Absorption Bands of Carbon Dioxide From 5.3 to 4.6 Microns

Measurements have been made of the frequencies of the infrared absorption lines of CO₂ in the region from 1850 cm⁻¹ to 2150 cm⁻¹. Observations were made at various pressures and pathlengths up to a maximum of 72 meter-atmospheres. Vibration-rotation constants were obtained characterizing the transitions 11^1c0–000, 11^1d0–000, 03^1c0–000, 03^1d0–000, 200–01^1c0, I2^2c0–01^1c0, 12^2d0–01^1d0 for C¹²O₂. The 11^1c0–000 band due to the C¹³O₂ molecule was also measured.     

Synthesis and X-ray Diffraction Study of Mixed-Metal Orthophosphates with NaZr2(PO4)3 and CePO4 Structures

Mixed-metal orthophosphates with Ca^{2 +}, Cd^{2 +}, Gd^{3 +}, Ti^{4 +}, Hf^{4 +}, Ce^{4 +}, U^{4 +}, and Pu^{4 +} were synthesized and studied by X-ray diffraction. Crystalline compounds containing cerium or plutonium, or both these elements were prepared. Cerium was taken as an imitator for plutonium. The phosphates containing Ti^{4 +} and Hf^{4 +} formed two-phase systems. One of the phases was assigned to the Zr₂(PO₄)₃ structural type (NZP), and the other phase, to the CePO₄ type (monazite). In the other cases, single-phase products were formed. The effect of the cationic composition on the crystal structure of the complex orthophosphates, including the unit cell parameters of the crystalline phases, was studied.     

Boson Inverse Operators and a New Family of Two-photon Annihilation Operators

Abstract

We introduce the inverse of the Hermitian operator (ââ ^?) and express the Boson inverse operators â ^?1 and â ^??1 in terms of the operators â, â ^? and (ââ ^?)^?1. We show that these Boson inverse operators may be realized by Susskind-Glogower phase operators. In this way, we find a new two-photon annihilation operator and denote it as â ²(ââ ^?)^?1. We show that the eigenstates of this operator have interesting non-classical properties. We find that the eigenstates of the operators (ââ ^?)^?1 â ², â(ââ ^?)^?1 â and â ²(ââ ^?)^?1 have many similar properties and thus they constitute a family of two-photon annihilation operators.     

The State of Disequilibrium between U and Th Series Isotopes in Marine Sediments from the Sudanese Red Sea Coast

The geochemical behavior of U, Th series nuclides in surface marine sediments collected fromthe Red Sea coastal environment of Sudan was examined using daughter/parent and nonisotopic activity ratios. Pronounced anomalous behavior of several series of nuclides has been observed, particularly at shallower depths. On the average, the ²³⁴U/²³⁸U ratio is fairly constant and close to 1.13, suggesting scavenging of ²³⁴U from the overlying water column. In shallow-water sediments collected from the biologically productive area of the fringing reef and from the tidal-flat of Sanganeb atoll, compared to harbor and deep-sea sediments, ²³⁸U was found in large excess relative to ²³²Th. The ²²⁸Th/²³²Th disequilibrium indicates rapid sedimentation at shallower sites, which agrees well with data reported in the literature for similar environments. Depletion was observed of precursor thorium isotopes (²³⁰Th, ²³²Th) with respect to their mobile daughter isotopes of radium (²²⁶Ra, ²²⁸Ra). On the other hand, there is surface enrichment of ²²⁸Th and ²¹⁰Po with respect to their progenitors ²²⁸Ra and ²²⁶Ra, as demonstrated by the ²²⁸Th : ²²⁸Ra and ²¹⁰Po : ²²⁶Ra activity ratio, which is greater than unity in all the sediments analyzed. The ²¹⁰Po/²²⁶Ra ratio is fairly constant (average 3.2).     

Influence of Ce on the luminescence properties of Er/Yb:YVO4 crystals

YVO₄ single crystals doped with Ce³⁺, Er³⁺ and Yb³⁺ ions were grown by the Czochralsski technology. The luminescence properties of Er³⁺/Yb³⁺:YVO₄ single crystals with different concentration of Ce³⁺ were studied, and the energy transfer mechanism between Er³⁺, Yb³⁺ and Ce³⁺ was discussed based on their energy level properties. The branching ratios of the ⁴I_11/2 → ⁴I_13/2 transition in different samples were calculated. The results indicate that codopants of Ce³⁺ greatly enhance the population rate of the ⁴I_13/2 level due to the fast resonant energy transfer between Er³⁺ and Ce³⁺, i.e., ⁴I_11/2(Er³⁺) + ²F_7/2(Ce³⁺) → ⁴I_13/2(Er³⁺) + ²F_5/2(Ce³⁺).     

Production of 2-[18F]Fluoro-2-deoxy-D-glucose at the Laboratory of Radiochemistry, University of Helsinki

Production 2-[^{1 8}F]fluoro-2-deoxy-D-glucose ([^{1 8}F]FDG) was started at the Laboratory of Radiochemistry in 1998 when a cyclotron, specially designed for the production of short-lived positron emitters, was bought to the laboratory. The radiosynthesis of [^{1 8}F]FDG is based on aminopolyether-mediated nucleophilic fluorination. [^{1 8}F]Fluoride is produced by the ^{1 8}O(p,n)^{1 8}F nuclear reaction. [^{1 8}F]FDG is synthesised with an automated device. The radiochemical yield of the synthesis is 50% (by the end of bombardment). Sterile and isotonic [^{1 8}F]FDG solution is produced within 55 min. [^{1 8}F]FDG is delivered for patient use by the medical company MAP Medical Technologies.     

Behavior of radioaerosols formed by evaporation of 137Cs131I and 137CsOH from the metal surface in an electrostatic field

The behavior of radioaerosols formed by condensation of supersaturated ¹³⁷Cs¹³¹I and/or ¹³⁷CsOH vapor in an electrostatic field was studied. Supersaturated ¹³⁷Cs¹³¹I and/or ¹³⁷CsOH vapor was generated by evaporation of salt crystals from a metal surface heated to high temperatures owing to ohmic resistance. By applying additional potential to the aerosol generator, it is possible to control the behavior of ¹³⁷Cs¹³¹I, ¹³⁷CsOH, or ¹³⁷Cs¹³¹I + ¹³⁷CsOH aerosols in an electrostatic field.     

Behavior of Trace Amounts of Cd and Zn in Sorption and Coprecipitation in Tetrahydrofuran Solutions

Sorption of trace amounts of ¹⁰⁹Cd and ⁶⁵Zn on zeolites NaX and NaA in the presence of divalent lanthanides Ln²⁺ (Ln = Tm, Dy, Nd) from tetrahydrofuran (THF) solutions is studied. In contrast to ¹³⁷Cs⁺ and similar to ⁸⁵Sr²⁺, trace amounts of ¹⁰⁹Cd and ⁶⁵Zn are not practically sorbed on zeolites (about 99% of these radionuclides remains in the solution). The distribution coefficients K _d of ¹⁰⁹Cd and ⁶⁵Zn are ∼0.3 and ∼0.4 ml g⁻¹, respectively. In THF solutions, Tm²⁺ is oxidized to Tm³⁺, and TmI₃ ⋅ 3THF is precipitated. Study of cocrystallization of trace amounts of ¹⁰⁹Cd and ⁶⁵Zn and also of ⁸⁵Sr with this precipitate from THF solutions containing Tm²⁺ revealed that, in contrast to ⁸⁵Sr²⁺, ¹⁰⁹Cd and ⁶⁵Zn traces cocrystallize with the solid solvate phase. The cocrystallization coefficients D of ¹⁰⁹Cd and ⁶⁵Zn increase with increasing Tm³⁺/Tm²⁺ ratio in the solution. The mechanism suggested is that, in the presence of Tm²⁺, ¹⁰⁹Cd²⁺ and ⁶⁵Zn²⁺ are reduced to single-charged cations M⁺, which then rapidly react with the double-charged cations M²⁺ with the formation of dimers M ₂ ³⁺ (M = Cd, Zn).__________Translated from Radiokhimiya, Vol. 47, No. 3, 2005, pp. 261–264.Original Russian Text Copyright © 2005 by Veleshko, Kulyukhin.     

Radionuclides in ground waters from observation holes in the Shelter local area

The volume activity of ³H, ⁹⁰Sr, ¹³⁷Cs, ²³⁴U, ²³⁵U, ²³⁸U, ²³⁸Pu, ^239+240Pu, and ²⁴¹Am in ground waters from observation holes 1-G-6-G in the north section of the Shelter local area of the Chernobyl Nuclear Power Plant (CNPP) was measured. The distribution of radionuclides in the suspension fractions of the ground waters was evaluated. The main contribution to the pollution of ground waters with uranium is due to natural uranium isotopes: ^234,235,238U. The activity ratios of ²³⁸Pu, ^239+240Pu, and ²⁴¹Am in ground waters are similar to those in the spent fuel of 4th CNPP block.     

Spatial distribution of radionuclides produced in copper by photonuclear spallation reactions

The spatial distribution of radionuclides produced in a 15 cm thick copper target, which is commonly used as accelerator material, was measured by bombarding the bremsstrahlung radiation generated by 900 MeV electrons. The production of radionuclides of ⁶⁴Cu, ⁶¹Cu, ⁶⁰Cu, ⁵⁸Co, ⁵⁷Co, ⁵⁵Co, ⁵⁶Mn, ⁵²Mn, ⁴⁸Sc, ⁴⁷Sc,and ^44mSc was clearly identified up to about 10 cm in depth. The spatial distribution of bremsstrahlung radiation in copper was also calculated by the electromagnetic cascade Monte Carlo code, EGS-4. By comparing the experimental data and the calculated results, the effective cross sections and the effective energy ranges were derived for ⁶⁵Cu(γ,n)⁶⁴Cu, ⁶³Cu(γ,2n)⁶¹Cu, ⁶³Cu(γ,3n)⁶⁰Cu and other photonuclear spallation reactions.     

High-pressure investigations of positive ion-molecule reactions in a mixtureof H2S and CH4

The positive ion-molecule reactions in the mixtures of hydrogen sulfide and methane have been examined by means of quadrupole mass spectrometer with the high-pressure ion source. The concentration of hydrogen sulfide in mixtures ranged from 10% to 90% with 10% increment. For each mixture major bimolecular ion-molecule reactions have been identified in the total pressure range from 0.7 to 33.3 Pa. The electron energy for all measurements was fixed at 300 eV and the repeller potential was maintained at 5 V. Relative intensities of ion currents for the observed ions C⁺, CH⁺, CH₂⁺, CH₃⁺, CH₄⁺, CH₅⁺, C₂H₃⁺, C₂H₄⁺, C₂H₅⁺, S⁺, HS⁺, H₂S⁺, H₃S⁺, H₃³⁴S⁺, CHS⁺, CH₃S⁺, S₂⁺, HS₂⁺ and H₂S₂⁺ were determined as a function of total gas pressure inside the ion source collision chamber, repeller potential and concentration of methane in the mixture.     

Production of Neptunium and Plutonium Tracers in Nuclear Reactions of 236U with 21-to-60-MeV 3He Ions1

Production of ²³⁶Pu, ²³⁷Pu, and ²³⁵Np by the reactions ²³⁶U(³He,t^-)²³⁶Pu, ²³⁶U(³He,2n)²³⁷Pu, and ²³⁶U(³He,p3n)²³⁵Np with 43- and 60-MeV ³He ion beams on the K-130 cyclotron of the University of Jyvüaskylüa was studied. The cross sections for the reactions were determined. The curves of yields with thick targets were derived from the cross sections. The results are discussed and compared with previous data on the other reactions yielding the same final products.     

Desorption of 90Sr and 137Cs from Flood Plain Deposits of the Sozh River and Rocks of the Adjacent Catchment Areas

Desorption of ⁹⁰Sr and ¹³⁷Cs from flood plain warps, meadow sod, humus-containing sandy loam, peat, clays, limonite, meadow marl, and friable rocks of the adjacent catchment areas (moraine clay, loam, sandy loam) was studied. ¹³⁷Cs is sorbed the most strongly on clays by the mechanism of isomorphic ion-exchange incorporation into the crystal lattice of montmorillonite-type minerals. ¹³⁷Cs is also tightly fixed on buried and peaty soils due to association with the poorly mobile species of humic acids and humin. The strong fixation of ⁹⁰Sr on amorphous iron hydroxides is caused by its association with poorly soluble ferrite-type minerals. Sorption of ⁹⁰Sr on peaty soils can be attributed to their association with aluminum and iron-containing organomineral complexes. ¹³⁷Cs sorbed on flood plain warps, sandy loams, and loams exhibits increased mobility and is leached with all the tested desorbing solutions. These deposits apparently contribute maximally to the redistribution of radiocesium over flood plain and the adjacent catchment areas. The desorption efficiency of cations of the desorbing solutions decreases in the order Cs⁺ > K⁺ > Fe^{3 +} > NH₄ ⁺ > Ca^{2 +} > H⁺ for radiocesium and Fe^{3 +} > Sr^{2 +} > K⁺ > H⁺ > Ca^{2 +} > NH₄ ⁺ for radiostrontium.     

Leaching of radionuclides from products of underground nuclear explosions in granite: Experiments with radioactive samples of melted rock from explosion cavities on Semipalatinsk test site

Leaching of ¹³⁷Cs, ⁹⁰Sr, and ^239+240Pu from products of underground nuclear explosions in tunnels 504R, 148/5, and 190 of the Semipalatinsk test site was studied. Samples were taken from central zones of the explosions. Sample characteristics are presented. Leaching experiments were performed in the batch and dynamic modes. The degrees and rates of ¹³⁷Cs, ⁹⁰Sr, and ^239+240Pu leaching with granite aqueous extract were determined. The leach rates determined in batch experiments are in the following ranges: ⁹⁰Sr 2.3 × 10^?6?1.6 × 10^?4, ¹³⁷Cs 5.0 × 10^?6?2.5 × 10^?4, and ^239+240Pu 5.6 × 10^?7?2.1 × 10^?4 g cm^?2 day^?1, and those determined in dynamic experiments are in the following ranges: ⁹⁰Sr 9.2 × 10^?10?10^?8, ¹³⁷Cs 1.0 × 10^?9?1.6 × 10^?7, and ^239+240Pu 1.3 × 10^?11?2.5 × 10^?11 g cm^?2 day^?1. The values obtained are close to those reported in the literature for vitrified radioactive wastes.     

Association of 90xSr, 137Cs, 239,240Pu, 241Am,and 244Cm with Soil Absorbing Complex in Soils Typical of the Vicinity of the Chernobyl NPP

Association of the main long-lived radionuclides ¹³⁷Cs, ⁹⁰Sr, ^239,240Pu, ²⁴¹Am, and ²⁴⁴Cm with various components of the soil absorbing complexes from soil samples collected along the western, northwestern, and northern tracks of radioactive fallout in the vicinity of the Chernobyl NPP was studied by the sequential leaching. In the samples of the sandy soil collected in the floodplain of the Pripyat river along the northwestern radioactive track, more than 85% of ⁹⁰Sr, 55% of ^239,240Pu, and 75% of ²⁴¹Am and ²⁴⁴Cm are associated with various components of the soil absorbing complex and are potentially mobile species. In the soil samples collected along the narrow western track, 80-85% of ¹³⁷Cs, ⁹⁰Sr, ^239,240Pu, ²⁴¹Am, and ²⁴⁴Cm are incorporated in hot particles. The degree of ¹³⁷Cs, ⁹⁰Sr, ^239,240Pu, ²⁴¹Am, and ²⁴⁴Cm association with different components of the soil absorbing complex is a function of the radionuclide type and physicochemical features of soil.     

Diffusion Monte Carlo Study of the Small Mixed 3He-4He Clusters

The ground state properties of helium mixed clusters ³He_2,3,4 ⁴He₂, ³He_2,3,4 ⁴He₃, ³He_2,3,4 ⁴He₄, ³He_2,3 ⁴He₅, consisting of up to eight helium atoms are studied using variational and diffusion Monte Carlo calculations. For clusters with three and four ³He atoms released-node diffusion Monte Carlo method is used. Our calculations show that, within errorbars, clusters ³He_3,4 ⁴He₂ have the same binding energy as the cluster ³He₂ ⁴He₂, and that ³He₃ ⁴He₃ has the same binding energy as ³He₂ ⁴He₃. The clusters ³He_3,4 ⁴He₂ and ³He₃ ⁴He₃ are in states in which one or two ³He atoms are far away from the rest of the system. Other considered clusters are bound. In particular, we have shown the stability of the cluster ³He₄ ⁴He₃, which was previously considered unstable. The calculations are performed using several different interatomic potentials and the conclusions concerning stability are insensitive to the particular form of the interaction potential. We compare our results with the recent experiment and other theoretical calculations.     

Realization of modulating broadband emission from Er–Tm codoped calcium boroaluminate glasses by dual-wavelength pumping

Near-infrared photoluminescence (PL) of calcium boroaluminate (CABAL) glasses codoped with Er₂O₃ and Tm₂O₃ has been investigated by dual-wavelength pumping at 795 and 476 nm. Spectrum shape of broadband emission could be modulated by controlling the power ratio of two pumping lines (P₄₇₆/P₇₉₅). The result shows that the full width at half maximum can reach ∼500 nm in the wavelength range from 1.3 to 2.0 μm by controlling P₄₇₆/P₇₉₅ = 12. The PL spectra show four characteristic peaks located at 1.46, 1.53, 1.58 and 1.80 μm, corresponding to Tm³⁺: ³H₄ → ³F₄, Er³⁺: ⁴I_13/2 → ⁴I_15/2, Tm³⁺: ¹G₄ → ³F₂ and Tm³⁺: ³F₄ → ³H₆ emissions, respectively. The energy transfer (ET) (ET1: Er³⁺: ⁴I_13/2, Tm³⁺: ³F₄ → Er³⁺: ⁴I_15/2, Tm³⁺: ³H₄ and ET2: Er³⁺: ⁴I_13/2, Tm³⁺: ³H₆ → Er³⁺: ⁴I_15/2, Tm³⁺: ³F₄) between Er³⁺ and Tm³⁺ ions play important roles in the luminescence mechanisms. In addition, a new ET process (ET: Tm³⁺: ¹G₄, Er³⁺: ⁴F_9/2 → Tm³⁺: ³F₂, Er³⁺: ⁴F_7/2) was identified. The flat broadband emission with the bandwidth of ∼500 nm could be realized by changing P₄₇₆/P₇₉₅ as a result of the radiative transitions, Tm–Tm cross-relaxation (Tm³⁺: ³H₄, ³H₆ → Tm³⁺: ³F₄, ³F₄) and Er–Tm ET processes.     

Kinetics of Plutonium(IV) Reduction with 3,3'-Bis(diaziridinyl) in HNO3 Solution

3,3'-Bis(diaziridinyl), H₂N₂C₂H₂N₂H₂, is oxidized with Pu(IV) ions in excess of reductant to bis(diazirinyl), N₂C₂H₂N₂, and in excess of oxidant, to nitrogen and acetic acid. The reaction rate in the HNO₃ solution at a constant ionic strength is described by the equation -d[Pu(IV)]/dt = k[Pu(IV)]²× [H₂N₂C₂H₂N₂H₂]^{1 . 7}[H⁺]^{- 3}, where k = 28400±1400 mol^{0 . 3} l^{- 0 . 3} min^{- 1} at 35°C. The activation energy of the reaction amounts to 126±11 kJ mol^{- 1}.     

16O contamination in 4He analysis beams

The ⁴He⁺ beam from a Van de Graaff accelerator is often accompanied by an ¹⁶O⁺ beam of the same energy. If, after acceleration and before magnetic analysis, one electron is stripped from the oxygen ion to form ¹⁶O²⁺, these ions will not be separated from ⁴He⁺ during magnetic analysis. The ¹⁶O²⁺ fraction in the ⁴He⁺ beam was measured by analyzing back-scattering spectra for a thin Au film and the O to He ion charge ratio of 2:1 was confirmed by electrostatic deflection. Ion source conditions and the pressure in the beam lines strongly affect the ¹⁶O²⁺ fraction and the dependence of the O²⁺/O⁺ ratio on pressure is found to be in approximate agreement with predicted values. A formula for estimating the ¹⁶O²⁺ beam intensity, based on charge exchange data and measurement of the primary ¹⁶O⁺ beam intensity, is N[O²⁺] = 13 P(torr) l(cm) N[O⁺], where P is the total gas pressure, l the length of the beam line between the accelerator and switching magnet and N[O²⁺] and N[O⁺] are the beam intensities of the respective species. The ¹⁶O²⁺ contamination of ⁴He⁺ beams is easily removed by electrostatic separation.     

Single phased Sr<Subscript>3</Subscript>La(PO<Subscript>4</Subscript>)<Subscript>3</Subscript>:Eu<Superscript>2+</Superscript>/Mn<Superscript>2+</Superscript> phosphors: solid state synthesis,tunable luminescence and potential applications in white light LEDs

A series of Sr₃La(PO₄)₃:Eu²⁺/Mn²⁺ phosphors were synthesized by a solid state reaction. The phase and the optical properties of the synthesized phosphors were investigated. The XRD results indicate that the doped Eu²⁺ and Mn²⁺ ions do not change the phase of Sr₃La(PO₄)₃. The peak wavelengths of Eu²⁺ single doped and Eu²⁺/Mn²⁺ codoped Sr₃La(PO₄)₃ phosphors shift to longer wavelength due to the larger crystal field splitting for Eu²⁺ and Mn²⁺. The increases of crystal field splitting for Eu²⁺ and Mn²⁺ are induced by the substitution of Sr²⁺ by Eu²⁺ and Mn²⁺ in Sr₃La(PO₄)₃ host. Due to energy transfer from Eu²⁺ to Mn²⁺ in Sr₃La(PO₄)₃:Eu²⁺/Mn²⁺ phosphors, tunable luminescence was obtained by changing the concentration of Mn²⁺. And the white light was emitted by Sr₃La(PO₄)₃:3.0 mol%Eu²⁺/4.0 mol%Mn²⁺ and Sr₃La(PO₄)₃:3.0 mol%Eu²⁺/5.0 mol%Mn²⁺ phosphors.