻ center. We have shown that in all cases, after relaxation the nanocrystals are formed as diamond-like structures. We have studied the features of the electronic structure of the nanocrystals. We have analyzed in detail the mechanism for the formation of energy levels in the bandgap due to [NV]⁻ centers. We have established that the optical absorption and fluorescence spectra for the [NV]⁻ centers are mainly associated with transitions of electrons between the highest occupied β orbitals (projection of the electron spin equal to +1/2) and lower unoccupied α orbitals (projection of the electron spin equal to −1/2). The results on the localization and energy position of the states in the bandgap match data obtained for the [NV]⁻ center in bulk diamond. __________ Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 74, No. 1, pp. 86–92, January–February, 2007.     

Optoacoustic determination of low concentrations of gases by the use of commercial CO2-lasers

Institute of Molecular and Atomic Physics, Academy of Sciences of Belarus, 70 F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Specktroskopii, Vol. 62, No. 6, pp. 81–86, November–December, 1995.