Amorphous iron phase formation in swift heavy ion irradiated electrodeposited iron thin films

⁵⁷Fe conversion electron Mössbauer spectroscopy, SEM, EDAX, XRD and AFM measurements were used to study the radiation effect of 246 MeV Kr ions on electrochemically deposited ⁵⁷Fe thin films. Amorphous iron phase formation has been shown to occur for the first time in electrodeposited iron thin films due to the irradiation with swift heavy ions.     

Local heating of a medium in the nanovicinity of the <Superscript>57</Superscript>Co nucleus that underwent radioactive decay to <Superscript>57</Superscript>Fe

Process of formation of the Auger blob (nanosized cloud of two or three hundred of ion–electron pairs) around a ⁵⁷Co radioactive atom after E-capture followed by the emission of a cascade of Auger electrons by the daughter atom ⁵⁷Fe has been considered. The effect of local temperature elevation in the Auger blob caused by energy emission during ionization slowing down of Auger electrons and the secondary electrons generated by them is discussed. Some consequences of this effect have been noted.     

Production of endohedral <Superscript>133</Superscript>Xe-higher fullerenes by ion implantation

Endohedral ¹³³Xe-higher fullerenes (¹³³Xe@C₇₆ and ¹³³Xe@C₈₄) were produced by implantation of ¹³³Xe ions using an isotope separator. A high performance liquid chromatography (HPLC) analysis showed that the peak of endohedral ¹³³Xe-higher fullerenes shifted backward from that of empty fullerenes, suggesting a possibility of the separation of endohedral ¹³³Xe-higher fullerenes from empty fullerenes. The yields of endohedral ¹³³Xe-fullerenes were in the order of ¹³³Xe@C₇₆<¹³³Xe@C₈₄<¹³³Xe@C₆₀<¹³³Xe@C₇₀.     

Kinetics of H<Superscript>+</Superscript>/Na<Superscript>+</Superscript> solid-phase ion exchange on iron(III) hydrogen sulfate

The kinetics of solid-phase reaction between iron(III) hydrogen sulfate and sodium chloride was studied by thermal analysis followed by analysis of leaving gases. The exchange kinetics are described by the soft cylinder model. The hydrogen and sodium ion interdiffusion coefficients were determined for various temperatures, as well as the activation energy of interdiffusion. Sodium ion diffusion through the product layer is the rate-controlling stage of the reaction.     

Systematic radiochemical separation for the determination of <Superscript>99</Superscript>Tc, <Superscript>90</Superscript>Sr, <Superscript>94</Superscript>Nb, <Superscript>55</Superscript>Fe and <Superscript>59,63</Superscript>Ni in low and intermediate radioactive waste samples

A simple and rapid separation procedure was systemized for the determination of ⁹⁹Tc, ⁹⁰Sr, ⁹⁴Nb, ⁵⁵Fe and ^59,63Ni in low and intermediate level radioactive wastes. The integrated procedure involves precipitation, anion exchange and extraction chromatography for the separation and purification of individual radionuclide from sample matrix elements and from other radionuclides. After separating Re (as a surrogate of ⁹⁹Tc) on an anion change resin column, Sr, Nb, Fe and Ni were sequentially separated as follows; Sr was separated as Sr (Ca-oxalate) co-precipitates from Nb, Fe and Ni followed by purification using Sr-Spec extraction chromatographic resin. Nb was separated from Fe and Ni by anion exchange chromatography. Fe was separated from Ni by anion exchange chromatography. Ni was separated as Ni-dimethylglyoxime precipitates after the removal of ^134,137Cs and ^110mAg by Cs-phosphotungstate and AgCl precipitation, respectively. Finally, the radionuclide sources were prepared by precipitation for their radioactivity measurements. The reliability of the procedure was evaluated by measuring the recovery of chemical carriers added to a synthetic radioactive waste solution.     

Time-space evolution of the cloud of ion-electron pairs formed by Auger electrons around Mossbauer ion <Superscript>57</Superscript>Fe<Superscript><Emphasis Type="Italic">n</Emphasis>+</Superscript>

It is shown that the emission of energetic Auger electrons during formation of the Mossbauer nucleus ⁵⁷Fe leads not only to the formation of multicharged ion ⁵⁷Fe ⁿ⁺, but also to the formation of a cloud of several hundred (200–300) ion-electron pairs (H₂O⁺, e ^?) around the Fe ion. This cloud is called an Auger blob. Its size (radius) is approximately ～100 Å. Fast radiation-chemical reactions in an Auger blob determine the experimentally observable ratio of yields of final chemically stable states (Fe³⁺ and Fe²⁺) of the Mossbauer ion. Knowledge of this ratio is important for an adequate interpretation of the results of Mossbauer emission spectroscopy. Although our assessments relate to iron nuclei in frozen aqueous solutions, they can be easily adjusted for media of other chemical composition.     

Extraction chromatographic separation of iron from complex liquid samples and the determination of <Superscript>55</Superscript>Fe

Summary Iron separation is described from liquid samples with a high concentration of ions that enables simple determination of ⁵⁵Fe. One of the described methods consists of iron precipitation from a large volume seawater by sodium hydroxide and/or ammonium carbonate and separation from other elements (Ca, Sr, Cu, Mg, etc.) on a TRU column with 4M HCl or 8M HNO₃. In the other procedure iron is separated directly from a mixture of seawater samples and HCl on a TRU column. In both methods, the iron recovery is almost 100%. After separation, ⁵⁵Fe is determined by counting with a liquid scintillation counter. The binding of Fe and Zn on TEVA, U/TEVA and TRU resins from seawater solutions of HCl and HNO₃depends on the type of the resin, concentration of acid and other ions. Iron and zinc can be separated from seawater on a U/TEVA column with 2M HCl.     

The effect of bias-temperature stress on Na<Superscript>+</Superscript> incorporation into thin insulating films

The action of Na⁺ incorporation into thin insulating films and transport therein under influence of a bias voltage and temperature (BT stress) is the subject of this work. Deposited onto highly n-doped Si wafers, the insulators get BT stressed and subsequently investigated by means of time-of-flight–secondary ion mass spectrometry (ToF-SIMS). A thin PMMA film, spin-coated onto the insulator, serves as host matrix for a defined amount of Na⁺, provided via sodium triflate. Combining BT stress and ToF-SIMS depth profiling enables the unambiguous detection of Na⁺, incorporated into the insulating material. The insulators of interest vary in their nitride content: SiO₂, SiO_xN_y, and Si₃N₄. For SiO₂, it is shown that once a threshold BT stress is exceeded, Na⁺ gets quantitatively incorporated from PMMA into the underlying insulator, finally accumulating at the SiO₂/Si interface. A quantitative assessment by combination of Butler–Volmer kinetics with hopping dynamics reveals activation energies of E _a = 1.55 − 2.04 eV for Na⁺ transport in SiO₂ with varying thickness. On the other hand, SiO_xN_y and Si₃N₄ films show a different Na⁺ incorporation characteristic in this type of experiment, which can be explained by the higher coordination of nitrogen and hence the reduced Na⁺ permeability within these insulators.     

Photochemical substitution of benzene in the iron cyclohexadienyl complex [(η<Superscript>5</Superscript>-C<Subscript>6</Subscript>H<Subscript>7</Subscript>)Fe(η-C<Subscript>6</Subscript>H<Subscript>6</Subscript>)]<Superscript>+</Superscript>

The visible light irradiation of the [(η⁵-C₆H₇)Fe(η-C₆H₆)]⁺ cation (1) in acetonitrile resulted in the substitution of the benzene ligand to form the labile acetonitrile species [(η⁵-C₆H₇)Fe(MeCN)₃]⁺ (2). The reaction of 1 with Bu^tNC in MeCN produced the stable isonitrile complex [(η⁵-C₆H₇)Fe(Bu^tNC)₃]⁺ (3). The photochemical reaction of cation 1 with pentaphosphaferrocene Cp*Fe(η-cyclo-P₅) afforded the triple-decker cation with the bridging pentaphospholyl ligand, [(η⁵-C₆H₇)Fe(μ-η:η-cyclo-P₅)FeCp*]⁺ (4). The latter complex was also synthesized by the reaction of cation 2 with Cp*Fe(η-cyclo-P₅). The structure of the complex [3]PF₆ was established by X-ray diffraction. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 11, pp. 2088–2091, November, 2007.     

Production and separation of no-carrier-added <Superscript>208,209,210</Superscript>At produced from heavy ion activation on natural thallium target

No-carrier-added (nca) ^208,209,210At was produced for the first time from ⁹Be induced reaction on thallium carbonate target at BARC-TIFR pelletron, Mumbai, India. The target of 4 mg/cm² thickness was prepared by centrifugation technique. Nca At was separated from the thallium target by liquid–liquid extraction using liquid cation exchanger HDEHP dissolved in cyclohexane and liquor ammonia.     

Silicate complexation of NpO<Subscript>2</Subscript><Superscript>+</Superscript> ion in perchlorate media

Complexation behavior of NpO₂ ⁺ with ortho-silicic acid (o-SA) has been studied using solvent extraction at ionic strengths varying from 0.10 to 1.00M (NaClO₄) at pcH 3.68±0.08 and 25 °C with bis-(2-ethylhexyl) phosphoric acid (HDEHP) as the extractant. The stability constant value (log β₁) for the 1:1 complex, NpO₂(OSi(OH)₃), was found to decrease with increase in ionic strength of the aqueous phase [6.83±0.01 at I=0.10M to 6.51±0.02 at I = 1.00M]. These values have been fitted in the SIT model expression and compared with similar values of complexation of the metal ions Am³⁺, Eu³⁺, UO₂ ²⁺, PuO₂ ²⁺, Np⁴⁺, Ni²⁺ and Co²⁺. The speciation of NpO₂ ⁺-o-silicate/carbonate system has been calculated as a function of pcH under ground water conditions. On leave from Radiochemistry Division, Bhabha Atomic Research Centre, Trombay, Mumbai-400 085, India.     

<Superscript>239</Superscript>Np as a tracer of <Superscript>237</Superscript>Np in effluent samples and low level nuclear waste

In this paper a technique to separate and measure both isotopes (²³⁷Np and ²³⁹Np) together is presented. A combined shape pulse discrimination liquid scintillation measurement with gamma-spectrometry, permits a precise measurement after the radiochemical separation. This technique was carried out by using an Eichrom chromatographic column (TEVA) as the first step of a more complete method, applied in the Nuclear Regulatory Authority, to separate actinides in nuclear waste and liquid effluents. The MCA is 0.08 Bq/l by alpha-spectrometry and 0.22 Bq/l (2σ) by liquid scintillation counting (LSC) for 93.7% of measurement efficiency and 98.4% of chemical recovery.     

<Superscript>103</Superscript>Rh, <Superscript>17</Superscript>O,and <Superscript>31</Superscript>P NMR study of Rh(III) complex formation in acidic sulfate-phosphate media

Rhodium(III) complex formation with phosphoric acid in strong acidic solutions has been studied by ¹⁰³Rh, ¹⁷O, and ³¹P NMR. Phosphoric acid is mainly coordinated to rhodium as a monodentate terminal HPO₄²⁻ ion, while the coordinated phosphate ion accounts for no more than 7%.     

Complex formation of maleic acid with the Zn<Superscript>2+</Superscript>, Ni<Superscript>2+</Superscript>, Co<Superscript>2+</Superscript>, Cu<Superscript>2+</Superscript> in aqueous solution

The process of complex formation of maleic acid (H₂L) with the ions Zn²⁺, Ni²⁺, Co²⁺, Cu²⁺ was studied by potentiometric titration in a wide range of concentration ratios at 298 K and I = 0.1 mol/l (NaNO₃). The moieties ZnL, CoL, NiL, NiL ₂ ^2? , CuL, and CuL ₂ ^2? were detected and their stability constants were determined.     

A biomonitoring study: <Superscript>210</Superscript>Po and heavy metals in mussels

In various samples of Mytilus galloprovincialis, ²¹⁰Po was determined by alpha-spectrometry while Mn, Fe, Ni, Cu, Zn, Cd, Sn, Hg and Pb by energy dispersive, polarised X-ray fluorescence spectrometry (EDPXRF). The mussels of different sizes were taken from 7 sites in the central Adriatic Sea along the Marche coastal region during the four seasons of the year. ²¹⁰Po activity concentration ranged between 57 and 343 Bq·kg⁻¹ dry weight. The concentration ranges of heavy metals (μg·g⁻¹ dry weight) were as follows: Mn: 72.9–83.1; Fe: 45.1–754; Ni: 1.3–7.6; Cu: 17.9–156; Zn: 60.9–189; Cd: 0.6–1.0; Sn: 0.6–3.9; Hg always <0.5; Pb: 2.0–9.0. The data obtained depend upon the site and the period of the sampling and they are also compared with those obtained by other authors for the same organism in the Mediterranean and other Italian seas.     

Quinolinephosphomolybdate as ion exchanger: synthesis,characterization, and application in separation of <Superscript>90</Superscript>Y from <Superscript>90</Superscript>Sr

An inorganic ion exchanger, quinolinephosphomolybdate has been synthesized and characterized by elemental analysis, infrared (IR) and X-ray diffraction (XRD) spectroscopy. This compound is highly stable toward thermal, chemical and radiation dose. This has been employed in the separation of carrier-free ⁹⁰Y from its parent ⁹⁰Sr from an equilibrium mixture. The absorbed daughter was recovered by using 0.0284 mol L⁻¹ ascorbic acid solutions at pH 5.0 as eluting agent.     

Conversion of endohedral <Superscript>133</Superscript>Xe-fullerene to endohedral <Superscript>133</Superscript>Xe-fullerenol to be used in nuclear medicine

Summary Hydrophilic endohedral ¹³³Xe-fullerenols, [¹³³Xe@C₆₀(OH)_xand ¹³³Xe@C₇₀(OH)_x], were synthesized from hydrophobic endohedral ¹³³Xe-fullerenes. The yield of endohedral ¹³³Xe-fullerenols extracted in water was about 40% and 23% for C₆₀and C₇₀, respectively. The products stored in 0.9% NaCl solution at 20 °C were stable enough to be used in nuclear medicine.