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Sample records for hyperfine structure isotope

  1. Measurements of isotope shifts and hyperfine structure in Ti II

    Energy Technology Data Exchange (ETDEWEB)

    Nouri, Z; Rosner, S D; Holt, R A [Department of Physics and Astronomy, University of Western Ontario, London, ON N6A 3K7 (Canada); Li, R [TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6 T 2A3 (Canada); Scholl, T J, E-mail: rholt@uwo.c [Department of Medical Biophysics, University of Western Ontario, London, ON N6A 5C1 (Canada)

    2010-06-01

    We have applied fast-ion-beam laser-fluorescence spectroscopy to measure the isotope shifts of 38 transitions in the wavelength range 429-457 nm and the hyperfine structures (hfs) of 22 levels in Ti II. The isotope shift and hfs measurements are the first for these transitions and levels. These atomic data are essential for astrophysical studies of chemical abundances, allowing correction for saturation and the effects of blended lines.

  2. Hyperfine structure and isotope shift study in singly ionized lead

    Science.gov (United States)

    Wąsowicz, T. J.; Drozdowski, R.; Kwela, J.

    2005-12-01

    Hyperfine structure and isotope shifts in five optical transitions: 424.5 nm (6s^25f ^2textrm{F}_{7/2} 6s^26d^2 textrm{D}_{5/2}), 537.2 nm (6s^25f ^2textrm{F}_{7/2} 6s6p^2 ^4textrm{P}_{5/2}), 554.5 nm (6s^27d ^2textrm{D}_{5/2} 6s^27p ^2textrm{P}_{3/2}), 560.9 nm (6s^27p^2 textrm{P}_{3/2} 6s^27s ^2textrm{S}_{1/2}) and 666.0 nm (6s^27p ^2textrm{P}_{1/2} 6s^27s ^2textrm{S}_{1/2}) of Pb II have been measured. As a light source the discharge tube was used. The hyperfine structure measurements were performed using metallic isotope 207Pb. For isotope shifts measurements natural lead was used. The high resolution spectral apparatus consisted of a silver coated Fabry-Perot etalon and a grating spectrograph combined with a CCD camera used as a detector. In the analysis of the spectra a computer simulation technique was used. The hyperfine structure observations yielded the splitting constants A for seven levels of Pb II. The isotope shift studies enabled to separate the mass and the field shifts and to determine values of changes of the mean square nuclear charge radii.

  3. Measurement of hyperfine structure and isotope shifts in Gd II

    Science.gov (United States)

    Del Papa, Dylan F.; Rose, Christopher D. M.; Rosner, S. David; Holt, Richard A.

    2017-07-01

    We have applied fast-ion-beam laser-fluorescence spectroscopy to measure the isotope shifts of 73 optical transitions in the wavelength range 421.5-455.8 nm and the hyperfine structures of 35 even parity and 33 odd parity levels in Gd II. Many of the isotope shifts and hyperfine structure measurements are the first for these transitions and levels. These atomic data can be used to correct for saturation and blending in the analysis of stellar spectra to determine chemical abundances. As a result, they have an important impact on studies of the history of nucleosynthesis in the Universe and on the use of photospheric abundance anomalies in Chemically Peculiar stars to infer indirect information about stellar interiors.

  4. Theoretical study of hyperfine structure constants of Ga isotopes

    Science.gov (United States)

    Wang, Q. M.; Li, J. G.; Fritzsche, S.; Godefroid, M.; Chang, Z. W.; Dong, C. Z.

    2012-11-01

    The hyperfine structure constants for the ground 4s24p 2P°3/2 and lowest excited states 4s25s 2S1/2 of 71Ga are calculated using the GRASP2K package based on the multi-configuration Dirac-Hartree-Fock method. Furthermore, the magnetic dipole (μ) and the electric quadrupole (Q) moments of the Ga isotopes from 67Ga to 81Ga are derived.

  5. Hyperfine Structure and Isotope Shifts in Dy II

    Directory of Open Access Journals (Sweden)

    Dylan F. Del Papa

    2017-01-01

    Full Text Available Using fast-ion-beam laser-fluorescence spectroscopy (FIBLAS, we have measured the hyperfine structure (hfs of 14 levels and an additional four transitions in Dy II and the isotope shifts (IS of 12 transitions in the wavelength range of 422–460 nm. These are the first precision measurements of this kind in Dy II. Along with hfs and IS, new undocumented transitions were discovered within 3 GHz of the targeted transitions. These atomic data are essential for astrophysical studies of chemical abundances, allowing correction for saturation and the effects of blended lines. Lanthanide abundances are important in diffusion modeling of stellar interiors, and in the mechanisms and history of nucleosynthesis in the universe. Hfs and IS also play an important role in the classification of energy levels, and provide a benchmark for theoretical atomic structure calculations.

  6. Towards isotope shift and hyperfine structure measurements of the element nobelium

    Energy Technology Data Exchange (ETDEWEB)

    Chhetri, Premaditya; Lautenschlaeger, Felix; Walther, Thomas [Institut fuer Angewandte Physik, TU Darmstadt, D-64289 Darmstadt (Germany); Laatiaoui, Mustapha [Helmholtz Institut Mainz, D-55099 Mainz (Germany); Block, Michael; Hessberger, Fritz-Peter [Helmholtz Institut Mainz, D-55099 Mainz (Germany); GSI, D-64291 Darmstadt (Germany); Lauth, Werner; Backe, Hartmut [Institut fuer Kernphysik, JGU Mainz, D-55122 Mainz (Germany); Kunz, Peter [TRIUMF, D-V6T2A3 Vancouver (Canada)

    2014-07-01

    Laser spectroscopy on the heaviest elements is of great interest as it allows the study of the evolution of relativistic effects on their atomic structure. In our experiment we exploit the Radiation Detected Resonance Ionization Spectroscopy technique and use excimer-laser pumped dye lasers to search for the first time the {sup 1}P{sub 1} level in {sup 254}No. Etalons will be used in the forthcoming experiments at GSI, Darmstadt, to narrow down the bandwidth of the dye lasers to 0.04 cm{sup -1}, for the determination of the isotope shift and hyperfine splitting of {sup 253,} {sup 255}No. In this talk results from preparatory hyperfine structure studies in nat. ytterbium and the perspectives for future experiments of the heaviest elements are discussed.

  7. Laser Spectroscopic Measurements of Isotope Shift and Hyperfine Structure in BISMUTH-207 and BISMUTH-208.

    Science.gov (United States)

    Fang, Zuyun

    1988-12-01

    Measurements of the hyperfine spectra of 38-yr ^{207}Bi and 3.7 times 10^5-yr ^{208}Bi in the 6p^3 ^4S_{3/2} - 6p^27s ^4P_{1/2} 306.7-nm resonance line were made using laser spectroscopic methods. The atomic excitation was produced with use of the frequency doubled output of a tunable ring dye laser. Laser absorption spectroscopy was used for the ^ {208}Bi measurement, while fluorescence spectroscopy, with photon counting detection, was used for ^{208}Bi. The experiments of ^{207}Bi were performed in both zero and high (0.7515 T) magnetic fields. The latter also provided a reliable measurement of the nuclear spin of ^{207}Bi. The results obtained from the ^ {208}Bi spectra are: A(^4P _{1/2}) = 4911(17)MHz and B( ^4S_{3/2}) = -314(92)MHz. These give the values: mu = 4.523(16) mu_{N} and Q = - 0.39(12)b. The measured isotope shift is: IS( ^{208}Bi-^{209 }Bi) = 1870(63)MHz. The results for ^{207} Bi are: I = 9/2, A(^4P_{1/2 }) = 4900.0(8.1)MHz, A(^4S_ {1/2}) = -444.6(1.5)MHz and B(^4S_{1/2}) = -443(17)MHz. These give the values: mu = 4.062(8)mu_ {N} and Q = -0.55(2)b. The measured isotope shift is: IS(^{207 }Bi-^{209}Bi) = 2997(10)MHz. The isotope shift odd-even staggering parameter for ^{208}Bi, gamma = 0.752(43), was derived and used for an isotonic comparison. The measured nuclear magnetic moments are in agreement with theoretical predictions. An improved calculation of the isotope shift constant using a diffuse nuclear charge model is given and a weak, but significant, model dependence of the isotope shifts was found.

  8. Hyperfine structure studies with the COMPLIS facility

    CERN Document Server

    Crawford, J E; Le Blanc, F; Lunney, M D; Obert, J; Oms, J; Putaux, J C; Roussière, B; Sauvage, J; Zemlyanoi, S G; Verney, D; Pinard, J; Cabaret, L A; Duong, H T; Huber, G; Krieg, M; Sebastian, V; Girod, M; Peru, S; Genevey, J; Ibrahim, F; Lettry, Jacques

    1998-01-01

    COMPLIS is an experimental facility designed to carry out spectroscopic studies on radioisotopes produced by disintegration of elements available at CERN's Booster-ISOLDE on-line isotope separator. During recent series of experimental runs, hyperfine structure measurements have yielded information on nuclear moments and deformations of platinum and iridium isotopes, For the first time, population by alpha -decay from Hg was exploited to investigate /sup 178/-/sup 181/Pt-the most neutron-deficient Pt isotopes yet studied. Successful measurements have recently been carried out on /sup 182-189/Ir. (10 refs).

  9. Hyperfine structure of S-states of muonic tritium

    Directory of Open Access Journals (Sweden)

    Martynenko F.A.

    2017-01-01

    Full Text Available On the basis of quasipotential method in quantum electrodynamics we carry out a precise calculation of hyperfine splitting of S-states in muonic tritium. The one-loop and two-loop vacuum polarization corrections, relativistic effects, nuclear structure corrections in first and second orders of perturbation theory are taken into account. The contributions to hyperfine structure are obtained in integral form and calculated analytically and numerically. Obtained results for hyperfine splitting can be used for a comparison with future experimental data of CREMA collaboration.

  10. Hyperfine structure and g-factor measurements in ion traps

    Science.gov (United States)

    Knab, H.; Knöll, K. H.; Arbes, F.; Becker, O.; Werth, G.

    1992-10-01

    We report about measurements on ground-state hyperfine splitting constants of stable Eu+ isotopes in radio frequency ion traps and experiments on the electronic g-factor of Ba+ in a Penning trap. From the precision of both measurements, which ranges between 3·10-6 and 5·10-7, we conclude that precise determination of the differential Bohr-Weisskopf effect in chains of isotopes will be possible in the near future.

  11. Measurement of the hyperfine structure of antihydrogen in a beam

    CERN Document Server

    Widmann, E.; Juhasz, B.; Malbrunot, C.; Massiczek, O.; Sauerzopf, C.; Suzuki, K.; Wunschek, B.; Zmeskal, J.; Federmann, S.; Kuroda, N.; Ulmer, S.; Yamazaki, Y.

    2013-01-01

    A measurement of the hyperfine structure of antihydrogen promises one of the best tests of CPT symmetry. We describe an experiment planned at the Antiproton Decelerator of CERN to measure this quantity in a beam of slow antihydrogen atoms.

  12. Quantum Theory of Hyperfine Structure Transitions in Diatomic Molecules.

    Science.gov (United States)

    Klempt, E.; And Others

    1979-01-01

    Described is an advanced undergraduate laboratory experiment in which radio-frequency transitions between molecular hyperfine structure states may be observed. Aspects of the quantum theory applied to the analysis of this physical system, are discussed. (Authors/BT)

  13. Full hyperfine structure analysis of singly ionized molybdenum

    Science.gov (United States)

    Bouazza, Safa

    2017-03-01

    For a first time a parametric study of hyperfine structure of Mo II configuration levels is presented. The newly measured A and B hyperfine structure (hfs) constants values of Mo II 4d5, 4d45s and 4d35s2 configuration levels, for both 95 and 97 isotopes, using Fast-ion-beam laser-induced fluorescence spectroscopy [1] are gathered with other few data available in literature. A fitting procedure of an isolated set of these three lowest even-parity configuration levels has been performed by taking into account second-order of perturbation theory including the effects of closed shell-open shell excitations. Moreover the same study was done for Mo II odd-parity levels; for both parities two sets of fine structure parameters as well as the leading eigenvector percentages of levels and Landé-factor gJ, relevant for this paper are given. We present also predicted singlet, triplet and quintet positions of missing experimental levels up to 85000 cm-1. The single-electron hfs parameter values were extracted in their entirety for 97Mo II and for 95Mo II: for instance for 95Mo II, a4d01 =-133.37 MHz and a5p01 =-160.25 MHz for 4d45p; a4d01 =-140.84 MHz, a5p01 =-170.18 MHz and a5s10 =-2898 MHz for 4d35s5p; a5s10 =-2529 (2) MHz and a4d01 =-135.17 (0.44) MHz for the 4d45s. These parameter values were analysed and compared with diverse ab-initio calculations. We closed this work with giving predicted values of magnetic dipole and electric quadrupole hfs constants of all known levels, whose splitting are not yet measured.

  14. Spin-torsion effects in the hyperfine structure of methanol

    Science.gov (United States)

    Coudert, L. H.; Gutlé, C.; Huet, T. R.; Grabow, J.-U.; Levshakov, S. A.

    2015-07-01

    The magnetic hyperfine structure of the non-rigid methanol molecule is investigated experimentally and theoretically. 12 hyperfine patterns are recorded using molecular beam microwave spectrometers. These patterns, along with previously recorded ones, are analyzed in an attempt to evidence the effects of the magnetic spin-torsion coupling due to the large amplitude internal rotation of the methyl group [J. E. M. Heuvel and A. Dymanus, J. Mol. Spectrosc. 47, 363 (1973)]. The theoretical approach setup to analyze the observed data accounts for this spin-torsion in addition to the familiar magnetic spin-rotation and spin-spin interactions. The theoretical approach relies on symmetry considerations to build a hyperfine coupling Hamiltonian and spin-rotation-torsion wavefunctions compatible with the Pauli exclusion principle. Although all experimental hyperfine patterns are not fully resolved, the line position analysis yields values for several parameters including one describing the spin-torsion coupling.

  15. High resolution spectroscopy of the hyperfine structure splitting in 97,99Tc

    Science.gov (United States)

    Raeder, Sebastian; Kron, Tobias; Heinke, Reinhard; Henares, Jose L.; Lecesne, Nathalie; Schönberg, Pascal; Trümper, Marcel; Wendt, Klaus

    2017-11-01

    Resonance ionization mass spectrometry is an efficient tool for detecting trace amounts of long-lived radio-isotopes in environmental samples. For absolute quantification a tracer with identical atomic properties and chemical behavior is needed to prevent a possible dependency onto the absolute efficiency for the analytical method. For an application in 99Tc, the isotope 97Tc could serve as a potential tracer. Therefore the optical transitions of an efficient ionization scheme for technetium were investigated for the two odd mass isotopes 97,99Tc, both with a nuclear spin of I={9}/{2}. Using a pulsed, single mode laser with narrow bandwidth, the hyperfine structures (HFS) of two transitions were fully resolved. The observed isotope shift is small in comparison to the width of the hyperfine structure splitting. This is ideal for the application of 97Tc as tracer isotope for 99Tc quantification. The evaluation of the observed HFS splitting results in a first experimental value for the magnetic dipole for 97Tc of μ=+5.82(9) μ N .

  16. Hadronic deuteron polarizability contribution the hyperfine structure in muonic deuterium

    Directory of Open Access Journals (Sweden)

    Eskin A.V.

    2017-01-01

    Full Text Available The calculation of the contribution to the polarizability of the nucleus to hyperfine structure of muonic hydrogen is carried out within the unitary isobar model and on the basis of experimental data on the structure functions of deep inelastic lepton-proton and lepton-deuteron scattering. The calculation of virtual absorption cross sections of transversely and longitudinally polarized photons by nucleons in the resonance region is performed in the framework of the program MAID.

  17. Calculation of hyperfine structure constants of small molecules using ...

    Indian Academy of Sciences (India)

    The Z-vector method in the relativistic coupled-cluster framework is employed to calculate the parallel and perpendicular components of the magnetic hyperfine structure constant of a few small alkaline earth hydrides (BeH, MgH, and CaH) and fluorides (MgF and CaF). We have compared our Z-vector results with the values ...

  18. Deuterium hyperfine structure in interstellar C3HD

    Science.gov (United States)

    Bell, M. B.; Watson, J. K.; Feldman, P. A.; Matthews, H. E.; Madden, S. C.; Irvine, W. M.

    1987-01-01

    The deuterium nuclear quadrupole hyperfine structure of the transition 1(10)-1(01) of the ring molecule cyclopropenylidene-d1 (C3HD) has been observed in emission from interstellar molecular clouds. The narrowest linewidths (approximately 7 kHz) so far observed are in the cloud L1498. The derived D coupling constants Xzz = 186.9(1.4) kHz, eta=0.063(18) agree well with correlations based on other molecules.

  19. Hyperfine Structure Measurements of Antiprotonic $^3$He using Microwave Spectroscopy

    CERN Document Server

    Friedreich, Susanne

    The goal of this project was to measure the hyperfine structure of $\\overline{\\text{p}}^3$He$^+$ using the technique of laser-microwave-laser spectroscopy. Antiprotonic helium ($\\overline{\\text{p}}$He$^+$) is a neutral exotic atom, consisting of a helium nucleus, an electron and an antiproton. The interactions of the angular momenta of its constituents cause a hyperfine splitting ({HFS}) within the energy states of this new atom. The 3\\% of formed antiprotonic helium atoms which remain in a metastable, radiative decay-dominated state have a lifetime of about 1-3~$\\mu$s. This time window is used to do spectroscopic studies. The hyperfine structure of $\\overline{\\text{p}}^4$He$^+$ was already extensively investigated before. From these measurements the spin magnetic moment of the antiproton can be determined. A comparison of the result to the proton magnetic moment provides a test of {CPT} invariance. Due to its higher complexity the new exotic three-body system of $\\overline{\\text{p}}^3$He$^+$ is a cross-check...

  20. Rotational spectra, nuclear quadrupole hyperfine tensors, and conformational structures of the mustard gas simulent 2-chloroethyl ethyl sulfide

    Science.gov (United States)

    Tubergen, M. J.; Lesarri, A.; Suenram, R. D.; Samuels, A. C.; Jensen, J. O.; Ellzy, M. W.; Lochner, J. M.

    2005-10-01

    Rotational spectra have been recorded for both the 35Cl and 37Cl isotopic forms of two structural conformations of 2-chloroethyl ethyl sulfide (CEES). The rotational constants of the 35Cl and 37Cl isotopomers were used to identify the conformational isomers. A total of 236 hyperfine transitions have been assigned for 47 rotational transitions of the 35Cl isotope of a GGT conformer, and 146 hyperfine have been assigned for 37 rotational transitions of the 37Cl isotopomer. For the second conformer, a total of 128 (110) hyperfine and 30 (28) rotational transitions have also been assigned to the 35Cl ( 37Cl) isotopes of a TGT conformation. The extensive hyperfine splitting data, measured to high resolution with a compact Fourier transform microwave spectrometer, were used to determine both the diagonal and off-diagonal elements of the 35Cl and 37Cl nuclear quadrupole coupling tensors in the inertial tensor principal axis system. The experimental rotational constant data, as well as the 35Cl and 37Cl nuclear quadrupole coupling tensors, were compared to the results from 27 optimized ab initio (HF/6-311++G ∗∗ and MP2/6-311++G ∗∗) model structures.

  1. Improved Study of the Antiprotonic Helium Hyperfine Structure

    CERN Document Server

    Pask, T.; Dax, A.; Hayano, R.S.; Hori, M.; Horvath, D.; Juhasz, B.; Malbrunot, C.; Marton, J.; Ono, N.; Suzuki, K.; Zmeskal, J.; Widmann, E.

    2008-01-01

    We report the initial results from a systematic study of the hyperfine (HF) structure of antiprotonic helium (n,l) = (37,~35) carried out at the Antiproton Decelerator (AD) at CERN. We performed a laser-microwave-laser resonance spectroscopy using a continuous wave (cw) pulse-amplified laser system and microwave cavity to measure the HF transition frequencies. Improvements in the spectral linewidth and stability of our laser system have increased the precision of these measurements by a factor of five and reduced the line width by a factor of three compared to our previous results. A comparison of the experimentally measured transition frequencies with three body QED calculations can be used to determine the antiproton spin magnetic moment, leading towards a test of CPT invariance.

  2. Proton structure in the hyperfine splitting of muonic hydrogen

    OpenAIRE

    Hagelstein, Franziska; Pascalutsa, Vladimir

    2015-01-01

    We present the leading-order prediction of baryon chiral perturbation theory for the proton polarizability contribution to the 2S hyperfine splitting in muonic hydrogen, and compare with the results of dispersive calculations.

  3. Systematic model calculations of the hyperfine structure in light and heavy ions

    CERN Document Server

    Tomaselli, M; Nörtershäuser, W; Ewald, G; Sánchez, R; Fritzsche, S; Karshenboim, S G

    2003-01-01

    Systematic model calculations are performed for the magnetization distributions and the hyperfine structure (HFS) of light and heavy ions with a mass close to A ~ 6 208 235 to test the interplay of nuclear and atomic structure. A high-precision measurement of lithium-isotope shifts (IS) for suitable transition, combined with an accurate theoretical evaluation of the mass-shift contribution in the respective transition, can be used to determine the root-mean-square (rms) nuclear-charge radius of Li isotopes, particularly of the halo nucleus /sup 11/Li. An experiment of this type is currently underway at GSI in Darmstadt and ISOLDE at CERN. However, the field-shift contributions between the different isotopes can be evaluated using the results obtained for the charge radii, thus casting, with knowledge of the ratio of the HFS constants to the magnetic moments, new light on the IS theory. For heavy charged ions the calculated n- body magnetization distributions reproduce the HFS of hydrogen-like ions well if QED...

  4. ISOTROPIC INELASTIC COLLISIONS IN A MULTITERM ATOM WITH HYPERFINE STRUCTURE

    Energy Technology Data Exchange (ETDEWEB)

    Belluzzi, Luca [Istituto Ricerche Solari Locarno, CH-6605 Locarno Monti (Switzerland); Landi Degl’Innocenti, Egidio [Dipartimento di Fisica e Astronomia, Università di Firenze, I-50125 Firenze (Italy); Bueno, Javier Trujillo [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)

    2015-10-10

    A correct modeling of the scattering polarization profiles observed in some spectral lines of diagnostic interest, the sodium doublet being one of the most important examples, requires taking hyperfine structure (HFS) and quantum interference between different J-levels into account. An atomic model suitable for taking these physical ingredients into account is the so-called multiterm atom with HFS. In this work, we introduce and study the transfer and relaxation rates due to isotropic inelastic collisions with electrons, which enter the statistical equilibrium equations (SEE) for the atomic density matrix of this atomic model. Under the hypothesis that the electron–atom interaction is described by a dipolar operator, we provide useful relations between the rates describing the transfer and relaxation of quantum interference between different levels (whose numerical values are in most cases unknown) and the usual rates for the atomic level populations, for which experimental data and/or approximate theoretical expressions are generally available. For the particular case of a two-term atom with HFS, we present an analytical solution of the SEE for the spherical statistical tensors of the upper term, including both radiative and collisional processes, and we derive the expression of the emission coefficient in the four Stokes parameters. Finally, an illustrative application to the Na i D{sub 1} and D{sub 2} lines is presented.

  5. Lamb shifts and hyperfine structure in 6Li+ and 7Li+: Theory and experiment

    DEFF Research Database (Denmark)

    Riis, E.; Sinclair, A. G.; Poulsen, Ove

    1994-01-01

    High-precision laser-resonance measurements accurate to +/-0.5 MHz, or better are reported for transitions among the 1s2s S-3(1)-1s2p P-3(J) hyperfine manifolds for each of J = 0, 1, and 2 in both Li-6(+) and Li-7(+). A detailed analysis of hyperfine structure is performed for both the S and P st...

  6. Hyperfine structure of the hydroxyl free radical (OH) in electric and magnetic fields

    Science.gov (United States)

    Maeda, Kenji; Wall, Michael L.; Carr, Lincoln D.

    2015-05-01

    We investigate single-particle energy spectra of the hydroxyl free radical (OH) in the lowest electronic and rovibrational level under combined static electric and magnetic fields, as an example of heteronuclear polar diatomic molecules. In addition to the fine-structure interactions, the hyperfine interactions and centrifugal distortion effects are taken into account to yield the zero-field spectrum of the lowest 2Π3 / 2 manifold to an accuracy of less than 2kHz. We also examine level crossings and repulsions in the hyperfine structure induced by applied electric and magnetic fields. Compared to previous work, we found more than 10 percent reduction of the magnetic fields at level repulsions in the Zeeman spectrum subjected to a perpendicular electric field. In addition, we find new level repulsions, which we call Stark-induced hyperfine level repulsions, that require both an electric field and hyperfine structure. It is important to take into account hyperfine structure when we investigate physics of OH molecules at micro-Kelvin temperatures and below. This research was supported in part by AFOSR Grant No.FA9550-11-1-0224 and by the NSF under Grants PHY-1207881 and NSF PHY-1125915. We appreciate the Aspen Center for Physics, supported in part by the NSF Grant No.1066293, for hospitality.

  7. The Theory of ESR Hyperfine-Structure Narrowing as Applied to Wide-Gap Semimagnetic Semiconductors

    Science.gov (United States)

    Aliev; Tagirov; Tagiev

    1996-11-01

    The theory of ESR hyperfine-structure exchange narrowing is developed. The kinetic equations describing the nonequilibrium magnetization dynamics of hyperfine components of ESR spectra are derived by using the nonequilibrium statistical-operator method. Numerical solution of these general equations is applied to the simulation of the experimental spectra of (Cd, Mn)Te crystals with a Mn2+ ion content of between 0.05 and 0.5%. The hyperfine-splitting constant, homogeneous ESR linewidth, and mean-square value of the exchange fluctuation frequency are obtained from the fitting of the spectra for different concentrations of manganese ions. The concentration dependence of the latter quantity is discussed in relation to the spatial dependence of magnetic-ion exchange interaction and the gap value in the band structure of semimagnetic semiconductors.

  8. Measurement of hyperfine structure in the $\\rm D_1$ line of $^{87}$Rb

    CERN Document Server

    Datar, Durgesh; Ananthamurthy, Sharath; Natarajan, Vasant

    2016-01-01

    This work reports a new measurement of the hyperfine structure constant of the $\\rm D_1 $ line in $ \\rm ^{87}Rb $ through precision laser spectroscopy. In a departure from methods that rely on locking the laser on the transitions of interest, the technique reported here relies on scanning around the transition. This is carried out so as to overcome potential frequency shifts caused by various noise sources including electronic noise and thermal fluctuations. The value of the hyperfine constant reported here is $ A = 408.29(25) $ MHz, which is in variance from an earlier value reported from our lab but is consistent with other recent measurements.

  9. Experimental investigation of the hyperfine structure of praseodymium-I lines using laser spectroscopy

    Science.gov (United States)

    Khan, Shamim; Gamper, Bettina; Iqbal, S. Tanweer; Windholz, Laurentius

    2011-05-01

    The electronic ground state configuration of praseodymium 59Pr141 is [Xe] 4f3 6s2 , with ground state level 4I9 / 2 . Our research is mainly devoted to find previously unknown energy levels by the investigation of spectral lines on the basis of their hyperfine (hf) structure. In a hollow cathode discharge lamp, praseodymium atoms and ions in ground and excited states are excited to high lying states by laser light. The laser induced fluorescence (LIF) signal is then recorded using lock-in detection techniques. From the recorded hyperfine structure we determine J-values and hyperfine constants A of the combining levels. This information, together with excitation and fluorescence wavelengths, allows us to find the energies of the involved new levels. Up to now we have discovered a large number of previously unknown energy levels with various angular momentum values. We present here the characteristic data (energy, parity, angular momentum J and magnetic hyperfine constant A) of ca. 40, until now unknown energy levels.

  10. Structural properties and hyperfine characterization of Sn-substituted goethites

    Energy Technology Data Exchange (ETDEWEB)

    Larralde, A.L. [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Ramos, C.P. [Departamento de Fisica de la Materia Condensada, GIyA - CAC - CNEA, Av. Gral. Paz 1499 (1650), San Martin, Bs. As. (Argentina); Arcondo, B. [Departamento de Fisica, Facultad de Ingenieria, Universidad de Buenos Aires, Av. Paseo Colon 850 (C1063ACV), Bs. As. (Argentina); Tufo, A.E. [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina); Saragovi, C. [Departamento de Fisica de la Materia Condensada, GIyA - CAC - CNEA, Av. Gral. Paz 1499 (1650), San Martin, Bs. As. (Argentina); Sileo, E.E., E-mail: sileo@qi.fcen.uba.ar [INQUIMAE, Departamento de Quimica Inorganica, Analitica y Quimica Fisica, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires (Argentina)

    2012-04-16

    Highlights: Black-Right-Pointing-Pointer Pure and tin-doped goethites were synthesized from Sn(II) solutions at ambient pressure and 70 Degree-Sign C. Black-Right-Pointing-Pointer The Rietveld refinement of PXRD data indicated that Sn partially substituted the Fe(III) ions. Black-Right-Pointing-Pointer The substitution provoked unit cell expansion, and a distortion of the coordination polyhedron. Black-Right-Pointing-Pointer {sup 119}Sn Moessbauer spectroscopy revealed that Sn(II) is incorporated as Sn(IV). Black-Right-Pointing-Pointer {sup 57}Fe Moessbauer spectroscopy showed a lower magnetic coupling as tin concentration increased. - Abstract: Tin-doped goethites obtained by a simple method at ambient pressure and 70 Degree-Sign C were characterized by inductively coupled plasma atomic emission spectrometry, scanning electron microscopy, Rietveld refinement of powder X-ray diffraction data, and {sup 57}Fe and {sup 119}Sn Moessbauer spectroscopy. The particles size and the length to width ratios decreased with tin-doping. Sn partially substituted the Fe(III) ions provoking unit cell expansion and increasing the crystallinity of the particles with enlarged domains that grow in the perpendicular and parallel directions to the anisotropic broadening (1 1 1) axis. Intermetallic E, E Prime and DC distances also change although the variations are not monotonous, indicating different variations in the coordination polyhedron. In general, the Sn-substituted samples present larger intermetallic distances than pure goethite, and the greatest change is shown in the E Prime distance which coincides with the c-parameter. {sup 119}Sn Moessbauer spectroscopy revealed that Sn(II) is incorporated as Sn(IV) in the samples. On the other hand, Fe(II) presence was not detected by {sup 57}Fe Moessbauer spectroscopy, suggesting the existence of vacancies in the Sn-doped samples. A lower magnetic coupling is also evidenced from the average magnetic hyperfine field values obtained as tin

  11. Fine- and hyperfine structure investigations of even configuration system of atomic terbium

    Science.gov (United States)

    Stefanska, D.; Elantkowska, M.; Ruczkowski, J.; Furmann, B.

    2017-03-01

    In this work a parametric study of the fine structure (fs) and the hyperfine structure (hfs) for the even-parity configurations of atomic terbium (Tb I) is presented, based in considerable part on the new experimental results. Measurements on 134 spectral lines were performed by laser induced fluorescence (LIF) in a hollow cathode discharge lamp; on this basis, the hyperfine structure constants A and B were determined for 52 even-parity levels belonging to the configurations 4f85d6s2, 4f85d26s or 4f96s6p; in all the cases those levels were involved in the transitions investigated as the lower levels. For 40 levels the hfs was examined for the first time, and for the remaining 12 levels the new measurements supplement our earlier results. As a by-product, also preliminary values of the hfs constants for 84 odd-parity levels were determined (the investigations of the odd-parity levels system in the terbium atom are still in progress). This huge amount of new experimental data, supplemented by our earlier published results, were considered for the fine and hyperfine structure analysis. A multi-configuration fit of 7 configurations was performed, taking into account second-order of perturbation theory, including the effects of closed shell-open shell excitations. Predicted values of the level energies, as well as of magnetic dipole and electric quadrupole hyperfine structure constants A and B, are quoted in cases when no experimental values are available. By combining our experimental data with our own semi-empirical procedure it was possible to identify correctly the lower and upper level of the line 544.1440 nm measured by Childs with the use of the atomic-beam laser-rf double-resonance technique (Childs, J Opt Soc Am B 9;1992:191-6).

  12. Electronic structure and hyperfine parameters of substitutional Al and P impurities in silica

    DEFF Research Database (Denmark)

    Lægsgaard, Jesper; Stokbro, Kurt

    2002-01-01

    The electronic structure of substitutional Al and P impurities in silica is investigated using supercell calculations within the framework of density functional theory (DFT). Evaluation of hyperfine matrices for the magnetic nuclei facilitates comparison to experimental data. It is found that the......The electronic structure of substitutional Al and P impurities in silica is investigated using supercell calculations within the framework of density functional theory (DFT). Evaluation of hyperfine matrices for the magnetic nuclei facilitates comparison to experimental data. It is found......, there is an "asymmetry" between electrons and holes in the electronic states of the silica network: The hole present at the Al impurity goes into a nonbonding O orbital while the extra electron present at the P impurity goes into a P-O antibonding state....

  13. New precise measurement of muonium hyperfine structure interval at J-PARC

    Energy Technology Data Exchange (ETDEWEB)

    Ueno, Y., E-mail: yueno@radphys4.c.u-tokyo.ac.jp [University of Tokyo, Graduate School of Arts and Sciences (Japan); Aoki, M. [Osaka University, Graduate School of Science (Japan); Fukao, Y. [KEK (Japan); Higashi, Y.; Higuchi, T. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Iinuma, H.; Ikedo, Y. [KEK (Japan); Ishida, K. [RIKEN (Japan); Ito, T. U. [Japan Atomic Energy Agency (Japan); Iwasaki, M. [RIKEN (Japan); Kadono, R. [KEK (Japan); Kamigaito, O. [RIKEN (Japan); Kanda, S. [University of Tokyo, Department of Physics (Japan); Kawall, D. [University of Massachusetts, Amherst, Department of Physics (United States); Kawamura, N.; Koda, A.; Kojima, K. M. [KEK (Japan); Kubo, M. K. [International Christian University, Graduate School of Arts and Science (Japan); Matsuda, Y. [University of Tokyo, Graduate School of Arts and Sciences (Japan); Mibe, T. [KEK (Japan); and others

    2017-11-15

    MuSEUM is an international collaboration aiming at a new precise measurement of the muonium hyperfine structure at J-PARC (Japan Proton Accelerator Research Complex). Utilizing its intense pulsed muon beam, we expect a ten-fold improvement for both measurements at high magnetic field and zero magnetic field. We have developed a sophisticated monitoring system, including a beam profile monitor to measure the 3D distribution of muonium atoms to suppress the systematic uncertainty.

  14. Development of atomic spectroscopy technologies - Hyperfine structure of 2 period atoms using optogalvanic effects

    Energy Technology Data Exchange (ETDEWEB)

    Kwon, Nam Ic [Hankuk University of foreign studies, Seoul (Korea)

    2000-03-01

    The source of anomalous broad linewidth of 3{sup 3}P{sub 1},{sub 2},{sub 3}-3{sup 3}D{sub 2},{sub 3},4(3s') transition was explained. The broad optogalvanic spectrum was consisted of two gaussian peaks of different linewidths, and they are separated by 250 MHz. The Narrow peak, which has linewidth of room temperature, is from oxygen atoms already separated, and the shifted broad peak, which has linewidth corresponding to a temperature of 9000 K, is from weakly bound molecular ions. Obtained hyperfine spectrum of fluorine atom at the expected frequency, was too weak to analyze hyperfine structure constants. Microwave discharge might be necessary for higher density of excited state. 16 refs., 11 figs. (Author)

  15. 7P1/2 hyperfine splitting in 206 , 207 , 209 , 213Fr and the hyperfine anomaly

    Science.gov (United States)

    Zhang, J.; Orozco, L. A.; Collister, R.; Gwinner, G.; Tandecki, M.; Behr, J. A.; Pearson, M. R.; Gomez, E.; Aubin, S.

    2013-05-01

    We perform precision measurements on francium, the heaviest alkali with no stable isotopes, at the recently commissioned Francium Trapping Facility at TRIUMF. A combination of RF and optical spectroscopy allows better than 10 ppm (statistical) measurements of the 7P1 / 2 state hyperfine splitting for the isotopes 206 , 207 , 209 , 213Fr, in preparation for weak interaction studies. Together with previous measurements of the ground state hyperfine structure, it is possible to extract the hyperfine anomaly. This is a correction to the point interaction of the nuclear magnetic moment and the electron wavefunction, known as the Bohr Weisskopf effect. Our measurements extend previous measurements to the neutron closed shell isotope (213) as well as further in the neutron deficient isotopes (206, 207). Work supported by NSERC and NRC from Canada, NSF and DOE from USA, CONYACT from Mexico.

  16. Host material induced hyperfine structure of F{sup +} centres EPR spectra in CaS

    Energy Technology Data Exchange (ETDEWEB)

    Seeman, Viktor, E-mail: viktor.seeman@ut.ee; Dolgov, Sergei; Maaroos, Aarne

    2017-05-15

    The hyperfine structure (HFS) of F{sup +} centres in CaS single crystals due to the interaction with {sup 33}S and {sup 43}Ca nuclei was observed in EPR spectra for the first time. Angular variations of the HFS were measured for rotation of magnetic field in {100} and {110} crystallographic planes. Using measured orientation-dependent EPR spectra and the EPR NMR program, the parameters of the spin Hamiltonian were determined. In case of {sup 33}S nucleus there is a strong dependence of the F{sup +} centre EPR spectrum on the quadrupole term whereas for {sup 43}Ca nucleus this dependence is insignificant.

  17. Analysis of structure of hyperfine poly(3-hydroxybutyrate) fibers (PHB) for controlled drug delivery

    Science.gov (United States)

    Olkhov, A. A.; Kosenko, R. Yu; Markin, V. S.; Zykova, A. K.; Pantyukhov, P. V.; Karpova, S. G.; Iordanskii, A. L.

    2017-12-01

    Hyperfine fibers based on biodegradable poly (3-hydroxybutyrate) with encapsulated drug substance (dipyridamol) were obtained by using electrospinning method. Addition of dipyridamol has a significant effect on geometrical shape and structure of microfibers as well as total porosity of fibrous material. Observation of fibers using scanning electron microscopy (SEM) method showed that without or at lower dipyridamol content (structures did not practically form, and fiber’s shape became cylindrical. The totality of morphological and structural characteristics determined the rate of dipyridamol diffusive transports. The simplified model of drug desorption from fibrous matrix was presented. In current work it was showed that the rate-limiting stage of transport was the diffusion of dipyridamol in the bulk of cylindrical fibers.

  18. Hyperfine structure in 229gTh3+ as a probe of the 229gTh→ 229mTh nuclear excitation energy.

    Science.gov (United States)

    Beloy, K

    2014-02-14

    We identify a potential means to extract the 229gTh→ 229mTh nuclear excitation energy from precision microwave spectroscopy of the 5F(5/2,7/2) hyperfine manifolds in the ion 229gTh3+. The hyperfine interaction mixes this ground fine structure doublet with states of the nuclear isomer, introducing small but observable shifts to the hyperfine sublevels. We demonstrate how accurate atomic structure calculations may be combined with the measurement of the hyperfine intervals to quantify the effects of this mixing. Further knowledge of the magnetic dipole decay rate of the isomer, as recently reported, allows an indirect determination of the nuclear excitation energy.

  19. Construction of the energy matrix for complex atoms. Part VIII: Hyperfine structure HPC calculations for terbium atom

    Science.gov (United States)

    Elantkowska, Magdalena; Ruczkowski, Jarosław; Sikorski, Andrzej; Dembczyński, Jerzy

    2017-11-01

    A parametric analysis of the hyperfine structure (hfs) for the even parity configurations of atomic terbium (Tb I) is presented in this work. We introduce the complete set of 4fN-core states in our high-performance computing (HPC) calculations. For calculations of the huge hyperfine structure matrix, requiring approximately 5000 hours when run on a single CPU, we propose the methods utilizing a personal computer cluster or, alternatively a cluster of Microsoft Azure virtual machines (VM). These methods give a factor 12 performance boost, enabling the calculations to complete in an acceptable time.

  20. Structural, electronic, and hyperfine properties of pure and Ta-doped m-ZrO2

    DEFF Research Database (Denmark)

    Taylor, M.A.; Alonso, R.E.; Errico, L.A.

    2012-01-01

    A combination of experiments and ab initio quantum-mechanical calculations has been applied to examine electronic, structural, and hyperfine interactions in pure and Ta-doped zirconium dioxide in its monoclinic phase (m-ZrO2). From the theoretical point of view, the full-potential linear augmente...

  1. Structural, magnetic and hyperfine characterizations of nanocrystalline Zn-Cd doped nickel ferrites

    Science.gov (United States)

    Aakash; Nordblad, Per; Rajendra Mohan; Mukherjee, Samrat

    2017-11-01

    In our present work, we have synthesized a series of Cd-Zn doped nickel ferrite ((Cd0.5-xZnx)Ni0.5Fe2O4; x = 0, 0.1, 0.2, 0.3, 0.4 and 0.5) through standard chemical co-precipitation method to study the influence of diamagnetic ions (Cd, Zn) on the magnetic properties of ferrites. XRD and Raman spectroscopy were employed for the structural characterizations. The refinement of the X-ray diffractogram data augmented by the Williamson-Hall plots showed the presence of Cd2+ vacancies and a strained crystal structure. The vibrational spectroscopy indicated the presence of lower space-group symmetry and a distorted crystal structure. Magnetic measurements showed the samples possessed low magnetic anisotropy along with a canted spin structure. The Mössbauer measurements confirmed the cation distribution and gave evidence of super transferred hyperfine interactions arising due to canted spin structure of the system.

  2. Wavelengths, energy levels and hyperfine structure of Mn II and Sc II.

    Science.gov (United States)

    Nave, Gillian; Pickering, Juliet C.; Townley-Smith, Keeley I. M.; Hala, .

    2015-08-01

    For many decades, the Atomic Spectroscopy Groups at the National Institute of Standards and Technology (NIST) and Imperial College London (ICL) have measured atomic data of astronomical interest. Our spectrometers include Fourier transform (FT) spectrometers at NIST and ICL covering the region 1350 Å to 5.5 μm and a 10.7-m grating spectrometer at NIST covering wavelengths from 300 - 5000 Å. Sources for these spectra include high-current continuous and pulsed hollow cathode (HCL) lamps, Penning discharges, and sliding spark discharges. Recent work has focused on the measurement and analysis of wavelengths, energy levels, and hyperfine structure (HFS) constants for iron-group elements. The analysis of FT spectra of Cr I, Mn I, and Mn II is being led by ICL and is described in a companion poster [1]. Current work being led by NIST includes the analysis of HFS in Mn II, analysis of Mn II in the vacuum ultraviolet, and a comprehensive analysis of Sc II.Comprehensive HFS constants for Mn II are needed for the interpretation of stellar spectra and incorrect abundances may be obtained when HFS is omitted. Holt et al. [2] have measured HFS constants for 59 levels of Mn II using laser spectroscopy. We used FT spectra of Mn/Ni and Mn/Cu HCLs covering wavelength ranges from 1350 Å to 5.4 μm to confirm 26 of the A constants of Holt et al. and obtain values for roughly 40 additional levels. We aim to obtain HFS constants for the majority of lines showing significant HFS that are observed in chemically-peculiar stars.Spectra of Sc HCLs have been recorded from 1800 - 6700 Å using a vacuum ultraviolet FT spectrometer at NIST. Additional measurements to cover wavelengths above 6700 Å and below 1800 Å are in progress. The spectra are being analyzed by NIST and Alighar Muslim University, India in order to derive improved wavelengths, energy levels, and hyperfine structure parameters.This work was partially supported by NASA, the STFC and PPARC (UK), the Royal Society of the UK

  3. Unravelling the local structure of topological crystalline insulators using hyperfine interactions

    CERN Document Server

    Phenomena emerging from relativistic electrons in solids have become one the main topical subjects in condensed matter physics. Among a wealth of intriguing new phenomena, several classes of materials have emerged including graphene, topological insulators and Dirac semi-metals. This project is devoted to one such class of materials, in which a subtle distortion of the crystalline lattice drives a material through different topological phases: Z$_{2}$ topological insulator (Z$_{2}$-TI), topological crystalline insulator (TCI), or ferroelectric Rashba semiconductor (FERS). We propose to investigate the local structure of Pb$_{1-x}$Sn$_{x}$Te and Ge$_{1-x}$Sn$_{x}$Te (with $\\textit{x}$ from 0 to 1) using a combination of experimental techniques based on hyperfine interactions: emission Mössbauer spectroscopy (eMS) and perturbed angular correlation spectroscopy (PAC). In particular, we propose to study the effect of composition ($\\textit{x}$ in Pb$_{1-x}$Sn$_{x}$Te and Ge$_{1-x}$Sn$_{x}$Te) on: \\\\ \\\\(1) the mag...

  4. Spectroscopy Apparatus for the Measurement of The Hyperfine Structure of Antihydrogen

    CERN Document Server

    Malbrunot, C.; Diermaier, M.; Dilaver, N.; Friedreich, S.; Kolbinger, B.; Lehner, S.; Lundmark, R.; Massiczek, O.; Radics, B.; Sauerzopf, C.; Simon, M.; Widmann, E.; Wolf, M.; Wünschek, B.; Zmeskal, J.

    2014-02-04

    The ASACUSA CUSP collaboration at the Antiproton Decelerator (AD) of CERN is planning to measure the ground-state hyperfine splitting of antihydrogen using an atomic spectroscopy beamline. We describe here the latest developments on the spectroscopy apparatus developed to be coupled to the antihydrogen production setup (CUSP).

  5. Nuclear radiative recoil corrections to the hyperfine structure of S-states in muonic hydrogen

    Science.gov (United States)

    Faustov, R. N.; Martynenko, A. P.; Martynenko, F. A.; Sorokin, V. V.

    2017-09-01

    Nuclear radiative recoil corrections of order α( Zα)5 to the hyperfine splitting of S-states in muonic hydrogen are calculated on the basis of quasipotential method in quantum electrodynamics. The calculation is performed in the infrared safe Fried-Yennie gauge. Modern experimental data on the proton form factors are used.

  6. First-principles investigation of electronic structure and hyperfine properties of heme and nitrosyl-hemoglobin systems

    Science.gov (United States)

    Pujari, Minakhi

    This thesis is devoted to study of electronic structures and associated hyperfine properties of molecular systems. The main emphasis of our work is on the electronic structure and hyperfine properties of nitrosyl-hemoglobin and the sensitiveness of the structure to external conditions as this compound is closely related to deoxy-hemoglobin, the most important enzyme of the human body. The other two systems of compounds, sixth group hexafluorides and five-liganded halogen-heme compounds have been studied to test the accuracy of the Hartree-Fock procedure employed in explaining the properties of systems related in different degrees to nitrosyl-hemoglobin. In the hexafluoride systems, the theoretical values obtained in our work for the Nuclear Quadrupole Coupling Constant (NQCC) of 19F*, explain the experimental trend of continuous decrease from lightest to the heaviest systems. This is in keeping with the empirical Townes and Dailey relation and the expected increase in ionicity in going to the heavier systems. In bromo-hemin and iodo-hemin, the magnetic hyperfine properties of 57Fe, 14N, 13C, protons and halogen nuclei were studied. The associated charge and unpaired spin population obtained using their calculated electronic structures indicated more localized charge and spin distribution than were found by the semi-empirical method of Self-Consistent Charge Extended Hückel Procedure. Our results for the hyperfine constants showed satisfactory agreement with available experimental data. The contact and dipolar contribution to the hyperfine constant and their breakdown into direct and exchange polarization contributions were analyzed. The isomer shift at the 57Fe nucleus for both the systems, bromo-hemin and iodo-hemin were also studied and the observed trend was in agreement with that for other related compounds. The studies of the sixth group hexafluorides, and bromo- hemin and iodo-hemin systems, have encouraged us to use the Hartree-Fock Roothaan procedure for

  7. Experimental investigation of the hyperfine spectra of Pr I - lines: discovery of new fine structure levels with low angular momentum

    Science.gov (United States)

    Shamim, K.; Siddiqui, I.; Windholz, L.

    2011-10-01

    We present 39 odd and 15 even parity newly discovered fine structure levels of Pr I with low angular momentum: J = 1/2, 3/2 and 5/2. Spectral lines in the range 4200 Å to 7500 Å were experimentally investigated using laser induced fluorescence spectroscopy in a hollow cathode discharge lamp. The levels were discovered by analysis of the recorded hyperfine patterns of the investigated transitions. With the help of these levels, 119 spectral lines were classified directly by laser excitation and 127 lines were classified as fluorescence lines.

  8. Hyperfine-induced hysteretic funnel structure in spin blockaded tunneling current of coupled vertical quantum dots at low magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Leary, A.; Wicha, A.; Harack, B.; Coish, W. A.; Hilke, M. [Department of Physics, McGill University, Ernest Rutherford Building, 3600 rue University, Montreal, Quebec H3A 2T8 (Canada); Yu, G.; Gupta, J. A. [National Research Council of Canada, M50, Montreal Road, Ottawa, Ontario K1A 0R6 (Canada); Payette, C.; Austing, D. G. [Department of Physics, McGill University, Ernest Rutherford Building, 3600 rue University, Montreal, Quebec H3A 2T8, Canada and National Research Council of Canada, M50, Montreal Road, Ottawa, Ontario K1A 0R6 (Canada)

    2013-12-04

    We outline the properties of the hyperfine-induced funnel structure observed in the two-electron spin blockade region of a weakly coupled vertical double quantum dot device. Hysteretic steps in the leakage current occur due to dynamic nuclear polarization when either the bias voltage or the magnetic field is swept up and down. When the bias voltage is swept, an intriguing ∼3 mT wide cusp near 0 T appears in the down-sweep position, and when the magnetic field is swept, the current at 0 T can be switched from 'low' to 'high' as the bias is increased.

  9. Shell structure of potassium isotopes deduced from their magnetic moments

    CERN Document Server

    Papuga, J; Kreim, K; Barbieri, C; Blaum, K; De Rydt, M; Duguet, T; Garcia Ruiz, R F; Heylen, H; Kowalska, M; Neugart, R; Neyens, G; Nortershauser, W; Rajabali, M M; Sanchez, R; Smirnova, N; Soma, V; Yordanov, D T

    2014-01-01

    $\\textbf{Background:}$ Ground-state spins and magnetic moments are sensitive to the nuclear wave function, thus they are powerful probes to study the nuclear structure of isotopes far from stability. \\\\ \\\\ $\\textbf{Purpose:}$ Extend our knowledge about the evolution of the $1/2^+$ and $3/2^+$ states for K isotopes beyond the $N = 28$ shell gap. \\\\ \\\\ $\\textbf{Method:}$ High-resolution collinear laser spectroscopy on bunched atomic beams. \\\\ \\\\ $\\textbf{Results:}$ From measured hyperfine structure spectra of K isotopes, nuclear spins and magnetic moments of the ground states were obtained for isotopes from $N = 19$ up to $N = 32$. In order to draw conclusions about the composition of the wave functions and the occupation of the levels, the experimental data were compared to shell-model calculations using SDPF-NR and SDPF-U effective interactions. In addition, a detailed discussion about the evolution of the gap between proton $1d_{3/2}$ and $2s_{1/2}$ in the shell model and $\\textit{ab initio}$ framework is al...

  10. High-precision QED calculations of the hyperfine structure in hydrogen and transition rates in multicharged ions

    Energy Technology Data Exchange (ETDEWEB)

    Volotka, A.V.

    2006-07-01

    Studies of the hyperfine splitting in hydrogen are strongly motivated by the level of accuracy achieved in recent atomic physics experiments, which yield finally model-independent informations about nuclear structure parameters with utmost precision. Considering the current status of the determination of corrections to the hyperfine splitting of the ground state in hydrogen, this thesis provides further improved calculations by taking into account the most recent value for the proton charge radius. Comparing theoretical and experimental data of the hyperfine splitting in hydrogen the proton-size contribution is extracted and a relativistic formula for this contribution is derived in terms of moments of the nuclear charge and magnetization distributions. An iterative scheme for the determination of the Zemach and magnetic radii of the proton is proposed. As a result, the Zemach and magnetic radii are determined and the values are compared with the corresponding ones deduced from data obtained in electron-proton scattering experiments. The extraction of the Zemach radius from a rescaled difference between the hyperfine splitting in hydrogen and in muonium is considered as well. Investigations of forbidden radiative transitions in few-electron ions within ab initio QED provide a most sensitive tool for probing the influence of relativistic electron-correlation and QED corrections to the transition rates. Accordingly, a major part of this thesis is devoted to detailed studies of radiative and interelectronic-interaction effects to the transition probabilities. The renormalized expressions for the corresponding corrections in one- and twoelectron ions as well as for ions with one electron over closed shells are derived employing the two-time Green's function method. Numerical results for the correlation corrections to magnetic transition rates in He-like ions are presented. For the first time also the frequency-dependent contribution is calculated, which has to be

  11. Shape of gold and platinum exotic isotopes by laser spectroscopy; Formes des noyaux exotiques d`or et de platine par spectroscopie laser

    Energy Technology Data Exchange (ETDEWEB)

    Le Blanc, F.; Obert, J.; Oms, J.; Putaux, J.C.; Roussiere, B.; Sauvage, J. [Inst. de Physique Nucleaire, Paris-11 Univ., 91 - Orsay (France); Pinard, J.; Cabaret, L.; Duong, H.T. [LAM Orsay (France); Hubert, G.; Krieg, M.; Sebastian, V. [Inst. fuer Physik, Mainz Univ. (Germany); Crawford, J.; Lee, J.K.P. [Foster Radiation Lab., McGill Univ., Montreal, PQ (Canada); Genevey, J.; Ibrahim, F. [Inst. des Sciences Nucleaires, Grenoble-1 Univ., 38 (France); ISOLDE Collaboration

    1997-12-31

    Resonance Ionisation Spectroscopy (RIS) was performed on desorbed {sup 184}Au{sup g,m} as well as on platinum isotopes and isomers from A = 189 to A 178. The complete hyperfine structure of both isomer and ground state was obtained for {sup 184}Au. In the platinum isotopes, 14 hyperfine structures were measured. (authors) 3 refs.

  12. Transitions between hyperfine-structure states of the 2s metastable muonic hydrogen in collision processes

    Energy Technology Data Exchange (ETDEWEB)

    Czaplinski, W.

    1992-12-31

    Hyperfine effects in the symmetric collisions of the 2s metastable muonic hydrogen with hydrogen atoms: (p{mu}){sub 2s} + H, (d{mu}){sub 2s} + D, (t{mu}){sub 2s} + t are presented. Elastic and spin-flip cross sections for the scattering of The 2s muonic atoms are calculated in the two-level approximation as a function of collision energy. The corresponding formulae are derived with inclusion of electron screening and Lamb-shift between 2s and 2p energy levels of the muonic atom. The obtained spin-flip cross sections are about two orders of magnitude higher than their ground state counterparts and are much more influenced by electron screening. The rates of the spin-flip transitions are also calculated and are found to be about three orders of magnitude higher than the decay rate of the 2s state. (author). 65 refs, 15 figs, 4 tabs.

  13. Structural and hyperfine evolution of the (Fe{sub 79}Mn{sub 21}){sub 1-x}Cu{sub x} system under milling time

    Energy Technology Data Exchange (ETDEWEB)

    Mizrahi, M., E-mail: mizrahi@fisica.unlp.edu.a [Departamento de Fisica, Facultad de Ciencias Exactas UNLP, IFLP-CONICET. C.C. 67 1900 La Plata (Argentina); Cabrera, A.F.; Desimoni, J. [Departamento de Fisica, Facultad de Ciencias Exactas UNLP, IFLP-CONICET. C.C. 67 1900 La Plata (Argentina)

    2010-04-16

    The evolution with milling time (t{sub m}) of the structural and hyperfine properties of mechanically alloyed (Fe{sub 79}Mn{sub 21}){sub 0.85}Cu{sub 0.15} and (Fe{sub 79}Mn{sub 21}){sub 0.70}Cu{sub 0.30} nominal composition samples are reported. The samples milled during t{sub m} = 1, 3, 6, 9, 12, 15 and 18 h are characterized by X-ray diffraction (XRD) and Moessbauer spectroscopy. From the XRD results two phases are observed, a BCC one corresponding to {alpha}-Fe(Mn, Cu) and a FCC-phase associated to Fe-Mn-Cu solid solution. Moessbauer spectra show complex structure evidencing several Fe environments. Two hyperfine magnetic field distributions were used to reproduce the spectra, a high magnetic field interaction ascribed to the BCC phase and a low hyperfine magnetic field distribution linked to the FCC solid solution. An increment in the average hyperfine magnetic field (B{sub hf}) and in the isomer shift ({delta}) values of the low hyperfine magnetic field distribution is observed when the milling time increases. All the structural and hyperfine parameters remain without changes after 9 h of milling. Once this stationary regime is archived, the B{sub hf} of the (Fe{sub 79}Mn{sub 21}){sub 0.85}Cu{sub 0.15} sample resulted higher than that of the (Fe{sub 79}Mn{sub 21}){sub 0.70}Cu{sub 0.30} one.

  14. The hyperfine structure in the rotational spectra of D2(17)O and HD(17)O: Confirmation of the absolute nuclear magnetic shielding scale for oxygen.

    Science.gov (United States)

    Puzzarini, Cristina; Cazzoli, Gabriele; Harding, Michael E; Vázquez, Juana; Gauss, Jürgen

    2015-03-28

    Guided by theoretical predictions, the hyperfine structures of the rotational spectra of mono- and bideuterated-water containing (17)O have been experimentally investigated. To reach sub-Doppler resolution, required to resolve the hyperfine structure due to deuterium quadrupole coupling as well as to spin-rotation (SR) and dipolar spin-spin couplings, the Lamb-dip technique has been employed. The experimental investigation and in particular, the spectral analysis have been supported by high-level quantum-chemical computations employing coupled-cluster techniques and, for the first time, a complete experimental determination of the hyperfine parameters involved was possible. The experimentally determined (17)O spin-rotation constants of D2 (17)O and HD(17)O were used to derive the paramagnetic part of the corresponding nuclear magnetic shielding constants. Together with the computed diamagnetic contributions as well as the vibrational and temperature corrections, the latter constants have been employed to confirm the oxygen nuclear magnetic shielding scale, recently established on the basis of spin-rotation data for H2 (17)O [Puzzarini et al., J. Chem. Phys. 131, 234304 (2009)].

  15. Calculation of vibrational branching ratios and hyperfine structure of 24Mg19F and its suitability for laser cooling and magneto-optical trapping

    Science.gov (United States)

    Xu, Liang; Yin, Yanning; Wei, Bin; Xia, Yong; Yin, Jianping

    2016-01-01

    More recently, laser cooling of the diatomic radical magnesium monofluoride (24Mg19F ) is being experimentally preformed [Appl. Phys. Express 8, 092701 (2015), 10.7567/APEX.8.092701 and Opt. Express 22, 28645 (2014), 10.1364/OE.22.028645] and was also studied theoretically [Phys. Rev. A 91, 042511 (2015), 10.1103/PhysRevA.91.042511]. However, some important problems still remain unsolved, so, in our paper, we perform further theoretical study for the feasibility of laser cooling and trapping the 24Mg19F molecule. At first, the highly diagonal Franck-Condon factors of the main transitions are verified by the closed-form approximation, Morse approximation, and Rydberg-Klein-Rees inversion methods, respectively. Afterwards, we investigate the lower X 2Σ1/2 + hyperfine manifolds using a quantum effective Hamiltonian approach and obtain the zero-field hyperfine spectrum with an accuracy of less than 30 kHz ˜5 μ K compared with the experimental results, and then find out that one cooling beam and one or two repumping beams with their first-order sidebands are enough to implement an efficient laser slowing and cooling of 24Mg19F . Meanwhile, we also calculate the accurate hyperfine structure magnetic g factors of the rotational state (X 2Σ1/2 +,N =1 ) and briefly discuss the influence of the external fields on the hyperfine structure of 24Mg19F as well as its possibility of preparing three-dimensional magneto-optical trapping. Finally we give an explanation for the difference between the Stark and Zeeman effects from the perspective of parity and time reversal symmetry. Our study shows that, besides appropriate excitation wavelengths, the short lifetime for the first excited state A 2Π1 /2 , and lighter mass, the 24Mg19F radical could be a good candidate molecule amenable to laser cooling and magneto-optical trapping.

  16. POLARIZED SCATTERING OF LIGHT FOR ARBITRARY MAGNETIC FIELDS WITH LEVEL-CROSSINGS FROM THE COMBINATION OF HYPERFINE AND FINE STRUCTURE SPLITTINGS

    Energy Technology Data Exchange (ETDEWEB)

    Sowmya, K.; Nagendra, K. N.; Sampoorna, M. [Indian Institute of Astrophysics, Koramangala, Bengaluru (India); Stenflo, J. O., E-mail: ksowmya@iiap.res.in, E-mail: knn@iiap.res.in, E-mail: sampoorna@iiap.res.in, E-mail: stenflo@astro.phys.ethz.ch [Institute of Astronomy, ETH Zurich, CH-8093 Zurich (Switzerland)

    2015-12-01

    Interference between magnetic substates of the hyperfine structure states belonging to different fine structure states of the same term influences the polarization for some of the diagnostically important lines of the Sun's spectrum, like the sodium and lithium doublets. The polarization signatures of this combined interference contain information on the properties of the solar magnetic fields. Motivated by this, in the present paper, we study the problem of polarized scattering on a two-term atom with hyperfine structure by accounting for the partial redistribution in the photon frequencies arising due to the Doppler motions of the atoms. We consider the scattering atoms to be under the influence of a magnetic field of arbitrary strength and develop a formalism based on the Kramers–Heisenberg approach to calculate the scattering cross section for this process. We explore the rich polarization effects that arise from various level-crossings in the Paschen–Back regime in a single scattering case using the lithium atomic system as a concrete example that is relevant to the Sun.

  17. Hyperfine anomalies in Fr: boundaries of the spherical single particle model

    CERN Document Server

    Zhang, J; Aubin, S; Behr, J A; Gomez, E; Gwinner, G; Orozco, L A; Pearson, M R; Sprouse, G D

    2015-01-01

    We have measured the hyperfine splitting of the $7P_{1/2}$ state at the 100 ppm level in Fr isotopes ($^{206g,206m, 207, 209, 213, 221}$Fr) near the closed neutron shell ($N$ = 126 in $^{213}$Fr). The measurements in five isotopes and a nuclear isomeric state of francium, combined with previous determinations of the $7S_{1/2}$ splittings, reveal the spatial distribution of the nuclear magnetization, i.e. the Bohr-Weisskopf effect. We compare our results with a simple shell model consisting of unpaired single valence nucleons orbiting a spherical nucleus, and find good agreement over a range of neutron-deficient isotopes ($^{207-213}$Fr). Also, we find near-constant proton anomalies for several even-$ N$ isotopes. This identifies a set of Fr isotopes whose nuclear structure can be understood well enough for the extraction of weak interaction parameters from parity non-conservation studies.

  18. Hyperfine Anomalies in Fr: Boundaries of the Spherical Single Particle Model

    Science.gov (United States)

    Zhang, J.; Tandecki, M.; Collister, R.; Aubin, S.; Behr, J. A.; Gomez, E.; Gwinner, G.; Orozco, L. A.; Pearson, M. R.; Sprouse, G. D.; FrPNC Collaboration

    2015-07-01

    We have measured the hyperfine splitting of the 7 P1 /2 state at the 100 ppm level in Fr isotopes (206g,206m,207,209,213,221Fr) near the closed neutron shell (N =126 in 213Fr). The measurements in five isotopes and a nuclear isomeric state of francium, combined with previous determinations of the 7 S1 /2 splittings, reveal the spatial distribution of the nuclear magnetization, i.e., the Bohr-Weisskopf effect. We compare our results with a simple shell model consisting of unpaired single valence nucleons orbiting a spherical nucleus, and find good agreement over a range of neutron-deficient isotopes (207-213Fr). Also, we find near-constant proton anomalies for several even-N isotopes. This identifies a set of Fr isotopes whose nuclear structure can be understood well enough for the extraction of weak interaction parameters from parity nonconservation studies.

  19. Investigations of the ground-state hyperfine atomic structure and beta decay measurement prospects of 21Na with improved laser trapping techniques

    Energy Technology Data Exchange (ETDEWEB)

    Rowe, Mary Anderson [Univ. of California, Berkeley, CA (United States)

    1999-05-01

    This thesis describes an experiment in which a neutral atom laser trap loaded with radioactive 21Na was improved and then used for measurements. The sodium isotope (half-life=22 sec) is produced on line at the 88 in. cyclotron at Lawrence Berkeley National Laboratory. The author developed an effective magnesium oxide target system which is crucial to deliver a substantive beam of 21Na to the experiment. Efficient manipulation of the 21Na beam with lasers allowed 30,000 atoms to be contained in a magneto-optical trap. Using the cold trapped atoms, the author measured to high precision the hyperfine splitting of the atomic ground state of 21Na. She measured the 3S1/2(F=1,m=0)-3S1/2(F=2,m=0) atomic level splitting of 21Na to be 1,906,471,870±200 Hz. Additionally, she achieved initial detection of beta decay from the trap and evaluated the prospects of precision beta decay correlation studies with trapped atoms.

  20. Experimental investigation of the hyperfine spectra of Pr I-lines: Discovery of new fine structure levels with high angular momentum

    Science.gov (United States)

    Siddiqui, Imran; Khan, Shamim; Windholz, Laurentius

    2014-05-01

    We present 66 even and 58 odd parity newly discovered fine structure levels of Pr I with high angular momentum: J = 15/2, 17/2 and 19/2 and 21/2. Spectral lines in the range 4200 Å to 7500 Å were experimentally investigated using laser induced fluorescence spectroscopy in a hollow cathode discharge lamp. The levels were discovered by analysis of the recorded hyperfine patterns of the investigated transitions. More than 800 spectral lines could be classified with help of these levels. Supplementary material in the form of one pdf file available from the Journal web page at http://dx.doi.org/10.1140/epjd/e2014-50025-7

  1. THE HYPERFINE STRUCTURE OF THE ROTATIONAL SPECTRUM OF HDO AND ITS EXTENSION TO THE THz REGION: ACCURATE REST FREQUENCIES AND SPECTROSCOPIC PARAMETERS FOR ASTROPHYSICAL OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Cazzoli, Gabriele; Lattanzi, Valerio; Puzzarini, Cristina [Dipartimento di Chimica “Giacomo Ciamician”, Università di Bologna, Via Selmi 2, I-40126 Bologna (Italy); Alonso, José Luis [Grupo de Espectroscopía Molecular (GEM), Unidad Asociada CSIC, Edificio Quifima, Laboratorios de Espectroscopia y Bioespectroscopia, Parque Científico UVa, Universidad de Valladolid, E-47005 Valladolid (Spain); Gauss, Jürgen, E-mail: cristina.puzzarini@unibo.it [Institut für Physikalische Chemie, Universität Mainz, D-55099 Mainz (Germany)

    2015-06-10

    The rotational spectrum of the mono-deuterated isotopologue of water, HD{sup 16}O, has been investigated in the millimeter- and submillimeter-wave frequency regions, up to 1.6 THz. The Lamb-dip technique has been exploited to obtain sub-Doppler resolution and to resolve the hyperfine (hf) structure due to the deuterium and hydrogen nuclei, thus enabling the accurate determination of the corresponding hf parameters. Their experimental determination has been supported by high-level quantum-chemical calculations. The Lamb-dip measurements have been supplemented by Doppler-limited measurements (weak high-J and high-frequency transitions) in order to extend the predictive capability of the available spectroscopic constants. The possibility of resolving hf splittings in astronomical spectra has been discussed.

  2. Decoupling of hyperfine structure of Cs $D_1$ line in strong magnetic field studied by selective reflection from a nanocell

    CERN Document Server

    Sargsyan, Armen; Hakhumyan, Grant; Tonoyan, Ara; Papoyan, Aram; Leroy, Claude; Sarkisyan, David

    2016-01-01

    Decoupling of total electronic and nuclear spin moments of Cs atoms in external magnetic field for the case of atomic $D_1$ line, leading to onset of the hyperfine Paschen-Back regime has been studied theoretically and experimentally. Selective reflection of laser radiation from an interface of dielectric window and atomic vapor confined in a nanocell with 300 nm gap thickness was implemented for the experimental studies. The real time derivative of selective reflection signal with a frequency position coinciding with atomic transitions was used in measurements, providing $\\sim$ 40 MHz spectral resolution and linearity of signal response in respect to transition probability. Behavior of 28 individual Zeeman transitions in a wide range of longitudinal magnetic field (0 - 6 kG) has been tracked under excitation of Cs vapor by a low-intensity $\\sigma^+$- polarized cw laser radiation. For $B\\ge 6~$kG, only 8 transitions with nearly equal probabilities and the same frequency slope remained in the spectrum, which i...

  3. Laser spectroscopy measurements of neutron-rich tellurium isotopes by COMPLIS

    Energy Technology Data Exchange (ETDEWEB)

    Sifi, R., E-mail: sifi@ipno.in2p3.fr; Blanc, F. Le; Barre, N. [Institut de Physique Nucleaire, IN2P3-CNRS (France); Cabaret, L. [Laboratoire Aime Cotton (France); Crawford, J. [Mc Gill University, Physics Department (Canada); Ducourtieux, M.; Essabaa, S. [Institut de Physique Nucleaire, IN2P3-CNRS (France); Genevey, J. [Institut des Sciences Nucleaires, IN2P3-CNRS (France); Huber, G.; Kowalska, M. [Institut fuer Physik der Universitaet Mainz (Germany); Lau, C. [Institut de Physique Nucleaire, IN2P3-CNRS (France); Lee, J. K. P. [Mc Gill University, Physics Department (Canada); Scornet, G. Le [CERN, 1211 (Switzerland); Oms, J. [Institut de Physique Nucleaire, IN2P3-CNRS (France); Pinard, J. [Laboratoire Aime Cotton (France); Roussiere, B.; Sauvage, J. [Institut de Physique Nucleaire, IN2P3-CNRS (France); Seliverstov, M. [Institut fuer Physik der Universitaet Mainz (Germany); Stroke, H. [New York University, Department of physics (United States)

    2006-07-15

    Laser spectroscopy based on resonant ionization of laser-desorbed atoms has been used to study the neutron-rich tellurium isotopes with the COMPLIS facility at ISOLDE-CERN. Isotope shifts and hyperfine structures of several neutron-rich Te isotopes: {sup 120-136}Te and {sup 123m-133m}Te have been measured. From the hyperfine structure we have extracted magnetic and quadrupole moments. Changes in the mean square charge radii have been deduced and their comparison with the known data for the other elements near Z = 50 is presented. The experimental {delta} < r{sup 2}> values are compared with those obtained from relativistic mean field calculations.

  4. The hyperfine structure of the lowest doublet states of the LiO2 isomers: a density-functional-theory assessment

    Science.gov (United States)

    Oliveira, João P. C.; Rivelino, Roberto

    2010-05-01

    Density-functional-theory (DFT) calculations of the hyperfine coupling constants (HFCCs) are systematically reported for the lithium superoxide (LiO2) structural isomers in the doublet ground states, \\tilde X 2A2 and 2Π. Also, structure, harmonic frequencies, rotational constants and dipole moments have been computed at different levels of theory. Our results calculated for the 2A2 state are compared with the available data of matrix-isolated LiO2. Geometric parameters and vibrational modes compare well with available experimental data. However, the present density-functional results show a strong dependence of the isotropic HFCCs on the level of approximation as well as the molecular geometry. Our results confirm that the anisotropic contributions are less sensitive to the exchange-correlation potentials and basis sets. We have obtained the best estimate of the isotropic HFCC (in comparison with the experimental trends) by using the hybrid scheme that combines the Perdew-Wang's 1991 correlation functional with the adiabatic connection. This study allows us to gauge DFT methods for future applications in the alkali superoxide series, as well as open-shell metal centres interacting with dioxygen in biological systems.

  5. The hyperfine structure of the lowest doublet states of the LiO{sub 2} isomers: a density-functional-theory assessment

    Energy Technology Data Exchange (ETDEWEB)

    Oliveira, Joao P C; Rivelino, Roberto, E-mail: rivelino@ufba.b [Instituto de FIsica, Universidade Federal da Bahia, 40210-340 Salvador, Bahia (Brazil)

    2010-05-14

    Density-functional-theory (DFT) calculations of the hyperfine coupling constants (HFCCs) are systematically reported for the lithium superoxide (LiO{sub 2}) structural isomers in the doublet ground states, (tilde X){sup 2}A{sub 2} and {sup 2{Pi}}. Also, structure, harmonic frequencies, rotational constants and dipole moments have been computed at different levels of theory. Our results calculated for the {sup 2}A{sub 2} state are compared with the available data of matrix-isolated LiO{sub 2}. Geometric parameters and vibrational modes compare well with available experimental data. However, the present density-functional results show a strong dependence of the isotropic HFCCs on the level of approximation as well as the molecular geometry. Our results confirm that the anisotropic contributions are less sensitive to the exchange-correlation potentials and basis sets. We have obtained the best estimate of the isotropic HFCC (in comparison with the experimental trends) by using the hybrid scheme that combines the Perdew-Wang's 1991 correlation functional with the adiabatic connection. This study allows us to gauge DFT methods for future applications in the alkali superoxide series, as well as open-shell metal centres interacting with dioxygen in biological systems.

  6. Isotopes through the looking glass

    Science.gov (United States)

    Mårtensson Pendrill, Ann Marie

    2000-08-01

    Nuclear distributions affect many aspects of atomic spectra. As an example, recent experimental results for the hyperfine anomaly in Fr isotopes are considered. These depend on nuclear charge and magnetization distributions. The variations in charge radii for these isotopes were studied earlier by measuring optical isotope shifts. The hyperfine anomalies for the odd-odd isotopes involve the neutron distributions, of interest for studies of parity nonconserving effects along a chain of isotopes.

  7. IMPROVED V II log(gf) VALUES, HYPERFINE STRUCTURE CONSTANTS, AND ABUNDANCE DETERMINATIONS IN THE PHOTOSPHERES OF THE SUN AND METAL-POOR STAR HD 84937

    Energy Technology Data Exchange (ETDEWEB)

    Wood, M. P.; Lawler, J. E.; Den Hartog, E. A. [Department of Physics, University of Wisconsin, Madison, WI 53706 (United States); Sneden, C. [Department of Astronomy and McDonald Observatory, University of Texas, Austin, TX 78712 (United States); Cowan, J. J., E-mail: mpwood@wisc.edu, E-mail: jelawler@wisc.edu, E-mail: eadenhar@wisc.edu, E-mail: chris@verdi.as.utexas.edu, E-mail: cowan@nhn.ou.edu [Homer L. Dodge Department of Physics and Astronomy, University of Oklahoma, Norman, OK 73019 (United States)

    2014-10-01

    New experimental absolute atomic transition probabilities are reported for 203 lines of V II. Branching fractions are measured from spectra recorded using a Fourier transform spectrometer and an echelle spectrometer. The branching fractions are normalized with radiative lifetime measurements to determine the new transition probabilities. Generally good agreement is found between this work and previously reported V II transition probabilities. Two spectrometers, independent radiometric calibration methods, and independent data analysis routines enable a reduction in systematic uncertainties, in particular those due to optical depth errors. In addition, new hyperfine structure constants are measured for selected levels by least squares fitting line profiles in the FTS spectra. The new V II data are applied to high resolution visible and UV spectra of the Sun and metal-poor star HD 84937 to determine new, more accurate V abundances. Lines covering a range of wavelength and excitation potential are used to search for non-LTE effects. Very good agreement is found between our new solar photospheric V abundance, log ε(V) = 3.95 from 15 V II lines, and the solar-system meteoritic value. In HD 84937, we derive [V/H] = –2.08 from 68 lines, leading to a value of [V/Fe] = 0.24.

  8. Hyperfine structure and magnetic properties of Zn doped Co{sub 2}Z hexaferrite investigated by high-field Mössbauer spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Jung Tae; Kim, Chul Sung, E-mail: cskim@kookmin.ac.kr [Department of Physics, Kookmin University, Seoul 136-702 (Korea, Republic of)

    2015-05-07

    The polycrystalline samples of Ba{sub 3}Co{sub 2−x}Zn{sub x}Fe{sub 24}O{sub 41} (x = 0.0, 0.5, 1.0, 1.5, and 2.0) were synthesized by the standard solid-state-reaction method. Based on the XRD patterns analyzed by Rietveld refinement, the structure was determined to be single-phased hexagonal with space group of P6{sub 3}/mmc. With increasing Zn ion concentration, the unit cell volume (V{sub u}) of samples was increased, as the sites of Fe{sup 3+} ions changed from tetrahedral to octahedral sites. We have obtained zero-field Mössbauer spectra of all samples at various temperatures ranging from 4.2 to 750 K. The measured spectra below T{sub C} were analyzed with six distinguishable sextets due to the superposition of ten-sextets for Fe sites, corresponding to the Z-type hexagonal ferrite. Also, the hyperfine field (H{sub hf}) and electric quadrupole shift (E{sub Q}) have shown abrupt changes around spin transition temperature (T{sub S}). In addition, Mössbauer spectra of all samples at 4.2 K were taken with an applied field ranging from 0 to 50 kOe, which indicates the decrease in the canting angle between applied field and H{sub hf} of samples with increasing Zn concentration.

  9. The hyperfine structure in the rotational spectra of D{sub 2}{sup 17}O and HD{sup 17}O: Confirmation of the absolute nuclear magnetic shielding scale for oxygen

    Energy Technology Data Exchange (ETDEWEB)

    Puzzarini, Cristina, E-mail: cristina.puzzarini@unibo.it; Cazzoli, Gabriele [Dipartimento di Chimica “Giacomo Ciamician,” Università degli Studi di Bologna, Via Selmi 2, I-40126 Bologna (Italy); Harding, Michael E. [Institut für Nanotechnologie, Karlsruher Institut für Technologie (KIT), Campus Nord, Postfach 3640, D-76021 Karlsruhe (Germany); Center for Theoretical Chemistry, Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712 (United States); Vázquez, Juana [Center for Theoretical Chemistry, Department of Chemistry and Biochemistry, University of Texas at Austin, Austin, Texas 78712 (United States); Gauss, Jürgen, E-mail: gauss@uni-mainz.de [Institut für Physikalische Chemie, Universität Mainz, D-55099 Mainz (Germany)

    2015-03-28

    Guided by theoretical predictions, the hyperfine structures of the rotational spectra of mono- and bideuterated-water containing {sup 17}O have been experimentally investigated. To reach sub-Doppler resolution, required to resolve the hyperfine structure due to deuterium quadrupole coupling as well as to spin-rotation (SR) and dipolar spin-spin couplings, the Lamb-dip technique has been employed. The experimental investigation and in particular, the spectral analysis have been supported by high-level quantum-chemical computations employing coupled-cluster techniques and, for the first time, a complete experimental determination of the hyperfine parameters involved was possible. The experimentally determined {sup 17}O spin-rotation constants of D{sub 2}{sup 17}O and HD{sup 17}O were used to derive the paramagnetic part of the corresponding nuclear magnetic shielding constants. Together with the computed diamagnetic contributions as well as the vibrational and temperature corrections, the latter constants have been employed to confirm the oxygen nuclear magnetic shielding scale, recently established on the basis of spin-rotation data for H{sub 2}{sup 17}O [Puzzarini et al., J. Chem. Phys. 131, 234304 (2009)].

  10. Nuclear structure of neutron-deficient Au and Pt isotopes from high-resolution laser spectroscopy at ISOLDE

    Energy Technology Data Exchange (ETDEWEB)

    Sauvage, J. [Institut de Physique Nucleaire, Orsay (France); Cabaret, L. [Lab. Aime Cotton, Orsay (France); Crawford, J. [Foster Radiation Laboratory, McGill University, Montreal (Canada)] [and others; ISOLDE Collaboration

    1999-05-01

    Atomic spectroscopy measurements were carried out using the COMPLIS setup installed at the ISOLDE-BOOSTER facility. Hyperfine structure (HFS) spectra and isotope shift (IS) values were obtained for the neutron-deficient {sup 178-185}Pt and for {sup 184}Au{sup gm}, providing deformation parameters {beta}, magnetic moments {mu} and spectroscopic quadrupole moments (for I {>=} 1) Q{sub s}. In Pt isotopes, a deformation drop for A = 178 and an inverted odd-even staggering for the charge radius around the neutron mid-shell N=104, have been observed very clearly. Furthermore, deformation changes {delta}{beta} between isomeric and ground states for {sup 183,185}Pt and {sup 184}Au have been put forward. Thus, the influence of the proton-neutron coupling on the {delta}{beta} value in {sup 184}Au relatively to that in its isotope {sup 183}Pt has been determined. Besides, the h{sub 9/2} proton state that is decoupled from the core in {sup 183,185}Au, becomes the 3/2 [532] state strongly coupled in {sup 184}Au. The spin and parity values I{sup {pi}} = 3{sup +} have been assigned to the {sup 182}Ir ground state from internal conversion electron measurements to prepare atomic spectroscopy studies in the Ir isotopic series. (author) 37 refs, 8 figs, 4 tabs

  11. Evolution of structure, microstructure and hyperfine properties of nanocrystalline Fe{sub 50}Co{sub 50} powders prepared by mechanical alloying

    Energy Technology Data Exchange (ETDEWEB)

    Akkouche, K. [LMMC, M' hamed Bougara University, Boumerdes 35000 (Algeria); Guittoum, A., E-mail: guittoum@yahoo.fr [Nuclear Research Centre of Algiers, 2 Bd Frantz Fanon, BP399 Alger-Gare, Algiers (Algeria); Boukherroub, N. [LMMC, M' hamed Bougara University, Boumerdes 35000 (Algeria); Souami, N. [Nuclear Research Centre of Algiers, 2 Bd Frantz Fanon, BP399 Alger-Gare, Algiers (Algeria)

    2011-11-15

    Nanostructured Fe{sub 50}Co{sub 50} powders were prepared by mechanical alloying of Fe and Co elements in a vario-planetary high-energy ball mill. The structural properties, morphology changes and local iron environment variations were investigated as a function of milling time (in the 0-200 h range) by means of X-ray diffraction, scanning electron microscopy (SEM), energy dispersive X-ray analysis and {sup 57}Fe Moessbauer spectroscopy. The complete formation of bcc Fe{sub 50}Co{sub 50} solid solution is observed after 100 h milling. As the milling time increases from 0 to 200 h, the lattice parameter decreases from 0.28655 nm for pure Fe to 0.28523 nm, the grain size decreases from 150 to 14 nm, while the meal level of strain increases from 0.0069% to 1.36%. The powder particle morphology at different stages of formation was observed by SEM. The parameters derived from the Moessbauer spectra confirm the beginning of the formation of Fe{sub 50}Co{sub 50} phase at 43 h of milling. After 200 h of milling the average hyperfine magnetic field of 35 T suggests that a disordered bcc Fe-Co solid solution is formed. - Highlights: > Nanostructured Fe{sub 50}Co{sub 50} powders were successfully prepared by mechanical alloying process. > Final average grain size value achieved after 200 h of milling was 14 nm. > For the longest milling time the majority of particle grains observed by SEM exhibits a round shape with small diameter.

  12. Hyperfine structure analysis in magnetic resonance spectroscopy: from astrophysical measurements towards endogenous biosensors in human tissue; Hyperfeinstruktur-Analyse in der Magnetresonanzspektroskopie: von astrophysikalischen Messungen zu endogenen Biosensoren in menschlichem Gewebe

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, L. [Deutsches Krebsforschungszentrum, Heidelberg (Germany). Medizinische Physik in der Radiologie; California Univ., Berkeley, CA (United States). Dept. of Chemistry; Lawrence Berkeley National Lab., Berkeley, CA (United States). Dept. of Chemistry

    2007-07-01

    The hyperfine interaction of two spins is a well studied effect in atomic systems. Magnetic resonance experiments demonstrate that the detectable dipole transitions are determined by the magnetic moments of the constituents and the external magnetic field. Transferring the corresponding quantum mechanics to molecular bound nuclear spins allows for precise prediction of NMR spectra obtained from metabolites in human tissue. This molecular hyperfine structure has been neglected so far in in vivo NMR spectroscopy but contains useful information, especially when studying molecular dynamics. This contribution represents a review of the concept of applying the Breit-Rabi formalism to coupled nuclear spins and discusses the immobilization of different metabolites in anisotropic tissue revealed by 1H NMR spectra of carnosine, phosphocreatine and taurine. Comparison of atomic and molecular spin systems allows for statements on the biological constraints for direct spin-spin interactions. Moreover, the relevance of hyperfine effects on the line shapes of multiplets of indirectly-coupled spin systems with more than two constituents can be predicted by analyzing quantum mechanical parameters. As an example, the superposition of eigenstates of the AMX system of adenosine 5'-triphosphate and its application for better quantification of 31P-NMR spectra will be discussed. (orig.)

  13. High-spin structure of neutron-rich Dy isotopes

    Indian Academy of Sciences (India)

    Abstract. In view of recent experimental progress on production and spectroscopy of neutron-rich isotopes of Dy with mass number A. 166 and 168, we have made theoretical investigations on the structure of high spin states of164 170Dy isotopes in the cranked Hartree–Fock–Bogoliubov (CHFB) theory employing a ...

  14. Large Deformation Change in Iridium Isotopes from Laser Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    D. Verney; L. Cabaret; J. Crawford; H.T. Duong; J. Genevey; G. Hubert; F. Ibrahim; M. Krieg; F. Le Blanc; J.K.P. Lee; G. Le Scornet; D. Lunney; J. Obert; J. Oms; J. Pinard; J.C. Putaux; B. Roussiere; J. Sauvage; V. Sebastian

    1999-12-31

    Laser spectroscopy measurements have been performed on neutron-deficient iridium isotopes. The hyperfine structure and isotope shift of the optical Ir I transition 5d{sup 7}6s{sup 2} {sup 4}F{sub 9/2} {yields}5d{sup 7}6s6p {sup 6}F{sub 11/2} have been studied for the {sup 182-189}Ir, {sup 186}Ir{sup m} and {sup 191,193}Ir isotopes. The nuclear magnetic and quadrupole moments were obtained from the hyperfine splitting measurements and the changes of the mean square charge radii from the isotope shift measurements. A large deformation change between {sup 187}Ir and {sup 186}Ir and between {sup 186}Ir{sup m} and {sup 186}Ir{sup g} has been observed.

  15. Effect of particle size distribution on the structure, hyperfine, and magnetic properties of Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanopowders

    Energy Technology Data Exchange (ETDEWEB)

    Bhattacharjee, Kaustav; Das, G. C. [Department of Metallurgical and Material Engineering, Jadavpur University, Kolkata 700032 (India); Pati, Satya P.; Das, D. [UGC-DAE Consortium for Scientific Research, Kolkata Centre, III/LB-8, Bidhannagar, Kolkata 700 098 (India); Chattopadhyay, K. K., E-mail: kalyan-chattopadhyay@yahoo.com [Thin Film and Nanoscience Laboratory, Department of Physics, Jadavpur University, Kolkata 700032 (India)

    2014-12-21

    Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nano powders were synthesized by an auto combustion method and then heat treated at different temperatures in air for a fixed time. As a consequence, a distribution in particle size and strain was incorporated within the specimens, as estimated from the Rietveld refinement analysis of the powder x-ray diffraction data. The changes in the microstructure and crystal structure parameters were carefully extracted through the refinement analysis. Thermal annealing causes increment in the dispersion and mean of the size distribution. Reallocation of cations in the lattice sites occur as a consequence of the heat treatment which was manifested in their altered unit cell length (a), r.m.s. strain (〈ε{sup 2}〉{sup 1/2}), oxygen positional parameter (u), metal-oxygen bond lengths (R{sub OA} and R{sub OB}), and the band positions (ν{sub 1}and ν{sub 2}) in the vibrational spectroscopy. We also investigate the hyperfine and magnetic properties of the samples using different instrumental techniques (with different operating time scales) like Mössbauer spectroscopy, electron paramagnetic resonance spectroscopy, and superconducting quantum interference device magnetometry. Results show that the effect of particle size distribution was manifested in their hyperfine field distribution profile, paramagnetic resonance spectra, and magnetic anisotropy energy distribution profile. Co-existence of superparamagnetic and ferrimagnetic phase was recorded at room temperature in the samples when annealed at lower temperature. However, with increase in annealing temperature, the nature of the size distribution changes and ferrimagnetic ordering predominates for the larger size nanoparticles. Thus, the effect of particle size distribution on the structural, hyperfine, and magnetic properties of various Ni{sub 0.5}Zn{sub 0.5}Fe{sub 2}O{sub 4} nanoparticles was investigated herein which hitherto has not been discussed in the literature.

  16. Reduced thermal conductivity of isotopically modulated silicon multilayer structures

    DEFF Research Database (Denmark)

    Bracht, H.; Wehmeier, N.; Eon, S.

    2012-01-01

    -resolved x-ray scattering. Comparison of the experimental results to numerical solutions of the corresponding heat diffusion equations reveals a factor of three lower thermal conductivity of the isotope structure compared to natural Si. Our results demonstrate that the thermal conductivity of silicon can......We report measurements of the thermal conductivity of isotopically modulated silicon that consists of alternating layers of highly enriched silicon-28 and silicon-29. A reduced thermal conductivity of the isotopically modulated silicon compared to natural silicon was measured by means of time...

  17. Laser Spectroscopy of Neutron Rich Bismuth Isotopes

    CERN Multimedia

    2002-01-01

    %IS344 :\\\\ \\\\ The aim of the experiment is to measure the optical isotope shifts and hyperfine structures of bismuth isotopes across the N=126 shell closure in order to extract the change in mean square charge radii ($\\delta\\langle r^{2}\\rangle$) and static moments. These include the first isotones of lead to be measured directly above the shell closure and will provide new information on the systematics of the kink ($\\delta\\langle r^{2}\\rangle)$ seen in the lead isotopic chain. After two very successful runs the programme has been extended to include the neutron deficient isotopes below $^{201}$Bi to study the systematics across the $i_{13/2}$ neutron sub-shell closure at N=118.\\\\ \\\\ During the initial 2 runs (9 shifts) the isotope shifts and hyperfine structures of three new isotopes, $ ^{210,212,213}$Bi and the 9$^{-}$ isomer of $^{210}$Bi have been measured. The accuracy of the previous measurements of $^{205,206,208}$Bi have been greatly improved. The samples of $ ^{208,210,210^{m}}$Bi were prepared by c...

  18. Hyperfine magnetic fields in substituted Finemet alloys

    Energy Technology Data Exchange (ETDEWEB)

    Brzózka, K., E-mail: k.brzozka@uthrad.pl [University of Technology and Humanities in Radom, Department of Physics (Poland); Sovák, P. [P.J. Šafárik University, Institute of Physics (Slovakia); Szumiata, T.; Gawroński, M.; Górka, B. [University of Technology and Humanities in Radom, Department of Physics (Poland)

    2016-12-15

    Transmission Mössbauer spectroscopy was used to determine the hyperfine fields of Finemet-type alloys in form of ribbons, substituted alternatively by Mn, Ni, Co, Al, Zn, V or Ge of various concentration. The comparative analysis of magnetic hyperfine fields was carried out which enabled to understand the role of added elements in as-quenched as well as annealed samples. Moreover, the influence of the substitution on the mean direction of the local hyperfine magnetic field was examined.

  19. Structure of potassium isotopes studied with collinear laser spectroscopy

    CERN Document Server

    AUTHOR|(CDS)2082445

    By exploring the structure of different nuclei, one can learn about the interaction between the nucleons, their building blocks. In this field of research, there is a strong interplay between experiment and theory. In particular, theory has a crucial role in the interpretation of the experimental results, while new experimental results provide testing ground and directions for theorists. In the light- and mid-mass regions of the nuclear chart, the shell model is very successful and widely used for calculations of the ground- as well as excited- states properties. It is based on associated larger energy gaps between single particle energy levels for isotopes with certain proton (Z) and neutron (N) numbers, which are called "magic numbers". It was believed that these numbers (8, 20, 28, ...) are preserved for all nuclei throughout the nuclear chart. However, during the last decades studies of the isotopes with an unbalanced number of protons and neutrons revealed that in these isotopes the shell gaps could chan...

  20. Isotope low-dimensional structures elementary excitations and applications

    CERN Document Server

    Plekhanov, Vladimir G

    2012-01-01

    This Briefs volume describes the properties and structure of  elementary excitations in isotope low-dimensional structures. Without assuming prior knowledge of quantum physics, the present book provides the basic knowledge needed to understand the recent developments in the sub-disciplines of nanoscience isotopetronics, novel device concepts and materials for nanotechnology. It is the first and comprehensive interdisciplinary account of the newly developed scientific discipline isotopetronics.

  1. Ab Initio Nuclear Structure and Reaction Calculations for Rare Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Draayer, Jerry P. [Louisiana State Univ., Baton Rouge, LA (United States)

    2014-09-28

    We have developed a novel ab initio symmetry-adapted no-core shell model (SA-NCSM), which has opened the intermediate-mass region for ab initio investigations, thereby providing an opportunity for first-principle symmetry-guided applications to nuclear structure and reactions for nuclear isotopes from the lightest p-shell systems to intermediate-mass nuclei. This includes short-lived proton-rich nuclei on the path of X-ray burst nucleosynthesis and rare neutron-rich isotopes to be produced by the Facility for Rare Isotope Beams (FRIB). We have provided ab initio descriptions of high accuracy for low-lying (including collectivity-driven) states of isotopes of Li, He, Be, C, O, Ne, Mg, Al, and Si, and studied related strong- and weak-interaction driven reactions that are important, in astrophysics, for further understanding stellar evolution, X-ray bursts and triggering of s, p, and rp processes, and in applied physics, for electron and neutrino-nucleus scattering experiments as well as for fusion ignition at the National Ignition Facility (NIF).

  2. Resonant ionization by laser beams: application to ions sources and to study the nuclear structure of radioactive tellurium isotopes; Ionisation resonante par faisceaux laser: application aux sources d'ions et a l'etude de la structure des noyaux radioactifs de tellure

    Energy Technology Data Exchange (ETDEWEB)

    Sifi, R

    2007-07-15

    The radioactive ion beams that are produced through current isotope separators are well separated according to the A mass but not according to the Z parameter. The resonant ionization through laser beams applied to ion sources allows the production of radioactive ion beam in a very selective and efficient way by eliminating the isobaric contamination. The first chapter is dedicated to the resonant ionization by laser beams, we describe the principle, the experimental setting, the lasers used, the ionization schemes and the domain of application. The second chapter deals with the application of resonant ionization to laser ion sources for the production of radioactive ion beams. We present experimental tests performed for getting copper ion beams. Resonant ionization through laser is also used in the spectroscopy experiments performed at the Isolde (isotope separation on-line device) installation in CERN where more than 20 elements are ionized very efficiently. The technique is based on a frequency scanning around the excitation transition of the atoms in order to probe the hyperfine structure. Laser spectroscopy allows the determination of the hyperfine structure as well as the isotopic shift of atoms. In the third chapter the method is applied to the spectroscopy of tellurium atoms. First, we define the 2 parameters on which the extraction is based: charge radius and nuclear moments, then we present several theoretical models that we have used to assess our experimental results. (A.C.)

  3. Electrical detection of hyperfine interactions in silicon

    Energy Technology Data Exchange (ETDEWEB)

    Hoehne, Felix

    2012-12-15

    The main focus of this work was the measurement of hyperfine interactions of defects in silicon using EDMR. We combined the high sensitivity of EDMR when compared to conventional ESR with the two most commonly used methods for the measurement of hyperfine interactions: ESEEM and ENDOR. We first demonstrated the electrical detection of ESEEM by measuring the hyperfine interactions of {sup 31}P donors in Si:P with {sup 29}Si nuclear spins. We then apply EDESEEM to P{sub b0} defects at the Si/SiO{sub 2} interface. In isotopically engineered, we observe an ESEEM modulation with a characteristic beating caused by {sup 29}Si nuclei at 4th and 5th nearest neighbor lattice sites. Then we combine pulsed ENDOR with the high sensitivity of EDMR (EDENDOR). First we demonstrate the measurement of {sup 31}P nuclear spin hyperfine transitions and the coherent manipulation and readout of the {sup 31}P nuclear spins under continuous illumination with above bandgap light. We further show that the EDENDOR method can be greatly improved by switching off the illumination during the microwave and rf pulses. This improves the signal-to-noise ratio by two orders of magnitude and removes the non-resonant background induced by the strong rf pulse allowing to measure ENDOR with a sensitivity <3000 nuclear spins. We apply EDENDOR to the {sup 31}P-P{sub b0} spin system and the {sup 31}P-SL1 spin system allowing us to compare the hyperfine interactions of bulk and interface-near donors. The pulsed illumination also makes spectroscopy of the {sup 31}P{sup +} nuclear spin possible, which due to its long coherence time of 18 ms compared to 280 {mu}s for the {sup 31}P{sub 0} nuclear spin, might be a candidate for a nuclear spin memory. In the last part, we devise a scheme for the hyperpolarization of {sup 31}P nuclei by combining pulsed optical excitation and pulsed ENDOR and demonstrate a {sup 31}P nuclear spin polarization of more than 50%. Crucial for these experiments was the development of a

  4. Nuclear Structure of N $\\simeq$ 56 Krypton Isotopes

    CERN Multimedia

    2002-01-01

    In view of the strong overlap in subject matter, the proposals IP-39 and 40 were considered together by the ISOLDE-Committee, and a combined investigation was suggested to be presented to the PSCC.\\\\ \\\\ First results on $\\beta$-decay properties of very neutron-rich Br isotopes (Z=35) indicate a rather smooth onset of deformation already below N=60 and the existence of a deformed N=56 subshell gap. This behaviour is in contrast to earlier observations of a sudden onset of strong deformations at N=60 for $ \\% Z ge $ 37 nuclei. \\\\ \\\\ We propose to study at CERN-ISOLDE nuclear structure properties of N=55 - 57 Kr isotopes from $\\beta$-decay of $^9

  5. The hyperfine properties of iron-gallium alloys

    Energy Technology Data Exchange (ETDEWEB)

    Elzain, M., E-mail: elzain@squ.edu.om; Gismelseed, A.; Al-Rawas, A.; Yousif, A.; Widatallah, H.; Al-Azri, Maya [Sultan Qaboos University, Department of Physics (Oman); Al-Barwani, M. [NYU Abu Dhabi (United Arab Emirates)

    2016-12-15

    The hyperfine properties at Fe site in iron-gallium alloy are calculated using the full-potential linear-augmented-plane-waves method. We have calculated the Fermi contact field (B{sub hf}) and isomer shift (δ) at the Fe site versus the number of neighbouring Ga atoms. We found that B{sub hf} decrease whereas δ increases with increasing number of neighbouring G atom. In addition we have calculated the hyperfine properties of FeGa system with DO{sub 3} structure, where various distributions of 4 the Ga atoms in the conventional unit cell are considered (including the regular DO{sub 3} structure). We found that the DO{sub 3} structure has the lowest energy as compared to the other configurations. The two distinct A and D sites of the ordered DO{sub 3} conventional unit cell have two distinct values for B{sub hf} and δ. On changing the atomic arrangement of the Ga atoms within the conventional unit cell, the configuration of the A site is maintained whereas that of the D site becomes imperfect. The contact magnetic hyperfine fields of the D-like sites in the imperfect structures are lower than that of the DO{sub 3}D site.

  6. Changes in the mean square charge radii and electromagnetic moments of neutron-deficient Bi isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Barzakh, A. E., E-mail: barzakh@mail.ru; Batist, L. Kh.; Fedorov, D. V.; Ivanov, V. S.; Molkanov, P. L.; Moroz, F. V.; Orlov, S. Yu.; Panteleev, V. N.; Seliverstov, M. D.; Volkov, Yu. M. [Petersburg Nuclear Physics Institute (PNPI), NRC Kurchatov Institute, Gatchina 188300 (Russian Federation)

    2015-10-15

    In-source laser spectroscopy experiments for neutron deficient bismuth isotopes at the 306.77 nm atomic transition were carried out at the IRIS (Investigation of Radioactive Isotopes on Synchrocyclotron) facility of Petersburg Nuclear Physics Institute (PNPI). New data on isotope shifts and hyperfine structure for {sup 189–198,} {sup 211}Bi isotopes and isomers were obtained. The changes in the mean-square charge radii and the magnetic moment values were deduced. Marked deviation from the nearly spherical behavior for ground states of bismuth isotopes at N < 109 is demonstrated, in contrast to the lead and thallium isotopic chains. The big isomer shift between I = 1/2 (intruder) and I = 9/2 (normal) states for odd Bi isotopes (A = 193, 195, 197) was found.

  7. Numerical Simulations of Hyperfine Transitions of Antihydrogen

    CERN Document Server

    Kolbinger, B.; Diermaier, M.; Lehner, S.; Malbrunot, C.; Massiczek, O.; Sauerzopf, C.; Simon, M.C.; Widmann, E.

    2015-02-04

    One of the ASACUSA (Atomic Spectroscopy And Collisions Using Slow Antiprotons) collaboration's goals is the measurement of the ground state hyperfine transition frequency in antihydrogen, the antimatter counterpart of one of the best known systems in physics. This high precision experiment yields a sensitive test of the fundamental symmetry of CPT. Numerical simulations of hyperfine transitions of antihydrogen atoms have been performed providing information on the required antihydrogen events and the achievable precision.

  8. Isotopic Diversity Indices: How Sensitive to Food Web Structure?

    Science.gov (United States)

    Brind'Amour, Anik; Dubois, Stanislas F.

    2013-01-01

    Recently revisited, the concept of niche ecology has lead to the formalisation of functional and trophic niches using stable isotope ratios. Isotopic diversity indices (IDI) derived from a set of measures assessing the dispersion/distribution of points in the δ-space were recently suggested and increasingly used in the literature. However, three main critics emerge from the use of these IDI: 1) they fail to account for the isotopic sources overlap, 2) some indices are highly sensitive to the number of species and/or the presence of rare species, and 3) the lack of standardization prevents any spatial and temporal comparisons. Using simulations we investigated the ability of six commonly used IDI to discriminate among different trophic food web structures, with a focus on the first two critics. We tested the sensitivity of the IDI to five food web structures along a gradient of sources overlap, varying from two distinct food chains with differentiated sources to two superimposed food chains sharing two sources. For each of the food web structure we varied the number of species (from 10 to 100 species) and the type of species feeding behaviour (i.e. random or selective feeding). Values of IDI were generally larger in food webs with distinct basal sources and tended to decrease as the superimposition of the food chains increased. This was more pronounced when species displayed food preferences in comparison to food webs where species fed randomly on any prey. The number of species composing the food web also had strong effects on the metrics, including those that were supposedly less sensitive to small sample size. In all cases, computing IDI on food webs with low numbers of species always increases the uncertainty of the metrics. A threshold of ∼20 species was detected above which several metrics can be safely used. PMID:24391910

  9. Isotopic diversity indices: how sensitive to food web structure?

    Directory of Open Access Journals (Sweden)

    Anik Brind'Amour

    Full Text Available Recently revisited, the concept of niche ecology has lead to the formalisation of functional and trophic niches using stable isotope ratios. Isotopic diversity indices (IDI derived from a set of measures assessing the dispersion/distribution of points in the δ-space were recently suggested and increasingly used in the literature. However, three main critics emerge from the use of these IDI: 1 they fail to account for the isotopic sources overlap, 2 some indices are highly sensitive to the number of species and/or the presence of rare species, and 3 the lack of standardization prevents any spatial and temporal comparisons. Using simulations we investigated the ability of six commonly used IDI to discriminate among different trophic food web structures, with a focus on the first two critics. We tested the sensitivity of the IDI to five food web structures along a gradient of sources overlap, varying from two distinct food chains with differentiated sources to two superimposed food chains sharing two sources. For each of the food web structure we varied the number of species (from 10 to 100 species and the type of species feeding behaviour (i.e. random or selective feeding. Values of IDI were generally larger in food webs with distinct basal sources and tended to decrease as the superimposition of the food chains increased. This was more pronounced when species displayed food preferences in comparison to food webs where species fed randomly on any prey. The number of species composing the food web also had strong effects on the metrics, including those that were supposedly less sensitive to small sample size. In all cases, computing IDI on food webs with low numbers of species always increases the uncertainty of the metrics. A threshold of ~20 species was detected above which several metrics can be safely used.

  10. Isotopic diversity indices: how sensitive to food web structure?

    Science.gov (United States)

    Brind'Amour, Anik; Dubois, Stanislas F

    2013-01-01

    Recently revisited, the concept of niche ecology has lead to the formalisation of functional and trophic niches using stable isotope ratios. Isotopic diversity indices (IDI) derived from a set of measures assessing the dispersion/distribution of points in the δ-space were recently suggested and increasingly used in the literature. However, three main critics emerge from the use of these IDI: 1) they fail to account for the isotopic sources overlap, 2) some indices are highly sensitive to the number of species and/or the presence of rare species, and 3) the lack of standardization prevents any spatial and temporal comparisons. Using simulations we investigated the ability of six commonly used IDI to discriminate among different trophic food web structures, with a focus on the first two critics. We tested the sensitivity of the IDI to five food web structures along a gradient of sources overlap, varying from two distinct food chains with differentiated sources to two superimposed food chains sharing two sources. For each of the food web structure we varied the number of species (from 10 to 100 species) and the type of species feeding behaviour (i.e. random or selective feeding). Values of IDI were generally larger in food webs with distinct basal sources and tended to decrease as the superimposition of the food chains increased. This was more pronounced when species displayed food preferences in comparison to food webs where species fed randomly on any prey. The number of species composing the food web also had strong effects on the metrics, including those that were supposedly less sensitive to small sample size. In all cases, computing IDI on food webs with low numbers of species always increases the uncertainty of the metrics. A threshold of ~20 species was detected above which several metrics can be safely used.

  11. Nuclear structure of light Ca and heavy Cr isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Buerger, A.

    2007-07-01

    In the present thesis, the shell structure in exotic nuclei has been investigated. The focus of the work was on finding new experimental data in neutron-rich Cr and proton-rich Ca isotopes. The investigation of light Ca isotopes concentrated on the nucleus {sup 36}Ca which was produced in a knockout reaction from a radioactive {sup 37}Ca beam. For {sup 36}Ca, the excitation energy of the first 2{sup +} state has been measured for the first time. Furthermore, momentum distributions were analyzed using a Monte-Carlo simulation of the knockout reaction. This analysis yielded the contributions of neutrons from individual orbitals to the total knockout cross section. In principle, these may be used to calculate spectroscopic factors, but such a calculation is hampered by difficulties of present knockout-reaction models in predicting precise single-particle cross sections. The measured branching ratio to the ground and excited states, on the other hand, is close to the predicted value. A remaining difference might be due to emission of protons which cannot be detected with the present experimental setup. Both the branching ratio and the large excitation energy are compatible with a large N=16 gap in {sup 36}Ca that leads to relatively pure configurations both in the ground state and the excited 2{sup +} state. As a by-product of the experiment, two excitation energies in the T=2 nuclei {sup 32}Ar and {sup 28}S have been confirmed, and two {gamma}-ray transitions have been observed for the first time in {sup 37}Ca. While the mirror energy differences in the T=2 pairs {sup 36}Ca-{sup 36}S, {sup 32}Ar-{sup 32}Si, and {sup 28}S-{sup 28}Mg can be reproduced in shell model calculations using a modified USD interaction, these modifications are not sufficient to explain the mirror energy differences for the pair {sup 37}Ca-{sup 37}Cl. In the heavy Cr isotopes, new experimental evidence for a sub-shell closure at N=32 was found in a measurement of B(E2) values using high

  12. Evolution of nuclear structure in neutron-rich odd-Zn isotopes and isomers

    Directory of Open Access Journals (Sweden)

    C. Wraith

    2017-08-01

    Full Text Available Collinear laser spectroscopy was performed on Zn (Z=30 isotopes at ISOLDE, CERN. The study of hyperfine spectra of nuclei across the Zn isotopic chain, N=33–49, allowed the measurement of nuclear spins for the ground and isomeric states in odd-A neutron-rich nuclei up to N=50. Exactly one long-lived (>10 ms isomeric state has been established in each 69–79Zn isotope. The nuclear magnetic dipole moments and spectroscopic quadrupole moments are well reproduced by large-scale shell–model calculations in the f5pg9 and fpg9d5 model spaces, thus establishing the dominant term in their wave function. The magnetic moment of the intruder Iπ=1/2+ isomer in 79Zn is reproduced only if the νs1/2 orbital is added to the valence space, as realized in the recently developed PFSDG-U interaction. The spin and moments of the low-lying isomeric state in 73Zn suggest a strong onset of deformation at N=43, while the progression towards 79Zn points to the stability of the Z=28 and N=50 shell gaps, supporting the magicity of 78Ni.

  13. Triple oxygen isotope systematics of structurally bonded water in gypsum

    Science.gov (United States)

    Herwartz, Daniel; Surma, Jakub; Voigt, Claudia; Assonov, Sergey; Staubwasser, Michael

    2017-07-01

    The triple oxygen isotopic composition of gypsum mother water (gmw) is recorded in structurally bonded water in gypsum (gsbw). Respective fractionation factors have been determined experimentally for 18O/16O and 17O/16O. By taking previous experiments into account we suggest using 18αgsbw-gmw = 1.0037; 17αgsbw-gmw = 1.00195 and θgsbw-gmw = 0.5285 as fractionation factors in triple oxygen isotope space. Recent gypsum was sampled from a series of 10 ponds located in the Salar de Llamara in the Atacama Desert, Chile. Total dissolved solids (TDS) in these ponds show a gradual increase from 23 g/l to 182 g/l that is accompanied by an increase in pond water 18O/16O. Gsbw falls on a parallel curve to the ambient water from the saline ponds. The offset is mainly due to the equilibrium fractionation between gsbw and gmw. However, gsbw represents a time integrated signal biased towards times of strong evaporation, hence the estimated gmw comprises elevated 18O/16O compositions when compared to pond water samples taken on site. Gypsum precipitation is associated with algae mats in the ponds with lower salinity. No evidence for respective vital effects on the triple oxygen isotopic composition of gypsum hydration water is observed, nor are such effects expected. In principle, the array of δ18Ogsbw vs. 17Oexcess can be used to: (1) provide information on the degree of evaporation during gypsum formation; (2) estimate pristine meteoric water compositions; and (3) estimate local relative humidity which is the controlling parameter of the slope of the array for simple hydrological situations. In our case study, local mining activities may have decreased deep groundwater recharge, causing a recent change of the local hydrology.

  14. Hyperfine characterization of {beta}-zirconium tetrafluoride

    Energy Technology Data Exchange (ETDEWEB)

    Rivas, P.C.; Martinez, J.A.; Rodriguez, A.M.; Lopez Garcia, A.R. [Universidad Nacional de La Plata, Departamento de Fisica, Facultad de Ciencias Exactas (Argentina); Dejneka, M. [Rutgers University, Center for Ceramic Research (United States)

    1997-10-15

    The evolution of the hyperfine quadrupole interaction in {beta}-ZrF{sub 4} at Zr sites, is measured between 273 and 740 K via the Perturbed Angular Correlations technique. Two different quadrupole interactions, in a ratio 1:2 of relative fractions, are determined. It is observed that the compound remains stable all over the thermal range. Moisture exposure at room temperature seems not to affect the hyperfine interaction suggesting that {beta}-ZrF{sub 4} is less sensitive to air water than other varieties of zirconium fluoride.

  15. Hyperfine interaction of Er3+ ions in Y2SiO5 : An electron paramagnetic resonance spectroscopy study

    Science.gov (United States)

    Guillot-Noël, O.; Goldner, Ph.; Du, Y. Le; Baldit, E.; Monnier, P.; Bencheikh, K.

    2006-12-01

    Electron paramagnetic resonance (EPR) spectroscopy of rare earth ions in crystals is a powerful tool to analyze the hyperfine structure of the rare earth ground state. This can be useful for coherent spectroscopy and quantum information applications where the hyperfine structure of the electronic levels is used. In this work, we give a detailed analysis of the hyperfine structure of the ground state [I15/24(0)] of Er3+ ions in Y2SiO5 . The electronic Zeeman, hyperfine, and quadrupole matrices are obtained from angular variations of the magnetic field in three orthogonal crystal planes. An excellent agreement is obtained between experimental and simulated magnetic field positions and relative intensities of EPR lines.

  16. Population inversion in hyperfine states of Rb with a single nanosecond chirped pulse in the framework of a four-level system

    Science.gov (United States)

    Liu, G.; Zakharov, V.; Collins, T.; Gould, P.; Malinovskaya, S. A.

    2014-04-01

    We implement a four-level semiclassical model of a single pulse interacting with the hyperfine structure in ultracold rubidium aimed at control of population dynamics and quantum state preparation. We discuss a method based on pulse chirping to achieve population inversion between hyperfine states of the 5S shell. The results may prove useful for quantum operations with ultracold atoms.

  17. Isotopic and structural signature of experimentally irradiated organic matter

    Science.gov (United States)

    Laurent, Boris; Roskosz, Mathieu; Remusat, Laurent; Leroux, Hugues; Vezin, Hervé; Depecker, Christophe

    2014-10-01

    The effects of electron irradiation on the structure and the D/H signature of a synthetic analogue of extraterrestrial insoluble organic matter (IOM) were studied. Polyethylene terephthalate (PET) was chosen because it contains both aliphatic and aromatic functional groups. A 900 nm-thick film was irradiated with electrons within the energy range 4-300 keV, for different run durations. Temperature influence was also tested. Irradiated residues were structurally and isotopically characterized by infrared spectroscopy (IR), electronic paramagnetic resonance (EPR), and Secondary Ion Mass Spectrometry (SIMS). With increasing energy deposition, spectroscopic results indicate (i) a gradual amorphization with chain scissions, (ii) an increase of CH2/CH3 and (iii) the formation of quinones. The EPR study shows that mono- and biradicals (organic species with one or several unpaired valence electrons) are also formed during irradiation. As these structural modifications occur, the δD (initially at -33‰ relative to SMOW) decreases first during a transient step and then stabilizes at ∼+300‰. There is a strong correlation between the changes recorded by the different methods and the electron dose. Deposited energy appears to be the key parameter to induce these modifications. In this respect a low-energy electron irradiation causes more damages than high energy ones. Based on our data and considering the current solar electron flux, the irradiation at moderate energy (1-10 keV) can produce significant D-enrichments of the IOM in a timescale compatible with the evolution of a typical protoplanetary disk.

  18. Helium Pressure Shift of the Hyperfine Clock Transition in Hg-201(+)

    Science.gov (United States)

    Larigani, S. Taghavi; Burt, E. A.; Tjoelker, R. L.

    2010-01-01

    There are two stable odd isotopes of mercury with singly ionized hyperfine structure suitable for a microwave atomic clock: Hg-199(+) and Hg-201(+). We are investigating the viability of a trapped ion clock based on Hg-201(+) in a configuration that uses a buffer gas to increase ion loading efficiency and counter ion heating from rf trapping fields. Traditionally, either helium or neon is used as the buffer gas at approx. 10(exp -5) torr to confine mercury ions near room temperature. In addition to the buffer gas, other residual background gasses such as H2O, N2, O2, CO, CO2, and CH2 may be present in trace quantities. Collisions between trapped ions and buffer gas or background gas atoms/molecules produce a momentary shift of the ion clock transition frequency and constitute one of the largest systematic effects in this type of clock. Here we report an initial measurement of the He pressure shift in Hg-201(+) and compare this to Hg-199(+).

  19. Hyperfine electric parameters calculation in Si samples implanted with {sup 57}Mn→{sup 57}Fe

    Energy Technology Data Exchange (ETDEWEB)

    Abreu, Y., E-mail: yabreu@ceaden.edu.cu [Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Calle 30 No. 502 e/5ta y 7ma Ave., 11300 Miramar, Playa, La Habana (Cuba); Cruz, C.M.; Piñera, I.; Leyva, A.; Cabal, A.E. [Centro de Aplicaciones Tecnológicas y Desarrollo Nuclear (CEADEN), Calle 30 No. 502 e/5ta y 7ma Ave., 11300 Miramar, Playa, La Habana (Cuba); Van Espen, P. [Departement Chemie, Universiteit Antwerpen, Middelheimcampus, G.V.130, Groenenborgerlaan 171, 2020 Antwerpen (Belgium); Van Remortel, N. [Departement Fysica, Universiteit Antwerpen, Middelheimcampus, G.U.236, Groenenborgerlaan 171, 2020 Antwerpen (Belgium)

    2014-07-15

    Nowadays the electronic structure calculations allow the study of complex systems determining the hyperfine parameters measured at a probe atom, including the presence of crystalline defects. The hyperfine electric parameters have been measured by Mössbauer spectroscopy in silicon materials implanted with {sup 57}Mn→{sup 57}Fe ions, observing four main contributions to the spectra. Nevertheless, some ambiguities still remain in the {sup 57}Fe Mössbauer spectra interpretation in this case, regarding the damage configurations and its evolution with annealing. In the present work several implantation environments are evaluated and the {sup 57}Fe hyperfine parameters are calculated. The observed correlation among the studied local environments and the experimental observations is presented, and a tentative microscopic description of the behavior and thermal evolution of the characteristic defects local environments of the probe atoms concerning the location of vacancies and interstitial Si in the neighborhood of {sup 57}Fe ions in substitutional and interstitial sites is proposed.

  20. Direct observation of the hyperfine transition of ground-state positronium.

    Science.gov (United States)

    Yamazaki, T; Miyazaki, A; Suehara, T; Namba, T; Asai, S; Kobayashi, T; Saito, H; Ogawa, I; Idehara, T; Sabchevski, S

    2012-06-22

    We report the first direct measurement of the hyperfine transition of the ground state positronium. The hyperfine structure between ortho-positronium and para-positronium is about 203 GHz. We develop a new optical system to accumulate about 10 kW power using a gyrotron, a mode converter, and a Fabry-Pérot cavity. The hyperfine transition has been observed with a significance of 5.4 standard deviations. The transition probability is measured to be A = 3.1(-1.2)(+1.6) × 10(-8) s(-1) for the first time, which is in good agreement with the theoretical value of 3.37 × 10(-8) s(-1).

  1. Determination of hyperfine-induced transition rates from observations of a planetary nebula.

    Science.gov (United States)

    Brage, Tomas; Judge, Philip G; Proffitt, Charles R

    2002-12-31

    Observations of the planetary nebula NGC3918 made with the STIS instrument on the Hubble Space Telescope reveal the first unambiguous detection of a hyperfine-induced transition 2s2p 3P(o)(0)-->2s2 1S0 in the berylliumlike emission line spectrum of N IV at 1487.89 A. A nebular model allows us to confirm a transition rate of 4x10(-4) sec(-1)+/-33% for this line. The measurement represents the first independent confirmation of the transition rate of hyperfine-induced lines in low ionization stages, and it provides support for the techniques used to compute these transitions for the determination of very low densities and isotope ratios.

  2. Muons as hyperfine interaction probes in chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Ghandi, Khashayar, E-mail: kghandi@triumf.ca; MacLean, Amy [Mount Allison University, Department of Chemistry & Biochemistry (Canada)

    2015-04-15

    Spin polarized positive muons injected in matter serve as magnetic probes for the investigation of physical and chemical properties of free radicals, mechanisms of free radical reactions and their formations, and radiation effects. All muon techniques rely on the evolution of spin polarization (of the muon) and in that respect are similar to conventional magnetic resonance techniques. The applications of the muon as a hyperfine probe in several fields in chemistry are described.

  3. Rotational spectra of rare isotopic species of fluoroiodomethane: determination of the equilibrium structure from rotational spectroscopy and quantum-chemical calculations.

    Science.gov (United States)

    Puzzarini, Cristina; Cazzoli, Gabriele; López, Juan Carlos; Alonso, José Luis; Baldacci, Agostino; Baldan, Alessandro; Stopkowicz, Stella; Cheng, Lan; Gauss, Jürgen

    2012-07-14

    Supported by accurate quantum-chemical calculations, the rotational spectra of the mono- and bi-deuterated species of fluoroiodomethane, CHDFI and CD(2)FI, as well as of the (13)C-containing species, (13)CH(2)FI, were recorded for the first time. Three different spectrometers were employed, a Fourier-transform microwave spectrometer, a millimeter/submillimter-wave spectrometer, and a THz spectrometer, thus allowing to record a huge portion of the rotational spectrum, from 5 GHz up to 1.05 THz, and to accurately determine the ground-state rotational and centrifugal-distortion constants. Sub-Doppler measurements allowed to resolve the hyperfine structure of the rotational spectrum and to determine the complete iodine quadrupole-coupling tensor as well as the diagonal elements of the iodine spin-rotation tensor. The present investigation of rare isotopic species of CH(2)FI together with the results previously obtained for the main isotopologue [C. Puzzarini, G. Cazzoli, J. C. López, J. L. Alonso, A. Baldacci, A. Baldan, S. Stopkowicz, L. Cheng, and J. Gauss, J. Chem. Phys. 134, 174312 (2011); G. Cazzoli, A. Baldacci, A. Baldan, and C. Puzzarini, Mol. Phys. 109, 2245 (2011)] enabled us to derive a semi-experimental equilibrium structure for fluoroiodomethane by means of a least-squares fit procedure using the available experimental ground-state rotational constants together with computed vibrational corrections. Problems related to the missing isotopic substitution of fluorine and iodine were overcome thanks to the availability of an accurate theoretical equilibrium geometry (computed at the coupled-cluster singles and doubles level augmented by a perturbative treatment of triple excitations).

  4. Improving the calculation of electron paramagnetic resonance hyperfine coupling tensors for d-block metals

    DEFF Research Database (Denmark)

    Hedegård, Erik Donovan; Kongsted, Jacob; Sauer, Stephan P. A.

    2012-01-01

    Calculation of hyperfine coupling constants (HFCs) of Electron Paramagnetic Resonance from first principles can be a beneficial compliment to experimental data in cases where the molecular structure is unknown. We have recently investigated basis set convergence of HFCs in d-block complexes...

  5. Nuclear moments of neutron deficient iridium isotopes from laser spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Verney, D.; Le Blanc, F. [IN2P3 CNRS, Institut de Physique Nucleaire (France); Cabaret, L. [Laboratoire Aime Cotton (France); Crawford, J. [McGill University, Physics Department (Canada); Duong, H.T. [Laboratoire Aime Cotton (France); Genevey, J. [IN2P3 CNRS/UJF, Institut des Sciences Nucleaires (France); Huber, G. [Universitaet Mainz, Institut fuer Physik (Germany); Ibrahim, F. [IN2P3 CNRS/UJF, Institut des Sciences Nucleaires (France); Krieg, M. [Universitaet Mainz, Institut fuer Physik (Germany); Lee, J.K.P. [McGill University, Physics Department (Canada); Lunney, D. [IN2P3 CNRS, CSNSM (France); Obert, J.; Oms, J. [IN2P3 CNRS, Institut de Physique Nucleaire (France); Pinard, J. [Laboratoire Aime Cotton (France); Putaux, J.C.; Roussiere, B.; Sauvage, J. [IN2P3 CNRS, Institut de Physique Nucleaire (France); Sebastian, V. [Universitaet Mainz, Institut fuer Physik (Germany)

    2000-08-15

    Laser spectroscopy measurements have been performed on neutron deficient iridium isotopes. The hyperfine structure and isotope shift of the optical Ir I transition 5d{sup 7}6s{sup 24}F{sub 9/2} {sup {yields}} 5d{sup 7}6s6p {sup 6}F{sub 11/2} at 351.5 nm have been studied for the {sup 182-189}Ir, {sup 186}Ir{sup 1}m and {sup 191,193}Ir isotopes. The nuclear magnetic and quadrupole moments were obtained from the HFS measurements and the changes of the mean square charge radii from the IS measurements. A large mean square charge radius change between {sup 187}Ir and {sup 186}Ir and between {sup 186}Ir{sup 1}m and {sup 186}Ir{sup 1}g has been observed.

  6. Atomic spectroscopy studies of short-lived isotopes and nuclear isomer separation with the ISOLDE RILIS

    CERN Document Server

    Fedosseev, V; Weissman, L; Mishin, V I; Federov, D V; Seliverstov, D M; Horn, R; Huber, G; Lassen, J; Wendt, K

    2003-01-01

    The Resonance Ionization Laser Ion Source (RILIS) at the ISOLDE on-line isotope separator is based on the selective excitation of atomic transitions by tunable laser radiation. Ion beams of isotopes of 20 elements have been produced using the RILIS setup. Together with the mass separator and a particle detection system it represents a tool for high-sensitive laser spectroscopy of short-lived isotopes. By applying narrow-bandwidth lasers for the RILIS one can study isotope shifts (IS) and hyperfine structure (HFS) of atomic optical transitions. Such measurements are capable of providing data on nuclear charge radii, spins and magnetic moments of exotic nuclides far from stability. Although the Doppler broadening of the optical absorption lines limits the resolution of the technique, the accuracy of the HFS measurements examined in experiments with stable Tl isotopes approaches a value of 100 MHz. Due to the hyperfine splitting of atomic lines the RILIS gives an opportunity to separate nuclear isomers. Isomer s...

  7. The structural and decay properties of Francium isotopes

    Science.gov (United States)

    Bhuyan, M.; Mahapatro, S.; Singh, S. K.; Patra, S. K.

    2015-04-01

    We study the bulk properties such as binding energy (BE), root-mean-square (RMS) charge radius, quadrupole deformation etc. for Francium (Fr) isotopes having mass number A = 180-240 within the framework of relativistic mean field (RMF) theory. Systematic comparisons are made between the calculated results from RMF theory, Finite Range Droplet Model (FRDM) and the experimental data. Most of the nuclei in the isotopic chain shows prolate configuration in their ground state. The α-decay properties like α-decay energy and the decay half-life are also estimated for three different chains of 198Fr, 199Fr and 200Fr. The calculation for the decay half-life are carried out by taking two different empirical formulae and the results are compared with the experimental data.

  8. Study of polonium isotopes ground state properties by simultaneous atomic- and nuclear-spectroscopy

    CERN Multimedia

    Koester, U H; Kalaninova, Z; Imai, N

    2007-01-01

    We propose to systematically study the ground state properties of neutron deficient $^{192-200}$Po isotopes by means of in-source laser spectroscopy using the ISOLDE laser ion source coupled with nuclear spectroscopy at the detection setup as successfully done before by this collaboration with neutron deficient lead isotopes. The study of the change in mean square charge radii along the polonium isotope chain will give an insight into shape coexistence above the mid-shell N = 104 and above the closed shell Z = 82. The hyperfine structure of the odd isotopes will also allow determination of the nuclear spin and the magnetic moment of the ground state and of any identifiable isomer state. For this study, a standard UC$_{x}$ target with the ISOLDE RILIS is required for 38 shifts.

  9. Measurement and modeling of hyperfine parameters in ferroic materials

    CERN Document Server

    Gonçalves, João Nuno; Correia, J G

    This thesis presents the results of perturbed angular correlation (PAC) experiments , an experimental technique which measures the hyperfine interaction at probes (radioactive ions implanted in the materials to study), from which one infers local information on an atomic scale. Furthermore, abinitio calculations using density functional theory electronic obtain results that directly complement the experiments, and are also used for theoretical research. These methods were applied in two families of materials. The manganites, with the possible existence of magnetic, charge, orbital and ferroelectric orders, are of fundamental and technological interest. The experimental results are obtained in the alkaline-earth manganites (Ca, Ba, Sr), with special interest due to the structural variety of possible polymorphs. With probes of Cd and In the stability of the probe and its location in a wide temperature range is established and a comparison with calculations allows the physical interpretation of the results. Cal...

  10. Directionally independent energy gap formation due to the hyperfine interaction

    NARCIS (Netherlands)

    Miyashita, Seiji; Raedt, Hans De; Michielsen, Kristel

    2003-01-01

    We study energy gap formation at the level-crossing point due to the hyperfine interaction. In contrast to the energy gap induced by the Dzyaloshinskii-Moriya interaction, the gap induced by the hyperfine interaction is independent of the direction of the magnetic field. We also study the dynamics

  11. Theoretical isotopic fractionation between structural boron in carbonates and aqueous boric acid and borate ion

    Science.gov (United States)

    Balan, Etienne; Noireaux, Johanna; Mavromatis, Vasileios; Saldi, Giuseppe D.; Montouillout, Valérie; Blanchard, Marc; Pietrucci, Fabio; Gervais, Christel; Rustad, James R.; Schott, Jacques; Gaillardet, Jérôme

    2018-02-01

    The 11B/10B ratio in calcite and aragonite is an important proxy of oceanic water pH. However, the physico-chemical mechanisms underpinning this approach are still poorly known. In the present study, we theoretically determine the equilibrium isotopic fractionation properties of structural boron species in calcium carbonates, BO33-, BO2(OH)2- and B(OH)4- anions substituted for carbonate groups, as well as those of B(OH)4- and B(OH)3 species in vacuum. Significant variability of equilibrium isotopic fractionation properties is observed among these structural species which is related to their contrasted coordination state, Bsbnd O bond lengths and atomic-scale environment. The isotopic composition of structural boron does not only depend on its coordination number but also on its medium range environment, i.e. farther than its first coordination shell. The isotopic fractionation between aqueous species and their counterparts in vacuum are assessed using previous investigations based on similar quantum-mechanical modeling approaches. At 300 K, the equilibrium isotope composition of structural trigonal species is 7-15‰ lighter than that of aqueous boric acid molecules, whereas substituted tetrahedral borate ions are heavier than their aqueous counterparts by 10-13‰. Although significant uncertainties are known to affect the theoretical prediction of fractionation factors between solids and solutions, the usually assumed lack of isotopic fractionation during borate incorporation in carbonates is challenged by these theoretical results. The present theoretical equilibrium fractionation factors between structural boron and aqueous species differ from those inferred from experiments which may indicate that isotopic equilibrium, unlike chemical equilibrium, was not reached in most experiments. Further research into the isotopic fractionation processes at the interface between calcium carbonates and aqueous solution as well as long duration experiments aimed at

  12. Trophic structure in a seabird host-parasite food web: insights from stable isotope analyses.

    Directory of Open Access Journals (Sweden)

    Elena Gómez-Díaz

    Full Text Available Ecological studies on food webs rarely include parasites, partly due to the complexity and dimensionality of host-parasite interaction networks. Multiple co-occurring parasites can show different feeding strategies and thus lead to complex and cryptic trophic relationships, which are often difficult to disentangle by traditional methods. We analyzed stable isotope ratios of C ((13C/(12C, delta(13C and N ((15N/(14N, delta(15N of host and ectoparasite tissues to investigate trophic structure in 4 co-occurring ectoparasites: three lice and one flea species, on two closely related and spatially segregated seabird hosts (Calonectris shearwaters. delta(13C isotopic signatures confirmed feathers as the main food resource for the three lice species and blood for the flea species. All ectoparasite species showed a significant enrichment in delta(15N relatively to the host tissue consumed (discrimination factors ranged from 2 to 5 per thousand depending on the species. Isotopic differences were consistent across multiple host-ectoparasite locations, despite of some geographic variability in baseline isotopic levels. Our findings illustrate the influence of both ectoparasite and host trophic ecology in the isotopic structuring of the Calonectris ectoparasite community. This study highlights the potential of stable isotope analyses in disentangling the nature and complexity of trophic relationships in symbiotic systems.

  13. Raman spectroscopic investigation of polycrystalline structures of CVD-grown graphene by isotope labeling.

    Science.gov (United States)

    Wang, Shengnan; Suzuki, Satoru; Hibino, Hiroki

    2014-11-21

    Topological defects, such as point defects, dislocations and grain boundaries, have a dramatic influence on the chemical and physical properties of large-scale graphene grown by chemical vapor deposition (CVD) method. Here we demonstrate the Raman visualization of polycrystalline structures in an isotopically modified CVD graphene. By means of the reversible reaction of methane on a copper catalyst, the etching of (12)C-lattice and surface deposition of (13)C-atoms occur in CVD graphene by sequentially introducing hydrogen and isotopic methane after standard growth of graphene with full monolayer coverage. Spatial Raman spectroscopic mapping on labeled graphene reveals pronounced network-like (13)C-rich regions, which are further identified to exist along the grain boundaries of graphene by low-energy electron microscopy. The structural defects inside the graphene grains are also targeted in the isotope labeling process. Our work opens a new way to investigate multiple grain structures in CVD graphene with a simple spectroscopic technique.

  14. Characterization of Oxygen Bridged Manganese Model Complexes Using Multifrequency (17)O-Hyperfine EPR Spectroscopies and Density Functional Theory.

    Science.gov (United States)

    Rapatskiy, Leonid; Ames, William M; Pérez-Navarro, Montserrat; Savitsky, Anton; Griese, Julia J; Weyhermüller, Thomas; Shafaat, Hannah S; Högbom, Martin; Neese, Frank; Pantazis, Dimitrios A; Cox, Nicholas

    2015-10-29

    Multifrequency pulsed EPR data are reported for a series of oxygen bridged (μ-oxo/μ-hydroxo) bimetallic manganese complexes where the oxygen is labeled with the magnetically active isotope (17)O (I = 5/2). Two synthetic complexes and two biological metallocofactors are examined: a planar bis-μ-oxo bridged complex and a bent, bis-μ-oxo-μ-carboxylato bridge complex; the dimanganese catalase, which catalyzes the dismutation of H2O2 to H2O and O2, and the recently identified manganese/iron cofactor of the R2lox protein, a homologue of the small subunit of the ribonuclotide reductase enzyme (class 1c). High field (W-band) hyperfine EPR spectroscopies are demonstrated to be ideal methods to characterize the (17)O magnetic interactions, allowing a magnetic fingerprint for the bridging oxygen ligand to be developed. It is shown that the μ-oxo bridge motif displays a small positive isotropic hyperfine coupling constant of about +5 to +7 MHz and an anisotropic/dipolar coupling of -9 MHz. In addition, protonation of the bridge is correlated with an increase of the hyperfine coupling constant. Broken symmetry density functional theory is evaluated as a predictive tool for estimating hyperfine coupling of bridging species. Experimental and theoretical results provide a framework for the characterization of the oxygen bridge in Mn metallocofactor systems, including the water oxidizing cofactor of photosystem II, allowing the substrate/solvent interface to be examined throughout its catalytic cycle.

  15. CRYOGENIC ADSORPTION OF HYDROGEN ISOTOPES OVER NANO-STRUCTURED MATERIALS

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, S.; Heung, L.

    2010-10-07

    Porous materials such as zeolites, activated carbon, silica gels, alumina and a number of industrial catalysts are compared and ranked for hydrogen and deuterium adsorption at liquid nitrogen temperature. All samples show higher D{sub 2} adsorption than that of H{sub 2}, in which a HY sample has the greatest isotopic effect while 13X has the highest hydrogen uptake capacity. Material's moisture content has significant impact to its hydrogen uptake. A material without adequate drying could result in complete loss of its adsorption capacity. Even though some materials present higher H{sub 2} adsorption capacity at full pressure, their adsorption at low vapor pressure may not be as good as others. Adsorption capacity in a dynamic system is much less than in a static system. A sharp desorption is also expected in case of temperature upset.

  16. Continuation of Atomic Spectroscopy on Alkali Isotopes at ISOLDE

    CERN Multimedia

    2002-01-01

    Laser optical measurements on Rb, Cs and Fr have already been performed at ISOLDE in 1978-79. The hyperfine structure and isotope shift of |7|6|-|9|8Rb, |1|1|8|-|1|4|5Cs, |2|0|8|-|2|1|3Fr and 14 of their isomers have been studied. Among the wealth of information which has been obtained, the most important are the first observation of an optical transition of the element Fr, the evidence of the onset of nuclear deformation at N~=~60 for Rb isotopes and the shape isomerism isotopes. \\\\ \\\\ From both the atomic and nuclear physics point of view, new studies seem very promising: \\item - the search for new optical transitions in Fr; the shell effect in the rms charge radius at N~=~126 for Fr isotopes \\item - the study of a possible onset of deformation for Cs isotopes beyond |1|4|5Cs \\item - the study of a region of static deformation in neutron-deficient Rb isotopes. \\\\ \\\\ \\end{enumerate} A new apparatus has been built. The principle remains the same as used in our earlier experiments. The improvements concern ess...

  17. Isotopic mapping of transition-state structural features associated with enzymic catalysis of methyl transfer

    Energy Technology Data Exchange (ETDEWEB)

    Rodgers, J.; Femec, D.A.; Schowen, R.L.

    1982-06-16

    For comparison of the molecular structures of nonenzymic and enzymic sulfur-to-oxygen transmethylation transition states by the use of kinetic isotope effects, a series of isotopic maps is produced. In these, contours of constant isotope effect are displayed vs. the Pauling bond orders B/sub CS/ and B/sub CO/, for the carbon-sulfur and carbon-oxygen bonds, respectively, taken as independent variables to describe the transition states. Maps are calculated by the BEBOVIB approach for k(CH/sub 3/)/k(CD/sub 3/), k(/sup 12/CH/sub 3/)/k(/sup 13/CH/sub 3/), k(/sup 16/O)/k(/sup 18/O), and k(/sup 32/S)/k(/sup 34/S), with two models for the reaction coordinate, two force-field assumptions, and four temperatures. Nonenzymic isotope effects and isotope effects for catechol-O-methyltransferase action are then used to construct figures on the CH/sub 3//CD/sub 3/ and /sup 12/CH/sub 3///sup 13/CH/sub 3/ maps which correspond to allowed spaces of transition-states structures. Superposition of the figures yields the spaces of transition-state structures simultaneously consistent with both hydrogen and carbon isotope effects. It is concluded that the enzyme compresses the S/sub N/2 transition state and that the compression of the C-O and C-S bonds may well be of the order of 0.15 A per bond and could conceivably be more than twice as large.

  18. Structures of the CAGE, Prism, and Book Hexamer Water Clusters from Multiple Isotopic Substitution

    Science.gov (United States)

    Lobsiger, Simon; Perez, Cristobal; Zaleski, Daniel P.; Seifert, Nathan; Pate, Brooks H.; Kisiel, Zbigniew; Temelso, Berhane; Shields, George C.

    2013-06-01

    The rotational spectra of the three lowest energy conformers of the water hexamer have recently been observed and assigned using chirped-pulse Fourier-transform microwave spectroscopy. In that study single ^{18}O isotopic substitution allowed determination of oxygen framework geometries for all three clusters. Further isotopic spectra have been recorded since then: of water samples with ^{18}O:^{16}O ratios of 3:1 and 1:3, and of weakly deuterated water. Each spectrum results from averaging of around 10M free-induction-decays and the achieved high S/N ratio allowed assignment for each cluster of isotopic species with practically all possible ^{16}O,^{18}O isotopic combinations, ranging from all ^{16}O to all ^{18}O species. In addition, all 12 single deuterium species of each conformer have been assigned. This unprecedented abundance of isotopic information, resulting in rotational constants for close to 228 different species, is combined in new determinations of the structures of these clusters, providing a deeper insight into the properties of the underlying hydrogen bonding. C. Perez, M. T. Muckle, D. P. Zaleski, N. A. Seifert, B. Temelso, G. C. Shields, Z. Kisiel, and B. H. Pate, Science {336}, 897 (2012).

  19. Structure of beryllium isotopes in fermionic molecular dynamics

    Energy Technology Data Exchange (ETDEWEB)

    Torabi, Bahram Ramin

    2009-02-16

    Modern theoretical nuclear physics faces two major challenges. The first is finding a suitable interaction, which describes the forces between nucleons. The second challenge is the solution of the nuclear many-body problem for a given nucleus while applying a realistic potential. The potential used in the framework of this thesis is based on the Argonne AV18 potential. It was transformed by means of the Unitary Correlation Operator Method (UCOM) to optimize convergence. The usual phenomenological corrections were applied to improve the potential for the Hilbert space used in Fermionic Molecular Dynamics (FMD). FMD is an approach to solve the nuclear many-body problem. It uses a single-particle basis which is a superposition of Gaussian distributions in phase-space. The most simple many-body state is the antisymmetric product of the singleparticle states: a Slater determinant, the so called intrinsic state. This intrinsic state is projected on parity, total angular momentum and a center of mass momentum zero. The Hilbert space is spanned by several of these projected states. The states are obtained by minimizing their energy while demanding certain constraints. The expectation values of Slater determinants, parity projected and additionally total angular momentum projected Slater determinants are used. The states that are relevant in the low energy regime are obtained by diagonalization. The lowest moments of the mass-, proton- or neutron-distribution and the excitation in proton- and neutron-shells of a harmonic oscillator are some of the used constraints. The low energy regime of the Beryllium isotopes with masses 7 to 14 is calculated by using these states. Energies, radii, electromagnetic transitions, magnetic moments and point density distributions of the low lying states are calculated and are presented in this thesis. (orig.)

  20. Influence of liquid structure on diffusive isotope separation in molten silicates and aqueous solutions

    Energy Technology Data Exchange (ETDEWEB)

    Watkins, J.M.; DePaolo, D.J.; Ryerson, F.J.; Peterson, B.

    2011-03-01

    Molecular diffusion in natural volcanic liquids discriminates between isotopes of major ions (e.g., Fe, Mg, Ca, and Li). Although isotope separation by diffusion is expected on theoretical grounds, the dependence on mass is highly variable for different elements and in different media. Silicate liquid diffusion experiments using simple liquid compositions were carried out to further probe the compositional dependence of diffusive isotopic discrimination and its relationship to liquid structure. Two diffusion couples consisting of the mineral constituents anorthite (CaAl{sub 2}Si{sub 2}O{sub 8}; denoted AN), albite (NaAlSi{sub 3}O{sub 8}; denoted AB), and diopside (CaMgSi{sub 2}O{sub 6}; denoted DI) were held at 1450°C for 2 h and then quenched to ambient pressure and temperature. Major-element as well as Ca and Mg isotope profiles were measured on the recovered quenched glasses. In both experiments, Ca diffuses rapidly with respect to Si. In the AB–AN experiment, D{sub Ca}/D{sub Si} ~ 20 and the efficiency of isotope separation for Ca is much greater than in natural liquid experiments where D{sub Ca}/D{sub Si} ~ 1. In the AB–DI experiment, D{sub Ca}/D{sub Si} ~ 6 and the efficiency of isotope separation is between that of the natural liquid experiments and the AB–AN experiment. In the AB–DI experiment, D{sub Mg}/D{sub Si} ~ 1 and the efficiency of isotope separation for Mg is smaller than it is for Ca yet similar to that observed for Mg in natural liquids. The results from the experiments reported here, in combination with results from natural volcanic liquids, show clearly that the efficiency of diffusive separation of Ca isotopes is systematically related to the solvent-normalized diffusivity—the ratio of the diffusivity of the cation (D{sub Ca}) to the diffusivity of silicon (D{sub Si}). The results on Ca isotopes are consistent with available data on Fe, Li, and Mg isotopes in silicate liquids, when considered in terms of the parameter D{sub cation

  1. Application of Nitrogen and Carbon Stable Isotopes ([delta]15N and [delta]13C) to Quantify Food Chain Length and Trophic Structure

    National Research Council Canada - National Science Library

    Matthew J Perkins; McDonald, Robbie; Veen, J; Kelly, Simon; Rees, Gareth; Bearhop, Stuart

    2014-01-01

      Increasingly, stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures...

  2. Structural properties of hydrogen isotopes in solid phase in the context of inertial confinement fusion

    Directory of Open Access Journals (Sweden)

    Guerrero Carlo

    2013-11-01

    Full Text Available Quality of Deuterium-Tritium capsules is a critical aspect in Inertial Confinement Fusion. In this work, we present a Quantum Molecular Dynamics methodology able to model hydrogen isotopes and their structural molecular organisation at extreme pressures and cryogenic temperatures (< 15 K. Our study sets up the basis for a future analysis on the mechanical and structural properties of DT-ice in inertial confinement fusion (ICF target manufacturing conditions.

  3. Nuclear moments of neutron-deficient iridium isotopes from laser spectroscopy

    CERN Document Server

    Verney, D; Cabaret, L A; Crawford, J; Duong, H T; Genevey, J; Huber, G; Ibrahim, F; Krieg, M; Lee, J K P; Lunney, M D; Obert, J; Oms, J; Pinard, J; Putaux, J C; Roussière, B; Sauvage, J; Sebastian, V

    2000-01-01

    Laser spectroscopy measurements have been performed on neutron- deficient iridium isotopes. The hyperfine structure and isotope shift of the optical Ir I transition 5d/sup 7/6s/sup 2/ /sup 4/F/sub 9/2/ to 5d/sup 7/6s6p /sup 6/F/sub 11/2/ at 351.5 nm have been studied for the /sup 182-189/Ir, /sup 186/Ir/sup m/ and /sup 191,193/Ir isotopes. The nuclear magnetic and quadrupole moments were obtained from the HFS measurements and the changes of the mean square charge radii from the IS measurements. A large mean square charge radius change between /sup 187/Ir and /sup 186/Ir and between /sup 186/Ir/sup m/ and /sup 186/Ir/sup g/ has been observed. (18 refs).

  4. Sensing site-specific structural characteristics and chirality using vibrational circular dichroism of isotope labeled peptides.

    Science.gov (United States)

    Keiderling, Timothy A

    2017-10-04

    Isotope labeling has a long history in chemistry as a tool for probing structure, offering enhanced sensitivity, or enabling site selection with a wide range of spectroscopic tools. Chirality sensitive methods such as electronic circular dichroism are global structural tools and have intrinsically low resolution. Consequently, they are generally insensitive to modifications to enhance site selectivity. The use of isotope labeling to modify vibrational spectra with unique resolvable frequency shifts can provide useful site-specific sensitivity, and these methods have been recently more widely expanded in biopolymer studies. While the spectral shifts resulting from changes in isotopic mass can provide resolution of modes from specific parts of the molecule and can allow detection of local change in structure with perturbation, these shifts alone do not directly indicate structure or chirality. With vibrational circular dichroism (VCD), the shifted bands and their resultant sign patterns can be used to indicate local conformations in labeled biopolymers, particularly if multiple labels are used and if their coupling is theoretically modeled. This mini-review discusses selected examples of the use of labeling specific amides in peptides to develop local structural insight with VCD spectra. © 2017 Wiley Periodicals, Inc.

  5. Hyperfine interactions in soybean and lupin oxy-leghemoglobins studied using Mössbauer spectroscopy with a high velocity resolution

    Science.gov (United States)

    Kumar, A.; Alenkina, I. V.; Zakharova, A. P.; Oshtrakh, M. I.; Semionkin, V. A.

    2015-04-01

    A comparative study of monomeric soybean and lupin leghemoglobins in the oxy-form was carried out using Mössbauer spectroscopy with a high velocity resolution at 90 K. The 57Fe hyperfine parameters of measured spectra were evaluated and compared with possible structural differences in the heme Fe(II)-O 2 bond.

  6. Hyperfine interactions in soybean and lupin oxy-leghemoglobins studied using Mössbauer spectroscopy with a high velocity resolution

    Energy Technology Data Exchange (ETDEWEB)

    Kumar, A. [University of Delhi South Campus, Department of Biochemistry (India); Alenkina, I. V. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation); Zakharova, A. P. [Ural Federal University, Department of Experimental Physics, Institute of Physics and Technology (Russian Federation); Oshtrakh, M. I., E-mail: oshtrakh@gmail.com; Semionkin, V. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation)

    2015-04-15

    A comparative study of monomeric soybean and lupin leghemoglobins in the oxy-form was carried out using Mössbauer spectroscopy with a high velocity resolution at 90 K. The {sup 57}Fe hyperfine parameters of measured spectra were evaluated and compared with possible structural differences in the heme Fe(II)–O {sub 2} bond.

  7. Stable isotopes provide insight into population structure and segregation in eastern North Atlantic sperm whales.

    Science.gov (United States)

    Borrell, Asunción; Velásquez Vacca, Adriana; Pinela, Ana M; Kinze, Carl; Lockyer, Christina H; Vighi, Morgana; Aguilar, Alex

    2013-01-01

    In pelagic species inhabiting large oceans, genetic differentiation tends to be mild and populations devoid of structure. However, large cetaceans have provided many examples of structuring. Here we investigate whether the sperm whale, a pelagic species with large population sizes and reputedly highly mobile, shows indication of structuring in the eastern North Atlantic, an ocean basin in which a single population is believed to occur. To do so, we examined stable isotope values in sequential growth layer groups of teeth from individuals sampled in Denmark and NW Spain. In each layer we measured oxygen- isotope ratios (δ(18)O) in the inorganic component (hydroxyapatite), and nitrogen and carbon isotope ratios (δ(15)N: δ(13)C) in the organic component (primarily collagenous). We found significant differences between Denmark and NW Spain in δ(15)N and δ(18)O values in the layer deposited at age 3, considered to be the one best representing the baseline of the breeding ground, in δ(15)N, δ(13)C and δ(18)O values in the period up to age 20, and in the ontogenetic variation of δ(15)N and δ(18)O values. These differences evidence that diet composition, use of habitat and/or migratory destinations are dissimilar between whales from the two regions and suggest that the North Atlantic population of sperm whales is more structured than traditionally accepted.

  8. Stable isotopes provide insight into population structure and segregation in eastern North Atlantic sperm whales.

    Directory of Open Access Journals (Sweden)

    Asunción Borrell

    Full Text Available In pelagic species inhabiting large oceans, genetic differentiation tends to be mild and populations devoid of structure. However, large cetaceans have provided many examples of structuring. Here we investigate whether the sperm whale, a pelagic species with large population sizes and reputedly highly mobile, shows indication of structuring in the eastern North Atlantic, an ocean basin in which a single population is believed to occur. To do so, we examined stable isotope values in sequential growth layer groups of teeth from individuals sampled in Denmark and NW Spain. In each layer we measured oxygen- isotope ratios (δ(18O in the inorganic component (hydroxyapatite, and nitrogen and carbon isotope ratios (δ(15N: δ(13C in the organic component (primarily collagenous. We found significant differences between Denmark and NW Spain in δ(15N and δ(18O values in the layer deposited at age 3, considered to be the one best representing the baseline of the breeding ground, in δ(15N, δ(13C and δ(18O values in the period up to age 20, and in the ontogenetic variation of δ(15N and δ(18O values. These differences evidence that diet composition, use of habitat and/or migratory destinations are dissimilar between whales from the two regions and suggest that the North Atlantic population of sperm whales is more structured than traditionally accepted.

  9. Tap water isotope ratios reflect urban water system structure and dynamics across a semiarid metropolitan area

    Science.gov (United States)

    Jameel, Yusuf; Brewer, Simon; Good, Stephen P.; Tipple, Brett J.; Ehleringer, James R.; Bowen, Gabriel J.

    2016-08-01

    Water extraction for anthropogenic use has become a major flux in the hydrological cycle. With increasing demand for water and challenges supplying it in the face of climate change, there is a pressing need to better understand connections between human populations, climate, water extraction, water use, and its impacts. To understand these connections, we collected and analyzed stable isotopic ratios of more than 800 urban tap water samples in a series of semiannual water surveys (spring and fall, 2013-2015) across the Salt Lake Valley (SLV) of northern Utah. Consistent with previous work, we found that mean tap water had a lower 2H and 18O concentration than local precipitation, highlighting the importance of nearby montane winter precipitation as source water for the region. However, we observed strong and structured spatiotemporal variation in tap water isotopic compositions across the region which we attribute to complex distribution systems, varying water management practices and multiple sources used across the valley. Water from different sources was not used uniformly throughout the area and we identified significant correlation between water source and demographic parameters including population and income. Isotopic mass balance indicated significant interannual and intra-annual variability in water losses within the distribution network due to evaporation from surface water resources supplying the SLV. Our results demonstrate the effectiveness of isotopes as an indicator of water management strategies and climate impacts within regional urban water systems, with potential utility for monitoring, regulation, forensic, and a range of water resource research.

  10. The impact of the intruder orbitals on the structure of neutron-rich Ag isotopes

    Directory of Open Access Journals (Sweden)

    Y.H. Kim

    2017-09-01

    Full Text Available The low-lying high-spin yrast band structure of neutron-rich 113,118–121Ag has been established for the first time using prompt γ-ray spectroscopy of isotopically identified fission fragments produced in the 9Be(238U, fγ fusion- and transfer-induced fission processes. The newly obtained level energies follow the systematics of the neighboring isotopes. The sequences of levels exhibit an energy inheritance from states in the corresponding Cd core. A striking constancy of a large signature splitting in odd-A Ag throughout the long chain of isotopes with 50isotopes, which are indications of triaxiality, were evidenced. These observed features were reproduced by large-scale shell-model calculations with a spherical basis for the first time in the Ag isotopic chain, revealing microscopically their complex nature with severely broken seniority ordering. The essential features of the observed signature splitting were further examined in the light of simplified, two-orbital shell-model calculations including only two intruder orbitals πg9/2 and νh11/2 from two consecutive shells above Z=50 and N=82 for protons and neutrons respectively, resulting in the πg9/2−3×νh11/2m configurations. The newly established bands were understood as fairly pure, built mainly on unique-parity intruder configurations and coupled to the basic states of the Cd core.

  11. Chromium isotope anomaly in an impactite sample from the El'gygytgyn structure, Russia: Evidence for a ureilite projectile?

    National Research Council Canada - National Science Library

    Foriel, Julien; Moynier, Frederic; Schulz, Toni; Koeberl, Christian

    2013-01-01

    ... that an achondritic projectile was involved. We studied the major and trace element composition in samples from the new ICDP drill core obtained near the center of the structure, as well as the chromium isotopic composition of an impact glass...

  12. Investigation of the single Particle Structure of the neutron-rich Sodium Isotopes $^{27-31}\\!$Na

    CERN Multimedia

    2002-01-01

    We propose to study the single particle structure of the neutron-rich isotopes $^{27-31}\\!$Na. These isotopes will be investigated via neutron pickup reactions in inverse kinematics on a deuterium and a beryllium target. Scattered beam particles and transfer products are detected in a position sensitive detector located around 0$^\\circ$. De-excitation $\\gamma$-rays emitted after an excited state has been populated will be registered by the MINIBALL Germanium array. The results will shed new light on the structure of the neutron-rich sodium isotopes and especially on the region of strong deformation around the N=20 nucleus $^{31}\\!$Na.

  13. Trophic structure of a coastal fish community determined with diet and stable isotope analyses.

    Science.gov (United States)

    Malek, A J; Collie, J S; Taylor, D L

    2016-09-01

    A combination of dietary guild analysis and nitrogen (δ(15) N) and carbon (δ(13) C) stable-isotope analysis was used to assess the trophic structure of the fish community in Rhode Island and Block Island Sounds, an area off southern New England identified for offshore wind energy development. In the autumn of 2009, 2010 and 2011, stomach and tissue samples were taken from 20 fish and invertebrate species for analysis of diet composition and δ(15) N and δ(13) C signatures. The food chain in Rhode Island and Block Island Sounds comprises approximately four trophic levels within which the fish community is divided into distinct dietary guilds, including planktivores, benthivores, crustacivores and piscivores. Within these guilds, inter-species isotopic and dietary overlap is high, suggesting that resource partitioning or competitive interactions play a major role in structuring the fish community. Carbon isotopes indicate that most fishes are supported by pelagic phytoplankton, although there is evidence that benthic production also plays a role, particularly for obligate benthivores such as skates Leucoraja spp. This type of analysis is useful for developing an ecosystem-based approach to management, as it identifies species that act as direct links to basal resources as well as species groups that share trophic roles. © 2016 The Fisheries Society of the British Isles.

  14. Applications of Structural Mass Spectrometry to Metabolomics: Clarifying Bond Specific Spectral Signatures with Isotope Edited Spectroscopy

    Science.gov (United States)

    Gorlova, Olga; Wolke, Conrad T.; Fournier, Joseph; Colvin, Sean; Johnson, Mark; Miller, Scott

    2015-06-01

    Comprehensive FTIR, MS/MS and NMR of pharmaceuticals are generally readily available but characterization of their metabolites has been an obstacle. Atorvastatin is a statin drug responsible for the maintenance of cholesterol in the body. Diovan is an angiostensin receptor antagonist used to treat high blood pressure and congestive heart failure. The field of metabolomics, however, is struggling to obtain the identity of their structures. We implement mass spectrometry with cryogenic ion spectroscopy to study gaseous ions of the desired metabolites which, in combination, not only identify the mass of the metabolite but also elucidate their structures through isotope-specific infrared spectroscopy.

  15. Charge radii of magnesium isotopes by laser spectroscopy a structural study over the $sd$ shell

    CERN Multimedia

    Schug, M; Krieger, A R

    We propose to study the evolution of nuclear sizes and shapes over the magnesium chain by measuring the root-mean-square charge radii of $^{21 - 32}$Mg, essentially covering the entire $\\textit{sd}$ shell. Our goal is to detect the structural changes, which in the neutron-deficient isotopes may originate from clustering, in a way similar to neon, and on the neutron-rich side would characterize the transition to the "island of inversion". We will combine, for the first time, the sensitive $\\beta$-detection technique with traditional fluorescence spectroscopy for isotope-shift measurements and in such a way gain access to the exotic species near the ${N}$ = 8 and ${N}$ = 20 shell closures.

  16. In-source laser spectroscopy of mercury isotopes

    CERN Multimedia

    This proposal follows on from the Letter of Intent, I-153. The neutron-deficient mercury isotopes are one of the prime examples of shape coexistence anywhere in the nuclear chart. Wide-ranging and complementary experimental and theoretical approaches have been used to investigate their structure over the last few years, however mean-square charge radii are unknown for isotopes with $\\textit{A}$ < 181. It is proposed to measure the isotope shift (IS) and hyperfine structure (HFS) of the 253-nm transition in $^{177-182}$Hg in an attempt to study the propagation of the famous odd-even staggering behaviour. At the other end of the chain, no information exists on the optical spectroscopy of Hg isotopes beyond the $\\textit{N}$ = 126 shell closure. There is a well-known "kink" in mean-square charge radii beyond this point in the even $\\textit{Z}$ $\\geq$ 82 elements. It is proposed to measure the IS of $^{207,208}$Hg in order to provide the first information on this effect below $\\textit{Z}$ = 82.

  17. Hyperfine fields of Fe in Nd2Fe14BandSm2Fe17N3

    Science.gov (United States)

    Akai, Hisazumi; Ogura, Masako

    2015-03-01

    High saturation magnetization of rare-earth magnets originates from Fe and the strong magnetic anisotropy stems from f-states of rare-earth elements such as Nd and Sm. Therefore the hyperfine fields of both Fe and rare-earth provide us with important pieces of information: Fe NMR enable us to detect site dependence of the local magnetic moment and magnetic anisotropy (Fe sites also contribute to the magnetic anisotropy) while rare-earth NQR directly give the information of electric field gradients (EFG) that are related to the shape of the f-electron cloud as well as the EFG produced by ligands. In this study we focus on the hyperfine fields of materials used as permanent magnets, Nd2Fe14BandSm2Fe17N3 from theoretical points of view. The detailed electronic structure together with the hyperfine interactions are discussed on the basis of the first-principles calculation. In particular, the relations between the observed hyperfine fields and the magnetic properties are studies in detail. The effects of doping of those materials by other elements such as Dy and the effects of N adding in Sm2Fe17N3 will be discussed. This work was supported by Elements Strategy Initiative Center for Magnetic Materials Project, the Ministry of Education, Culture, Sports, Science and Technology, Japan.

  18. Decay study of neutron-deficient La isotopes for atomic masses and nuclear structure

    Energy Technology Data Exchange (ETDEWEB)

    Osa, Akihiko; Koizumi, Mitsuo; Sekine, Toshiaki [Department of Materials Science, Japan Atomic Energy Research Institute, Takasaki, Gunma (JP)] [and others

    2000-06-01

    We report the decay spectroscopic studies with the TIARA-ISOL connected to an AVF cyclotron at the Takasaki site of JAERI between 1994 and 1998 under the Universities-JAERI Collaborative Research Project. Decay spectroscopic studies have been carried out for neutron-deficient La-Ce-Pr isotopes in the mass 120-130 region, which were prepared by on-line mass-separation following the fusion-evaporation reactions {sup 92,nat}Mo({sup 36}Ar, 3pxn). The {sup 125}Pr isotope was newly identified with a half-life of 3.3(7) s and its decay scheme was presented. The assignment of the 135.8 keV {gamma}-ray to the decay of {sup 125}Pr was supported by its coincidence with Ce X-rays and {beta}{sup +} rays. Low-spin states in {sup 124,} {sup 126,} {sup 128,} {sup 130}Ba fed by the {beta}{sup +}/EC decay of their La parents were investigated by means of the {gamma}-{gamma} angular correlation measurement. Q{sub EC}-values/atomic masses of neutron-deficient {sup 124-130}La were determined by {beta}{sup +}-ray maximum energy measurement. Half-lives of the first 2{sup +} state in {sup 122,} {sup 124,} {sup 126}Ba were measured using a {beta}-{gamma} delayed coincidence method. The experimental results obtained for the nuclear structure of the Ba isotopes are discussed in comparison with theory. (author)

  19. Isotopic quantum effects on the structure of low density amorphous ice

    CERN Document Server

    Urquidi, J; Neuefeind, J; Tomberli, B; Tulk, C A; Guthrie, M; Egelstaff, P A; Klug, D D

    2003-01-01

    Careful neutron diffraction measurements on deuterated low density amorphous (LDA) ice confirm that at 120 K it can be considered a fully 'annealed' structure, as no significant changes are observed in the amorphous spectra until crystallization occurred over time at 130 K. On this basis, the measurement of structural differences between the hydrogenated and deuterated forms of LDA ice at 120 K, have been carried out using 98 keV electromagnetic radiation diffraction techniques. The maximum observed isotope effect in LDA ice is approx 3.4% at 40 K when compared to the magnitude of the first peak in the electronic structure factor at Q = 1.70 A sup - sup 1. This compares to a maximum effect of approx 1.6% previously measured in liquid water at room temperature (Tomberli et al 2000 J. Phys.: Condens. Matter. 12 2597). The isotope effect is shown to be similar to a temperature shift in the structure of light LDA ice. However, the existence of a first sharp diffraction peak at Q = 1.0 A sup - sup 1 in the isotopi...

  20. Hyperfine field distributions in disordered Mn2CoSn and Mn2NiSn ...

    Indian Academy of Sciences (India)

    Unknown

    Mössbauer studies using Sn-119 were carried out to investigate the hyperfine fields present at the Sn site in these alloys. The hyperfine field distribution in these alloys as well as X-ray studies point to the chemical disorder present in both alloys. Co-existence of a paramagnetic portion along with the magnetic hyperfine part.

  1. Magnetic moment of Ag-104(m) and the hyperfine magnetic field of Ag in Fe using nuclear magnetic resonance on oriented nuclei

    CERN Document Server

    Golovko, V.V.; Phalet, T.; Delaure, B.; Beck, M.; Kozlov, V.Yu.; Coeck, S.; Wauters, F.; Herzog, P.; Tramm, Ch.; Zakoucky, D.; Venos, D.; Srnka, D.; Honusek, M.; Koster, U.; Severijns, N.

    2010-01-01

    Nuclear magnetic resonance (NMR/ON) measurements with beta- and gamma-ray detection have been performed on oriented Ag-104(g,m) nuclei with the NICOLE He-3-He-4 dilution refrigerator setup at ISOLDE/CERN. For Ag-104(g) (I-pi = 5(+)) the gamma-NMR/ON resonance signal was found at nu = 266.70(5) MHz. Combining this result with the known magnetic moment for this isotope, the magnetic hyperfine field of Ag impurities in an Fe host at low temperature (< 1 K) is found to be vertical bar B-hf(AgFe)vertical bar = 44.709(35) T. A detailed analysis of other relevant data available in the literature yields three more values for this hyperfine field. Averaging all four values yields a new and precise value for the hyperfine field of Ag in Fe; that is, vertical bar B-hf(AgFe)vertical bar = 44.692(30) T. For Ag-104(m) (I-pi = 2(+)), the anisotropy of the beta particles provided the NMR/ON resonance signal at nu = 627.7(4) MHz. Using the new value for the hyperfine field of Ag in Fe, this frequency corresponds to the mag...

  2. Kinetic models in spin chemistry. 1. The hyperfine interaction

    DEFF Research Database (Denmark)

    Mojaza, M.; Pedersen, J. B.

    2012-01-01

    Kinetic models for quantum systems are quite popular due to their simplicity, although they are difficult to justify. We show that the transformation from quantum to kinetic description can be done exactly for the hyperfine interaction of one nuclei with arbitrary spin; more spins are described...

  3. Effect of thermal history on Mossbauer signature and hyperfine interaction parameters of copper ferrite

    Science.gov (United States)

    Modi, K. B.; Raval, P. Y.; Dulera, S. V.; Kathad, C. R.; Shah, S. J.; Trivedi, U. N.; Chandra, Usha

    2015-06-01

    Two specimens of copper ferrite, CuFe2O4, have been synthesized by double sintering ceramic technique with different thermal history i.e. slow cooled and quenched. X-ray diffractometry has confirmed single phase fcc spinel structure for slow cooled sample while tetragonal distortion is present in quenched sample. Mossbauer spectral analysis for slow-cooled copper ferrite reveals super position of two Zeeman split sextets along with paramagnetic singlet in the centre position corresponds to delafossite (CuFeO2) phase that is completely absent in quenched sample. The hyperfine interaction parameters are highly influenced by heat treatment employed.

  4. Cryogenic tunable microwave cavity at 13 GHz for hyperfine spectroscopy of antiprotonic helium

    CERN Document Server

    Sakaguchi, J; Hayano, R S; Ishikawa, T; Suzukia, K; Widmann, E; Yamaguchi, H; Caspers, Friedhelm; Eades, John; Horib, M; Barna, D; Horváth, D; Juhász, B; Torie, H A; Yamazakif, T

    2004-01-01

    For the precise measurement of the hyperfine structure of antiprotonic helium, microwave radiation of 12.9 GHz frequency is needed, tunable over . A cylindrical microwave cavity is used whose front and rear faces are meshed to allow the antiprotons and laser beams to enter. The cavity is embedded in a cryogenic helium gas target. Frequency tuning of with Q values of 2700?3000 was achieved using over-coupling and an external triple stub tuner. We also present Monte-Carlo simulations of the stopping distribution of antiprotons in the low-density helium gas using the GEANT4 package with modified energy loss routines.

  5. Cryogenic Tunable Microwave Cavity at 13 GHz for Hyperfine Spectroscopy of Antiprotonic Helium

    CERN Document Server

    Barna, D; Eades, John; Gilg, H; Hayano, R S; Hori, Masaki; Horváth, M; Hayano, R S; Ishikawa, T; Juhász, B; Sakaguchi, J; Suzuki, K; Torii, H A; Widmann, E; Yamaguchi, H; Yamazaki, T

    2004-01-01

    For the precise measurement of the hyperfine structure of antiprotonic helium microwave radiation of 12.9 GHz frequency is needed, tunable over ±100 MHz. A cylindrical microwave cavity is used whose front and rear faces are meshed to allow the antiprotons and laser beams to enter. The cavity is embedded in a cryogenic helium gas target. Frequency tuning of 300 MHz with Q values of 2700-3000 was achieved using over-coupling and an external triple stub tuner. We also present Monte-Carlo simulations of the stopping distribution of antiprotons in the low-density helium gas using the GEANT4 package with modified energy loss routines.

  6. Isotope-based quantum information

    CERN Document Server

    G Plekhanov, Vladimir

    2012-01-01

    The present book provides to the main ideas and techniques of the rapid progressing field of quantum information and quantum computation using isotope - mixed materials. It starts with an introduction to the isotope physics and then describes of the isotope - based quantum information and quantum computation. The ability to manipulate and control electron and/or nucleus spin in semiconductor devices provides a new route to expand the capabilities of inorganic semiconductor-based electronics and to design innovative devices with potential application in quantum computing. One of the major challenges towards these objectives is to develop semiconductor-based systems and architectures in which the spatial distribution of spins and their properties can be controlled. For instance, to eliminate electron spin decoherence resulting from hyperfine interaction due to nuclear spin background, isotopically controlled devices are needed (i.e., nuclear spin-depleted). In other emerging concepts, the control of the spatial...

  7. Structural classification of the amide I sites of a beta-hairpin with isotope label 2DIR spectroscopy

    NARCIS (Netherlands)

    Roy, Santanu; Jansen, Thomas L. C.; Knoester, Jasper

    2010-01-01

    We present a theoretical study of the possibility to use isotope label two-dimensional infrared (2DIR) spectroscopy to obtain site specific structural information in trpzip2. This small beta-hairpin peptide was designed as a model system for studying protein folding in beta-sheet structures. In

  8. Hyperfine splitting in simple ions for the search of the variation of fundamental constants

    Science.gov (United States)

    Oreshkina, Natalia S.; Cavaletto, Stefano M.; Michel, Niklas; Harman, Zoltán; Keitel, Christoph H.

    2017-09-01

    Numerous few-electron atomic systems are considered which can be used effectively for observing a potential variation of the fine-structure constant α and the electron-proton mass ratio me/mp . We examine optical magnetic dipole transitions between hyperfine-structure components in heavy highly charged H-like and Li-like ions with observably high sensitivity to a variation of α and me/mp . The experimental spectra of the proposed systems consist of a strong single line, which simplifies significantly the data analysis and shortens the necessary measurement time. Furthermore, we propose systems for an experimental test of the variation of quark masses and discuss the expected level of accuracy in assessing its limitations. Finally, we establish which constraints on the variation of these fundamental constants could be provided by measurements with a hyperfine-structure highly-charged-ion clock and some reference clock, showing that a significant improvement of the current limitations can be reached.

  9. Isotopic metrics for structure, connectivity, and residence time in urban water supply systems

    Science.gov (United States)

    Bowen, Gabriel; Kennedy, Casey; Good, Stephen; Ehleringer, James

    2014-05-01

    Public water supply systems are the life-blood of urban areas, accessing, managing, and distributing water from an often complex array of sources to provide on-demand access to safe, potable water at the point-of-use. Water managers are faced with a wide range of potential threats, ranging from climate change to infrastructure failure to supply contamination. Information on the structure of supply and conveyance systems, connectivity within these systems, and links between the point-of-use and environmental water sources are thus critical to assessing the stability of water supplies and responding efficiently and effectively to water supply threats. We report datasets documenting stable hydrogen and oxygen isotope ratios of public supply water in cities of the United States across a range of scales. The data show a wide range of spatial and temporal variability that can be attributed to a combination of regional hydroclimate and water supply characteristics. Comparisons of public supply waters with model-based estimates of the isotopic composition of regional water sources suggests that major factors reflected in the tap water data include the degree of fragmentation of natural and man-made storage and conveyance systems, inter-basinal transfer of water, evaporative losses, and the total residence time of the natural and artificial systems being exploited. Because each of these factors contributes to determining the sustainability of water supply systems and their sensitivity to environmental disturbance, we propose a set of isotope-based metrics that can be used to efficiently assess and monitor the characteristics of public-supply systems in water security assessments and in support of management, planning, and outreach activities.

  10. Study of hyperfine parameters in Co-doped tin dioxide using PAC spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Juliana M.; Carbonari, Artur W.; Martucci, Thiago; Costa, Messias S.; Saxena, Rajendra N. [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Vianden, R.; Kessler, P.; Geruschke, T.; Steffens, M., E-mail: vianden@hiskp.uni-bonn.d [Rheinische Friedrich-Wilhelms-Universitaet Bonn (HISKP- Bonn) (Germany). Helmholtz - Institut fuer Strahlen- und Kernphysik

    2011-07-01

    PAC technique has been used to measure the hyperfine interactions in nano-structured powder samples of semiconducting SnO{sub 2} doped with Co. The aim of this work is to compare the results of PAC measurements using two different techniques of introducing the radioactive {sup 111}In probe nuclei in the sample of SnO{sub 2} doped with Co. The perturbed gamma-gamma angular correlation (PAC) spectroscopy is used for the measurements of the magnetic hyperfine field (MHF) and the electric field gradient (EFG) at {sup 111}Cd sites in SnO{sub 2} doped with 1% and 2% Co. The measurement of EFG is used to study the defects introduced in the semiconductor material and also for the identification of different phases formed within the compound. The techniques utilized for introducing the radioactive {sup 111}In in the sample are the ion-implantation using radioactive ion beam of {sup 111}In and the chemical process in which {sup 111}InCl{sub 3} solution is added during the preparation of SnO{sub 2} doped with Co using sol gel method. The ion-implantation of {sup 111}In in SnO{sub 2} doped with Co was carried out using the University of Bonn ion-implanter with beam energy of 160 keV. The PAC measurements were carried out with four BaF{sub 2} detector gamma spectrometer in the temperature range of 10-295 K. The results show no significant difference in the values of hyperfine parameters. Both techniques show practically the same electric quadrupole interaction for the substitutional site. The results were compared with previous PAC and Moessbauer measurements of SnO{sub 2} powder samples using {sup 111}In-{sup 111}Cd probe. (author)

  11. ENDOR investigations of the Ce.sup.3+./sup. ions in YAG: Transferred hyperfine interaction with nearest aluminum ions

    Czech Academy of Sciences Publication Activity Database

    Azamat, Dmitry; Badalyan, A. G.; Feng, D.H.; Lančok, Ján; Jastrabík, Lubomír; Dejneka, Alexandr; Baranov, P. G.; Yakovlev, D.R.; Bayer, M.

    2017-01-01

    Roč. 122, č. 24 (2017), s. 1-3, č. článku 243903. ISSN 0021-8979 R&D Projects: GA MŠk LO1409; GA ČR GA16-22092S Institutional support: RVO:68378271 Keywords : laser materials * magnetic resonance imaging * electron nuclear double resonance * hyperfine structure Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.068, year: 2016

  12. Upper trophic structure in the Atlantic Patagonian shelf break as inferred from stable isotope analysis

    Science.gov (United States)

    Zhu, Guoping; Zhang, Haiting; Yang, Yang; Wang, Shaoqin; Wei, Lian; Yang, Qingyuan

    2017-09-01

    The Patagonian Shelf is a very productive region with different ecosystem structures. A long history of fishing in the Southwestern Atlantic Ocean combined with a complex hydrographic structure, with a permanent front over the shelf-break and different coastal frontal regions, and a wide non-frontal area in between have made the food web in this area more complex and have resulted in changes to the spatial-temporal scale. Stable isotopes of carbon and nitrogen were used to determine the trophic structure of the Patagonian shelf break which was previously poorly understood. The results indicated that the average δ15N value of pelagic guild (Illex argentinus) was remarkable lower than those of the other guilds. The δ13C values of almost all species ranged from -17‰ to -18‰, but Stromateus brasiliensis had a significant lower δ13C value. Compared with the southern Patagonian shelf, short food chain length also occurred. The impact of complex oceanographic structures has resulted in food web structure change to the temporal-spatial scale on the Patagonian shelf. The Patagonian shelf break can be considered as a separated ecosystem structure with lower δ15N values.

  13. QUDeX-MS: hydrogen/deuterium exchange calculation for mass spectra with resolved isotopic fine structure.

    Science.gov (United States)

    Salisbury, Joseph P; Liu, Qian; Agar, Jeffrey N

    2014-12-11

    Hydrogen/deuterium exchange (HDX) coupled to mass spectrometry permits analysis of structure, dynamics, and molecular interactions of proteins. HDX mass spectrometry is confounded by deuterium exchange-associated peaks overlapping with peaks of heavy, natural abundance isotopes, such as carbon-13. Recent studies demonstrated that high-performance mass spectrometers could resolve isotopic fine structure and eliminate this peak overlap, allowing direct detection and quantification of deuterium incorporation. Here, we present a graphical tool that allows for a rapid and automated estimation of deuterium incorporation from a spectrum with isotopic fine structure. Given a peptide sequence (or elemental formula) and charge state, the mass-to-charge ratios of deuterium-associated peaks of the specified ion is determined. Intensities of peaks in an experimental mass spectrum within bins corresponding to these values are used to determine the distribution of deuterium incorporated. A theoretical spectrum can then be calculated based on the estimated distribution of deuterium exchange to confirm interpretation of the spectrum. Deuterium incorporation can also be detected for ion signals without a priori specification of an elemental formula, permitting detection of exchange in complex samples of unidentified material such as natural organic matter. A tool is also incorporated into QUDeX-MS to help in assigning ion signals from peptides arising from enzymatic digestion of proteins. MATLAB-deployable and standalone versions are available for academic use at qudex-ms.sourceforge.net and agarlabs.com . Isotopic fine structure HDX-MS offers the potential to increase sequence coverage of proteins being analyzed through mass accuracy and deconvolution of overlapping ion signals. As previously demonstrated, however, the data analysis workflow for HDX-MS data with resolved isotopic fine structure is distinct. QUDeX-MS we hope will aid in the adoption of isotopic fine structure HDX

  14. Experimental and ab initio study of the hyperfine parameters of ZnFe {sub 2}O{sub 4} with defects

    Energy Technology Data Exchange (ETDEWEB)

    Quintero, J. Melo; Salcedo Rodríguez, K. L.; Pasquevich, G. A.; Zélis, P. Mendoza; Stewart, S. J., E-mail: stewart@fisica.unlp.edu.ar; Rodríguez Torres, C. E.; Errico, L. A. [Universidad Nacional de La Plata, IFLP-CCT- La Plata-CONICET and Departamento de Física, Facultad de Ciencias Exactas, C. C. 67 (Argentina)

    2016-12-15

    We present a combined Mössbauer and ab initio study on the influence of oxygen-vacancies on the hyperfine and magnetic properties of the ZnFe {sub 2}O{sub 4} spinel ferrite. Samples with different degree of oxygen-vacancies were obtained from zinc ferrite powder that was thermally treated at different temperatures up to 650 {sup ∘}C under vacuum.Theoretical calculations of the hyperfine parameters, magnetic moments and magnetic alignment have been carried out considering different defects such as oxygen vacancies and cation inversion. We show how theoretical and experimental approaches are complementary to characterize the local structure around Fe atoms and interpret the observed changes in the hyperfine parameters as the level of defects increases.

  15. Aliphatic Claisen rearrangement transition state structure from secondary. cap alpha. -deuterium isotope effects

    Energy Technology Data Exchange (ETDEWEB)

    Gajewski, J.J.; Conrad, N.D.

    1979-05-09

    The kinetics isotope effects (KIE) at C/sub 4/ and C/sub 6/ in the 3,3 shift of 3-oxa-1,5-hexadiene appear to reveal that the transition state comes early, and that it involves much more bond breaking than making in contrast to the carbon 3,3 shift of relatively unperturbed dienes. At 160/sup 0/C the normal KIE at C/sub 4/ is 1.092 and the inverse KIE at C/sub 6/ is 1.025. The ratio of the KIE to the equilibrium isotope effect at the bond breaking site is (0.09/1.27) or 1/3, while that of the bond making site is only (1.025/1.16) or < 1/6. These results seem to confirm that the transition state is early because of the exothermicity of the reaction. The transition state structure suggests that radical stabilizing substituents on C/sub 1/, C/sub 4/, and C/sub 6/ will stabilize the transition state to a greater extent than placement of the same substituents on C/sub 2/ and C/sub 5/.

  16. Assessment of trophic structure of Cretaceous communities based on stable nitrogen isotope analyses

    Science.gov (United States)

    Ostrom, P. H.; Macko, S. A.; Engel, M. H.; Russell, D. A.

    1993-06-01

    New δ15N data suggest the retention of an indigenous signal in ancient high molecular weight organic material. These data open the possibility of obtaining new paleoecological information, based on isotopic analyses, on ancient, well-preserved fossil communities. Stable carbon and nitrogen isotope analyses were performed on high molecular weight organic material isolated from 22 taxa of Late Cretaceous vertebrates (Judith River Formation, Alberta,Canada). The majority of δ13C and δ15N values (-27‰ to -23‰ and 4‰ to 12‰, for δ13C and δ15N, respectively) are similar to those reported for modern consumers. An assessment of trophic levels based on δ15N is consistent with previous interpretations of food web structure derived from paleoecological interpretations. Among terrestrial consumers, carnivorous theropods (tyrannosaurids and dromaeosaurids) have high δ15N values (6.6‰ ±0.4‰ and 7.9‰, respectively) relative to those of the dominant megaherbivore (hadrosaurids, 4.7‰ ±0.5‰). Within aquatic environments, the values of δ15N of the bowfin Amia (11.6‰) and plesiosaur (11.0‰),distinguish the piscivorous tendencies of these organisms from those of tower trophic level consumers such as the benthic feeding sturgeon Acipenser and the turtle Aspideretes (δ15N = 5.1‰ and 4.5‰, respectively). The correlation in trophic position between δ15N values and paleoecological evidence is unlikely to be coincidental.

  17. Electron spin dynamics due to hyperfine coupling in quantum dots

    Science.gov (United States)

    Woods, L. M.; Reinecke, T. L.; Rajagopal, A. K.

    2008-02-01

    The dynamics of spins in semiconductor quantum dots often is controlled by their hyperfine coupling to nuclear spins. We develop a straightforward and efficient approach to describe the dynamics and the effective decoherence of the electron spins due to hyperfine coupling in realistic quantum dots. Systems with a large number of nuclei and an arbitrary initial nuclear polarization for which the number of nuclei initially flipped over is much less than the total number of nuclei are treated. This treatment employs a pole approximation within a Schrödinger equation of motion for the state of the coupled electron and nuclear spin system, and it allows us to treat systems with arbitrary initial conditions. We find that typical time scales for the effective spin decoherence are on the order of tens of microseconds.

  18. The first direct measurement of the hyperfine splitting in positronium

    Energy Technology Data Exchange (ETDEWEB)

    Suehara, T; Ishida, A; Namba, T; Asai, S; Kobayashi, T [Department of Physics and ICEPP, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 33-0033 (Japan); Saitot, H [Institute of Physics, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902 (Japan); Yoshida, M [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801 (Japan); Idehara, T; Ogawa, I; Kobayashi, S [FIR Center, University of Fukui, 3-9-1 Bunkyo, Fukui, 910-8507 (Japan); Sabchevski, S, E-mail: suehara@icepp.s.u-tokyo.ac.j [Bulgarian Academy of Science, 1, 15 Noemvri Str., 1040 Sofia (Bulgaria)

    2009-03-01

    Positronium is an ideal system for the research of the QED. The hyperfine splitting of positronium (Ps-HFS) is sensitive to the new physics beyond the Standard Model via a vacuum oscillation. Previous experimental results of the Ps-HFS show 3.5 {sigma} discrepancy from the QED calculation, and it might be caused by uncertainties of the indirect method with static magnetic field and a few GHz RF. We developed a new direct measurement system of the Ps-HFS without static magnetic field, using a sub-THz gyrotron and a quasi-optical Fabry-Perot cavity. Status (hopefully the first result) of the direct positronium hyperfine transition observation will be presented.

  19. Chiral Extrapolation of Lattice Data for Heavy Meson Hyperfine Splittings

    Energy Technology Data Exchange (ETDEWEB)

    X.-H. Guo; P.C. Tandy; A.W. Thomas

    2006-03-01

    We investigate the chiral extrapolation of the lattice data for the light-heavy meson hyperfine splittings D*-D and B*-B to the physical region for the light quark mass. The chiral loop corrections providing non-analytic behavior in m{sub {pi}} are consistent with chiral perturbation theory for heavy mesons. Since chiral loop corrections tend to decrease the already too low splittings obtained from linear extrapolation, we investigate two models to guide the form of the analytic background behavior: the constituent quark potential model, and the covariant model of QCD based on the ladder-rainbow truncation of the Dyson-Schwinger equations. The extrapolated hyperfine splittings remain clearly below the experimental values even allowing for the model dependence in the description of the analytic background.

  20. Dephasing and hyperfine interaction in carbon nanotubes double quantum dots

    DEFF Research Database (Denmark)

    Reynoso, Andres Alejandro; Flensberg, Karsten

    2012-01-01

    We study theoretically the return probability experiment, which is used to measure the dephasing time T-2*, in a double quantum dot (DQD) in semiconducting carbon nanotubes with spin-orbit coupling and disorder-induced valley mixing. Dephasing is due to hyperfine interaction with the spins of the C...... with these for DQDs in clean nanotubes, whereas the disorder effect is always relevant when the magnetic field is perpendicular to the nanotube axis....

  1. Hyperfine-interaction-driven suppression of quantum tunneling at zero field in a holmium(III) single-ion magnet

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Yan-Cong; Liu, Jun-Liang; Chen, Xiao-Ming; Tong, Ming-Liang [Key Lab. of Bioinorganic and Synthetic Chemistry of Ministry of Education, School of Chemistry, Sun Yat-Sen Univ., Guangzhou (China); Wernsdorfer, Wolfgang [Institut Neel, CNRS and Universite Joseph Fournier, Grenoble (France); Institute of Nanotechnology, Karlsruhe Institute of Technology (Germany); Physikalisches Institut, Karlsruhe Institute of Technology (Germany); Liu, Dan; Chibotaru, Liviu F. [Theory of Nanomaterials Group and INPAC-Institute of Nanoscale Physics and Chemistry, Katholieke Universiteit Leuven (Belgium)

    2017-04-24

    An extremely rare non-Kramers holmium(III) single-ion magnet (SIM) is reported to be stabilized in the pentagonal-bipyramidal geometry by a phosphine oxide with a high energy barrier of 237(4) cm{sup -1}. The suppression of the quantum tunneling of magnetization (QTM) at zero field and the hyperfine structures originating from field-induced QTMs can be observed even from the field-dependent alternating-current magnetic susceptibility in addition to single-crystal hysteresis loops. These dramatic dynamics were attributed to the combination of the favorable crystal-field environment and the hyperfine interactions arising from {sup 165}Ho (I=7/2) with a natural abundance of 100 %. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  2. Stable isotopes in ecosystem science: structure, function and dynamics of a subtropical Savanna.

    Science.gov (United States)

    Boutton, T W; Archer, S R; Midwood, A J

    1999-01-01

    Stable isotopes are often utilized as intrinsic tracers to study the effects of human land uses on the structural and functional characteristics of ecosystems. Here, we illustrate how stable isotopes of H, C, and O have been utilized to document changes in ecosystem structure and function using a case study from a subtropical savanna ecosystem. Specifically, we demonstrate that: (1) delta 13C values of soil organic carbon record a vegetation change in this ecosystem from C4 grassland to C3 woodland during the past 40-120 years, and (2) delta 2H and delta 18O of plant and soil water reveal changes in ecosystem hydrology that accompanied this grassland-to-woodland transition. In the Rio Grande Plains of North America, delta 13C values of plants and soils indicate that areas now dominated by C3 subtropical thorn woodland were once C4 grasslands. delta 13C values of current organic matter inputs from wooded landscape elements in this region are characteristic of C3 plants (-28 to -25/1000), while those of the associated soil organic carbon are higher and range from -20 to -15/1000. Approximately 50-90% of soil carbon beneath the present C3 woodlands is derived from C4 grasses. A strong memory of the C4 grasslands that once dominated this region is retained by delta 13C values of organic carbon associated with fine and coarse clay fractions. When delta 13C values are evaluated in conjunction with 14C measurements of that same soil carbon, it appears that grassland-to-woodland conversion occurred largely within the past 40-120 years, coincident with the intensification of livestock grazing and reductions in fire frequency. These conclusions substantiate those based on demographic characteristics of the dominant tree species, historical aerial photography, and accounts of early settlers and explores. Concurrent changes in soil delta 13C values and organic carbon content over the past 90 years also indicate that wooded landscape elements are behaving as sinks for

  3. Inputs of anthropogenic nitrogen influence isotopic composition and trophic structure in SE Australian estuaries.

    Science.gov (United States)

    Mazumder, Debashish; Saintilan, Neil; Alderson, Brendan; Hollins, Suzanne

    2015-11-15

    Urban development in coastal settings has increased the input of nitrogen into estuaries globally, in many cases changing the composition of estuarine ecosystems. By focussing on three adjacent estuaries with a gradient of anthropogenic N loadings, we used stable isotopes of N and C to test for changes due to increased anthropogenic N input on the structure of some key trophic linkages in estuaries. We found a consistent enrichment in δ(15)N corresponding to increased anthropogenic N at the three ecosystem levels studied: fine benthic organic matter, grazing invertebrate, and planktivorous fish. The degree of enrichment in δ(15)N between fine benthic organic matter and the grapsid crab Parasesarma erythrodactyla was identical across the three sites. The glassfish Ambassis jacksoniensis showed lower levels of enrichment compared to basal food sources at the higher N-loaded sites, suggesting a possible effect of anthropogenic N in decreasing food-chain length in these estuaries. Copyright © 2015 Elsevier Ltd. All rights reserved.

  4. Calcium Isotopic Evidence for Vulnerable Marine Ecosystem Structure Prior to the K/Pg Extinction.

    Science.gov (United States)

    Martin, Jeremy E; Vincent, Peggy; Tacail, Théo; Khaldoune, Fatima; Jourani, Essaid; Bardet, Nathalie; Balter, Vincent

    2017-06-05

    The collapse of marine ecosystems during the end-Cretaceous mass extinction involved the base of the food chain [1] up to ubiquitous vertebrate apex predators [2-5]. Large marine reptiles became suddenly extinct at the Cretaceous-Paleogene (K/Pg) boundary, whereas other contemporaneous groups such as bothremydid turtles or dyrosaurid crocodylomorphs, although affected at the familial, genus, or species level, survived into post-crisis environments of the Paleocene [5-9] and could have found refuge in freshwater habitats [10-12]. A recent hypothesis proposes that the extinction of plesiosaurians and mosasaurids could have been caused by an important drop in sea level [13]. Mosasaurids are unusually diverse and locally abundant in the Maastrichtian phosphatic deposits of Morocco, and with large sharks and one species of elasmosaurid plesiosaurian recognized so far, contribute to an overabundance of apex predators [3, 7, 14, 15]. For this reason, high local diversity of marine reptiles exhibiting different body masses and a wealth of tooth morphologies hints at complex trophic interactions within this latest Cretaceous marine ecosystem. Using calcium isotopes, we investigated the trophic structure of this extinct assemblage. Our results are consistent with a calcium isotope pattern observed in modern marine ecosystems and show that plesiosaurians and mosasaurids indiscriminately fall in the tertiary piscivore group. This suggests that marine reptile apex predators relied onto a single dietary calcium source, compatible with the vulnerable wasp-waist food webs of the modern world [16]. This inferred peculiar ecosystem structure may help explain plesiosaurian and mosasaurid extinction following the end-Cretaceous biological crisis. Copyright © 2017 Elsevier Ltd. All rights reserved.

  5. Ultra-sensitive probe of spectral line structure and detection of isotopic oxygen

    Science.gov (United States)

    Garner, Richard M.; Dharamsi, A. N.; Khan, M. Amir

    2018-01-01

    We discuss a new method of investigating and obtaining quantitative behavior of higher harmonic (> 2f) wavelength modulation spectroscopy (WMS) based on the signal structure. It is shown that the spectral structure of higher harmonic WMS signals, quantified by the number of zero crossings and turnings points, can have increased sensitivity to ambient conditions or line-broadening effects from changes in temperature, pressure, or optical depth. The structure of WMS signals, characterized by combinations of signal magnitude and spectral locations of turning points and zero crossings, provides a unique scale that quantifies lineshape parameters and, thus, useful in optimization of measurements obtained from multi-harmonic WMS signals. We demonstrate this by detecting weaker rotational-vibrational transitions of isotopic atmospheric oxygen (16O18O) in the near-infrared region where higher harmonic WMS signals are more sensitive contrary to their signal-to-noise ratio considerations. The proposed approach based on spectral structure provides the ability to investigate and quantify signals not only at linecenter but also in the wing region of the absorption profile. This formulation is particularly useful in tunable diode laser spectroscopy and ultra-precision laser-based sensors where absorption signal profile carries information of quantities of interest, e.g., concentration, velocity, or gas collision dynamics, etc.

  6. New techniques of laser spectroscopy on exotic isotopes of gallium and francium

    CERN Document Server

    Procter, Thomas John

    The neutron-deficient gallium isotopes down to ${N}$=32 have had their hyperfine structures and isotope shifts measured via collinear laser spectroscopy using the COLLAPS (COllinear LAser sPectroScopy) beam line. The ground-state spin of $^{63}$Ga has been determined as ${I}$ = 3/2 and its magnetic dipole and electric quadrupole moments were measured to be $\\mu$ = +1.469(5) $_{\\mu N}$ and ${ Q}$s = +0.212(14) b respectively. The nuclear moments of $^{70}$Ga were measured to be ${\\mu}$= +0.571(2) $_{\\mu}$ and ${Q}$s = +0.105(7) b. New isotope shift results were combined with previously measured values of the neutron-rich isotopes and the changes in mean-square charge radii of the entire gallium isotope chain were investigated. Analysis of the trend in the neutron-deficient charge radii demonstrated that there is no evidence of anomalous charge radii behaviour in gallium in the region of ${N}$=32. A sudden increase of the charge radii was observed at the ${N}$=50 shell gap and an inversion of the normal odd-eve...

  7. Biomarker and carbon isotopic constraints on bacterial and algal community structure and functioning in a turbid, tidal estuary

    NARCIS (Netherlands)

    Boschker, H.T.S.; Kromkamp, J.C.; Middelburg, J.J.

    2005-01-01

    We studied planktonic community structure and isotopic composition using compound-specific 13C analysis of phospholipid-derived fatty acids (PLFA) along the Scheldt estuary during a spring bloom. A comprehensive set of other carbon cycle parameters was also determined. Based on dissolved carbon

  8. Controlling the Rotational and Hyperfine State of Ultracold $^{87}$Rb$^{133}$Cs Molecules

    CERN Document Server

    Gregory, Philip D; Hutson, Jeremy M; Cornish, Simon L

    2016-01-01

    We demonstrate coherent control of both the rotational and hyperfine state of ultracold, chemically stable $^{87}$Rb$^{133}$Cs molecules with external microwave ?fields. We create a sample of ~2000 molecules in the lowest hyperfine level of the rovibronic ground state N = 0. We measure the transition frequencies to 8 different hyperfine levels of the N = 1 state at two magnetic fields ~23 G apart. We determine accurate values of rotational and hyperfine coupling constants that agree well with previous calculations. We observe Rabi oscillations on each transition, allowing complete population transfer to a selected hyperfine level of N = 1. Subsequent application of a second microwave pulse allows transfer of molecules back to a different hyperfine level of N = 0.

  9. Long-term sunspot forcing of savanna structure inferred from carbon and oxygen isotopes

    Science.gov (United States)

    Woodborne, Stephan; Mélice, Jean-Luc; Scholes, Robert J.

    2008-01-01

    We used the δ 18O and δ 13C isotopes from a speleothem and Δ14C values from known age tree rings as proxies for vegetation structure, rainfall and sunspot activity over the last 10,000 years. The δ 18O and δ 13C signals are significantly correlated and wavelet coherence analysis shows that a phase locked responses is only found to occur over periods less than 150 years. The δ 13C and Δ14C signals are also significantly correlated but the wavelet coherence analysis shows phase locked responses at periods in the order of 320 and 1100 years at various times in the past. We conclude that savanna vegetation structure responds to rainfall over periods of decades to about 150 years, and to solar forcing over periods greater than 150 years. We propose that elevated UV-B radiation at the earth surface during periods of low sunspot activity favours the productivity of C4 plants over C3 plants possibly because of the metabolic cost of structural adaptive responses and of producing UV-B absorbing compounds in the latter.

  10. Self- and dopant diffusion in extrinsic boron doped isotopically controlled silicon multilayer structures

    Energy Technology Data Exchange (ETDEWEB)

    Sharp, Ian D.; Bracht, Hartmut A.; Silvestri, Hughes H.; Nicols, Samuel P.; Beeman, Jeffrey W.; Hansen, John L.; Nylandsted Larsen, Arne; Haller, Eugene E.

    2002-04-01

    Isotopically controlled silicon multilayer structures were used to measure the enhancement of self- and dopant diffusion in extrinsic boron doped silicon. {sup 30}Si was used as a tracer through a multilayer structure of alternating natural Si and enriched {sup 28}Si layers. Low energy, high resolution secondary ion mass spectrometry (SIMS) allowed for simultaneous measurement of self- and dopant diffusion profiles of samples annealed at temperatures between 850 C and 1100 C. A specially designed ion- implanted amorphous Si surface layer was used as a dopant source to suppress excess defects in the multilayer structure, thereby eliminating transient enhanced diffusion (TED) behavior. Self- and dopant diffusion coefficients, diffusion mechanisms, and native defect charge states were determined from computer-aided modeling, based on differential equations describing the diffusion processes. We present a quantitative description of B diffusion enhanced self-diffusion in silicon and conclude that the diffusion of both B and Si is mainly mediated by neutral and singly positively charged self-interstitials under p-type doping. No significant contribution of vacancies to either B or Si diffusion is observed.

  11. Metastable structures and isotope exchange reactions in polyoxometalate ions provide a molecular view of oxide dissolution

    Science.gov (United States)

    Rustad, James R.; Casey, William H.

    2012-03-01

    Reactions involving minerals and glasses in water are slow and difficult to probe spectroscopically but are fundamental to the performance of oxide materials in green technologies such as automotive thermoelectric power generation, CO2 capture and storage and water-oxidation catalysis; these must be made from geochemically common elements and operate in hydrous environments. Polyoxometalate ions (POMs) have structures similar to condensed oxide phases and can be used as molecular models of the oxide/water interface. Oxygen atoms in POM exchange isotopes at different rates, but, at present, there is no basis for predicting how the coordination environment and metal substitution influences rates and mechanisms. Here we identify low-energy metastable configurations that form from the breaking of weak bonds between metals and underlying highly coordinated oxygen atoms, followed by facile hydroxide, hydronium or water addition. The mediation of oxygen exchange by these stuffed structures suggests a new view of the relationship between structure and reactivity at the oxide/solution interface.

  12. Nuclear structure studies of rare francium isotopes using Collinear Resonance Ionization Spectroscopy (CRIS)

    CERN Document Server

    AUTHOR|(CDS)2084441

    It was known for many years that nuclei possessing certain numbers of protons (Z) and neutrons (N), called the magic numbers (8,20,28,50,82,126...), exhibit characteristic behavior and are in general more stable than their neighboring isotopes. As the capabilities of producing isotopes with more extreme values of Z and N increased, it was realized that those spherical nuclei only represent a small fraction of the total number of isotopes and that most isotopes are deformed. In order to study exotic isotopes and their deformation, it was necessary to develop new experimental techniques that would be powerful enough to be able to cope with very small production yields, but precise enough to measure the nuclear properties (such as radii and moments) with relatively small uncertainties. One technique that can measure nuclear properties of scarcely produced isotopes is in-source resonant ionization, but this technique does not allow for sufficient precision to deduce nuclear quadrupole moments. Furthermore, this t...

  13. Computation of hyperfine tensors for dinuclear Mn(III) Mn(IV) complexes by broken-symmetry approaches: anisotropy transfer induced by local zero-field splitting.

    Science.gov (United States)

    Schraut, Johannes; Arbuznikov, Alexei V; Schinzel, Sandra; Kaupp, Martin

    2011-12-09

    Based on broken-symmetry density functional calculations, the (55)Mn hyperfine tensors of a series of exchange-coupled, mixed-valence, dinuclear Mn(III) Mn(IV) complexes have been computed. We go beyond previous quantum chemical work by fully including the effects of local zero-field splitting (ZFS) interactions in the spin projection, following the first-order perturbation formalism of Sage et al. [J. Am. Chem. Soc. 1989, 111, 7239]. This allows the ZFS-induced transfer of hyperfine anisotropy from the Mn(III) site to the Mn(IV) site to be described with full consideration of the orientations of local hyperfine and ZFS tensors. After scaling to correct for systematic deficiencies in the quantum chemically computed local ZFS tensors, good agreement with experimental (55)Mn anisotropies at the Mn(IV) site is obtained. The hyperfine coupling anisotropies on the Mn(III) site depend sensitively on structural distortions for a d(4) ion. The latter are neither fully reproduced by using a DFT-optimized coordination environment nor by using experimental structures. For very small exchange-coupling constants, the perturbation treatment breaks down and a dramatic sensitivity to the scaling of the local ZFS tensors is observed. These results are discussed with respect to ongoing work to elucidate the structure of the oxygen-evolving complex of photosystem II by analysis of the EPR spectra. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Exchange variation of hyperfine characteristics of tetrameric [Mn 3(III)Mn(IV)] and [Mn 3(IV)Mn(III)] clusters

    Science.gov (United States)

    Belinskii, M. I.

    1994-12-01

    The dependences of the cluster g-factor, the effective hyperfine constants Ai and the hyperfine structure of the EPR signal on the exchange interaction were studied for the [Mn 3(III)Mn(IV)] and [Mn 3(IV)Mn(III)] clusters - possible prototypes of the Mn center of Photosystem II in the S 2 state. The mixing of the states with different S12 intermediate spins in the Heisenberg model HB = -2[ J12s1s2 + Jα( s1s3 + s1s4) + Jβ( s2s3 + s2s4) + J34s3s4] leads to essential exchange modification of the expectation values for each manganese ion. The exchange dependence of the Ki = / coefficients results in the exchange modification and reduction of the cluster g-factor. The / variations control also the values and signs of the effective hyperfine constants Ai. The Ai( Jtm) exchange dependences for the S = 1/2 ground state of the [Mn 3(III)Mn(IV)] and [Mn 3(IV)Mn(III)] clusters with complex structures were obtained in the framework of the general Heisenberg model of tetramer. The calculated hyperfine structures show a strong dependence on the total spin, intermediate spins and on the variation of the Heisenberg exchange parameters.

  15. Calculated hyperfine coupling constants for 5,5-dimethyl-1-pyrroline N-oxide radical products in water and benzene

    Science.gov (United States)

    Nardali, Ş.; Ucun, F.; Karakaya, M.

    2017-11-01

    The optimized structures of some radical adducts of 5,5-dimethyl-1-pyrroline N-oxide were computed by different methods on ESR spectra. As trapped radicals, H, N3, NH2, CH3, CCl3, OOH in water and F, OH, CF3, CH2OH, OC2H5 in benzene solutions were used. The calculated isotropic hyperfine coupling constants of all the trapped radicals were compared with the corresponding experimental data. The hyperfine coupling constant due to the β proton of the nitroxide radical was seen to be consist with the McConnel's relation αβ = B 0 + B 1cos2θ and, to be effected with the opposite spin density of oxygen nucleus bonded to the nitrogen. It was concluded that in hyperfine calculations the DFT(B3PW91)/LanL2DZ level is superior computational quantum model relative to the used other level. Also, the study has been enriched by the computational of the optimized geometrical parameters, the hyper conjugative interaction energies, the atomic charges and spin densities for all the radical adducts.

  16. Stable isotope assessment of water quality, primary productivity, nutrient sources, and food web structure in Lake Winnipeg

    Science.gov (United States)

    Wassenaar, L. I.

    2008-12-01

    Lake Winnipeg (Canada) is a shallow great lake currently undergoing extensive eutrophication. A 4-year stable isotope project is currently underway to examine water quality, primary productivity, nutrient sources, and food web structure in the lake. The isotope hydrology (18O, 2H) of Lake Winnipeg is needed in order to gain a picture of spatial isotopic patterns in the lake that can be related to the unique fingerprints imposed by contributing watersheds, and to verify hydrodynmamic mixing models. Stable isotope assays of key nutrients (nitrate, phosphate), particulate organic matter (POM), and dissolved oxygen in Lake Winnipeg are being applied to assess (1) the sources of nutrients, (2) the sources of the organic matter (internal vs external), (3) the biogeochemical cycling of nutrients and organic matter that lead to algal formation and enhanced biological oxygen demand and 4) quantify the rates of aquatic photoautotrophic activity, respiration and gas exchange. Altogether, these assays will allow us to better link nutrient sources and cycling to enhanced aquatic productivity. Foodweb structure and function is being examined using 13C and 15N while DH and 34S are being evaluated as tracer of inter basin fish migration. Only if the current foodweb structure is well understood can predictions regarding the negative impacts of eutrophication and invasive species on the foodweb be possible.

  17. Structural, microstructural and hyperfine properties of nanocrystalline iron particles

    Energy Technology Data Exchange (ETDEWEB)

    Guittoum, A., E-mail: guittoum@yahoo.f [Centre de Recherche Nucleaire d' Alger, 2 Bd Frantz Fanon, BP 399 Alger-Gare, Alger (Algeria); Layadi, A. [Departement de Physique, Faculte des Sciences, Universite Ferhat Abbas, Setif 19000 (Algeria); Tafat, H. [Faculte de Mecanique et Genie des Procedes, USTHB de Bab Ezzouar (Algeria); Souami, N. [Centre de Recherche Nucleaire d' Alger, 2 Bd Frantz Fanon, BP 399 Alger-Gare, Alger (Algeria)

    2010-03-15

    Nanocrystalline Fe particles were successfully prepared by the mechanical milling process using a high-energy planetary ball mill. The physical properties of the samples were investigated as a function of the milling time, t (in the 0-54 h range) by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray (EDX) and Moessbauer spectroscopy. After 54 h of milling, the lattice parameter increases from 0.28620 (3) nm for the starting Fe powder to 0.28667 (3) nm, the grain size decreases from 110 to 13 nm, while the strain increases from 0.09% to 0.7%. The powder particle morphology was observed by SEM at different stages of milling. For t less than 24 h, the Moessbauer spectra are characterized by one sextet corresponding to the crystalline bcc Fe phase, while for t greater than 24 h, the iron particles exhibit a two-component Moessbauer spectrum due to the presence of two phases: the crystallites bcc Fe phase and the grain-boundary region. The appearance and the increase in intensity of the second sextet with t may indicate that the interfacial region effect increases with milling time due to the grain size reduction and a probable disordered state of the grain boundaries.

  18. Hyperfine Structure and Exchange Narrowing of Paramagnetic Resonance

    Science.gov (United States)

    Townes, C. H.; Turkevich, J.

    1950-01-01

    Discussion of electronic paramagnetic resonance for the free radical á, á-diphenyl â-picryl hydrazyl as observed by its effect on the transmission of microwave through a TE{sub 01} cavity with a small amount of the free radical placed approximately on the axis of the cavity; the half-width of this resonance at half maximum absorption was 1.45 oersteds.

  19. High precision hyperfine measurements in Bismuth challenge bound-state strong-field QED.

    Science.gov (United States)

    Ullmann, Johannes; Andelkovic, Zoran; Brandau, Carsten; Dax, Andreas; Geithner, Wolfgang; Geppert, Christopher; Gorges, Christian; Hammen, Michael; Hannen, Volker; Kaufmann, Simon; König, Kristian; Litvinov, Yuri A; Lochmann, Matthias; Maaß, Bernhard; Meisner, Johann; Murböck, Tobias; Sánchez, Rodolfo; Schmidt, Matthias; Schmidt, Stefan; Steck, Markus; Stöhlker, Thomas; Thompson, Richard C; Trageser, Christian; Vollbrecht, Jonas; Weinheimer, Christian; Nörtershäuser, Wilfried

    2017-05-16

    Electrons bound in highly charged heavy ions such as hydrogen-like bismuth 209 Bi 82+ experience electromagnetic fields that are a million times stronger than in light atoms. Measuring the wavelength of light emitted and absorbed by these ions is therefore a sensitive testing ground for quantum electrodynamical (QED) effects and especially the electron-nucleus interaction under such extreme conditions. However, insufficient knowledge of the nuclear structure has prevented a rigorous test of strong-field QED. Here we present a measurement of the so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like bismuth 209 Bi 82+,80+ with a precision that is improved by more than an order of magnitude. Even though this quantity is believed to be largely insensitive to nuclear structure and therefore the most decisive test of QED in the strong magnetic field regime, we find a 7-σ discrepancy compared with the theoretical prediction.

  20. High precision hyperfine measurements in Bismuth challenge bound-state strong-field QED

    Science.gov (United States)

    Ullmann, Johannes; Andelkovic, Zoran; Brandau, Carsten; Dax, Andreas; Geithner, Wolfgang; Geppert, Christopher; Gorges, Christian; Hammen, Michael; Hannen, Volker; Kaufmann, Simon; König, Kristian; Litvinov, Yuri A.; Lochmann, Matthias; Maaß, Bernhard; Meisner, Johann; Murböck, Tobias; Sánchez, Rodolfo; Schmidt, Matthias; Schmidt, Stefan; Steck, Markus; Stöhlker, Thomas; Thompson, Richard C.; Trageser, Christian; Vollbrecht, Jonas; Weinheimer, Christian; Nörtershäuser, Wilfried

    2017-05-01

    Electrons bound in highly charged heavy ions such as hydrogen-like bismuth 209Bi82+ experience electromagnetic fields that are a million times stronger than in light atoms. Measuring the wavelength of light emitted and absorbed by these ions is therefore a sensitive testing ground for quantum electrodynamical (QED) effects and especially the electron-nucleus interaction under such extreme conditions. However, insufficient knowledge of the nuclear structure has prevented a rigorous test of strong-field QED. Here we present a measurement of the so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like bismuth 209Bi82+,80+ with a precision that is improved by more than an order of magnitude. Even though this quantity is believed to be largely insensitive to nuclear structure and therefore the most decisive test of QED in the strong magnetic field regime, we find a 7-σ discrepancy compared with the theoretical prediction.

  1. Nuclear moments and charge radii of magnesium isotopes from N=8 up to (and beyond) N=20

    CERN Multimedia

    Mattolat, C F; Mallion, S N; Himpe, P

    2002-01-01

    We propose to measure the nuclear monopole, dipole and quadrupole moments of magnesium isotopes from the neutron deficient nuclei near the N=8 shell closure ($^{21}$Mg), up to the neutron rich Mg nuclei beyond N=20 ($^{33}$Mg). The physics issues that will be addressed in this project are related to: \\begin{itemize} \\item The properties of mirror nuclei (e.g. $^{21}$Mg - $^{21}$F being members of a T=3/2 multiplet) \\item The evolution of shell structure and deformation with isospin. \\item Changes in the shell structure in the "island of inversion" around $^{32}$Mg and along the N=9 isotones. \\end{itemize} Radioactive beams of Mg isotopes will be produced by the RILlS ion source. The Mg isotopes will be resonantly polarized at the COLLAPS set-up. With $\\beta$-NMR techniques, precision measurements of g-factors and quadrupole moments of the radioactive $^{21,23}$Mg and $^{29,31,33}$Mg isotopes will be performed. Isotope shifts, thus changes in mean square charge radii, will be deduced from hyperfine spectra mea...

  2. Measuring the Effect of Fuel Structures and Blend Distribution on Diesel Emissions Using Isotope Tracing

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, A S; Mueller, C J; Buchholz, B A; Dibble, R W

    2004-02-10

    Carbon atoms occupying specific positions within fuel molecules can be labeled and followed in emissions. Renewable bio-derived fuels possess a natural uniform carbon-14 ({sup 14}C) tracer several orders of magnitude above petroleum-derived fuels. These fuels can be used to specify sources of carbon in particulate matter (PM) or other emissions. Differences in emissions from variations in the distribution of a fuel component within a blend can also be measured. Using Accelerator Mass Spectrometry (AMS), we traced fuel components with biological {sup 14}C/C levels of 1 part in 10{sup 12} against a {sup 14}C-free petroleum background in PM and CO{sub 2}. Different carbon atoms in the ester structure of the diesel oxygenate dibutyl maleate displayed far different propensities to produce PM. Homogeneous cosolvent and heterogeneous emulsified ethanol-in-diesel blends produced significantly different PM despite having the same oxygen content in the fuel. Emulsified blends produced PM with significantly more volatile species. Although ethanol-derived carbon was less likely to produce PM than diesel fuel, it formed non-volatile structures when it resided in PM. The contribution of lubrication oil to PM was determined by measuring an isotopic difference between 100% bio-diesel and the PM it produced. Data produced by the experiments provides validation for combustion models.

  3. A study of platinum-supported catalysts through hyperfine interactions

    Science.gov (United States)

    Saitovitch, H.; Silva, P. R. J.; Rodriguez, A. M.; Weberszpil, J.; Passos, F. B.; Schmal, M.

    1994-12-01

    The effect of indium addition on alumina-supported platinum catalysts was investigated by measurements of hyperfine interactions. Via lime differential perturbed angular correlation spectroscopy (TDPAC) on111Cd, Pt/Al2O3 catalysts were studied in the flow of a heptane/H2 gas stream. The results indicate that some amount of indium sticks to platinum which is then dispersed on the support surface. The amount of In that is free from platinum is mobile under reaction conditions, being capable of diluting platinum particles and draining off coke precursors from the platinum surface.

  4. A study of platinum-supported catalysts through hyperfine interactions

    Energy Technology Data Exchange (ETDEWEB)

    Saitovitch, H. (Centro Brasileiro de Pesquisas Fisicas (CBPF/CNPq), Rio de Janeiro, RJ (Brazil)); Silva, P.R.J. (Centro Brasileiro de Pesquisas Fisicas (CBPF/CNPq), Rio de Janeiro, RJ (Brazil)); Rodriguez, A.M. (Centro Brasileiro de Pesquisas Fisicas (CBPF/CNPq), Rio de Janeiro, RJ (Brazil)); Weberszpil, J. (Centro Brasileiro de Pesquisas Fisicas (CBPF/CNPq), Rio de Janeiro, RJ (Brazil)); Passos, F.B. (Dept. Eng. Quimica, Univ. Fed. Fluminense, Niteroi, RJ (Brazil)); Schmal, M. (COPPE/EQ, Univ. Fed. Rio de Janeiro, RJ (Brazil))

    1994-05-01

    The effect of indium addition on alumina-supported platinum catalysts was investigated by measurements of hyperfine interactions. Via time differential perturbed angular correlation spectroscopy (TDPAC) on [sup 111]Cd, Pt/Al[sub 2]O[sub 3] catalysts were studied in the flow of a heptane/H[sub 2] gas stream. The results indicate that some amount of indium sticks to platinum which is then dispersed on the support surface. The amount of In that is free from platinum is mobile under reaction conditions, being capable of diluting platinum particles and draining off coke precursors from the platinum surface. (orig.)

  5. Pre-Existing Carbon Structure and Its Effect on Site-Specific Carbon Isotopes in Small Organic Molecules

    Science.gov (United States)

    Piasecki, A.; Eiler, J. M.

    2014-12-01

    The ability to measure site-specific isotopes in organic molecules allows for better understanding of the mechanisms of their biosynthetic and/or catagenic formation and destruction. Here we examine for site-specific isotopic composition of propane from natural and synthetic sources using novel instruments and techniques gas source mass spectrometry 1, and discuss the possible relationship of our findings to recent independent evidence from NMR measurements for the isotopic structures of long-chain alkanes2. A recent NMR study2 demonstrates that n-alkanes can be divided into three groups according to their site-specific carbon isotope structure: long (C16+) even carbon number, long (C17+) odd carbon number , and short (C11-C15). We modeled the isotopic site-specific composition of propane derived from these three distinct groups. If propane is cleaved from such long-chain hydrocarbons without fractionation, the long odd-numbered and the shorter alkanes would produce propane with an average terminal position 6-7‰ lighter than the center position, while the long even-numbered chain compounds would produce propane with a terminal position averaging around 7‰ heavier than the center. If, instead the fractionation associated with cleaving propane from such parent molecules is ~10‰ (as seems likely), then these average terminal — center differences should be decreased by ~5 ‰ (i.e., to -11-12 and +1-2 ‰, respectively). We will compare these predictions with our previous demonstrations of the changes in bulk and site specific compositions in propane due to isotope exchange equilibria, diffusion and conventional models of kerogen 'cracking', and will use these models as a framework for interpreting the observed site-specific isotopic compositions of propane from diverse natural gas deposits. 1. Piasecki, A. et al. Site-Specific Carbon Isotope Measurement of Organics by Gas Source Mass Spectrometry. Mineralogical Magazine 77, (2013). 2. Gilbert, A., Yamada, K

  6. Spatial subsidies in spider diets vary with shoreline structure: Complementary evidence from molecular diet analysis and stable isotopes.

    Science.gov (United States)

    Hambäck, Peter A; Weingartner, Elisabeth; Dalén, Love; Wirta, Helena; Roslin, Tomas

    2016-12-01

    Inflow of matter and organisms may strongly affect the local density and diversity of organisms. This effect is particularly evident on shores where organisms with aquatic larval stages enter the terrestrial food web. The identities of such trophic links are not easily estimated as spiders, a dominant group of shoreline predator, have external digestion. We compared trophic links and the prey diversity of spiders on different shore types along the Baltic Sea: on open shores and on shores with a reed belt bordering the water. A priori, we hypothesized that the physical structure of the shoreline reduces the flow between ecosystem and the subsidies across the sea-land interface. To circumvent the lack of morphologically detectable remains of spider prey, we used a combination of stable isotope and molecular gut content analyses. The two tools used for diet analysis revealed complementary information on spider diets. The stable isotope analysis indicated that spiders on open shores had a marine signal of carbon isotopes, while spiders on reedy shores had a terrestrial signal. The molecular analysis revealed a diverse array of dipteran and lepidopteran prey, where spiders on open and reedy shores shared a similar diet with a comparable proportion of chironomids, the larvae of which live in the marine system. Comparing the methods suggests that differences in isotope composition of the two spider groups occurred because of differences in the chironomid diets: as larvae, chironomids of reedy shores likely fed on terrestrial detritus and acquired a terrestrial isotope signature, while chironomids of open shores utilized an algal diet and acquired a marine isotope signature. Our results illustrate how different methods of diet reconstruction may shed light on complementary aspects of nutrient transfer. Overall, they reveal that reed belts can reduce connectivity between habitats, but also function as a source of food for predators.

  7. Population-level metrics of trophic structure based on stable isotopes and their application to invasion ecology.

    Science.gov (United States)

    Jackson, Michelle C; Donohue, Ian; Jackson, Andrew L; Britton, J Robert; Harper, David M; Grey, Jonathan

    2012-01-01

    Biological invasions are a significant driver of human-induced global change and many ecosystems sustain sympatric invaders. Interactions occurring among these invaders have important implications for ecosystem structure and functioning, yet they are poorly understood. Here we apply newly developed metrics derived from stable isotope data to provide quantitative measures of trophic diversity within populations or species. We then use these to test the hypothesis that sympatric invaders belonging to the same functional feeding group occupy a smaller isotopic niche than their allopatric counterparts. Two introduced, globally important, benthic omnivores, Louisiana swamp crayfish (Procambarus clarkii) and carp (Cyprinus carpio), are sympatric in Lake Naivasha, Kenya. We applied our metrics to an 8-year data set encompassing the establishment of carp in the lake. We found a strong asymmetric interaction between the two invasive populations, as indicated by inverse correlations between carp abundance and measures of crayfish trophic diversity. Lack of isotopic niche overlap between carp and crayfish in the majority of years indicated a predominantly indirect interaction. We suggest that carp-induced habitat alteration reduced the diversity of crayfish prey, resulting in a reduction in the dietary niche of crayfish. Stable isotopes provide an integrated signal of diet over space and time, offering an appropriate scale for the study of population niches, but few isotope studies have retained the often insightful information revealed by variability among individuals in isotope values. Our population metrics incorporate such variation, are robust to the vagaries of sample size and are a useful additional tool to reveal subtle dietary interactions among species. Although we have demonstrated their applicability specifically using a detailed temporal dataset of species invasion in a lake, they have a wide array of potential ecological applications.

  8. Population-level metrics of trophic structure based on stable isotopes and their application to invasion ecology.

    Directory of Open Access Journals (Sweden)

    Michelle C Jackson

    Full Text Available Biological invasions are a significant driver of human-induced global change and many ecosystems sustain sympatric invaders. Interactions occurring among these invaders have important implications for ecosystem structure and functioning, yet they are poorly understood. Here we apply newly developed metrics derived from stable isotope data to provide quantitative measures of trophic diversity within populations or species. We then use these to test the hypothesis that sympatric invaders belonging to the same functional feeding group occupy a smaller isotopic niche than their allopatric counterparts. Two introduced, globally important, benthic omnivores, Louisiana swamp crayfish (Procambarus clarkii and carp (Cyprinus carpio, are sympatric in Lake Naivasha, Kenya. We applied our metrics to an 8-year data set encompassing the establishment of carp in the lake. We found a strong asymmetric interaction between the two invasive populations, as indicated by inverse correlations between carp abundance and measures of crayfish trophic diversity. Lack of isotopic niche overlap between carp and crayfish in the majority of years indicated a predominantly indirect interaction. We suggest that carp-induced habitat alteration reduced the diversity of crayfish prey, resulting in a reduction in the dietary niche of crayfish. Stable isotopes provide an integrated signal of diet over space and time, offering an appropriate scale for the study of population niches, but few isotope studies have retained the often insightful information revealed by variability among individuals in isotope values. Our population metrics incorporate such variation, are robust to the vagaries of sample size and are a useful additional tool to reveal subtle dietary interactions among species. Although we have demonstrated their applicability specifically using a detailed temporal dataset of species invasion in a lake, they have a wide array of potential ecological applications.

  9. Spectra of charmed and bottom baryons with hyperfine interaction

    Science.gov (United States)

    Wang, Zhen-Yang; Qi, Jing-Juan; Guo, Xin-Heng; Wei, Ke-Wei

    2017-09-01

    Up to now, the excited charmed and bottom baryon states have still not been well studied experimentally or theoretically. In this paper, we predict the mass of , the only L = 0 baryon state which has not been observed, to be 6069.2 MeV. The spectra of charmed and bottom baryons with the orbital angular momentum L = 1 are studied in two popular constituent quark models, the Goldstone boson exchange (GBE) model and the one gluon exchange (OGE) hyperfine interaction model. Inserting the latest experimental data from the “Review of Particle Physics", we find that in the GBE model, there exist some multiplets (Σc(b), and Ωc(b)) in which the total spin of the three quarks in their lowest energy states is 3/2, but in the OGE model there is no such phenomenon. This is the most important difference between the GBE and OGE models. These results can be tested in the near future. We suggest more efforts to study the excited charmed and bottom baryons both theoretically and experimentally, not only for the abundance of baryon spectra, but also for determining which hyperfine interaction model best describes nature. Supported by National Natural Science Foundation of China (11175020, 11575023, U1204115)

  10. All-Optical dc Nanotesla Magnetometry Using Silicon Vacancy Fine Structure in Isotopically Purified Silicon Carbide

    Directory of Open Access Journals (Sweden)

    D. Simin

    2016-07-01

    Full Text Available We uncover the fine structure of a silicon vacancy in isotopically purified silicon carbide (4H-^{28}SiC and reveal not yet considered terms in the spin Hamiltonian, originated from the trigonal pyramidal symmetry of this spin-3/2 color center. These terms give rise to additional spin transitions, which would be otherwise forbidden, and lead to a level anticrossing in an external magnetic field. We observe a sharp variation of the photoluminescence intensity in the vicinity of this level anticrossing, which can be used for a purely all-optical sensing of the magnetic field. We achieve dc magnetic field sensitivity better than 100  nT/sqrt[Hz] within a volume of 3×10^{-7}mm^{3} at room temperature and demonstrate that this contactless method is robust at high temperatures up to at least 500 K. As our approach does not require application of radio-frequency fields, it is scalable to much larger volumes. For an optimized light-trapping waveguide of 3  mm^{3}, the projection noise limit is below 100  fT/sqrt[Hz].

  11. Secondary deuterium isotope effects and transition state structure in the aromatic claisen rearrangement

    Energy Technology Data Exchange (ETDEWEB)

    McMichael, K.D.; Korver, G.L.

    1979-05-09

    Kinetic experiments were carried out simultaneously on separate methyl salicylate solutions of allyl phenyl ether and its deuterated phenyl analogues at 170 to 195/sup 0/C. Gas chromatographic analysis for allyl phenyl ether using an internal standard (anisole) and mechanical integration produced concentration/time data which were fitted to the exponential form of the first-order rate equation by a standard and nonlinear least-square program. At least 15 points were obtained for each run, covering 10 to 85% reaction. The derived isotope effects show no temperature dependence. Averages for 6 runs with each compound are k/sub H//k/sub ..cap alpha..-D/sub 2// = 1.18 and K/sub H//k/sub ..gamma..-D/sub 2// = 0.95. An equilibrium ..cap alpha.. effect of 1.30 and a ..gamma.. effect of 0.87 may be calculated for both deuterium atoms at 185/sup 0/C. These results show that the C--H vibration frequencies are approximately (1.18 - 1)/(1.27 - 1) or 57 to 77% of the way from those of allyl phenyl ether to those of the cyclohexadiene intermediate. The C--H frequencies of the ..gamma.. carbon in the transition state are about (0.95 - 1)/(0.88 - 1) or 22 to 62% of the way to those of the intermediate. The structure of the transition state, as far as these bonding frequencies are concerned, is consistent with the Claisen rearrangement.

  12. Calculation of Radiative Corrections to Hyperfine Splitting in p3/2 States

    Energy Technology Data Exchange (ETDEWEB)

    Sapirstein, J; Cheng, K T

    2008-07-15

    A recent calculation of the one-loop radiative correction to hyperfine splitting (hfs) of p{sub 1/2} states that includes binding corrections to all orders is extended to p{sub 3/2} states. Nuclear structure plays an essentially negligible role for such states, which is highly advantageous, as difficulties in controlling the Bohr-Weisskopf effect complicate the isolation of QED contributions for both s{sub 1/2} and p{sub 1/2} states. Three cases are studied. We first treat the hydrogen isoelectronic sequence, which is completely nonperturbative in Z{alpha} for high Z. Secondly the lowest lying p{sub 3/2} states of the neutral alkalis are treated, and finally lithium-like bismuth, where extensive theoretical and experimental studies of the hfs of 2s and 2p{sub 1/2} states have been made, is addressed.

  13. Fine and hyperfine excitation of C2H by collisions with He at low temperature

    Science.gov (United States)

    Spielfiedel, A.; Feautrier, N.; Najar, F.; Ben Abdallah, D.; Dayou, F.; Senent, M. L.; Lique, F.

    2012-04-01

    Modelling of molecular emission from interstellar clouds requires the calculation of rate coefficients for excitation by collisions with the most abundant species. From a new, highly correlated, two-dimensional potential energy surface, rotational excitation of the C2H(X2Σ+) molecule by collision with He is investigated. State-to-state collisional excitation cross-sections between the 25 first fine structure levels of C2H are calculated for energies up to 800 cm-1 which yields after thermal averaging rate coefficients up to T= 100 K. The exact spin splitting of the energy levels is taken into account. The recoupling technique introduced by Alexander & Dagdigian allows us to deduce the corresponding temperature-dependent hyperfine state-to-state rate coefficients. Propensity rules are discussed.

  14. Spatial variations in food web structures with alternative stable states: evidence from stable isotope analysis in a large eutrophic lake

    Science.gov (United States)

    Li, Yunkai; Zhang, Yuying; Xu, Jun; Zhang, Shuo

    2017-05-01

    Food web structures are well known to vary widely among ecosystems. Moreover, many food web studies of lakes have generally attempted to characterize the overall food web structure and have largely ignored internal spatial and environmental variations. In this study, we hypothesize that there is a high degree of spatial heterogeneity within an ecosystem and such heterogeneity may lead to strong variations in environmental conditions and resource availability, in turn resulting in different trophic pathways. Stable carbon and nitrogen isotopes were employed for the whole food web to describe the structure of the food web in different sub-basins within Taihu Lake. This lake is a large eutrophic freshwater lake that has been intensively managed and highly influenced by human activities for more than 50 years. The results show significant isotopic differences between basins with different environmental characteristics. Such differences likely result from isotopic baseline differences combining with a shift in food web structure. Both are related to local spatial heterogeneity in nutrient loading in waters. Such variation should be explicitly considered in future food web studies and ecosystem-based management in this lake ecosystem.

  15. Mössbauer studies of hyperfine fields in disordered Fe CrAl

    Indian Academy of Sciences (India)

    The paramagnetic part of the hyperfine field is explained in terms of the clustering of Cr atoms. Keywords. Mössbauer spectroscopy; disordered alloy; magnetic hyperfine fields. PACS Nos 75.50.Bb; 61.18.Fs. 1. Introduction. Heusler alloys are ternary alloys of stoichiometric composition bearing the general for- mula X2YZ.

  16. Fast-ion-beam laser probing of ion-source energy distributions and atomic structure

    Energy Technology Data Exchange (ETDEWEB)

    Holt, Richard A., E-mail: rholt@uwo.ca; Rosner, S. David [University of Western Ontario, Physics and Astronomy Department (Canada)

    2013-04-15

    Collinear fast-ion-beam laser spectroscopy is a very high resolution probe for measuring ion-beam energy distributions and atomic structure parameters of interest in nuclear physics, atomic physics, and astrophysics. We have used offline 10-keV beams of atomic ions and a CW laser system to study the behavior of a Penning ion source and to measure hyperfine structure, isotope shifts, atomic lifetimes, spontaneous-emission branching fractions, oscillator strengths, and absolute wavelengths of a variety of atomic species from the lanthanide and transition-metal groups.

  17. Detection of the Direct Hyperfine Transition of Positronium Atoms using sub-THz High-power Radiation

    OpenAIRE

    Suehara, T.; Miyazaki, A.; Yamazaki, T; G. Akimoto; Ishida, A; NAMBA, T; Asai, S.; Kobayashi, T; Saito, H.(Institute of Physics, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo 153-8902, Japan); Yoshida, M.; IDEHARA, T; Ogawa, I.; Urushizaki, Y.; SABCHEVSKI, S

    2010-01-01

    Hyperfine splitting of positronium is an important parameter for particle physics. This paper gives experimental techniques and results of R&D studies of our experiment to observe direct hyperfine transition of ortho-positronium to para-positronium.

  18. Evaluating ecological equivalence of created marshes: comparing structural indicators with stable isotope indicators of blue crab trophic support

    Science.gov (United States)

    Llewellyn, Chris; LaPeyre, Megan K.

    2010-01-01

    This study sought to examine ecological equivalence of created marshes of different ages using traditional structural measures of equivalence, and tested a relatively novel approach using stable isotopes as a measure of functional equivalence. We compared soil properties, vegetation, nekton communities, and δ13C and δ15N isotope values of blue crab muscle and hepatopancreas tissue and primary producers at created (5-24 years old) and paired reference marshes in SW Louisiana. Paired contrasts indicated that created and reference marshes supported equivalent plant and nekton communities, but differed in soil characteristics. Stable isotope indicators examining blue crab food web support found that the older marshes (8 years+) were characterized by comparable trophic diversity and breadth compared to their reference marshes. Interpretation of results for the youngest site was confounded by the fact that the paired reference, which represented the desired end goal of restoration, contained a greater diversity of basal resources. Stable isotope techniques may give coastal managers an additional tool to assess functional equivalency of created marshes, as measured by trophic support, but may be limited to comparisons of marshes with similar vegetative communities and basal resources, or require the development of robust standardization techniques.

  19. Trawling disturbance on the isotopic signature of a structure-building species, the sea urchin Gracilechinus acutus (Lamarck, 1816)

    Science.gov (United States)

    González-Irusta, José M.; Preciado, Izaskun; López-López, Lucia; Punzón, Antonio; Cartes, Joan E.; Serrano, Alberto

    2014-08-01

    Bottom trawling is one of the main sources of anthropogenic disturbance in benthic habitats with important direct and indirect effects on the ecosystem functional diversity. In this study, the effect of this impact on a structure-building species, the sea urchin Gracilechinus acutus, was studied in the Central Cantabrian Sea (southern Bay of Biscay) comparing its isotopic signature and additional population descriptors across different trawling pressures. Trawling disturbance had a significant effect on the studied descriptors. In trawling areas, this urchin showed significantly lower values of biomass and mean size and significantly higher values of fullness index. Moreover, the trawling disturbance effect was also significant in the isotopic signature of G. acutus. Urchins inhabiting untrawled areas showed significant lower values of δ15N than urchins dwelling areas under trawling pressure. The urchins' isotopic enrichment increased along the species ontogeny regardless of the trawling effort level. Stable isotope analyses are a suitable tool to detect trawling disturbance on the trophic pathways but do not suffice to explain these changes, especially if there is a lack of baseline information.

  20. Structure and superconductivity of isotope-enriched boron-doped diamond

    Directory of Open Access Journals (Sweden)

    Evgeny A Ekimov, Vladimir A Sidorov, Andrey V Zoteev, Yury B Lebed, Joe D Thompson and Sergey M Stishov

    2008-01-01

    Full Text Available Superconducting boron-doped diamond samples were synthesized with isotopes of 10B, 11B, 13C and 12C. We claim the presence of a carbon isotope effect on the superconducting transition temperature, which supports the 'diamond-carbon'-related nature of superconductivity and the importance of the electron–phonon interaction as the mechanism of superconductivity in diamond. Isotope substitution permits us to relate almost all bands in the Raman spectra of heavily boron-doped diamond to the vibrations of carbon atoms. The 500 cm−1 Raman band shifts with either carbon or boron isotope substitution and may be associated with vibrations of paired or clustered boron. The absence of a superconducting transition (down to 1.6 K in diamonds synthesized in the Co–C–B system at 1900 K correlates with the small boron concentration deduced from lattice parameters.

  1. Resolution of hyperfine transitions in metastable 83Kr using Electromagnetically Induced Transparency

    CERN Document Server

    Kale, Y B; Tiwari, V B; Singh, S; Rawat, H S

    2015-01-01

    Narrow linewidth signals of Electromagnetically Induced Transparency (EIT) in the metastable 83Kr have been observed for the first time. Various hyperfine transitions in 4p55s[3/2]2 to 4p55p[5/2]3 manifolds of 83Kr have been identified through the experimentally observed EIT signals. Some unresolved or poorly resolved hyperfine transitions in saturated absorption spectroscopy (SAS) are clearly resolved in the present work. Using the spectral separation of these EIT identified hyperfine transitions, the magnetic hyperfine constant (A) and the electric quadrupole hyperfine constant (B) are determined with improved accuracy for 4p55s[3/2]2 and 4p55p[5/2]3 manifolds.

  2. ISOTOPE SEPARATORS

    Science.gov (United States)

    Bacon, C.G.

    1958-08-26

    An improvement is presented in the structure of an isotope separation apparatus and, in particular, is concerned with a magnetically operated shutter associated with a window which is provided for the purpose of enabling the operator to view the processes going on within the interior of the apparatus. The shutier is mounted to close under the force of gravity in the absence of any other force. By closing an electrical circuit to a coil mouated on the shutter the magnetic field of the isotope separating apparatus coacts with the magnetic field of the coil to force the shutter to the open position.

  3. Shape-coexistence and shape-evolution studies for bismuth isotopes by insource laser spectroscopy and $\\beta$-delayed fission in $^{188}$Bi

    CERN Multimedia

    The proposal aims at the two main goals: \\\\ \\\\1) the studies of shape-coexistence and shape-evolution phenomena in the long chain of bismuth isotopes (Z=83) by in-source laser spectroscopy measurements of isotopic shifts (IS) and hyperfine structures (hfs), and \\\\ 2) $\\beta$-delayed fission ($\\beta$DF) of two isomeric states in $^{188}$Bi. \\\\ \\\\Isomer-selective $\\beta$DF studies for $^{188m1, 188m2}$Bi isomers will enable us for the first time to investigate the spin-dependence of the $\\beta$DF process and to check theoretical predictions of asymmetrical fission fragment mass-distribution in this region of nuclei. The measurements will be performed with the well-proven Windmill and MR-TOF MS/Penning Trap techniques.

  4. Fine and hyperfine collisional excitation of C6H by He

    Science.gov (United States)

    Walker, Kyle M.; Lique, François; Dawes, Richard

    2018-01-01

    Hydrogenated carbon chains have been detected in interstellar and circumstellar media and accurate modelling of their abundances requires collisional excitation rate coefficients with the most abundant species. Among them, the C6H molecule is one of the most abundant towards many lines of sight. Hence, we determined fine and hyperfine-resolved rate coefficients for the excitation of C6H(X2Π) due to collisions with He. We present the first interaction potential energy surface for the C6H-He system, obtained from highly correlated ab initio calculations and characterized by a large anisotropy due to the length of the molecule. We performed dynamical calculations for transitions among the first fine structure levels (up to J = 30.5) of both spin-orbit manifolds of C6H using the close-coupling method, and rate coefficients are determined for temperatures ranging from 5 to 100 K. The largest rate coefficients for even ΔJ transitions conserve parity, while parity-breaking rate coefficients are favoured for odd ΔJ. Spin-orbit changing rate coefficients are several orders of magnitude lower than transitions within a single manifold. State-to-state hyperfine-resolved cross-sections for the first levels (up to J = 13.5) in the Ω = 3/2 spin-orbit manifold are deduced using recoupling techniques. Rate coefficients are obtained and the propensity rule ΔJ = ΔF is seen. These new data will help determine the abundance of C6H in astrophysical environments such as cold dense molecular clouds, star-forming regions and circumstellar envelopes, and will help in the interpretation of the puzzling C6H-/C6H abundance ratios deduced from observations.

  5. A source of antihydrogen for in-flight hyperfine spectroscopy

    CERN Document Server

    Kuroda, N; Murtagh, D J; Van Gorp, S; Nagata, Y; Diermaier, M; Federmann, S; Leali, M; Malbrunot, C; Mascagna, V; Massiczek, O; Michishio, K; Mizutani, T; Mohri, A; Nagahama, H; Ohtsuka, M; Radics, B; Sakurai, S; Sauerzopf, C; Suzuki, K; Tajima, M; Torii, H A; Venturelli, L; Wünschek, B; Zmeskal, J; Zurlo, N; Higaki, H; Kanai, Y; Lodi Rizzini, E; Nagashima, Y; Matsuda, Y; Widmann, E; Yamazaki, Y

    2014-01-01

    Antihydrogen, a positron bound to an antiproton, is the simplest antiatom. Its counterpart—hydrogen—is one of the most precisely investigated and best understood systems in physics research. High-resolution comparisons of both systems provide sensitive tests of CPT symmetry, which is the most fundamental symmetry in the Standard Model of elementary particle physics. Any measured difference would point to CPT violation and thus to new physics. Here we report the development of an antihydrogen source using a cusp trap for in-flight spectroscopy. A total of 80 antihydrogen atoms are unambiguously detected 2.7 m downstream of the production region, where perturbing residual magnetic fields are small. This is a major step towards precision spectroscopy of the ground-state hyperfine splitting of antihydrogen using Rabi-like beam spectroscopy.

  6. Nuclear structure studies of neutron-rich heavy nuclei by mass measurements of francium and radium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Rosenbusch, Marco [Ernst-Moritz-Arndt-Universitaet, Institut fuer Physik, 17487 Greifswald (Germany); Collaboration: ISOLTRAP-Collaboration

    2013-07-01

    The mass is a unique property of an atomic nucleus reflecting its binding energy and thus the sum of all interactions at work. Precise measurements of nuclear masses especially of short-lived exotic nuclides provide important input for nuclear structure, nuclear astrophysics, tests of the Standard Model, and weak interaction studies. The Penning-trap mass spectrometer ISOLTRAP at the on-line isotope separator ISOLDE/CERN has been set up for precision mass measurements and continuously improved for accessing more exotic nuclides. The mass uncertainty is typically δm / m=10{sup -8} and the accessible half-life has been reduced to about 50 ms. In this contribution, the results of a measurement campaign of neutron-rich francium and radium isotopes will be presented, i.e. the masses of the isotopic chain of {sup 224-233}Fr and {sup 233,234}Ra, one of the most neutron-rich ensemble obtainable at ISOL facilities. The mass {sup 234}Ra denotes the heaviest mass ever measured with ISOLTRAP. Experimental data in the neutron-rich, heavy mass region is of great interest for studies of structural evolution far from stability, especially because the knowledge from nuclear mass models is scarce. The impact of the new data on the physics in this mass region as well as recent technical developments of ISOLTRAP are discussed.

  7. Medium and high spin structure in the 94Y isotope produced in fission induced by cold neutrons

    Science.gov (United States)

    Iskra, Ł. W.; Fornal, B.; Leoni, S.; Bocchi, G.; Blanc, A.; Bottoni, S.; Cieplicka-Oryńczak, N.; Jentschel, M.; Köster, U.; Michelagnoli, C.; Mutti, P.; Soldner, T.; de France, G.; Simpson, G. S.; Ur, C. A.; Urban, W.

    2017-10-01

    The level scheme of the neutron-rich 94Y isotope has been extended up to the 5324 keV excitation energy. During the analysis, a structure above the previously known (5+) isomer, at 1202 keV, was extended by employing multifold gamma-ray coincidence relationships measured with the EXILL array. For some of the new states, the spin-parity assignment has been proposed on the basis of gamma angular correlations and shell-model considerations. The newly identified structure is characteristic of spherical or nearly spherical configurations and no evidence for new isomers and rotational patterns was found.

  8. Copper isotope fractionation during its interaction with soil and aquatic microorganisms and metal oxy(hydr)oxides: Possible structural control

    Science.gov (United States)

    Pokrovsky, O. S.; Viers, J.; Emnova, E. E.; Kompantseva, E. I.; Freydier, R.

    2008-04-01

    Brantley S. (2005) Cu isotopic fractionation in the supergene environment with and without bacteria. Geochim. Cosmochim. Acta69, 5233-5246] and Balistrieri et al. [Balistrieri L. S., Borrok D. M., Wanty R. B. and Ridley W. I. (2008) Fractionation of Cu and Zn isotopes during adsorption onto amorhous Fe(III) oxyhydroxide: experimental mixing of acid rock drainage and ambient river water. Geochim. Cosmochim. Acta72, 311-328] who reported heavy Cu isotope enrichment onto amorphous ferric oxyhydroxide and on metal hydroxide precipitates on the external membranes of Fe-oxidizing bacteria, respectively. Although measured isotopic fractionation does not correlate with the relative thermodynamic stability of surface complexes, it can be related to their structures as found with available EXAFS data. Indeed, strong, bidentate, inner-sphere complexes presented by tetrahedrally coordinated Cu on metal oxide surfaces are likely to result in enrichment of the heavy isotope on the surface compared to aqueous solution. The outer-sphere, monodentate complex, which is likely to form between Cu 2+ and surface phosphoryl groups of bacteria in acidic solutions, has a higher number of neighbors and longer bond distances compared to inner-sphere bidentate complexes with carboxyl groups formed on bacterial and diatom surfaces in circumneutral solutions. As a result, in acidic solution, light isotopes become more enriched on bacterial surfaces (as opposed to the surrounding aqueous medium) than they do in neutral solution. Overall, the results of the present study demonstrate important isotopic fractionation of copper in both organic and inorganic systems and provide a firm basis for using Cu isotopes for tracing metal transport in earth-surface aquatic systems. It follows that both adsorption on oxides in a wide range of pH values and adsorption on bacteria in acidic solutions are capable of producing a significant (up to 2.5-3‰ (±0.1-0.15‰)) isotopic offset. At the same time, Cu

  9. Laser spectroscopy of cadmium isotopes: probing the nuclear structure between the neutron 50 and 82 shell closures

    CERN Multimedia

    Blaum, K; Stroke, H H; Krieger, A R

    We propose to study the isotopic chain of cadmium with high-resolution laser spectroscopy for the first time. Our goal is to determine nuclear spins, moments and root-mean-square charge radii of ground and isomeric states between the neutron 50 and 82 shell closures, contributing decisively to a better understanding of the nuclear structure in the vicinity of the doubly-magic $^{100}$Sn and $^{132}$Sn. On the neutron-rich side this is expected to shed light on a shell-quenching hypothesis and consequently on the duration of the r-process along the waiting-point nuclei below $^{130}$Cd. On the neutron-deficient side it may elucidate the role of the cadmium isotopes in the rp-process for rapidly accreting neutron stars.

  10. The effect of dipolar interaction on the magnetic isotope effect

    DEFF Research Database (Denmark)

    Mojaza, Matin; Pedersen, Jørgen Boiden; Lukzen, Nikita

    2010-01-01

    A multi-channel kinetic description is used to study the magnetic isotope effect (MIE) in zero magnetic field. The maximal isotope effect is equal to the number of channels, two for the hyperfine interaction but four for the electron spin dipole–dipole interaction of the intermediate radical pair....... Quantum mechanical calculations agree with these conclusion and show that large MIE may be obtained even in the presence of a strong exchange interaction. The observed magnesium isotope effect on the rate of enzymatic synthesis of adenosine triphosphate (ATP) is approximately 3 implying that the dipolar...... interaction is responsible for the effect. Our calculations provide support for the proposed mechanism....

  11. Stable isotope evidence of long-term changes in North Sea food web structure

    DEFF Research Database (Denmark)

    Richardson, Katherine; Christensen, Jens Tang

    2008-01-01

    occurred during this period and we have not been able to find material that would allow us to test the assumption that there has been no temporal development of d15N at the lowest levels of the food web. Thus, we cannot eliminate the possibility that the change in d15N in harbour porpoise skeletons...... reported here may be a reflection of a change in the isotope signature of nitrogen entering the food web. Regardless of its underlying cause, the recorded change in isotopic signature in harbour porpoises is noteworthy as it represents the first fisheries-independent documentation of a long-term temporal...

  12. In-source laser spectroscopy of polonium isotopes: From atomic physics to nuclear structure

    CERN Multimedia

    Rothe, S

    2014-01-01

    The Resonance Ionization Laser Ion Source RILIS [1] at the CERN-ISOLDE on-line radioactive ion beam facility is essential for ion beam production for the majority of experiments, but it is also powerful tool for laser spectroscopy of rare isotopes. A series of experiments on in-source laser spectroscopy of polonium isotopes [2, 3] revealed the nuclear ground state properties of 191;211;216;218Po. However, limitations caused by the isobaric background of surface-ionized francium isotopes hindered the study of several neutron rich polonium isotopes. The development of the Laser Ion Source and Trap (LIST) [4] and finally its integration at ISOLDE has led to a dramatic suppression of surface ions. Meanwhile, the RILIS laser spectroscopy capabilities have advanced tremendously. Widely tunable titanium:sapphire (Ti:Sa) lasers were installed to complement the established dye laser system. Along with a new data acquisition system [5], this more versatile laser setup enabled rst ever laser spectroscopy of the radioact...

  13. Role of zero-point vibrational corrections to carbon hyperfine coupling constants in organic π radicals.

    Science.gov (United States)

    Chen, X; Rinkevicius, Z; Ruud, K; Ågren, H

    2013-02-07

    By analyzing a set of organic π radicals, we demonstrate that zero-point vibrational corrections give significant contributions to carbon hyperfine coupling constants, in one case even inducing a sign reversal for the coupling constant. We discuss the implications of these findings for the computational analysis of electron paramagnetic spectra based on hyperfine coupling constants evaluated at the equilibrium geometry of radicals. In particular, we note that a dynamical description that involves the nuclear motion is in many cases necessary in order to achieve a semi-quantitatively predictive theory for carbon hyperfine coupling constants. In addition, we discuss the implications of the strong dependence of the carbon hyperfine coupling constants on the zero-point vibrational corrections for the selection of exchange-correlation functionals in density functional theory studies of these constants.

  14. Benthic Food Web Structure across the Canadian Arctic Ocean: Insights from stable isotopes and the IP25 biomarker

    Science.gov (United States)

    Friscourt, N.; Archambault, P.; Masse, G.; Nozais, C.

    2016-02-01

    In recent decades, the Arctic Ocean has undergone unprecedented changes, such as an increase in the surface temperature and a reduction of sea ice cover. These changes may cause variations in the intensity and spatial distribution of primary production and the nature of pelagic-benthic coupling. This could affect the amount and quality of organic matter that settles onto the seafloor, and the benthic communities that feed upon it. The objectives of this study were i) to describe the trophic structure and resilience of regional benthic food webs using stable carbon and nitrogen isotope analyses and ii) to evaluate the significance of ice algae in the diet of benthic communities using the sea ice proxy IP25. The study area extends from the North Water Polynya to the Chukchi Sea across five geographic regions (North Water Polynya, Canadian Archipelago, Amundsen Gulf, Beaufort Sea and Chukchi Sea) based on environmental factors. To reach these objectives, we collected particulate organic matter (POM), sediments and zoobenthic samples from July to October 2014 aboard the CCGS Amundsen. Stable isotope and IP25 data, the trophic structure within regions and comparison between regions will be presented. Potential impacts of climate change and human activities on benthic ecosystems in the Arctic are still difficult to assess because of the lack of baseline data. The baseline data once provided will enable us to make further predictions on how these changes may affect benthic food web structure.

  15. Claisen rearrangement of allyl phenyl ether: heavy-atom kinetic isotope effects and bond orders in the transition structure

    Energy Technology Data Exchange (ETDEWEB)

    Kupczyk-Subotkowska, L.; Saunders, W.H. Jr.; Shine, H.J.

    1988-10-12

    Kinetic isotope effects (KIE) were measured for the rearrangement at 220/degree/C of allyl ether (1) which was labeled successively at its oxygen atom ((/sup 18/O)-1), /alpha/-carbon atom ((/alpha/-/sup 14/C)-1), /gamma/-carbon atom ((/gamma/-/sup 14/C)-1), and ortho-carbon atom ((2-/sup 14/C)-1). The KIE were 1.0297 (/sup 18/O), 1.0306 (/alpha/-/sup 14/C), 1.0362 (/gamma/-/sup 14/C), and 1.0375 (2-/sup 14/C). KIE were determined from isotopic abundances in the product, o-allylphenol (2), which were measured by multiscan mass spectrometry (/sup 18/O) and scintillation counting (/sup 14/C). A model of the transition structure was then developed, whose bond orders gave calculated KIE in reasonably good agreement not only with the experimentally determined heavy-atom KIE but also with the deuterium KIE reported earlier by McMichael and Korver. A loose transition structure was thus found for the rearrangement of 1 into 2. In this transition structure the C/sub /alpha//-O bond is 50-60% broken while the C/sub /gamma//-C/sub ortho/ bond is only 10-20% complete. The results thus define this concerted, nonsynchronous rearrangement more explicitly than hitherto possible. 40 references, 8 tables.

  16. Study of the evolution of the hyperfine parameters in nanostructured Fe-Mn-Cu system

    Energy Technology Data Exchange (ETDEWEB)

    Mizrahi, M., E-mail: mizrahi@fisica.unlp.edu.ar; Cabrera, A. F.; Desimoni, J. [Facultad de Ciencias Exactas UNLP, Departamento de Fisica (Argentina)

    2007-09-15

    Hyperfine parameters evolution with the Cu content obtained by Moessbauer spectroscopy from mechanical milled (Fe{sub 79}Mn{sub 21}){sub 1-x}Cu{sub x} (x = 0.00 to 0.30) are presented. Results indicate that the Cu addition favors the formation of a FCC phase with two different magnetic states at room temperature. The trend of the hyperfine parameters with Cu composition suggests the incorporation of the Cu atoms at the regular FCC lattice sites.

  17. Exchange variation of hyperfine characteristics of tetrameric (Mn3(III)Mn(IV) and (Mn3(IV)Mn(III)) clusters

    Science.gov (United States)

    Belinskii, M. I.

    1994-12-01

    The dependences of the cluster g-factor, the effective hyperfine constants A(sub i) and the hyperfine structure of the EPR signal on the exchange interaction were studied for the (Mn3(III)Mn(IV) and (Mn3(IV)Mn(III)) clusters - possible prototypes of the Mn center of Photosystem II in the S2 state. The mixing of the states with different S12 intermediate spins in the Heisenberg model H(sub B) = -2(J12 s1 s2 J-alpha(s1 s3 + s1 s4) + J-beta(s2 s3 + s2 s4) + J34 s3 s4) leads to essential exchange modification of the expectation values the average value of s(sub iz) for each manganese ion. The exchange dependence of the K(sub i) = the average value of s(sub iz)/the average value of S(sub Z) coefficients results in the exchange modification and reduction of the cluster g-factor. The average value of s(sub iz)/the average value of S(sub Z) variations control also the values and signs of the effective hyperfine constants A(sub i). The A(sub i)J(sub lm) exchange dependences for the S = 1/2 ground state of the (Mn2(III)Mn(IV) and (Mn3(IV)Mn(III)) clusters with complex structures were obtained in the framework of the general Heisenberg model of tetramer. The calculated hyperfine structures show a strong dependence on the total spin, intermediate spins and on the variation of the Heisenberg exchange parameters.

  18. Measurement of (n,α cross section for set of structural material isotopes

    Directory of Open Access Journals (Sweden)

    Khryachkov Vitaly

    2017-01-01

    Full Text Available A novel spectrometer was developed and used to measure the cross section for the (n,α reaction at IPPE. Direct measurements of the α-particles yield from solid isotopic pure targets of 50, 52 and 53 chromium, 54 and 57 iron, 60 nickel, and 64 zinc were carried out in the neutron energy range from 4.7 to 7.2 MeV. For some isotopes the (n,α reaction cross-section for neutron energies less than 14 MeV were measured for the first time. The result of the comparison of new experimental data with the evaluated data from libraries ENDF/B VII, JENDL 4.0, JEFF 3.1, ROSFOND 2010 and BROND 3 and with the experimental data of other authors is presented.

  19. Nitrogen isotope variations in the subarctic northeast Pacific: relationships to nitrate utilization and trophic structure

    Science.gov (United States)

    Wu, Jinping; Calvert, S. E.; Wong, C. S.

    1997-02-01

    The isotopic composition of dissolved nitrate, size-fractionated suspended particulate organic matter (SPOM) and zooplankton was determined on a transect (Line P) between a coastal upwwelling domain and Station Papa in the subarctic northeast Pacific. Station Papa lies in one of the three extensive high-nutrient low-chlorophyll (HNLC) domains of the open ocean, where plankton standing stocks are seasonally uniform and production is lower than the potential production based on available nutrients. In spring 1993, surface water δ15NO 3- decreased from east to west along the transect, from ca 12%. in the coastal domain to 8%. at Station Papa, while nitrate concentration ([N0 3-) increased from 3 to 12 μM in the same direction. Concurrently, δ15NO 3- at 400 m depth showed a much smaller change, from 5.3 to 3.1%., indicating a larger δ15N difference between deep and surface waters at the coastal end of the transect. The isotopic trend for SPOM was similar, from approximately 11 to 3%. for bulk SPOM, 8.5 to 3%. for the ocean where [NO 3-] > 7 μM, it increases rapidly where nitrate utilization is high (that is, where biological uptake is greater than physical supply), and it decreases during upwelling events when physical supply of nutrients overwhelms the biological uptake rate. Finally, the nitrogen isotopes show the expected trophic enrichment 15N, with bulk zooplankton being isotopically heavier than SPOM by 3.9%. at Station Papa and 2.2%. in the coastal domain. This difference possibly reflects the existence of a relatively short food chain in the coastal domain and a longer food chain, involving microzooplanktonic grazers, at Station Papa. The range of δ15N among seven zooplankton groups was 3.7%., the data suggesting an increasing trophic hierarchy: pteropods, salps, euphausiids, copepods-medusaeamphipods, chaetognaths.

  20. Commercial-Off-The-Shelf (COTS) Indirect Energy Conversion Isotope (IDEC) Design Structure and Power Management

    Science.gov (United States)

    2014-12-01

    Three power management parameters of interest are initial energy capacity, self- discharge , and chemical degradation rate. Isotope-based power...including avalanche photodiodes (APDs) that operate at reduced voltages, low-power wireless network protocols, high efficiency boost converters, and...However, radiation detection characterization has been integrated into the radio using a photon pulse -height binning system. The result is the ability to

  1. Nuclear structure studies of the neutron-rich Rubidium isotopes using Coulomb excitation

    CERN Multimedia

    Reiter, P; Blazhev, A A; Voulot, D; Meot, V H; Simpson, G S; Georgiev, G P; Gaudefroy, L; Roig, O

    We propose to study the properties of odd-mass neutron-rich rubidium isotopes by the Coulomb-excitation technique, using the Miniball array coupled to the REX-ISOLDE facility. The results from similar measurements from the recent years (e.g. for the odd-mass and the odd-odd Cu isotopes, IS435) have shown the strong potential in such measurements for gaining information both for single-particle-like and collective states in exotic nuclei. Since there is practically no experimental information for excited states in the odd-mass Rb isotopes beyond $^{93}$Rb, the present study should be able to provide new data in a region of spherical ($^{93}$Rb and $^{95}$Rb) as well as well-deformed nuclei ($^{97}$Rb and $^{99}$Rb). Of particular interest is the rapid shape change that occurs when going from $^{95}$Rb (${\\varepsilon}_{2}$=0.06) to $^{97}$Rb (${\\varepsilon}_{2}$=0.3). These results should be of significant astrophysical interest as well, due to the close proximity of the r-process path.

  2. The Role of Radiation in the Solar Nebula: Correlated Chemistry-Structure- Isotope Studies of Laboratory and Extraterrestrial Organics

    Science.gov (United States)

    Nittler, Larry

    This proposal outlines an interdisciplinary effort aimed at quantitatively evaluating the roles that irradiation played in the evolution of ices and organics in the solar nebula and the potential trapping of noble gases in primitive solids. The collective effort outlined here and in two partnered proposals (PIs Scott Sandford and Fred Ciesla) involves individuals at five primary institutions. We define a series of coordinated experimental, theoretical, and observational projects that are necessary to begin to recognize and understand the complex effects of irradiation in the early Solar System. This coordinated effort is in line with the latest emphasis on interdisciplinary work by the Origins of Solar System program. The specific goal of the CIW-NRL component of the effort is to conduct comparative studies of the isotope composition, chemistry and structure of organic residues from ices subjected to controlled radiation exposures, with those of organic matter in primitive Solar System materials, primarily interplanetary dust particles (IDPs). Three broad tasks will be undertaken: 1) Evaluate the extent to which organic molecules were formed and restructured as they and their icy precursors were irradiated by UV, x-rays and cosmic-rays in the solar nebula. Specifically, we will revisit the model of Ciesla and Sandford (Science, 2012), and evaluate the irradiation doses seen by ices and organics in the disk, as well as the chemical evolution of these species as they move through more realistic disk structures. The detailed consequences of this irradiation, as well as the rates and fluences required to drive changes in chemistry and physical structure, will be determined by complementary experiments and analytic studies. 2) Quantitatively explore the history of noble gases in ices and organics in the outer solar nebula as water ice is desorbed (due to thermal or photo effects) and reformed in the solar nebula. We will also explore how such ices are irradiated and the

  3. Hyperfine coupling constants from internally contracted multireference perturbation theory

    CERN Document Server

    Shiozaki, Toru

    2016-01-01

    We present an accurate method for calculating hyperfine coupling constants (HFCCs) based on the complete active space second-order perturbation theory (CASPT2) with full internal contraction. The HFCCs are computed as a first-order property using the relaxed CASPT2 spin-density matrix that takes into account orbital and configurational relaxation due to dynamical electron correlation. The first-order unrelaxed spin-density matrix is calculated from one- and two-body spin-free counterparts that are readily available in the CASPT2 nuclear gradient program [M. K. MacLeod and T. Shiozaki, J. Chem. Phys. 142, 051103 (2015)], whereas the second-order part is computed directly using the newly extended automatic code generator. The relaxation contribution is then calculated from the so-called Z-vectors that are available in the CASPT2 nuclear gradient program. Numerical results are presented for the CN and AlO radicals, for which the CASPT2 values are comparable (or, even superior in some cases) to the ones computed ...

  4. Preparation of the anapole moment measurement in a chain of isotopes

    Science.gov (United States)

    Sheng, Dong; Hood, Jonathan; Orozco, Luis

    2010-02-01

    We present the current status of the experimental effort towards the measurement of the anapole moment in different isotopes of francium. The anapole is a parity violating, time reversal conserving nuclear moment that arises from the weak interaction among nucleons, and should be sensitive to the changes in the nuclear structure configuration among the isotopes. The anapole is a unique probe of the weak interaction in the presence of the strong interaction. The system is currently being tested with rubidium and we have analyzed the sensitivity to measurements with a chain of Rb isotopes. Our experimental scheme involves a collection of cold atoms in a blue-detuned dipole trap located at the anti-node of a microwave cavity. The standing wave would drive a parity forbidden E1 transition between hyperfine ground states, interfering with an allowed transition. The rate of transitions depends on the positive or negative handedness of the apparatus and the measurement of their difference is proportional to the anapole moment. The experiment will use of the ISAC radioactive beam facility at TRIUMF. )

  5. Hyperfine interactions of Er3 + ions in Y2SiO5 : Electron paramagnetic resonance in a tunable microwave cavity

    Science.gov (United States)

    Chen, Yu-Hui; Fernandez-Gonzalvo, Xavier; Horvath, Sebastian P.; Rakonjac, Jelena V.; Longdell, Jevon J.

    2018-01-01

    The hyperfine structure of the ground state of erbium-doped yttrium orthosilicate is analyzed with the use of electron paramagnetic resonance experiments in a tunable microwave resonator. This work was prompted by the disagreement between a recent measurement made at zero magnetic field and a previously published spin Hamiltonian. The ability to vary magnetic field strength, resonator frequency, and the orientation of our sample enabled us to monitor how the frequencies of hyperfine transitions change as a function of a vector magnetic field. We arrived at a different set of spin Hamiltonian parameters, which are also broadly consistent with the existing data. We discuss the reliability of our spin Hamiltonian parameters to make predictions outside the magnetic field and frequency regimes of our data. We also discuss why it proved to be difficult to determine spin Hamiltonian parameters for this material and present data collection strategies that improve the model reliability.

  6. Hyperfine field, electric field gradient, quadrupole coupling constant and magnetic properties of challenging actinide digallide

    Science.gov (United States)

    Khan, Sajid; Yazdani-Kachoei, M.; Jalali-Asadabadi, S.; Ahmad, Iftikhar

    2017-12-01

    In this paper, we explore the structural and magnetic properties as well as electric field gradient (EFG), hyperfine field (HFF) and quadrupole coupling constant in actinide digallide AcGa2 (Ac = U, Np, Pu) using LDA, GGA, LDA+U, GGA+U and hybrid functional with Wu-Cohen Generalized Gradient approximation HF-WC. Relativistic effects of the electrons are considered by including spin-orbit coupling. The comparison of the calculated structural parameters and magnetic properties with the available experimental results confirms the consistency and hence effectiveness of our theoretical tools. The calculated magnetic moments demonstrate that UGa2 and NpGa2 are ferromagnetic while PuGa2 is antiferromagnetic in nature. The EFG of AcGa2 is reported for the first time. The HFF, EFG and quadrupole coupling constant in AcGa2 (Ac = U, Np, Pu) are mainly originated from f-f and p-p contributions of Ac atom and p-p contribution of Ga atom.

  7. Transition from spin-orbit to hyperfine interaction dominated spin relaxation in a cold fluid of dipolar excitons

    Science.gov (United States)

    Finkelstein, Ran; Cohen, Kobi; Jouault, Benoit; West, Ken; Pfeiffer, Loren N.; Vladimirova, Masha; Rapaport, Ronen

    2017-08-01

    We measure the spin-resolved transport of dipolar excitons in a biased GaAs double quantum well structure. From these measurements we extract both spin lifetime and mobility of the excitons. We find that below a temperature of 4.8 K there is a sharp increase in the spin lifetime of the excitons, together with a sharp reduction in their mobility. Below a critical power the spin lifetime increases with increasing mobility and density, while above the critical power the opposite trend is observed. We interpret this transition as evidence of the interplay between two different spin dephasing mechanisms: at low mobility the dephasing is dominated by the hyperfine interaction with the lattice nuclei spins, while at higher mobility the spin-orbit interaction dominates and a Dyakonov-Perel spin relaxation takes over. The excitation power and temperature regime where the hyperfine interaction induced spin dephasing is observed correlates with the regime where a dark dipolar quantum liquid was reported recently on a similar sample.

  8. Trophic structure of mesopelagic fishes in the Gulf of Mexico revealed by gut content and stable isotope analyses

    Science.gov (United States)

    McClain-Counts, Jennifer P.; Demopoulos, Amanda W.J.; Ross, Steve W.

    2017-01-01

    Mesopelagic fishes represent an important component of the marine food web due to their global distributions, high abundances and ability to transport organic material throughout a large part of the water column. This study combined stable isotope (SIAs) and gut content analyses (GCAs) to characterize the trophic structure of mesopelagic fishes in the North-Central Gulf of Mexico. Additionally, this study examined whether mesopelagic fishes utilized chemosynthetic energy from cold seeps. Specimens were collected (9–25 August 2007) over three deep (>1,000 m) cold seeps at discrete depths (surface to 1,503 m) over the diurnal cycle. GCA classified 31 species (five families) of mesopelagic fishes into five feeding guilds: piscivores, large crustacean consumers, copepod consumers, generalists and mixed zooplanktivores. However, these guilds were less clearly defined based on stable isotope mixing model (MixSIAR) results, suggesting diets may be more mixed over longer time periods (weeks–months) and across co-occurring species. Copepods were likely important for the majority of mesopelagic fishes, consistent with GCA (this study) and previous literature. MixSIAR results also identified non-crustacean prey items, including salps and pteropods, as potentially important prey items for mesopelagic fishes, including those fishes not analysed in GCA (Sternoptyx spp. and Melamphaidae). Salps and other soft-bodied species are often missed in GCAs. Mesopelagic fishes had δ13C results consistent with particulate organic matter serving as the baseline organic carbon source, fueling up to three trophic levels. Fishes that undergo diel vertical migration were depleted in 15N relative to weak migrators, consistent with depth-specific isotope trends in sources and consumers, and assimilation of 15N-depleted organic matter in surface waters. Linear correlations between fish size and δ15N values suggested ontogenetic changes in fish diets for several species. While there was

  9. Theory of box-model hyperfine couplings and transport signatures of long-range nuclear-spin coherence in a quantum-dot spin valve

    Science.gov (United States)

    Chesi, Stefano; Coish, W. A.

    2015-06-01

    We have theoretically analyzed coherent nuclear-spin dynamics induced by electron transport through a quantum-dot spin valve. The hyperfine interaction between electron and nuclear spins in a quantum dot allows for the transfer of angular momentum from spin-polarized electrons injected from ferromagnetic or half-metal leads to the nuclear spin system under a finite voltage bias. Accounting for a local nuclear-spin dephasing process prevents the system from becoming stuck in collective dark states, allowing a large nuclear polarization to be built up in the long-time limit. After reaching a steady state, reversing the voltage bias induces a transient current response as the nuclear polarization is reversed. Long-range nuclear-spin coherence leads to a strong enhancement of spin-flip transition rates (by an amount proportional to the number of nuclear spins) and is revealed by an intense current burst, analogous to superradiant light emission. The crossover to a regime with incoherent spin flips occurs on a relatively long-time scale, on the order of the single-nuclear-spin dephasing time, which can be much longer than the time scale for the superradiant current burst. This conclusion is confirmed through a general master equation. For the two limiting regimes (coherent/incoherent spin flips), the general master equation recovers our simpler treatment based on rate equations, but is also applicable at intermediate dephasing. Throughout this work, we assume uniform hyperfine couplings, which yield the strongest coherent enhancement. We propose realistic strategies, based on isotopic modulation and wave-function engineering in core-shell nanowires, to realize this analytically solvable "box-model" of hyperfine couplings.

  10. Hyperfine and Zeeman measurements in the infrared spectrum of doubly charged molecule D sup 3 sup 5 C1 sup 2 sup +

    CERN Document Server

    Cox, S G

    2001-01-01

    An experimental investigation of the X sup 3 SIGMA sup - ground electronic state of the doubly charged molecule D sup 3 sup 5 Cl sup 2 sup + was performed using the Fast-lon-Beam/Laser-Beam-Spectrometer (FIBLBS), with a CO sub 2 infrared laser acting as the source of exciting radiation. Hyperfine resolved transitions between the nu=1->2 vibrational bands were observed for D sup 3 sup 5 Cl sup 2 sup +. The observed spectrum was analysed for transition frequencies, linewidths and relative signal intensities. A solenoid was designed, built and incorporated into the FIBLBS for the inducement of Zeeman splitting in the hyperfine structure of D sup 3 sup 5 Cl sup 2 sup +. The solenoid was used to investigate the splitting of a P branch hyperfine quartet over a variety of magnetic fields and was subsequently assigned unambiguously as a P sub Q sub sub 2 sub sub 3 (6) transition, with F quantum numbers 7/2, 9/2, 11/2 and 13/2

  11. Evolution of the quadrupole hyperfine interaction while milling a Si-HfO{sub 2} blend

    Energy Technology Data Exchange (ETDEWEB)

    Chain, C.Y., E-mail: yamil@fisica.unlp.edu.ar [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Ferrari, S.; Damonte, L.C. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (Argentina); Consejo Nacional de Investigaciones Cientificas y Tecnicas (CONICET) (Argentina); Martinez, J.A.; Pasquevich, A.F. [Departamento de Fisica, Facultad de Ciencias Exactas, Universidad Nacional de La Plata (Argentina); Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CIC-PBA) (Argentina)

    2012-09-25

    Highlights: Black-Right-Pointing-Pointer Perturbed angular correlations and X-ray diffraction studies in equimolar Si-HfO{sub 2}. Black-Right-Pointing-Pointer Mixture subjected to progressive mechanical milling and a final annealing. Black-Right-Pointing-Pointer Short milling distorts monoclinic hafnia to tetragonal forms. Black-Right-Pointing-Pointer Long milling forms hafnon precursor. Black-Right-Pointing-Pointer Moderate temperature annealing ends in hafnon. - Abstract: As HfO{sub 2} appears as a good candidate to replace SiO{sub 2} in Si complementary metal-oxide-semiconductor devices, a refined knowledge of the possible solid-state reactions between Si and HfO{sub 2} is valuable. Being the Perturbed Angular Correlations technique a very sensitive method to detect small changes in solid state, the goal of this work is to follow the different stages that occur while ball milling a blend Si-HfO{sub 2} by inspecting the hyperfine quadrupole interaction at Hf sites. The characterization is complemented by X-ray diffraction analysis. For comparison, a similar study on pure m-HfO{sub 2} is carried out. The results seem to reveal a gradual incorporation of Si in a tetragonal defective phase of hafnia with milling time. In addition, the formation of precursor arrays of the HfSiO{sub 4} structure takes place. After an annealing at 1000 Degree-Sign C an important amount of crystalline hafnon appears.

  12. In-beam measurement of the hydrogen hyperfine splitting and prospects for antihydrogen spectroscopy

    Science.gov (United States)

    Diermaier, M.; Jepsen, C. B.; Kolbinger, B.; Malbrunot, C.; Massiczek, O.; Sauerzopf, C.; Simon, M. C.; Zmeskal, J.; Widmann, E.

    2017-06-01

    Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of νHF=1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10-9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration.

  13. Structure, phase transitions, and isotope effects in [(CH3)4N]2PuCl6

    Energy Technology Data Exchange (ETDEWEB)

    Wilson, Richard E.

    2015-11-02

    The single crystal X-ray diffraction structure of [(CH3)4N]2PuCl6 is presented for the first time, resolving long standing confusion and speculation regarding the structure of this compound in the literature. A temperature dependent study of this compound shows that the structure of [(CH3)4N]2PuCl6 undergoes no fewer than two phase transitions between 100 and 360 K. The phase of [(CH3)4N]2PuCl6 at room temperature is Fd-3c a = 26.012(3) Å. At 360 K, the structure is in space group Fm-3m with a = 13.088(1) Å. The plutonium octahedra and tetramethylammonium cations undergo a rotative displacement and the degree of rotation varies with temperature, giving rise to the phase transition from Fm-3m to Fd-3c as the crystal is cooled. Synthesis and structural studies of the deuterated salt [(CD3)4N]2PuCl6 suggest that there is an isotopic effect associated with this phase transition as revealed by a changing transition temperature in the deuterated versus protonated compound indicating that the donor-acceptor interactions between the tetramethylammonium cations and the hexachloroplutonate anions are driving the phase transformation.

  14. Reconstruction of seawater chemistry from deeply subducted oceanic crust; hydrogen and oxygen isotope of lawsonite eclogites preserving pillow structure

    Science.gov (United States)

    Hamabata, D., VI; Masuyama, Y.; Tomiyasu, F.; Ueno, Y.; Yui, T. F.; Okamoto, K.

    2014-12-01

    In order to understand evolution of life, change of seawater chemistry from Hadean, Archean to present is significant. Pillow structure is well-preserved in the Archean greenstone belt (e.g. Komiya et al., 1999). Oxygen and hydrogen isotope of rims in the pillow is useful conventional tool to decipher chemistry of Paleao-seawater from Archean to Present. However, Archean greenstone belt suffered regional metamorphism from greenschist to Amphibolite facies conditions. Therefore, it is necessary to testify the validity of pillow chemistry from recent (Phanerozoic) metamorphosed greenstone. We have systematically collected pillowed greenstone from blueschist and eclogites. Two eclogite exhibiting pillow structures were chosen for oxygen and hydrogen isotope analysis. One is from Corsica (lawsonite eclogite collected with Dr. Alberto Vidale Barbarone) and another is from Cazadero, Franciscan belt (collected by Dr. Tatsuki Tsujimori). The both are ascribed as MORB from major and trace bulk chemistry and Ca is rich in the core and Na is poor in the rims. The former exhibits garnet, omphacite, lawsonite, and glacophane. Phengite is in core of the pillow and chlorite is in the rims. In the latter, besides garnet, omphacite, epdiote and glaucophane, chlorite is recognized with phengite in the core. Glaucophane is richer in the rims from the both samples, therefore istope analysis of glaucophane was done. Mineral separation was carefully done using micro-mill, heavy liquid and isodynamic separator. 20 mg specimens were used for oxygen isotope analysis and 2mg were for hydrogen analysis. δ18O of the all analysis (7.7 to 8.3) is within the range of unaltered igneous oceanic crust and high temperature hydrothermal alteration although rims (8.3 for Franciscan and 8.0 for Corsica) are higher than cores (7.7 for Franciscan and Corsica). δD data is also consistent with hydrothermal alteration. It is relative higher in core from the Corsica and Franciscan (-45 and -56) than of the

  15. Preparing the measurement of anapole moment in a chain of francium isotopes

    Science.gov (United States)

    Sheng, Dong

    This thesis presents the current status of the experimental efforts towards the measurement of the anapole moment in francium. The anapole moment is a parity violating, time-reversal conserving nuclear moment that arises from the weak interaction among nucleons. It is nuclear spin dependent and sensitive to the configuration of nuclear structure. Our experimental scheme is to perform a direct measurement of the anapole moment, by driving a parity forbidden E1 transition between ground hyperfine states in a series of francium isotopes inside a blue detuned dipole trap at the electric anti-node of a microwave cavity. We explore the tests using rubidium isotopes. The francium experiment will be moved to the ISAC radioactive beam facility of TRIUMF, Canada. During the preparation of the apparatus, we test the coherent control of the ground states via microwave and Raman beams, characterize the performance of a blue detuned dipole trap and study the atomic dynamics inside it using both classical and quantum methods. We also measure the lifetime of excited 5d states in Rb, with less than 1% uncertainty, to test and help to improve the current atomic structure theories.

  16. Nuclear radii of thorium isotopes from laser spectroscopy of stored ions

    Energy Technology Data Exchange (ETDEWEB)

    Kaelber, W.; Rink, J.; Bekk, K.; Goering, S.; Meisel, G.; Rebel, H.; Faubel, W.; Thompson, R.C.

    1989-09-01

    Isotope shifts and hyperfine splittings in optical transitions for atomic ions of the thorium isotopes /sup 227/Th to /sup 230/Th and /sup 232/Th have been measured by laser spectroscopy on stored ions. From the isotope shift data, changes of the mean square charge radii are determined. A continuous increase of the charge radius with mass number A is observed, in agreement with droplet model calculations. The results indicate that the odd-even staggering for Th is different from that one of the neighbouring isotones of Fr and Ra. There is some empirical evidence from systematics for an inversion of the staggering and the appearance of an octupole deformation at N/le/137. The hyperfine splitting for /sup 229/Th for 3 electronic levels is given. (orig.).

  17. Redox reactions and the influence of natural Mn oxides on Cr oxidation in a contaminated site in northern Italy: evidence from Cr stable-isotopes and EPR spectroscopy

    Directory of Open Access Journals (Sweden)

    Marafatto F. F.

    2013-04-01

    Full Text Available Hexavalent chromium-contaminated groundwaters and sediments in northern Italy have been studied using the Cr stable-isotope systematics and electron spin resonance spectroscopy (ESR, in order to explore redox changes and soil-groundwater interactions. The isotopic data indicate a possible Cr(VI source released into the environment from an industrial plant. EPR spectra on the sediments which constitute the aquifers show a broad asymmetric absorption due to coupled Fe(III and coupled Cr(III ions and a well resolved hyperfine structure due to manganese ions, resulting from Mn(IV and Mn(II. The isotopic and EPR data support the hypothesis of Cr(III being oxidized by Mn oxides which are widespread in the aquifer, possibly related to the oscillation of the phreatic level. The obtained results highlight the usefulness of chromium stable isotopes as environmental tracers and support the observations that naturally occurring Mn oxides in soils may catalize Cr oxidation from the stable Cr(III form to the toxic Cr(VI soluble form, yielding valuable information in planning remediation interventions.

  18. Towards the measurement of the ground-state hyperfine splitting of antihydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Juhasz, Bertalan, E-mail: bertalan.juhasz@oeaw.ac.at [Austrian Academy of Sciences, Stefan Meyer Institute for Subatomic Physics (Austria)

    2012-12-15

    The ASACUSA collaboration at the Antiproton Decelerator of CERN is planning to measure the ground-state hyperfine splitting of antihydrogen using an atomic beam line, which will consist of a superconducting cusp trap as a source of partially polarized antihydrogen atoms, a radiofrequency spin-flip cavity, a superconducting sextupole magnet as spin analyser, and an antihydrogen detector. This will be a measurement of the antiproton magnetic moment, and also a test of the CPT invariance. Monte Carlo simulations predict that the antihydrogen ground-state hyperfine splitting can be determined with a relative precision of better than {approx} 10{sup - 6}. The first preliminary measurements of the hyperfine transitions will start in 2011.

  19. Hyperfine frequency shift of atomic hydrogen in the presence of helium buffer gas

    Energy Technology Data Exchange (ETDEWEB)

    Jochemsen, R.; Berlinsky, A.J. (British Columbia Univ., Vancouver (Canada). Dept. of Physics)

    1982-02-01

    A quantum mechanical thermal average is performed to obtain the temperature dependence of the hyperfine frequency shift (HFS) of hydrogen atoms in the presence of He buffer gas. The calculations are based on existing ab initio calculations of the hyperfine frequency shift as a function of internuclear separation and of the interatomic potential. We find that the HFS changes sign at fairly low temperature and has a small negative value at T = 1 K in agreement with recent measurements. The overall temperature dependence is shown to be quite sensitive to the interatomic potential.

  20. Hyperfine fields and field gradients of thin films of face-centred-cubic Fe on Cu(001)

    CERN Document Server

    Gomez, J A

    2002-01-01

    The discrete variational method in density functional theory was employed to perform first-principles electronic structure calculations for embedded clusters representing thin films of face-centred-cubic Fe on a Cu(001) substrate. 3, 4 and 5 ML of Fe were investigated; the ferromagnetic and several types of antiferromagnetic spin configurations were considered. Layer-by-layer calculations of the contact and dipolar components of the magnetic hyperfine field are reported, as well as electric-field gradients at the surface and interface layers. Significant field gradients were found at the surfaces. Clusters modelling the interdiffusion of Fe and Cu between two layers at the interface were also investigated, to determine the effects on the properties.

  1. Hyperfine-induced valley mixing and the spin-valley blockade in carbon-based quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Palyi, Andras; Burkard, Guido [Department of Physics, University Konstanz (Germany)

    2010-07-01

    Hyperfine interaction (HFI) in carbon nanotube and graphene quantum dots is due to the presence of {sup 13}C atoms. We theoretically show that in these structures the short-range nature of the HFI gives rise to a coupling between the valley degree of freedom of the electron and the nuclear spin, in addition to the usual electron spin-nuclear spin coupling. We predict that this property of the HFI affects the Pauli blockade transport in carbon-based double quantum dots. In particular, we show that transport is blocked only if both the spin and the valley degeneracies of the quantum dot levels are lifted, e.g., by an appropriately oriented magnetic field. The blockade is caused by four ''supertriplet'' states in the (1,1) charge configuration.

  2. Hyperfine coupling in gadolinium-praseodymium alloys by specific heat measurements; Etude du couplage hyperfin dans les alliages gadolinium-praseodyme par mesures de chaleur specifique

    Energy Technology Data Exchange (ETDEWEB)

    Michel, J. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1967-12-01

    We have studied the hyperfine coupling in gadolinium-praseodymium alloys by specific heat measurements down to 0.3 K. In the first part we describe the apparatus used to perform our measurements. The second part is devoted to some theoretical considerations. We have studied in detail the case of praseodymium which is an exception in the rare earth series. The third part shows the results we have obtained. (author) [French] Nous avons etudie le couplage hyperfin d'alliages de gadolinium-praseodyme par des mesures de chaleur specifique jusqu'a 0.3 K. Dans la premiere partie de cette etude nous decrivons le dispositif experimental. La deuxieme partie est consacree a des considerations theoriques. Nous avons etudie en detail le cas du praseodyme qui est une exception dans la serie des terres rares. La troisieme partie est consacree aux resultats experimentaux. (auteur)

  3. Isotope shift measurements on the D1 line in francium isotopes at TRIUMF

    Science.gov (United States)

    Collister, R.; Tandecki, M.; Gwinner, G.; Behr, J. A.; Pearson, M. R.; Gomez, E.; Aubin, S.; Zhang, J.; Orozco, L. A.

    2013-05-01

    Francium is the heaviest alkali and has no stable isotopes. The longest-lived among them, with half-lives from seconds to a few minutes, are now available in the new Francium Trapping Facility at TRIUMF, Canada, for future weak interaction studies. We present isotope shift measurements on the 7S1 / 2 --> 7P1 / 2 (D 1) transition on three isotopes, 206, 207 and 213 in a magneto-optical trap. The shifts are measured using a c.w. Ti:sapphire laser locked to a stabilized cavity at the mid-point between two hyperfine transitions of the reference isotope 209Fr. Scanning tunable microwave sidebands locate transitions in the other isotopes. In combination with the D 2 isotope shifts, analysis can provide a separation of the field shift, due to a changing nuclear charge radius, and specific mass shift, due to changing electron correlations, in these isotopes. Work supported by NSERC and NRC from Canada, NSF and DOE from USA, CONYACT from Mexico.

  4. Impact of forest harvesting on trophic structure of eastern Canadian Boreal Shield lakes: insights from stable isotope analyses.

    Science.gov (United States)

    Glaz, Patricia; Sirois, Pascal; Archambault, Philippe; Nozais, Christian

    2014-01-01

    Perturbations on ecosystems can have profound immediate effects and can, accordingly, greatly alter the natural community. Land-use such as forestry activities in the Canadian Boreal region have increased in the last decades, raising concerns about their potential impact on aquatic ecosystems. The objective of this study was to evaluate the impact of forest harvesting on trophic structure in eastern Canadian Boreal Shield lakes. We measured carbon and nitrogen stable isotopes values for aquatic primary producers, terrestrial detritus, benthic macroinvertebrates, zooplankton and brook trout (Salvelinus fontinalis) over a three-year period in eight eastern Boreal Shield lakes. Four lakes were studied before, one and two years after forest harvesting (perturbed lakes) and compared with four undisturbed reference lakes (unperturbed lakes) sampled at the same time. Stable isotope mixing models showed leaf-litter to be the main food source for benthic primary consumers in both perturbed and unperturbed lakes, suggesting no logging impact on allochthonous subsidies to the littoral food web. Brook trout derived their food mainly from benthic predatory macroinvertebrates in unperturbed lakes. However, in perturbed lakes one year after harvesting, zooplankton appeared to be the main contributor to brook trout diet. This change in brook trout diet was mitigated two years after harvesting. Size-related diet shift were also observed for brook trout, indicating a diet shift related to size. Our study suggests that carbon from terrestrial habitat may be a significant contribution to the food web of oligotrophic Canadian Boreal Shield lakes. Forest harvesting did not have an impact on the diet of benthic primary consumers. On the other hand, brook trout diet composition was affected by logging with greater zooplankton contribution in perturbed lakes, possibly induced by darker-colored environment in these lakes one year after logging.

  5. Turbulence and sheared flow structures behind the isotopic dependence of the L-H power threshold on DIII-D

    Science.gov (United States)

    Yan, Z.; Gohil, P.; McKee, G. R.; Eldon, D.; Grierson, B.; Rhodes, T.; Petty, C. C.

    2017-12-01

    Measurements of long wavelength ({{k}\\bot }{{ρ }i}   power threshold (P LH) and can help explain the isotopic and density dependence of P LH, and how the P LH difference is reduced at higher density. Understanding and accurately predicting the L-H power threshold is critical to accessing to H-mode, and operating and achieving high confinement in burning plasmas such as ITER. Above about n e ~ 4  ×  1019 m-3, P LH is seen to converge for H and D, and increases for both with higher density. Surprisingly, the P LH increases significantly at low density in H but not in D plasmas. Two distinct frequency bands of density fluctuations are observed in the D plasmas at low density, n e ~ 1.2-1.5  ×  1019 m-3, but not in H plasmas with similar density, which appears to be correlated to the much lower power threshold in D at low density. Consistently, E  ×  B shear in the region of r/a ~ 0.95-1.0 is larger in D plasmas than in H plasmas at low density; as the P LH increases with increasing density, the dual mode structure disappears while E  ×  B shear becomes similar and small for both D and H plasmas at higher density, n e ~ 5  ×  1019 m-3, where P LH is similar for both D and H plasmas. The increased edge fluctuations, increased flow shear, and the dual-band nature of edge turbulence correlating with lower P LH may account for the strong isotope and density dependencies of P LH and support current L-H transition theories but suggest a complex behavior that can inform a more complete model of the L-H transition threshold.

  6. Identification of volatile and semivolatile compounds in chemical ionization GC-MS using a mass-to-structure (MTS) Search Engine with integral isotope pattern ranking.

    Science.gov (United States)

    Liao, Wenta; Draper, William M

    2013-02-21

    The mass-to-structure or MTS Search Engine is an Access 2010 database containing theoretical molecular mass information for 19,438 compounds assembled from common sources such as the Merck Index, pesticide and pharmaceutical compilations, and chemical catalogues. This database, which contains no experimental mass spectral data, was developed as an aid to identification of compounds in atmospheric pressure ionization (API)-LC-MS. This paper describes a powerful upgrade to this database, a fully integrated utility for filtering or ranking candidates based on isotope ratios and patterns. The new MTS Search Engine is applied here to the identification of volatile and semivolatile compounds including pesticides, nitrosoamines and other pollutants. Methane and isobutane chemical ionization (CI) GC-MS spectra were obtained from unit mass resolution mass spectrometers to determine MH(+) masses and isotope ratios. Isotopes were measured accurately with errors of Search Engine and details performance testing with over 50 model compounds.

  7. Electron linac for medical isotope production with improved energy efficiency and isotope recovery

    Science.gov (United States)

    Noonan, John; Walters, Dean; Virgo, Matt; Lewellen, John

    2015-09-08

    A method and isotope linac system are provided for producing radio-isotopes and for recovering isotopes. The isotope linac is an energy recovery linac (ERL) with an electron beam being transmitted through an isotope-producing target. The electron beam energy is recollected and re-injected into an accelerating structure. The ERL provides improved efficiency with reduced power requirements and provides improved thermal management of an isotope target and an electron-to-x-ray converter.

  8. Ion beam production and study of radioactive isotopes with the laser ion source at ISOLDE

    Science.gov (United States)

    Fedosseev, Valentin; Chrysalidis, Katerina; Day Goodacre, Thomas; Marsh, Bruce; Rothe, Sebastian; Seiffert, Christoph; Wendt, Klaus

    2017-08-01

    At ISOLDE the majority of radioactive ion beams are produced using the resonance ionization laser ion source (RILIS). This ion source is based on resonant excitation of atomic transitions by wavelength tunable laser radiation. Since its installation at the ISOLDE facility in 1994, the RILIS laser setup has been developed into a versatile remotely operated laser system comprising state-of-the-art solid state and dye lasers capable of generating multiple high quality laser beams at any wavelength in the range of 210-950 nm. A continuous programme of atomic ionization scheme development at CERN and at other laboratories has gradually increased the number of RILIS-ionized elements. At present, isotopes of 40 different elements have been selectively laser-ionized by the ISOLDE RILIS. Studies related to the optimization of the laser-atom interaction environment have yielded new laser ion source types: the laser ion source and trap and the versatile arc discharge and laser ion source. Depending on the specific experimental requirements for beam purity or versatility to switch between different ionization mechanisms, these may offer a favourable alternative to the standard hot metal cavity configuration. In addition to its main purpose of ion beam production, the RILIS is used for laser spectroscopy of radioisotopes. In an ongoing experimental campaign the isotope shifts and hyperfine structure of long isotopic chains have been measured by the extremely sensitive in-source laser spectroscopy method. The studies performed in the lead region were focused on nuclear deformation and shape coexistence effects around the closed proton shell Z = 82. The paper describes the functional principles of the RILIS, the current status of the laser system and demonstrated capabilities for the production of different ion beams including the high-resolution studies of short-lived isotopes and other applications of RILIS lasers for ISOLDE experiments. This article belongs to the Focus on

  9. Solid state NMR of isotope labelled murine fur: a powerful tool to study atomic level keratin structure and treatment effects

    Energy Technology Data Exchange (ETDEWEB)

    Wong, Wai Ching Veronica; Narkevicius, Aurimas; Chow, Wing Ying; Reid, David G.; Rajan, Rakesh [University of Cambridge, Department of Chemistry (United Kingdom); Brooks, Roger A. [University of Cambridge, Department of Trauma and Orthopaedic Surgery, Addenbrooke’s Hospital (United Kingdom); Green, Maggie [University of Cambridge, Central Biomedical Resources, School of Clinical Medicine (United Kingdom); Duer, Melinda J., E-mail: mjd13@cam.ac.uk [University of Cambridge, Department of Chemistry (United Kingdom)

    2016-10-15

    We have prepared mouse fur extensively {sup 13}C,{sup 15}N-labelled in all amino acid types enabling application of 2D solid state NMR techniques which establish covalent and spatial proximities within, and in favorable cases between, residues. {sup 13}C double quantum–single quantum correlation and proton driven spin diffusion techniques are particularly useful for resolving certain amino acid types. Unlike 1D experiments on isotopically normal material, the 2D methods allow the chemical shifts of entire spin systems of numerous residue types to be determined, particularly those with one or more distinctively shifted atoms such as Gly, Ser, Thr, Tyr, Phe, Val, Leu, Ile and Pro. Also the partial resolution of the amide signals into two signal envelopes comprising of α-helical, and β-sheet/random coil components, enables resolution of otherwise overlapped α-carbon signals into two distinct cross peak families corresponding to these respective secondary structural regions. The increase in resolution conferred by extensive labelling offers new opportunities to study the chemical fate and structural environments of specific atom and amino acid types under the influence of commercial processes, and therapeutic or cosmetic treatments.

  10. Collinear Laser Spectroscopy of Manganese Isotopes using the Radio Frequency Quadrupole Cooler and Buncher at ISOLDE

    CERN Document Server

    AUTHOR|(CDS)2083426

    The hyperfine structure of the odd-even $^{51−63}$Mn isotopes (N = 26 − 38) were measured using bunched beam collinear laser spectroscopy with the COLLAPS experimental setup at ISOLDE, CERN. The properties of these nuclei were investigated over the course of two experiments. During the first experiment, nuclear spins and magnetic dipole moments were extracted from spectroscopy on manganese atoms. These nuclear properties were then compared to the predictions of two large-scale shell model effective interactions (GXPF1A [1, 2] and LNPS [3]) which use different model spaces. In the case of $^{61,63}$Mn, these results show the increasing importance of neutron excitations across the proposed N = 40 subshell closure, and of proton excitations across the Z = 28 shell gap. These measurements provide the first direct proof that proton and neutron excitations across shell gaps are playing an important role in the ground state wave functions of the neutron-rich Mn isotopes. The electric quadrupole moment provides c...

  11. Towards Measuring the Ground State Hyperfine Splitting of Antihydrogen -- A Progress Report

    CERN Document Server

    Sauerzopf, C.

    2016-06-20

    We report the successful commissioning and testing of a dedicated field-ioniser chamber for measuring principal quantum number distributions in antihydrogen as part of the ASACUSA hyperfine spectroscopy apparatus. The new chamber is combined with a beam normalisation detector that consists of plastic scintillators and a retractable passivated implanted planar silicon (PIPS) detector.

  12. ENDOR study of nitrogen hyperfine and quadrupole tensors in vanadyl porphyrins of heavy crude oil

    Directory of Open Access Journals (Sweden)

    Gracheva I.N., Gafurov M.R., Mamin G.V., Biktagirov T.B., Rodionov A.A., Galukhin A.V., Orlinskii S.B.

    2016-11-01

    Full Text Available We report the observation of pulsed electron-nuclear double resonance (ENDOR spectrum caused by interactions of the nitrogen nuclei 14N with the unpaired electron of the paramagnetic vanadyl complexes VO2+ of vanadyl porphyrins in natural crude oil. We provide detailed experimental and theoretical characterization of the nitrogen hyperfine and quadrupole tensors.

  13. Hyperfine contributions to spin-exchange frequency shifts in the hydrogen maser

    NARCIS (Netherlands)

    Verhaar, B.J.; Koelman, J.M.V.A.; Stoof, H.T.C.; Luiten, O.J.; Crampton, S.B.

    1987-01-01

    We have rigorously included hyperfine interactions during electron-spin-exchange collisions between ground state hydrogen atoms. We predict additional frequency shifts which are not compensated for by the usual methods of tuning maser cavities. These shifts are large compared to the potential

  14. Towards measuring the ground state hyperfine splitting of antihydrogen – a progress report

    Energy Technology Data Exchange (ETDEWEB)

    Sauerzopf, C., E-mail: clemens.sauerzopf@oeaw.ac.at; Capon, A. A.; Diermaier, M. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Dupré, P. [Atomic Physics Laboratory, RIKEN (Japan); Higashi, Y. [University of Tokyo, Institute of Physics, Graduate School of Arts and Sciences (Japan); Kaga, C. [Hiroshima University, Graduate School of Advanced Sciences of Matter (Japan); Kolbinger, B. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Leali, M. [Università di Brescia, Dipartimento di Ingegneria dell’ Informazione (Italy); Lehner, S. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Rizzini, E. Lodi [Università di Brescia, Dipartimento di Ingegneria dell’ Informazione (Italy); Malbrunot, C. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Mascagna, V. [Università di Brescia, Dipartimento di Ingegneria dell’ Informazione (Italy); Massiczek, O. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Murtagh, D. J.; Nagata, Y.; Radics, B. [Atomic Physics Laboratory, RIKEN (Japan); Simon, M. C.; Suzuki, K. [Stefan Meyer Institute for subatomic physics, Austrian Academy of Sciences (Austria); Tajima, M. [University of Tokyo, Institute of Physics, Graduate School of Arts and Sciences (Japan); Ulmer, S. [Ulmer Initiative Research Unit, RIKEN (Japan); and others

    2016-12-15

    We report the successful commissioning and testing of a dedicated field-ioniser chamber for measuring principal quantum number distributions in antihydrogen as part of the ASACUSA hyperfine spectroscopy apparatus. The new chamber is combined with a beam normalisation detector that consists of plastic scintillators and a retractable passivated implanted planar silicon (PIPS) detector.

  15. Relativistic DFT calculations of hyperfine coupling constants in the 5d hexafluorido complexes

    DEFF Research Database (Denmark)

    Haase, Pi Ariane Bresling; Repisky, Michal; Komorovsky, Stanislav

    2017-01-01

    ions. We find that both methods lead to very similar deviations from the experimental values for the [ReF6]2- complex, i.e. ~20% for the coupling constant using hybrid functionals. None of the methods is, however, able to reproduce the large anisotropy of the [ReF6]2- hyperfine tensor. For [IrF6...

  16. Hyperfine Quenching of the 2s2p 3P0 State of Berylliumlike Ions

    Energy Technology Data Exchange (ETDEWEB)

    Cheng, K T; Chen, M H; Johnson, W R

    2008-03-13

    The hyperfine-induced 2s2p {sup 3}P{sub 0}-2s{sup 2} {sup 1}S{sub 0} transition rate for Be-like {sup 47}Ti{sup 18+} was recently measured in a storage-ring experiment by Schippers et al. [Phys. Rev. Lett. 98, 033001 (2007)]. The measured value of 0.56(3) s{sup -1} is almost 60% larger than the theoretical value of 0.356 s{sup -1} from a multiconfiguration Dirac-Fock calculation by Marques et al. [Phys. Rev. A 47, 929 (1993)]. In this work, we use a large-scale relativistic configuration-interaction method to calculate these hyperfine-induced rates for ions with Z = 6-92. Coherent hyperfine-quenching effects between the 2s2p {sup 1,3}P{sub 1} states are included in a perturbative as well as a radiation damping approach. Contrary to the claims of Marques et al., contributions from the {sup 1}P{sub 1} state are substantial and lead to a hyperfine-induced rate of 0.67 s{sup -1}, in better agreement with, though larger than, the measured value.

  17. Stable isotopes provide insight into population structure and segregation in eastern North Atlantic sperm whales

    DEFF Research Database (Denmark)

    Borrell, Asunción; Velásquez Vacca, Adriana; Pinela, Ana M.

    2013-01-01

    In pelagic species inhabiting large oceans, genetic differentiation tends to be mild and populations devoid of structure. However, large cetaceans have provided many examples of structuring. Here we investigate whether the sperm whale, a pelagic species with large population sizes and reputedly...... in the layer deposited at age 3, considered to be the one best representing the baseline of the breeding ground, in delta N-15, delta C-13 and delta O-18 values in the period up to age 20, and in the ontogenetic variation of delta N-15 and delta O-18 values. These differences evidence that diet composition......, use of habitat and/or migratory destinations are dissimilar between whales from the two regions and suggest that the North Atlantic population of sperm whales is more structured than traditionally accepted....

  18. Visualization of 57Fe-Labeled Heme Isotopic Fine Structure and Localization of Regions of Erythroblast Maturation in Mouse Spleen by MALDI FTICR-MS Imaging

    Science.gov (United States)

    Kihara, Makoto; Matsuo-Tezuka, Yukari; Noguchi-Sasaki, Mariko; Yorozu, Keigo; Kurasawa, Mitsue; Shimonaka, Yasushi; Hirata, Michinori

    2017-08-01

    Epoetin beta pegol (continuous erythropoiesis receptor activator; C.E.R.A.), or methoxy-polyethylene glycol-modified epoetin beta, is a long-acting erythropoiesis stimulating agent (ESA) that effectively maintains hemoglobin levels. It promotes proliferation of erythroid progenitor cells in hematopoietic organs and leads to increased reticulocyte and hemoglobin levels. However, the detailed erythropoietic effects of various ESAs on their target organs have yet to be clarified, and new approaches are needed to analyze tissue iron localization with structural information. Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry imaging (MSI) techniques are widely used in basic pharmaceutical research. High-resolution Fourier transform ion cyclotron resonance (FTICR) mass spectrometry (MS) imaging enables the spatial mapping and identification of biomolecules. In this study, mice administered with C.E.R.A. were fed a diet containing the stable iron isotope 57Fe. The 57Fe-heme+ isotopic fine structure peak (m/z 617.1772) was separated from the non-labeled heme+ isotopic peak (Δ0.0029) by FTICR-MS with a resolving power of more than 500,000. We optimized the platform to analyze the distribution of 57Fe-heme in the spleen using MALDI FTICR-MS imaging. The combination of the ultrahigh resolution power of FTICR-MS and a stable isotope labeling technique has the potential to be very effective in basic pharmaceutical research. [Figure not available: see fulltext.

  19. Isotope Fractionation Studies in Prestellar Cores: The Case of Nitrogen

    Science.gov (United States)

    Milam, Stefanie N.; Charnley, Steven B.

    2011-01-01

    Isotopically fractionated material is found in many solar system objects, including meteorites and comets. It is considered, in some cases, to trace interstellar material that was incorporated into the solar system without undergoing significant processing, thus preserving the fractionation. In interstellar molecular clouds, ion-molecule chemistry continually cycles nitrogen between the two main reservoirs - N and N2 - leading to only minor N-15 enrichments. Charnley and Rodgers showed that depletion of CO removes oxygen from the gas and weakens this cycle such that significant N-15 fractionation can occur for N2 and other N-bearing species in such cores. Observations are being conducted at millimeter and submillimeter wavelengths employing various facilities in order to both spatially and spectrally, resolve emission from these cores. A preliminary study to obtain the N-14/N-15 ratio in nitriles (HCN and HNC) was conducted at the Arizona Radio Observatory's 12m telescope on Kitt Peak, AZ. Spectra were obtained at high resolution (0.08 km/s) in order to resolve dynamic properties of each source as well as to resolve hyperfine structure present in certain isotopologues. This study included four dark cloud cores, observed to have varying levels of molecular depletion: L1521E, L1498, L1544, and L1521F. Previous studies of the N-14/N-15 ratio towards LI544 were obtained with N2H+ and NIH3, yielding ratios of 446 and >700, respectively. The discrepancy observed in these two measurements suggests a strong chemical dependence on the fractionation of nitrogen. Ratios (C,N, and D) obtained from isotopologues for a particular molecule are likely tracing the same chemical heritage and are directly comparable within a given source. Results and comparisons between the protostellar evolutionary state and isomer isotope fractionation as well as between other N-bearing species will be presented.

  20. Observations of Nitrogen Isotope Fractionation in Prestellar Cores

    Science.gov (United States)

    Milam, Stefanie N.; Charnley, Steven B.

    2011-01-01

    Isotopically fractionated material is found in many solar system objects, including meteorites and comets [1]. It is considered, in some cases, to trace interstellar material that was incorporated into the solar system without undergoing significant processing, thus preserving the fractionation. In interstellar molecular clouds, ion-molecule chemistry continually cycles nitrogen between the two main reservoirs - Nand N2 - leading to only minor N-15 enrichments [2]. Charnley and Rodgers [3,4] showed that depletion of CO removes oxygen from the gas and weakens this cycle such that significant N-15 fractionation can occur for N2 and other N-bearing species in such cores. Observations are being conducted at millimeter and submillimeter wavelengths employing various facilities in order to both spatially and spectrally, resolve emission from these cores. A preliminary study to obtain the N-14/N-15 ratio in nitriles was conducted at the Arizona Radio Observatory's 12m telescope on Kitt Peak, AZ. Spectra were obtained at high resolution (0.08 km/s) in order to resolve dynamic properties of each source as well as to resolve hyperfine structure present in certain isotopologues. This study included four dark cloud cores, observed to have varying levels of molecular depletion: Ll521E, Ll498, Ll544, and Ll521F. Previous studies of the N-14/N-15 ratio towards Ll544 were obtained with N2H(+) and NH3 yielding ratios of 446 and greater than 700, respectively [5,6]. The discrepancy observed in these two measurements suggests a strong chemical dependence on the fractionation of nitrogen. Ratios (C,N, and D) obtained from isotopologues for a particular molecule are likely tracing the same chemical heritage and are directly comparable within a given source. Results and comparisons between the protostellar evolutionary state and isomer isotope fractionation as well as between other N-bearing species will be presented.

  1. The {sup 57}Fe hyperfine interactions in human liver ferritin and its iron-polymaltose analogues: the heterogeneous iron core model

    Energy Technology Data Exchange (ETDEWEB)

    Oshtrakh, M. I., E-mail: oshtrakh@gmail.com; Alenkina, I. V.; Semionkin, V. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation)

    2016-12-15

    Human liver ferritin and its iron-polymaltose pharmaceutical analogues Ferrum Lek, Maltofer® and Ferrifol® were studied using Mössbauer spectroscopy at 295 and 90 K. The Mössbauer spectra were fitted on the basis of a new model of heterogeneous iron core structure using five quadrupole doublets. These components were related to the corresponding more or less close-packed iron core layers/regions demonstrating some variations in the {sup 57}Fe hyperfine parameters for the studied samples.

  2. Stable carbon and nitrogen isotope quantitative structural assessment of dominant species from the Vaccarès Lagoon trophic web (Camargue Biosphere Reserve, France)

    Science.gov (United States)

    Persic, Ana; Roche, Hélène; Ramade, François

    2004-06-01

    The Vaccarès Lagoon (Camargue Biosphere Reserve), a complex brackish ecosystem, is the natural habitat for numerous freshwater, marine and euryhaline species forming a particularly intricate food web. The main objectives of this study were to describe its trophic relations and investigate factors influencing its structure and dynamics. The combined stable C and N isotope method was used to establish a quantitative assessment of the trophic status of Vaccarès organisms. Although the levels of δ15N and δ13C showed large intraspecific and interspecific variations, the isotopic signatures of the species assessed revealed a general trend of 15N enrichment with trophic level. Distribution of the biota into four trophic compartments—depositivore, zooplanktivore, predator, and top-predator—was corroborated by the general analysis of the relationship between δ13C and δ15N. Analysis of seasonal and annual isotopic variations showed that natural environmental changes (increase in food abundance, climatic and salinity variations) as well as individual metabolic capacities would affect the relative stability of an organism's trophic position. No significant correlation was found between isotopic variation and size and growth in fishes except for the eel population where the positive correlation between these two parameters confirmed intra-population trophic variations. Finally, separately examined species exhibited significant, although incoherent, correlation between their isotopic signature and lipid content. This study confirms the efficiency of the isotopic approach in trophic studies and highlights the need for further investigations of anthropic environmental modifications occurring in this protected area and frequently disturbing its food web.

  3. Design of 57.5 MHz CW RFQ structure for the Rare Isotope ...

    Indian Academy of Sciences (India)

    The principal specifications of the RFQ are: (1) formation of extremely low longitudinal emittance; (2) stable operation over a wide range of voltage for ... CW operation of an accelerating structure leads to a number of requirements for the resonators such as high shunt impedance, efficient water cooling of all parts of the ...

  4. The two Suvasvesi impact structures, Finland: Argon isotopic evidence for a "false" impact crater doublet

    Science.gov (United States)

    Schmieder, Martin; Schwarz, Winfried H.; Trieloff, Mario; Buchner, Elmar; Hopp, Jens; Tohver, Eric; Pesonen, Lauri J.; Lehtinen, Martti; Moilanen, Jarmo; Werner, Stephanie C.; Öhman, Teemu

    2016-05-01

    The two neighboring Suvasvesi North and South impact structures in central-east Finland have been discussed as a possible impact crater doublet produced by the impact of a binary asteroid. This study presents 40Ar/39Ar geochronologic data for impact melt rocks recovered from the drilling into the center of the Suvasvesi North impact structure and melt rock from glacially transported boulders linked to Suvasvesi South. 40Ar/39Ar step-heating analysis yielded two essentially flat age spectra indicating a Late Cretaceous age of ~85 Ma for the Suvasvesi North melt rock, whereas the Suvasvesi South melt sample gave a Neoproterozoic minimum (alteration) age of ~710 Ma. Although the statistical likelihood for two independent meteorite strikes in close proximity to each other is rather low, the remarkable difference in 40Ar/39Ar ages of >600 Myr for the two Suvasvesi impact melt samples is interpreted as evidence for two temporally separate, but geographically closely spaced, impacts into the Fennoscandian Shield. The Suvasvesi North and South impact structures are, thus, interpreted as a "false" crater doublet, similar to the larger East and West Clearwater Lake impact structures in Québec, Canada, recently shown to be unrelated. Our findings have implications for the reliable recognition of impact crater doublets and the apparent rate of binary asteroid impacts on Earth and other planetary bodies in the inner solar system.

  5. Stable isotopes document the trophic structure of a deep-sea cephalopod assemblage including giant octopod and giant squid.

    Science.gov (United States)

    Cherel, Y; Ridoux, V; Spitz, J; Richard, P

    2009-06-23

    Although deep-sea cephalopods are key marine organims, their feeding ecology remains essentially unknown. Here, we report for the first time the trophic structure of an assemblage of these animals (19 species) by measuring the isotopic signature of wings of their lower beaks, which accumulated in stomachs of stranded sperm whales. Overall, the species encompassed a narrow range in delta(13)C values (1.7 per thousand), indicating that they lived in closely related and overlapping habitats. delta(13)C values can be interpreted in terms of distribution with the more (13)C-depleted species (e.g. Stigmatoteuthis arcturi, Vampyroteuthis infernalis) having a more pelagic habitat than the more (13)C-enriched, bathyal species (e.g. Todarodes sagittatus and the giant squid Architeuthis dux). The cephalopods sampled had delta(15)N values ranging 4.6 per thousand, which is consistent with the species spanning approximately 1.5 trophic levels. Neither the giant octopod (Haliphron atlanticus) nor the giant squid reached the highest trophic position. Species delta(15)N was independent of body size, with large squids having both the highest (Taningia danae) and lowest (Lepidoteuthis grimaldii) delta(15)N values. Their trophic position indicates that some species share the top of the food web, together with other megacarnivores such as the sperm whale.

  6. Electrical Resistivity Structure and Helium Isotopes around Naruko Volcano, Northeastern Japan and Its Implication for the Distribution of Crustal Magma

    Directory of Open Access Journals (Sweden)

    Koichi Asamori

    2010-01-01

    Full Text Available The two-dimensional electrical resistivity structure beneath Naruko volcano was determined using magnetotelluric soundings. The resulting model shows that a prominent conductor exists through the middle crust to the uppermost mantle beneath the volcano. The location of the conductor agrees closely with a seismic low-velocity zone. Low-frequency microearthquakes occur near the conductor around the Moho depth. The cutoff depth of crustal earthquakes is coincident with the upper boundary of the conductor, implying that the conductor has a temperature appreciably higher than 400∘C. Furthermore, new helium isotope data from hot springs around the volcano were obtained. The spatial distribution of the observed 3He/4He ratios reveals the extent of mantle-derived materials beneath Naruko volcano. Consequently, it is apparent that the conductor determined beneath the volcano reflects the presence of high-temperature mantle-derived materials such as magmas and/or related fluids derived from active magmatism in the northeastern Japan subduction zone.

  7. Effects of surface structural disorder and surface coverage on isotopic fractionation during Zn(II) adsorption onto quartz and amorphous silica surfaces

    Science.gov (United States)

    Nelson, Joey; Wasylenki, Laura; Bargar, John R.; Brown, Gordon E.; Maher, Kate

    2017-10-01

    Metal ion-mineral surface interactions and the attendant isotopic fractionation depend on the properties of the mineral surface and the local atomic-level chemical environment. However, these factors have not been systematically examined for phases of the same composition with different levels of surface disorder. We present pH-dependent adsorption edges, X-ray absorption spectra, and isotopic measurements to illustrate the effects of surface structural disorder and surface coverage on zinc(II) (Zn(II)) surface complexation and isotope fractionation. Our results demonstrate that Zn(II) surface complexes on quartz and amorphous silica (SiO2(am)) transition from octahedral to tetrahedral coordination by oxygen as surface coverage increases. In low ionic strength solutions (I = 0.004 M) and at low surface loadings (Γ isotopic fractionation (Δ66/64Znaqueous-sorbed = -0.01 ± 0.06‰) from aqueous Zn(II). In contrast, under similar chemical conditions and surface loading, outer-sphere Zn(II) adsorption complexes are not observed on SiO2(am) surfaces. At high ionic strength (I = 0.1 M) and low surface loading (Γ isotope fractionation factors for inner-sphere octahedral and tetrahedral complexes versus dissolved Zn, under the same conditions and on the same silica substrate, are not distinguishable beyond uncertainties. However, there is a larger measured equilibrium isotope fractionation with preferential sorption of heavy Zn as inner-sphere complexes on SiO2(am) (Δ66/64Znaqueous-sorbed = -0.94 ± 0.11‰) than on quartz (Δ66/64Znaqueous-sorbed = -0.60 ± 0.11‰).The propensity for Zn(II) to occur in tetrahedral and octahedral coordination with oxygen may help explain these observations. We posit that the low energetic difference between octahedral and tetrahedral Zn(II) may be why changes in inner-sphere Zn(II) coordination numbers with increasing coverage do not manifest as distinguishable isotope fractionations or as an observable alteration to the macroscopic

  8. An assessment of the trophic structure of the Bay of Biscay continental shelf food web: Comparing estimates derived from an ecosystem model and isotopic data

    OpenAIRE

    Lassalle, Géraldine; Chouvelon, Tiphaine; Bustamante, Paco; Niquil, Nathalie

    2014-01-01

    Comparing outputs of ecosystem models with estimates derived from experimental and observational approaches is important in creating valuable feedback for model construction, analyses and validation. Stable isotopes and mass-balanced trophic models are well-known and widely used as approximations to describe the structure of food webs, but their consistency has not been properly established as attempts to compare these methods remain scarce. Model construction is a data-consuming step, meanin...

  9. Application of nitrogen and carbon stable isotopes (δ(15N and δ(13C to quantify food chain length and trophic structure.

    Directory of Open Access Journals (Sweden)

    Matthew J Perkins

    Full Text Available Increasingly, stable isotope ratios of nitrogen (δ(15N and carbon (δ(13C are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR using δ(15N, and carbon range (CR using δ(13C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ(15N or δ(13C from source to consumer between trophic levels and among food chains. δ(15N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰, and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ(13C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ(13C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority

  10. Application of nitrogen and carbon stable isotopes (δ(15)N and δ(13)C) to quantify food chain length and trophic structure.

    Science.gov (United States)

    Perkins, Matthew J; McDonald, Robbie A; van Veen, F J Frank; Kelly, Simon D; Rees, Gareth; Bearhop, Stuart

    2014-01-01

    Increasingly, stable isotope ratios of nitrogen (δ(15)N) and carbon (δ(13)C) are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR) using δ(15)N, and carbon range (CR) using δ(13)C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ(15)N or δ(13)C from source to consumer) between trophic levels and among food chains. δ(15)N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰), and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ(13)C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ(13)C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority of

  11. Application of Nitrogen and Carbon Stable Isotopes (δ15N and δ13C) to Quantify Food Chain Length and Trophic Structure

    Science.gov (United States)

    Perkins, Matthew J.; McDonald, Robbie A.; van Veen, F. J. Frank; Kelly, Simon D.; Rees, Gareth; Bearhop, Stuart

    2014-01-01

    Increasingly, stable isotope ratios of nitrogen (δ15N) and carbon (δ13C) are used to quantify trophic structure, though relatively few studies have tested accuracy of isotopic structural measures. For laboratory-raised and wild-collected plant-invertebrate food chains spanning four trophic levels we estimated nitrogen range (NR) using δ15N, and carbon range (CR) using δ13C, which are used to quantify food chain length and breadth of trophic resources respectively. Across a range of known food chain lengths we examined how NR and CR changed within and between food chains. Our isotopic estimates of structure are robust because they were calculated using resampling procedures that propagate variance in sample means through to quantified uncertainty in final estimates. To identify origins of uncertainty in estimates of NR and CR, we additionally examined variation in discrimination (which is change in δ15N or δ13C from source to consumer) between trophic levels and among food chains. δ15N discrimination showed significant enrichment, while variation in enrichment was species and system specific, ranged broadly (1.4‰ to 3.3‰), and importantly, propagated variation to subsequent estimates of NR. However, NR proved robust to such variation and distinguished food chain length well, though some overlap between longer food chains infers a need for awareness of such limitations. δ13C discrimination was inconsistent; generally no change or small significant enrichment was observed. Consequently, estimates of CR changed little with increasing food chain length, showing the potential utility of δ13C as a tracer of energy pathways. This study serves as a robust test of isotopic quantification of food chain structure, and given global estimates of aquatic food chains approximate four trophic levels while many food chains include invertebrates, our use of four trophic level plant-invertebrate food chains makes our findings relevant for a majority of ecological systems

  12. Observation of 7pP23/2→7dD2 optical transitions in 209 and 210 francium isotopes.

    Science.gov (United States)

    Agustsson, S; Bianchi, G; Calabrese, R; Corradi, L; Dainelli, A; Khanbekyan, A; Marinelli, C; Mariotti, E; Marmugi, L; Mazzocca, G; Moi, L; Ricci, L; Stiaccini, L; Tomassetti, L

    2017-09-15

    We report on the direct experimental observation of the 7pP23/2→7dD2 optical transitions in 209 and 210 francium isotopes. By continuously monitoring the fluorescence emitted by the isotopes collected in a magneto-optical trap (MOT), the electric dipole transitions 7pP23/2→7dD25/2 of Fr209, not yet experimentally observed, and 7pP23/2→7dD25/2, 7pP23/2→7dD25/2 of Fr210 were detected as sub-Doppler depletion dips of the cold atom population. This approach allowed unambiguous identification of the excited state hyperfine structures, even in the absence of a large stable vapor. Our findings demonstrate the effectiveness and the flexibility of fluorescence monitoring of trap depletion upon laser excitation, and broaden the experimental knowledge of francium isotopes and their electronic and nuclear properties. These results will have a relevant impact on ongoing researches for low-energy testing of fundamental symmetries with francium, from atomic parity non-conservation to the electron dipole moment.

  13. Isotope separation

    Science.gov (United States)

    Bartlett, Rodney J.; Morrey, John R.

    1978-01-01

    A method and apparatus is described for separating gas molecules containing one isotope of an element from gas molecules containing other isotopes of the same element in which all of the molecules of the gas are at the same electronic state in their ground state. Gas molecules in a gas stream containing one of the isotopes are selectively excited to a different electronic state while leaving the other gas molecules in their original ground state. Gas molecules containing one of the isotopes are then deflected from the other gas molecules in the stream and thus physically separated.

  14. Experimental Determination of Zinc Isotope Fractionation in Complexes with the Phytosiderophore 2'-Deoxymugeneic Acid (DMA) and Its Structural Analogues, and Implications for Plant Uptake Mechanisms.

    Science.gov (United States)

    Marković, Tamara; Manzoor, Saba; Humphreys-Williams, Emma; Kirk, Guy Jd; Vilar, Ramon; Weiss, Dominik J

    2017-01-03

    The stable isotope signatures of zinc and other metals are increasingly used to study plant and soil processes. Complexation with phytosiderophores is a key reaction and understanding the controls of isotope fractionation is central to such studies. Here, we investigated isotope fractionation during complexation of Zn2+ with the phytosiderophore 2'-deoxymugeneic acid (DMA), and with three commercially available structural analogues of DMA: EDTA, TmDTA, and CyDTA. We used ion exchange chromatography to separate free and complexed zinc, and identified appropriate cation exchange resins for the individual systems. These were Chelex-100 for EDTA and CyDTA, Amberlite CG50 for TmDTA and Amberlite IR120 for DMA. With all the ligands we found preferential partitioning of isotopically heavy zinc in the complexed form, and the extent of fractionation was independent of the Zn:ligand ratio used, indicating isotopic equilibrium and that the results were not significantly affected by artifacts during separation. The fractionations (in ‰) were +0.33 ± 0.07 (1σ, n = 3), + 0.45 ± 0.02 (1σ, n = 2), + 0.62 ± 0.05 (1σ, n = 3) and +0.30 ± 0.07 (1σ, n = 4) for EDTA, TmDTA, CyDTA, and DMA, respectively. Despite the similarity in Zn-coordinating donor groups, the fractionation factors are significantly different and extent of fractionation seems proportional to the complexation stability constant. The extent of fractionation with DMA agreed with observed fractionations in zinc uptake by paddy rice in field experiments, supporting the possible involvement of DMA in zinc uptake by rice.

  15. Isotope shifts of the (3s3p) 3P0,1,2-(3s4s) 3S1 Mg I transitions

    DEFF Research Database (Denmark)

    He, Ming; Therkildsen, Kasper T.; Jensen, Brian B.

    2009-01-01

    We report measurements of the isotope shifts of the (3s3p)P30,1,2-(3s4s)S31 Mg I transitions for the stable isotopes M24g (I=0) , M25g (I=5/2) , and M26g (I=0) . Furthermore, the M25g S31 hyperfine coefficient A(S31)=(-321.6±1.5)MHz is extracted and found to be in excellent agreement with state...

  16. Boric acid adsorption on humic acids: Ab initio calculation of structures, stabilities, 11B NMR and 11B, 10B isotopic fractionations of surface complexes

    Science.gov (United States)

    Tossell, J. A.

    2006-10-01

    Boric acid, B(OH) 3, forms complexes in aqueous solution with a number of bidentate O-containing ligands, HL -, where H 2L is C 2O 4H 2 (oxalic acid), C 3O 4H 4 (malonic acid), C 2H 6O 2 (ethylene glycol), C 6H 6O 2 (catechol), C 10H 8O 2 (dioxynaphthalene) and C 2O 3H 4 (glycolic acid). McElligott and Byrne [McElligott, S., Byrne, R.H., 1998. Interaction of B(OH)30 and HCO3- in seawater: Formation of B(OH)CO3-. Aquat. Geochem.3, 345-356.] have also found B(OH) 3 to form an aqueous complex with HCO3-1. Recently Lemarchand et al. [Lemarchand, E., Schott, J., Gaillardeet, J., 2005. Boron isotopic fractionation related to boron sorption on humic acid and the structure of surface complexes formed. Geochim. Cosmochim. Acta69, 3519-3533] have studied the formation of surface complexes of B(OH) 3 on humic acid, determining 11B NMR shifts and fitted values of formation constants, and 11B, 10B isotope fractionations for a number of surface complexation models. Their work helps to clarify both the nature of the interaction of boric acid with the functional groups in humic acid and the nature of some of these coordinating sites on the humic acid. The determination of isotope fractionations may be seen as a form of vibrational spectroscopy, using the fractionating element as a local probe of the vibrational spectrum. We have calculated quantum mechanically the structures, stabilities, vibrational spectra, 11B NMR spectra and 11B, 10B isotope fractionations of a number of complexes B(OH) 2L - formed by reactions of the type: B(OH)3+HL-⇒B(OH)2L+HO using a 6-311G(d,p) basis set and the B3LYP method for determination of structures, vibrational frequencies and isotopic fractionations, the highly accurate Complete Basis Set-QB3 method for calculating the free energies and the GIAO HF method with a 6-311+G(2d,p) basis for the NMR shieldings. The calculations indicate that oxalic acid, malonic acid, catechol and glycolic acid all form stable complexes (Δ G Byrne, R.H., Yao, W

  17. Mössbauer studies of hyperfine fields in disordered Fe

    Indian Academy of Sciences (India)

    Heusler-like alloy Fe2CrAl was prepared and studied. Structure determination was done by X-ray. The structure was found to conform to the B2 type. Magnetic hyperfine fields in this sample were studied by the Mössbauer effect. The Mössbauer spectra were recorded over a range of temperature from 40 to 296 K. The ...

  18. Probing an Excited-State Atomic Transition Using Hyperfine Quantum Beat Spectroscopy

    CERN Document Server

    Wade, Christopher G; Keaveney, James; Adams, Charles S; Weatherill, Kevin J

    2014-01-01

    We describe a method to observe the dynamics of an excited-state transition in a room temperature atomic vapor using hyperfine quantum beats. Our experiment using cesium atoms consists of a pulsed excitation of the D2 transition, and continuous-wave driving of an excited-state transition from the 6P$_{3/2}$ state to the 7S$_{1/2}$ state. We observe quantum beats in the fluorescence from the 6P$_{3/2}$ state which are modified by the driving of the excited-state transition. The Fourier spectrum of the beat signal yields evidence of Autler-Townes splitting of the 6P$_{3/2}$, F = 5 hyperfine level and Rabi oscillations on the excited-state transition. A detailed model provides qualitative agreement with the data, giving insight to the physical processes involved.

  19. Robust Two-Qubit Gates for Donors in Silicon Controlled by Hyperfine Interactions

    Directory of Open Access Journals (Sweden)

    Rachpon Kalra

    2014-06-01

    Full Text Available We present two strategies for performing two-qubit operations on the electron spins of an exchange-coupled pair of donors in silicon, using the ability to set the donor nuclear spins in arbitrary states. The effective magnetic detuning of the two electron qubits is provided by the hyperfine interaction when the two nuclei are prepared in opposite spin states. This can be exploited to switch SWAP operations on and off with modest tuning of the electron exchange interaction. Furthermore, the hyperfine detuning enables high-fidelity conditional rotation gates based on selective resonant excitation. The latter requires no dynamic tuning of the exchange interaction at all and offers a very attractive scheme to implement two-qubit logic gates under realistic experimental conditions.

  20. AB-INITIO SIMULATION OF ELECTRONIC FEATURES OF HYPERFINE RARE EARTH OXIDE FILMS FOR SENSORY NANOSYSTEMS

    Directory of Open Access Journals (Sweden)

    A. V. Gulay

    2014-01-01

    Full Text Available Ab-Initio simulation of electronic features of sensoring nanomaterials based on rare earth oxides has been made by the example of yttrium oxide. The simulation method for thin films of nanometer scale consisted in the simulation of the material layer of the thickness equal to unit crystal cell size has been proposed within the VASP simulation package. The atomic bond breakdown in the crystal along one of the coordinate axes is simulated by the increase of a distance between the atomic layers along this axis up to values at which the value of free energy is stabilized. It has been found that the valence and conductivity bands are not revealed explicitly and the band gap is not formed in the hyperfine rare earth oxide film (at the film thickness close to 1 nm. In fact the hyperfine rare earth oxide film loses dielectric properties which were exhibited clear enough in continuum.

  1. Measurement of the excited-state transverse hyperfine coupling in NV centers via dynamic nuclear polarization

    Science.gov (United States)

    Poggiali, F.; Cappellaro, P.; Fabbri, N.

    2017-05-01

    Precise knowledge of a quantum system's Hamiltonian is a critical pre-requisite for its use in many quantum information technologies. Here, we report a method for the precise characterization of the nonsecular part of the excited-state Hamiltonian of an electronic-nuclear spin system in diamond. The method relies on the investigation of the dynamic nuclear polarization mediated by the electronic spin, which is currently exploited as a primary tool for initializing nuclear qubits and performing enhanced nuclear magnetic resonance. By measuring the temporal evolution of the population of the ground-state hyperfine levels of a nitrogen-vacancy center, we obtain the first direct estimation of the excited-state transverse hyperfine coupling between its electronic and nitrogen nuclear spin. Our method could also be applied to other electron-nuclear spin systems, such as those related to defects in silicon carbide.

  2. Hyperfine Level Interactions of Diamond Nitrogen Vacancy Ensembles Under Transverse Magnetic Fields

    Science.gov (United States)

    2015-10-06

    excited and ground state cross- ings, which have been used for nuclear spin polarization to decrease resonance line width and increase resonance ...into ac- count the zero-field splitting, nuclear and electronic zee- man shifts, stark shifts, hyperfine splitting, and nuclear quadrupole effects: Hgs...describing interactions with local nuclear spins, Pgs is the nuclear electric quadrupole parameter, and Sk is the spin projection onto the k axis with

  3. Magnetic field dependent intensity variation in the hyperfine split Rb D1 and D2 lines

    Science.gov (United States)

    Hu, Jianping; Ummal Momeen, M.

    2017-11-01

    We present the variation of intensity in Doppler-free hyperfine lines for rubidium atoms with the application of magnetic field. Different polarization configurations have been studied systematically with varying magnetic fields. There is a significant increase in the intensity variation with applied magnetic field related to different polarization configurations. These variations are explained with the theoretical calculations. The calculations are performed by adopting Nakayama's four level model with the varying magnetic field induced transition probability.

  4. Hyperfine interactions of {beta}-emitter {sup 12}N in TiO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Maruyama, Yukiko [Osaka Univ., Toyonaka (Japan). Faculty of Science; Izumikawa, Takuji; Tanigaki, Minoru [and others

    1997-03-01

    Hyperfine interactions of {beta}-emitter {sup 12}N (I{sup {pi}} = 1{sup -}, T{sub 1/2} 11ms) in TiO{sub 2} has been studied. A {beta}-NMR spectrum on the polarized {sup 12}N implanted in TiO{sub 2} shows that {sup 12}N are located at two different sites and maintain about 100% of initial polarization. These are the first phenomena observed in ionic crystals. (author)

  5. Investigation of ferromagnetic spinel semiconductors by hyperfine interactions of implanted nuclear probes

    CERN Document Server

    Samokhvalov, V; Dietrich, M; Schneider, F; Tiginyanu, I M; Tsurkan, V; Unterricker, S

    2003-01-01

    The semiconducting ferromagnetic spinel compounds CdCr//2Se //4, CdCr //2S//4, HgCr//2Se//4 and CuCr//2Se//4 (metallic) were investigated by the perturbed angular correlations (PAC) method with the radioactive probes **1**1**1In, **1**1**1**mCd, **1**1**1Ag, **1**1**7Cd, **1**9**9**mHg and **7**7Br. The probes were implanted at the ISOLDE on-line separator (CERN-Geneva) into single crystals. From the time dependence of the PAC spectra and the measured hyperfine interaction parameters: electric field gradient and magnetic hyperfine field, the probe positions and the thermal behavior of the probes could be determined. Cd, Ag and Hg are substituted at the A-site, In at the A- and B-site in the semiconducting compounds and Br at the anion position. Electric and magnetic hyperfine fields were used as test quantities for theoretical charge and spin density distributions of LAPW calculations (WIEN97).

  6. Investigation of hyperfine interactions in DNA nitrogenous bases using perturbed angular correlation spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Andreia dos Santos; Carbonari, Artur Wilson; Lapolli, Andre Luis; Saxena, Rajendra Narain [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil); Saitovitch, Henrique, E-mail: asilva@usp.br [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    Perturbed γγ angular correlations (PAC) spectroscopy has been used to study the DNA nitrogenous bases (adenine, cytosine, guanine, thymine), using {sup 111}In→{sup 111}Cd and {sup 111m}Cd→{sup 111}Cd probe nuclei. One of the advantages of applying PAC technique to biological molecules is that the experiments can be carried out on molecules in aqueous solution [1], approaching the function of molecules under conditions that are close to in vivo conditions. The measurements were carried out for DNA nitrogenous bases molecules at 295 K and 77 K in order to investigate dynamic and static hyperfine interactions, respectively. The interpretation of the results was based on the measurements of dynamic interaction characterized by the decay constant from which valuable information on the macroscopic behavior of the molecules was obtained [2; 3]. On the other hand, PAC measurements at low temperature showed interaction frequency (ν{sub Q}), asymmetry parameter (η) and the distribution of the quadrupole frequency (δ). These parameters provide a local microscopic description of the chemical environment in the neighborhood of the probe nuclei. Results showed differences in the hyperfine interactions of probe nuclei bound to the studied biomolecules. Such differences were observed by variations in the hyperfine parameters, which depended on the type of biomolecule and the results also showed that the probe nuclei bounded at the molecules in some cases and at others did not. (author)

  7. Diffusive, Structural, Optical, and Electrical Properties of Defects in Semiconductors

    CERN Multimedia

    Wagner, F E

    2002-01-01

    Electronic properties of semiconductors are extremely sensitive to defects and impurities that have localized electronic states with energy levels in the band gap of the semiconductor. Spectroscopic techniques like photoluminescence (PL), deep level transient spectroscopy (DLTS), or Hall effect, that are able to detect and characterize band gap states do not reveal direct information about their microscopic origin. To overcome this chemical "blindness", the present approach is to use radioactive isotopes as a tracer. Moreover, the recoil energies involved in $\\beta$ and $\\gamma$-decays can be used to create intrinsic isolated point defects (interstitials, vacancies) in a controlled way. A microscopic insight into the structure and the thermodynamic properties of complexes formed by interacting defects can be gained by detecting the hyperfine interaction between the nuclear moments of radioactive dopants and the electromagnetic fields present at the site of the radioactive nucleus. The understanding and the co...

  8. Microscopical Studies of Structural and Electronic Properties of Semiconductors

    CERN Multimedia

    2002-01-01

    The electronic and structural properties of point defects in semiconductors, e.g. radiation defects, impurities or passivating defects can excellently be studied by the hyperfine technique of Perturbed Angular Correlation (PAC). The serious limitation of this method, the small number of chemically different radioactive PAC probe atoms can be widely overcome by means of ISOLDE. Providing shortliving isotopes, which represent common dopants as well as suitable PAC probe atoms, the ISOLDE facility enables a much broader application of PAC to problems in semiconductor physics.\\\\ Using the probe atom $^{111m}$ Cd , the whole class of III-V compounds becomes accessible for PAC investigations. First successful experiments in GaAs, InP and GaP have been performed, concerning impurity complex formation and plasma induced defects. In Si and Ge, the electronic properties~-~especially their influence on acceptor-donor interaction~-~could be exemplarily st...

  9. Hyperfine properties of La(V{sub 1−x}Fe{sub x})O{sub 3} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Tupan, L. F. S.; Ivashita, F. F.; Barco, R. [Universidade Estadual de Maringá (Brazil); Hallouche, B. [Universidade de Santa Cruz do Sul (Brazil); Paesano, A., E-mail: paesano@wnet.com.br [Universidade Estadual de Maringá (Brazil)

    2017-11-15

    LaV{sub 1−x}Fe{sub x}O{sub 3} perovskites were synthesized in the vanadium-rich concentration range (i.e., x < 0.5) and characterized structurally and for the hyperfine properties of the iron nuclear probe. The aim of this investigation was to better understand the physical transformations that take place in the undoped compound (LaVO{sub 3}) at low temperatures. For that, X-ray diffraction analysis and, more extensively, {sup 57}Fe Mössbauer spectroscopy were applied. The results revealed that the LaV{sub 1}-xFexO{sub 3} vanadium-rich perovskites are orthorhombic at RT, and their lattice parameters decrease with increasing vanadium concentration. Lowering the temperature, the system becomes magnetic, with the iron moment freezing progressively. The presence of two magnetic subspectral components obtained at the lowest measurement temperatures suggests that the vanadium-rich samples, including LaVO{sub 3}, undergo a phase transition from an orthorhombic to a monoclinic structure at low temperatures.

  10. Chemical and Structural Dependences of the Fractionation of Oxygen and Silicon Isotopes Between Rock-forming Minerals: a First-Principles Density Functional Study

    Science.gov (United States)

    Meheut, M.; Schauble, E. A.

    2008-12-01

    Ab initio methods based on density functional theory have proven to be successful in reproducing the physical and chemical properties of complex systems. Within this framework, we have recently developed a methodology to predict equilibrium fractionation factors as a function of temperature (1). We use PBE functionals, combined with the use of pseudopotentials and planewave basis sets. Our previous work focused on the effect of the polymerization of the silicate network on Si-isotope fractionation (2), which had previously been predicted to be a determining factor. Our work does not confirm this assumption. In particular, a large fractionation was estimated between kaolinite and lizardite, despite identical polymerization structures. To investigate the origin of this fractionation, we studied minerals with structures closely related to lizardite and kaolinite, such as talc, pyrophyllite, muscovite and phlogopite. In terms of Si-isotope fractionation, muscovite is very similar to kaolinite (with Δ qtz-musc = 0.18 ‰ at 700°C) whereas talc and pyrophyllite appear significantly heavier than lizardite and kaolinite, respectively, despite their similar structures and cation contents (Δ qtz-talc = 0.35 ‰, Δ qtz-pyro = 0.08 ‰ at 700°C). In terms of O-isotopes fractionation, calculated quartz-muscovite and muscovite-water fractionations agree well with existing estimates at high temperature, based on experimental and empirical data. Interestingly, talc is calculated to be very similar to muscovite, whereas pyrophyllite will be significantly heavier (Δ qtz-pyro = 3.3 ‰ at 200°C ). Those similarities and differences will be discussed in terms of structures and cation contents. In previous studies, oxygen fractionation systematics have been related to the nature of the first neighbors of oxygen atoms (bond-type models), or to more precise structural features, through the modified increment method for example (3). We will critically analyze these concepts to help

  11. An assessment of the trophic structure of the Bay of Biscay continental shelf food web: Comparing estimates derived from an ecosystem model and isotopic data

    Science.gov (United States)

    Lassalle, G.; Chouvelon, T.; Bustamante, P.; Niquil, N.

    2014-01-01

    Comparing outputs of ecosystem models with estimates derived from experimental and observational approaches is important in creating valuable feedback for model construction, analyses and validation. Stable isotopes and mass-balanced trophic models are well-known and widely used as approximations to describe the structure of food webs, but their consistency has not been properly established as attempts to compare these methods remain scarce. Model construction is a data-consuming step, meaning independent sets for validation are rare. Trophic linkages in the French continental shelf of the Bay of Biscay food webs were recently investigated using both methodologies. Trophic levels for mono-specific compartments representing small pelagic fish and marine mammals and multi-species functional groups corresponding to demersal fish and cephalopods, derived from modelling, were compared with trophic levels calculated from independent carbon and nitrogen isotope ratios. Estimates of the trophic niche width of those species, or groups of species, were compared between these two approaches as well. A significant and close-to-one positive (rSpearman2 = 0.72 , n = 16, p < 0.0001) correlation was found between trophic levels estimated by Ecopath modelling and those derived from isotopic signatures. Differences between estimates were particularly low for mono-specific compartments. No clear relationship existed between indices of trophic niche width derived from both methods. Given the wide recognition of trophic levels as a useful concept in ecosystem-based fisheries management, propositions were made to further combine these two approaches.

  12. Hyperfine interactions at europium sites in oxide glasses

    Science.gov (United States)

    Concas, G.; Congiu, F.; Muntoni, C.; Bettinelli, M.; Speghini, A.

    1996-03-01

    The shape of the γ resonance absorption peak of the Eu3+ ion in a disordered structure was investigated in some phosphate, borate, and silicate glasses by using 151Eu Mössbauer spectroscopy. The quality of the fits was tested by using the Durbin-Watson d statistics. The observed full width at half maximum of the peak was resolved in a contribution of the broadening and a contribution of the quadrupole splitting, due to the distortion of the Eu site compared to a cubic symmetry. The Eu-O bond was found to have a covalent admixture with 6s character. The axial component of the electric-field gradient at the Eu site was found to be correlated with the optical basicity of the glass.

  13. Towards high precision measurements of nuclear g-factors for the Be isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Takamine, A., E-mail: icot@riken.jp [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Wada, M. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Okada, K. [Department of Physics, Sophia University, Chiyoda Ward, Tokyo (Japan); Ito, Y. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Schury, P.; Arai, F. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Institute of Physics, University of Tsukuba, Tsukuba City, Ibaraki (Japan); Katayama, I. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Imamura, K. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Department of Physics, Meiji University, Kawasaki City, Kanagawa (Japan); Ichikawa, Y.; Ueno, H. [RIKEN, Nishina Center for Accelerator Based Science, Wako City, Saitama (Japan); Wollnik, H. [Department of Chemistry and BioChemistry, New Mexico State University, Las Cruces, NM (United States); Schuessler, H.A. [Department of Physics, Texas A& M University, College Station, TX (United States)

    2016-06-01

    We describe the present status of future high-precision measurements of nuclear g-factors utilizing laser-microwave double and laser-microwave-rf triple resonance methods for online-trapped, laser-cooled radioactive beryllium isotope ions. These methods have applicability to other suitably chosen isotopes and for beryllium show promise in deducing the hyperfine anomaly of {sup 11}Be with a sufficiently high precision to study the nuclear magnetization distribution of this one-neutron halo nucleus in a nuclear-model-independent manner.

  14. Towards high precision measurements of nuclear g-factors for the Be isotopes

    Science.gov (United States)

    Takamine, A.; Wada, M.; Okada, K.; Ito, Y.; Schury, P.; Arai, F.; Katayama, I.; Imamura, K.; Ichikawa, Y.; Ueno, H.; Wollnik, H.; Schuessler, H. A.

    2016-06-01

    We describe the present status of future high-precision measurements of nuclear g-factors utilizing laser-microwave double and laser-microwave-rf triple resonance methods for online-trapped, laser-cooled radioactive beryllium isotope ions. These methods have applicability to other suitably chosen isotopes and for beryllium show promise in deducing the hyperfine anomaly of 11Be with a sufficiently high precision to study the nuclear magnetization distribution of this one-neutron halo nucleus in a nuclear-model-independent manner.

  15. Raman transitions between hyperfine clock states in a magnetic trap

    CERN Document Server

    Naber, J B; Hubert, T; Spreeuw, R J C

    2016-01-01

    We present our experimental investigation of an optical Raman transition between the magnetic clock states of $^{87}$Rb in an atom chip magnetic trap. The transfer of atomic population is induced by a pair of diode lasers which couple the two clock states off-resonantly to an intermediate state manifold. This transition is subject to destructive interference of two excitation paths, which leads to a reduction of the effective two-photon Rabi-frequency. Furthermore, we find that the transition frequency is highly sensitive to the intensity ratio of the diode lasers. Our results are well described in terms of light shifts in the multi-level structure of $^{87}$Rb. The differential light shifts vanish at an optimal intensity ratio, which we observe as a narrowing of the transition linewidth. We also observe the temporal dynamics of the population transfer and find good agreement with a model based on the system's master equation and a Gaussian laser beam profile. Finally, we identify several sources of decoheren...

  16. Leatherback Isotopes

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — SWFSC is currently working on a project identifying global marine isotopes using leatherback turtles (Dermochelys coriacea) as the indicator species. We currently...

  17. Isotope Identification

    Energy Technology Data Exchange (ETDEWEB)

    Karpius, Peter Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-09-18

    The objective of this training modules is to examine the process of using gamma spectroscopy for radionuclide identification; apply pattern recognition to gamma spectra; identify methods of verifying energy calibration; and discuss potential causes of isotope misidentification.

  18. Crystal structure of monoclinic samarium and cubic europium sesquioxides and bound coherent neutron scattering lengths of the isotopes {sup 154}Sm and {sup 153}Eu

    Energy Technology Data Exchange (ETDEWEB)

    Kohlmann, Holger [Leipzig Univ. (Germany). Inst. of Inorganic Chemistry; Hein, Christina; Kautenburger, Ralf [Saarland Univ., Saarbruecken (Germany). Inorganic Solid State Chemistry; Hansen, Thomas C.; Ritter, Clemens [Institut Laue-Langevin, Grenoble (France); Doyle, Stephen [Karlsruhe Institute of Technology, Eggenstein-Leopoldshafen (Germany). Inst. for Synchrotron Radiation (ISS)

    2016-11-01

    The crystal structures of monoclinic samarium and cubic europium sesquioxide, Sm{sub 2}O{sub 3} and Eu{sub 2}O{sub 3}, were reinvestigated by powder diffraction methods (laboratory X-ray, synchrotron, neutron). Rietveld analysis yields more precise structural parameters than previously known, especially for oxygen atoms. Interatomic distances d(Sm-O) in Sm{sub 2}O{sub 3} range from 226.3(4) to 275.9(2) pm [average 241.6(3) pm] for the monoclinic B type Sm{sub 2}O{sub 3} [space group C2/m, a = 1418.04(3) pm, b = 362.660(7) pm, c = 885.48(2) pm, β = 100.028(1) ], d(Eu-O) in Eu{sub 2}O{sub 3} from 229.9(2) to 238.8(2) pm for the cubic bixbyite (C) type [space group Ia anti 3, a = 1086.87(1) pm]. Neutron diffraction at 50 K and 2 K did not show any sign for magnetic ordering in Sm{sub 2}O{sub 3}. Isotopically enriched {sup 154}Sm{sub 2}O{sub 3} and {sup 153}Eu{sub 2}O{sub 3} were used for the neutron diffraction work because of the enormous absorption cross section of the natural isotopic mixtures for thermal neutrons. The isotopic purity was determined by inductively coupled plasma - mass spectrometry to be 98.9% for {sup 154}Sm and 99.8% for {sup 153}Eu. Advanced analysis of the neutron diffraction data suggest that the bound coherent scattering lengths of {sup 154}Sm and {sup 153}Eu need to be revised. We tentatively propose b{sub c}({sup 154}Sm) = 8.97(6) fm and b{sub c}({sup 153}Eu) = 8.85(3) fm for a neutron wavelength of 186.6 pm to be better values for these isotopes, showing up to 8% deviation from accepted literature values. It is shown that inaccurate scattering lengths may result in severe problems in crystal structure refinements causing erroneous structural details such as occupation parameters, which might be critically linked to physical properties like superconductivity in multinary oxides.

  19. Annihilation detector for an in-beam spectroscopy apparatus to measure the ground state hyperfine splitting of antihydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Sauerzopf, Clemens, E-mail: clemens.sauerzopf@oeaw.ac.at [Stefan Meyer Institute for subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Wien (Austria); Capon, Aaron A.; Diermaier, Martin; Fleck, Markus; Kolbinger, Bernadette [Stefan Meyer Institute for subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Wien (Austria); Malbrunot, Chloé [Stefan Meyer Institute for subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Wien (Austria); Organisation Européenne pour la Recherche Nucléaire (CERN), 1211 Geneva 23 (Switzerland); Massiczek, Oswald; Simon, Martin C.; Vamosi, Stefan; Zmeskal, Johann; Widmann, Eberhard [Stefan Meyer Institute for subatomic Physics, Austrian Academy of Sciences, Boltzmanngasse 3, 1090 Wien (Austria)

    2017-02-11

    The matter-antimatter asymmetry observed in the universe today still lacks a quantitative explanation. One possible mechanism that could contribute to the observed imbalance is a violation of the combined Charge-, Parity- and Time symmetries (CPT). A test of CPT symmetry using anti-atoms is being carried out by the ASACUSA-CUSP collaboration at the CERN Antiproton Decelerator using a low temperature beam of antihydrogen—the most simple atomic system built only of antiparticles. While hydrogen is the most abundant element in the universe, antihydrogen is produced in very small quantities in a laboratory framework. A detector for in-beam measurements of the ground state hyperfine structure of antihydrogen has to be able to detect very low signal rates within high background. To fulfil this challenging task, a two layer barrel hodoscope detector was developed. It is built of plastic scintillators with double sided readout via Silicon Photomultipliers (SiPMs). The SiPM readout is done using novel, compact and cost efficient electronics that incorporate power supply, amplifier and discriminator on a single board. This contribution will evaluate the performance of the new hodoscope detector. - Highlights: • A novel detector for Antihydrogen was successfully commissioned. • A time of flight resolution of better than 1 ns was achieved. • Rudimentary 3D tracking is possible without bar segmentation.

  20. Nuclear spins and moments of Ga isotopes reveal sudden structural changes between N=40 and N=50.

    Science.gov (United States)

    Cheal, B; Mané, E; Billowes, J; Bissell, M L; Blaum, K; Brown, B A; Charlwood, F C; Flanagan, K T; Forest, D H; Geppert, C; Honma, M; Jokinen, A; Kowalska, M; Krieger, A; Krämer, J; Moore, I D; Neugart, R; Neyens, G; Nörtershäuser, W; Schug, M; Stroke, H H; Vingerhoets, P; Yordanov, D T; Záková, M

    2010-06-25

    Collinear laser spectroscopy was performed on Ga (Z=31) isotopes at ISOLDE, CERN. A gas-filled linear Paul trap (ISCOOL) was used to extend measurements towards very neutron-rich isotopes (N=36-50). A ground state (g.s.) spin I=1/2 is measured for 73Ga, being near degenerate with a 3/2{-} isomer (75  eV≲E{ex}≲1  keV). The 79Ga g.s., with I=3/2, is dominated by protons in the πf{5/2} orbital and in 81Ga the 5/2{-} level becomes the g.s. The data are compared to shell-model calculations in the f{5/2}pg{9/2} model space, calling for further theoretical developments and new experiments.

  1. Hyperfine interaction in the Autler-Townes effect: The formation of bright, dark, and chameleon states

    Science.gov (United States)

    Kirova, T.; Cinins, A.; Efimov, D. K.; Bruvelis, M.; Miculis, K.; Bezuglov, N. N.; Auzinsh, M.; Ryabtsev, I. I.; Ekers, A.

    2017-10-01

    This paper is devoted to clarifying the implications of hyperfine (HF) interaction in the formation of adiabatic (i.e., "laser-dressed") states and their expression in the Autler-Townes (AT) spectra. We first use the Morris-Shore model [J. R. Morris and B. W. Shore, Phys. Rev. A 27, 906 (1983), 10.1103/PhysRevA.27.906] to illustrate how bright and dark states are formed in a simple reference system where closely spaced energy levels are coupled to a single state with a strong laser field with the respective Rabi frequency ΩS. We then expand the simulations to realistic hyperfine level systems in Na atoms for a more general case when non-negligible HF interaction can be treated as a perturbation in the total system Hamiltonian. A numerical analysis of the adiabatic states that are formed by coupling of the 3 p3 /2 and 4 d5 /2 states by the strong laser field and probed by a weak laser field on the 3 s1 /2-3 p3 /2 transition yielded two important conclusions. Firstly, the perturbation introduced by the HF interaction leads to the observation of what we term "chameleon" states—states that change their appearance in the AT spectrum, behaving as bright states at small to moderate ΩS, and fading from the spectrum similarly to dark states when ΩS is much larger than the HF splitting of the 3 p3 /2 state. Secondly, excitation by the probe field from two different HF levels of the ground state allows one to address orthogonal sets of adiabatic states; this enables, with appropriate choice of ΩS and the involved quantum states, a selective excitation of otherwise unresolved hyperfine levels in excited electronic states.

  2. What the multiline signal (MLS) simulation data with average of weighted computations reveal about the Mn hyperfine interactions and oxidation states of the manganese cluster in OEC?

    Science.gov (United States)

    Baituti, Bernard

    2017-11-01

    Understanding the structure of oxygen evolving complex (OEC) fully still remains a challenge. Lately computational chemistry with the data from more detailed X-ray diffraction (XRD) OEC structure, has been used extensively in exploring the mechanisms of water oxidation in the OEC (Gatt et al., J. Photochem. Photobiol. B 104(1-2), 80-93 2011). Knowledge of the oxidation states is very crucial for understanding the core principles of catalysis by photosystem II (PSII) and catalytic mechanism of OEC. The present study involves simulation studies of the X-band continuous wave electron-magnetic resonance (CW-EPR) generated S 2 state signals, to investigate whether the data is in agreement with the four manganese ions in the OEC, being organised as a `3 + 1' (trimer plus one) model (Gatt et al., Angew. Chem. Int. Ed. 51, 12025-12028 2012; Petrie et al., Chem. A Eur. J. 21, 6780-6792 2015; Terrett et al., Chem. Commun. (Camb.) 50, 8-11 2014) or `dimer of dimers' model (Terrett et al. 2016). The question that still remains is how much does each Mn ion contribute to the " g2multiline" signal through its hyperfine interactions in OEC also to differentiate between the `high oxidation state (HOS)' and `low oxidation state (LOS)' paradigms? This is revealed in part by the structure of multiline (ML) signal studied in this project. Two possibilities have been proposed for the redox levels of the Mn ions within the catalytic cluster, the so called `HOS' and `LOS' paradigms (Gatt et al., J. Photochem. Photobiol. B 104(1-2), 80-93 2011). The method of data analysis involves numerical simulations of the experimental spectra on relevant models of the OEC cluster. The simulations of the X-band CW-EPR multiline spectra, revealed three manganese ions having hyperfine couplings with large anisotropy. These are most likely Mn III centres and these clearly support the `LOS' OEC paradigm model, with a mean oxidation of 3.25 in the S2 state. This is consistent with the earlier data by Jin et

  3. Forward two-photon exchange in elastic lepton-proton scattering and hyperfine-splitting correction

    Energy Technology Data Exchange (ETDEWEB)

    Tomalak, Oleksandr [Johannes Gutenberg Universitaet, Institut fuer Kernphysik and PRISMA Cluster of Excellence, Mainz (Germany)

    2017-08-15

    We relate the forward two-photon exchange (TPE) amplitudes to integrals of the inclusive lepton-proton scattering cross sections. These relations yield an alternative way for the evaluation of the TPE correction to hyperfine-splitting (HFS) in the hydrogen-like atoms with an equivalent to the standard approach (Iddings, Drell and Sullivan) result implying the Burkhardt-Cottingham sum rule. For evaluation of the individual effects (e.g., elastic contribution) our approach yields a distinct result. We compare both methods numerically on examples of the elastic contribution and the full TPE correction to HFS in electronic and muonic hydrogen. (orig.)

  4. Variations of 57Fe hyperfine parameters in medicaments containing ferrous fumarate and ferrous sulfate

    Science.gov (United States)

    Oshtrakh, M. I.; Novikov, E. G.; Dubiel, S. M.; Semionkin, V. A.

    2010-04-01

    Several commercially available medicaments containing ferrous fumarate (FeC4H2O4) and ferrous sulfate (FeSO4), as a source of ferrous iron, were studied using a high velocity resolution Mössbauer spectroscopy. A comparison of the 57Fe hyperfine parameters revealed small variations for the main components in both medicaments indicating some differences in the ferrous fumarates and ferrous sulfates. It was also found that all spectra contained additional minor components probably related to ferrous and ferric impurities or to partially modified main components.

  5. Study of the Neutron Deficient Pb and Bi Isotopes by Simultaneous Atomic- and Nuclear-Spectroscopy

    CERN Multimedia

    Kessler, T

    2002-01-01

    We propose to study systematically nuclear properties of the neutron deficient lead $^{183-189}$Pb, $^{191g}$Pb, $^{193g}$Pb and bismuth isotopes $^{188-200}$Bi by atomic spectroscopy with the ISOLDE resonance ionisation laser ion source (RILIS) combined with simultaneous nuclear spectroscopy at the detection set-up. The main focus is the determination of the mean square charge radii of $^{183-190}$Pb and $^{188-193}$Bi from which the influence of low-lying intruder states should become obvious. Also the nuclear spin and magnetic moments of ground-states and long-lived isomers will be determined unambiguously through evaluation of the hyperfine structure, and new isomers could be discovered. The decay properties of these nuclei can be measured by $\\alpha$-$\\gamma$ and $\\beta$-$\\gamma$ spectroscopy. With this data at hand, possible shape transitions around mid-shell at N$\\sim$104 will be studied. This data is crucial for the direct test of nuclear theory in the context of intruder state influence (e.g. energy ...

  6. Laser fluorescence on radio-active isotopes produced in very low yield

    Science.gov (United States)

    Dancy, M. P.; Billowes, J.; Grant, I. S.; Evans, D. E.; Griffith, J. A. R.; Wells, S. A.; Eastham, D. A.; Groves, J.; Smith, J. R. H.; Tolfree, D. W. L.; Walker, P. M.

    1990-08-01

    East particle-photon coincidence techniques, developed at Daresbury with strontium isotopes, allow ultrasensitive laser fluorescence spectroscopy of beams of radio-active isotopes which can only be produced in very low yields. The technique has now been applied to neutron-deficient barium isotopes down to120Ba. From measured hyperfine splittings and isotope shifts, nuclear moments and changes in mean square radii have been determined. The work has revealed an abrupt increase in the mean square radius for121Ba large enough to disrupt the systematic staggering of nuclear size seen for the series. In a recent experiment an isomeric state of127Ba with a half-life of about 2 seconds has been produced in a very low yield; nevertheless we have succeeded in obtaining a fluorescence spectrum.

  7. Energetics and control of ultracold isotope-exchange reactions between heteronuclear dimers in external fields

    Science.gov (United States)

    Tomza, Michal

    2017-04-01

    We show that isotope-exchange reactions between ground-state alkali-metal, alkaline-earth-metal, and lanthanide heteronuclear dimers consisting of two isotopes of the same atom are exothermic with an energy change in the range of 1-8000 MHz, thus resulting in cold or ultracold products. For these chemical reactions, there are only one rovibrational and at most several hyperfine possible product states. The number and energetics of open and closed reactive channels can be controlled by the laser and magnetic fields. We suggest a laser-induced isotope- and state-selective Stark shift control to tune the exothermic isotope-exchange reactions to become endothermic, thus providing the ground for testing models of the chemical reactivity. The present proposal opens the way for studying the state-to-state dynamics of ultracold chemical reactions beyond the universal limit with a meaningful control over the quantum states of both reactants and products.

  8. Exploring template-bound dinuclear copper porphyrin nanorings by EPR spectroscopy† †Electronic supplementary information (ESI) available: Description of the experimental conditions and parameters applied; supplementary data sets and simulations; visualization of the calculated hyperfine and nuclear quadrupole tensors. See DOI: 10.1039/c6sc01810f Click here for additional data file.

    Science.gov (United States)

    Richert, Sabine; Cremers, Jonathan; Anderson, Harry L.

    2016-01-01

    Electron paramagnetic resonance (EPR) spectroscopy has been used to study the molecular geometry as well as metal–ligand interactions in ten-membered porphyrin nanorings (c-P10Cu2) containing two copper and eight zinc centers. The presence of copper in the structures allows intramolecular interactions, including dipolar interactions between electron spins and hyperfine interactions to be quantified. Results obtained for c-P10Cu2 samples bound to two molecular templates with four or five binding sites, respectively, are compared to those obtained for a sample of the porphyrin ring in the absence of any templates. It is shown that the observed lower binding affinity of the nitrogen ligand to copper as compared to zinc has a strong impact on the geometries of the respective template-bound c-P10Cu2 structures. The interaction between the central copper atom and nitrogen ligands is weak, but pulsed EPR hyperfine techniques such as ENDOR and HYSCORE are very sensitive to this interaction. Upon binding of a nitrogen ligand to copper, the hyperfine couplings of the in-plane nitrogen atoms of the porphyrin core are reduced by about 3 MHz. In addition, the copper hyperfine couplings as well as the g-factors are altered, as detected by continuous wave EPR. DFT calculations of the hyperfine coupling tensors support the assignment of the measured couplings to the nuclei within the structure and reproduce the experimentally observed trends. Finally, Double Electron Electron Resonance (DEER) is used to measure the distances between the copper centers in a range between 2.5 and 5 nm, revealing the preferred geometries of the template-bound nanorings. PMID:28451129

  9. Stable isotopes and mercury in a model estuarine fish: Multibasin comparisons with water quality, community structure, and available prey base

    Energy Technology Data Exchange (ETDEWEB)

    Adams, Douglas H., E-mail: Doug.Adams@MyFWC.com; Paperno, Richard

    2012-01-01

    Stable-isotope ratios ({delta}{sup 13}C and {delta}{sup 15}N) and mercury in a model predator, and associated prey community assessments were used to make inferences regarding food web relationships and how these relationships are influenced by habitat variability and anthropogenic factors. Although interconnected, the three major basins of the Indian River Lagoon system on the Atlantic coast of Florida comprise noticeably different available habitat types with spatially distinct faunal communities and available prey for spotted seatrout, Cynoscion nebulosus, a model predatory fish species. Water quality, degree of urbanization, human population density, and levels of nitrogen enrichment clearly differ between these representative estuarine basins. The differences can influence feeding ecology and therefore result in different mercury concentrations and different stable-isotope signatures of spotted seatrout between basins. Mercury concentrations in spotted seatrout were greatest in Mosquito Lagoon (ML) and least in the Indian River Lagoon proper (IRL), although concentrations were low for all basins. Spotted seatrout from IRL were carbon-depleted and nitrogen-enriched compared with those from the other basins; this suggests either that the fish's primary source of carbon in IRL is an algae- or phytoplankton-based food web or that the pathway through the food web is shorter there. The {delta}{sup 15}N values of IRL spotted seatrout were greater than those in the Banana River Lagoon or ML, suggesting slightly different trophic positioning of fish in these basins. The greater {delta}{sup 15}N values in IRL spotted seatrout may also reflect the greater human population density and resultant anthropogenic inputs (e.g., observed higher total nitrogen levels) in IRL compared with the other more pristine basins examined. Understanding species' responses to broad-scale habitat heterogeneity in estuaries and knowing basin-specific differences in stable isotopes

  10. Consensus structures of the Mo(v) sites of sulfite-oxidizing enzymes derived from variable frequency pulsed EPR spectroscopy, isotopic labelling and DFT calculations.

    Science.gov (United States)

    Enemark, John H

    2017-10-10

    Sulfite-oxidizing enzymes from eukaryotes and prokaryotes have five-coordinate distorted square-pyramidal coordination about the molybdenum atom. The paramagnetic Mo(v) state is easily generated, and over the years four distinct CW EPR spectra have been identified, depending upon enzyme source and the reaction conditions, namely high and low pH (hpH and lpH), phosphate inhibited (Pi) and sulfite (or blocked). Extensive studies of these paramagnetic forms of sulfite-oxidizing enzymes using variable frequency pulsed electron spin echo (ESE) spectroscopy, isotopic labeling and density functional theory (DFT) calculations have led to the consensus structures that are described here. Errors in some of the previously proposed structures are corrected.

  11. Hyperfine interactions and some thermomagnetic properties of amorphous FeZr(CrNbBCu alloys

    Directory of Open Access Journals (Sweden)

    Łukiewska Agnieszka

    2017-06-01

    Full Text Available In this research, we studied the magnetic phase transition by Mössbauer spectroscopy and using vibrating sample magnetometer for amorphous Fe86-xZr7CrxNb2Cu1B4 (x = 0 or 6 alloys in the as-quenched state and after accumulative annealing in the temperature range 600-750 K. The Mössbauer investigations were carried out at room and nitrogen temperatures. The Mössbauer spectra of the investigated alloys at room temperature are characteristic of amorphous paramagnets and have a form of asymmetric doublets. However, at nitrogen temperature, the alloys behave like ferromagnetic amorphous materials. The two components are distinguished in the spectrum recorded at both room and nitrogen temperatures. The low field component in the distribution of hyperfine field induction shifts towards higher field with the annealing temperature. It is assumed that during annealing at higher temperature, due to diffusion processes, the grains of α-Fe are created in the area corresponding to this component. Both investigated alloys show the invar effect and the decrease of hyperfine field induction after annealing at 600 K for 10 min is observed. It is accompanied by the lowering of Curie temperature.

  12. Precision measurement of the +25Mg ground-state hyperfine constant

    Science.gov (United States)

    Xu, Z. T.; Deng, K.; Che, H.; Yuan, W. H.; Zhang, J.; Lu, Z. H.

    2017-11-01

    We report an experimental determination of the ground-state hyperfine constant A of the +25Mg ions by measuring the | S1 /2,F =2 ,m =0 〉 to | S1 /2,F =3 ,m =0 〉 transition (0-0 transition) frequency of the two ground-state hyperfine energy levels. The frequency is measured by rf resonant method in a Paul trap under a magnetic field of about 0.1 mT. The result is A =-596.254 248 7(42) MHz. Different frequency shifts and uncertainties are evaluated. The main effect is quadratic Zeeman shift. Since the Paul trap is driven by rf on the electrodes, ac magnetic field can be induced by the rf at the site of the ion. The ac magnetic field causes quadratic Zeeman shift for ion frequency standards and also reduces the coherence time when the ion acts as a quantum bit. Precision measurement of this ac magnetic field can help evaluating the related uncertainty when a single-ion optical clock is established on the trap.

  13. Seasonal and inter-annual dynamics of growth, non-structural carbohydrates and C stable isotopes in a Mediterranean beech forest.

    Science.gov (United States)

    Scartazza, Andrea; Moscatello, Stefano; Matteucci, Giorgio; Battistelli, Alberto; Brugnoli, Enrico

    2013-07-01

    Seasonal and inter-annual dynamics of growth, non-structural carbohydrates (NSC) and carbon isotope composition (δ(13)C) of NSC were studied in a beech forest of Central Italy over a 2-year period characterized by different environmental conditions. The net C assimilated by forest trees was mainly used to sustain growth early in the season and to accumulate storage carbohydrates in trunk and root wood in the later part of the season, before leaf shedding. Growth and NSC concentration dynamics were only slightly affected by the reduced soil water content (SWC) during the drier year. Conversely, the carbon isotope analysis on NSC revealed seasonal and inter-annual variations of photosynthetic and post-carboxylation fractionation processes, with a significant increase in δ(13)C of wood and leaf soluble sugars in the drier summer year than in the wetter one. The highly significant correlation between δ(13)C of leaf soluble sugars and SWC suggests a decrease of the canopy C isotope discrimination and, hence, an increased water-use efficiency with decreasing soil water availability. This may be a relevant trait for maintaining an acceptable plant water status and a relatively high C sink capacity during dry seasonal periods. Our results suggest a short- to medium-term homeostatic response of the Collelongo beech stand to variations in water availability and solar radiation, indicating that this Mediterranean forest was able to adjust carbon-water balance in order to prevent C depletion and to sustain plant growth and reserve accumulation during relatively dry seasons.

  14. Hyperfine and Spin-Orbit Coupling Effects on Decay of Spin-Valley States in a Carbon Nanotube

    Science.gov (United States)

    Pei, T.; Pályi, A.; Mergenthaler, M.; Ares, N.; Mavalankar, A.; Warner, J. H.; Briggs, G. A. D.; Laird, E. A.

    2017-04-01

    The decay of spin-valley states is studied in a suspended carbon nanotube double quantum dot via the leakage current in Pauli blockade and via dephasing and decoherence of a qubit. From the magnetic field dependence of the leakage current, hyperfine and spin-orbit contributions to relaxation from blocked to unblocked states are identified and explained quantitatively by means of a simple model. The observed qubit dephasing rate is consistent with the hyperfine coupling strength extracted from this model and inconsistent with dephasing from charge noise. However, the qubit coherence time, although longer than previously achieved, is probably still limited by charge noise in the device.

  15. Defects in ZnO, CdTe, and Si: Optical, structural, and electrical characterization

    CERN Multimedia

    Deicher, M; Kronenberg, J; Johnston, K; Roder, J; Byrne, D J

    Electronic and optical properties of semiconductors are extremely sensitive to defects and impurities that have localized electronic states with energy levels in the band gap of the semiconductor. Spectroscopic techniques like photo-luminescence (PL), deep level transient spectroscopy (DLTS), or Hall effect that are able to detect and characterize band gap states do not reveal direct information about their microscopic origin. To overcome this chemical "blindness" radioactive isotopes are used as a tracer. Moreover, the recoil energies involved in ${\\beta}$- and ${\\gamma}$-decays can be used to create intrinsic, isolated point defects (interstitials, vacancies) in a controlled way. A microscopic insight into the structure and the thermodynamic properties of complexes formed by interacting defects can be gained by detecting the hyperfine interaction between the nuclear moments of radioactive dopants and the electromagnetic fields present at the site of the radioactive nucleus. These techniques will be used to...

  16. Stable isotope compounds - production, detection, and application.

    Science.gov (United States)

    Zachleder, Vilém; Vítová, Milada; Hlavová, Monika; Moudříková, Šárka; Mojzeš, Peter; Heumann, Hermann; Becher, Johannes R; Bišová, Kateřina

    2018-01-19

    Stable isotopes are used in wide fields of application from natural tracers in biology, geology and archeology through studies of metabolic fluxes to their application as tracers in quantitative proteomics and structural biology. We review the use of stable isotopes of biogenic elements (H, C, N, O, S, Mg, Se) with the emphasis on hydrogen and its heavy isotope deuterium. We will discuss the limitations of enriching various compounds in stable isotopes when produced in living organisms. Finally, we overview methods for measuring stable isotopes, focusing on methods for detection in single cells in situ and their exploitation in modern biotechnologies. Copyright © 2018. Published by Elsevier Inc.

  17. Design and operation of a continuous 13C and 15N labeling chamber for uniform or differential, metabolic and structural, plant tissue isotope labeling

    Science.gov (United States)

    Tracing heavy stable isotopes from plant material through the ecosystem provides the most sensitive information about ecosystem processes; from CO2 fluxes and soil organic matter formation to small-scale stable-isotope biomarker probing. Coupling multiple stable isotopes such as 13C with 15N, 18O o...

  18. A large column analog experiment of stable isotope variations during reactive transport: II. Carbon mass balance, microbial community structure and predation

    Science.gov (United States)

    Druhan, Jennifer L.; Bill, Markus; Lim, HsiaoChien; Wu, Cindy; Conrad, Mark E.; Williams, Kenneth H.; DePaolo, Donald J.; Brodie, Eoin L.

    2014-01-01

    Here we report a combined analysis of carbon mass balance based on isotopic labeling and microbiological characterization during organic carbon stimulated bioreduction of a subsurface sediment in a large laboratory column experimental system. This combination of approaches allows quantification of both the cycling of carbon through multiple redox pathways and the associated spatial and temporal evolution of bacterial communities in response to this nutrient source. Carbon isotope mass balance facilitated by the use of 13C-labeled acetate as the electron donor showed evidence for a net loss of sediment organic carbon over the course of the amendment experiment. Furthermore, these data clearly demonstrated a source of isotopically labeled inorganic carbon that was not attributable to primary metabolism by acetate-oxidizing microorganisms. Fluid samples collected weekly over the duration of the 43-day amendment at course of the experiment. In combination with DNA sequencing data, the anomalous carbon cycling process is shown to occur exclusively during the period of predominant Geobacter species growth. Pyrosequencing indicated, and targeted cloning and sequencing confirmed the presence of several bacteriovorous protozoa, including species of the Breviata, Planococcus and Euplotes genera. Cloning and qPCR analysis demonstrated that Euplotes species were most abundant and displayed a growth trajectory that closely followed that of the Geobacter population. These results suggest a previously undocumented secondary turnover of biomass carbon related to protozoan grazing that was not sufficiently prevalent to be observed in bulk concentrations of carbon species in the system, but was clearly identified in the partitioning of carbon isotopes. This study demonstrates evidence for predator-prey relationships that impact subsurface microbial community dynamics and provides a novel indication of the impact of this relationship on the flux of carbon through a system via the

  19. Stable isotope

    African Journals Online (AJOL)

    Results of the study suggest that there are two main carbon pathways for plankton and nekton in the Kariega estuary, carbon derived from the eelgrass and its associated epiphytes and carbon which has its origins in the salt marsh riparian vegetation and zooplankton. Keywords: stable isotope analysis; temperate estuary; ...

  20. Compilation of Spectroscopic Data of Radium (Ra I and Ra II)

    NARCIS (Netherlands)

    Dammalapati, U.; Jungmann, K.; Willmann, L.

    2016-01-01

    Energy levels, wavelengths, lifetimes, and hyperfine structure constants for the isotopes of the first and second spectra of radium, Ra I and Ra II, have been compiled. Wavelengths and wavenumbers are tabulated for 226Ra and for other Ra isotopes. Isotope shifts and hyperfine structure constants of

  1. The novel isotopically coded short-range photo-reactive crosslinker 2,4,6-triazido-1,3,5-triazine (TATA) for studying protein structures.

    Science.gov (United States)

    Brodie, Nicholas I; Petrotchenko, Evgeniy V; Borchers, Christoph H

    2016-10-21

    Short-distance molecular-modeling constraints are advantageous for elucidating the structures of individual proteins and protein conformational changes. Commonly used amine-reactive crosslinks are relatively long (14Å), partly due to the length of the lysine side-chain, and are sparsely distributed throughout a protein. Short-distance non-specific crosslinkers can provide a larger number of tighter molecular-modeling constraints. Here we describe the use of a short-range homo-trifunctional isotopically-coded non-specific photo-reactive crosslinking reagent, 2,4,6-triazido-1,3,5-triazine (TATA)-(12)C3/(13)C3, for MS-based protein crosslinking studies. Upon activation by 254nm UV light, TATA-(12)C3/(13)C3 generates up to three nitrene radicals capable of non-selective crosslinking at ~5Å. This reagent was validated using cyclohexane, several test peptides, and myoglobin, and was found to react with a large number of amino acids, forming multiple crosslinked products. The myoglobin crosslinks detected by MS agreed with the known structure of myoglobin; arranging the protein's secondary-structure motifs into their correct fold was possible based solely on the constraints imposed by the crosslinks. Finally, TATA was used to crosslink the α-synuclein monomer. The 10 short-distance constraints provided by TATA crosslinking led to an initial model of the molten-globule form of the native α-synuclein monomer; this provides a suggested structure for the precursor of the misfolded α-synuclein proteoforms involved in synucleopathies. The isotopically labeled short-range non-specific crosslinker TATA-(12)C3/(13)C3 was characterized for use in crosslinking-based protein structural studies. The crosslinking products of TATA can provide a distance constraint of merely 5Ǻ between crosslinked residues. TATA-(12)C3/(13)C3 had broad reactivity, crosslinking a wide variety of amino acids, including lysine, glutamic and aspartic acid, asparagine, glutamine, glycine, alanine

  2. Observations of nitrogen isotope fractionation in deeply embedded protostars⋆

    Science.gov (United States)

    Wampfler, S. F.; Jørgensen, J. K.; Bizzarro, M.; Bisschop, S. E.

    2015-01-01

    Context The terrestrial planets, comets, and meteorites are significantly enriched in 15N compared to the Sun and Jupiter. While the solar and jovian nitrogen isotope ratio is believed to represent the composition of the protosolar nebula, a still unidentified process has caused 15N-enrichment in the solids. Several mechanisms have been proposed to explain the variations, including chemical fractionation. However, observational results that constrain the fractionation models are scarce. While there is evidence of 15N-enrichment in prestellar cores, it is unclear how the signature evolves into the protostellar phases. Aims The aim of this study is to measure the 14N/15N ratio around three nearby, embedded low- to intermediate-mass protostars. Methods Isotopologues of HCN and HNC were used to probe the 14N/15N ratio. A selection of J = 3–2 and 4–3 transitions of H13CN, HC15N, HN13C, and H15NC was observed with the Atacama Pathfinder EXperiment telescope (APEX). The 14N/15N ratios were derived from the integrated intensities assuming a standard 12C/13C ratio. The assumption of optically thin emission was verified using radiative transfer modeling and hyperfine structure fitting. Results Two sources, IRAS 16293A and R CrA IRS7B, show 15N-enrichment by a factor of ~1.5–2.5 in both HCN and HNC with respect to the solar composition. IRAS 16293A falls in the range of typical prestellar core values. Solar composition cannot be excluded for the third source, OMC-3 MMS6. Furthermore, there are indications of a trend toward increasing 14N/15N ratios with increasing outer envelope temperature. Conclusions The enhanced 15N abundances in HCN and HNC found in two Class 0 sources (14N/15N ~ 160–290) and the tentative trend toward a temperature-dependent 14N/15N ratio are consistent with the chemical fractionation scenario, but 14N/15N ratios from additional tracers are indispensable for testing the models. Spatially resolved observations are needed to distinguish between

  3. Microbial food web mapping: linking carbon cycling and community structure in soils through pyrosequencing enabled stable isotope probing

    Energy Technology Data Exchange (ETDEWEB)

    Buckley, Daniel H. [Cornell Univ., Ithaca, NY (United States)

    2015-03-15

    Soil represents a massive reservoir of active carbon and climate models vary dramatically in predicting how this carbon will respond to climate change over the coming century. A major cause of uncertainty is that we still have a very limited understand the microorganisms that dominate the soil carbon cycle. The vast majority of soil microbes cannot be cultivated in the laboratory and the diversity of organisms and enzymes that participate in the carbon cycle is staggeringly complex. We have developed a new toolbox for exploring the carbon cycle and the metabolic and ecological characteristics of uncultivated microorganisms. The high-resolution nucleic acid stable isotope probing approach that we have developed makes it possible to characterize microbial carbon cycling dynamics in soil. The approach allows us to track multiple 13C-labeled substrates into thousands of microbial taxa over time. Using this approach we have discovered several major lineages of uncultivated microorganisms that participate in cellulose metabolism and are found widely in soils (including Verrucomicrobia and Chloroflexi, which have not previously been implicated as major players in the soil carbon cycle). Furthermore, isotopic labelling of nucleic acids enables community genomics and permits genome fragment binning for a majority of these cellulolytic microorganisms allowing us to explore the metabolic underpinnings of cellulose degradation. This approach has allowed us to describe unexpected dynamics of carbon metabolism with different microbial taxa exhibiting characteristic patterns of carbon substrate incorporation, indicative of distinct ecological strategies. The data we describe allows us to characterize the activity of novel microorganisms as they occur in the environment and these data provide a basis for understanding how the physiological traits of discrete microorganisms sum to govern the complex responses of the soil carbon cycle.

  4. Hyperfine interactions in nanocrystallized NANOPERM-type metallic glass containing Mo

    Energy Technology Data Exchange (ETDEWEB)

    Cesnek, M., E-mail: martin.cesnek@fjfi.cvut.cz [Czech Technical University in Prague, Department of Nuclear Reactors, Faculty of Nuclear Science and Physical Engineering (Czech Republic); Kubániová, D.; Kohout, J.; Křišťan, P.; Štěpánková, H.; Závěta, K. [Charles University, Department of Low Temperature Physics, Faculty of Mathematics and Physics (Czech Republic); Lančok, A. [Institute of Inorganic Chemistry AS CR (Czech Republic); Štefánik, M.; Miglierini, M. [Czech Technical University in Prague, Department of Nuclear Reactors, Faculty of Nuclear Science and Physical Engineering (Czech Republic)

    2016-12-15

    NANOPERM-type alloy with chemical composition Fe{sub 76}Mo{sub 8}CuB{sub 15} was studied by combination of {sup 57}Fe Mössbauer spectroscopy and {sup 57}Fe({sup 10}B, {sup 11}B) nuclear magnetic resonance in order to determine distribution of hyperfine magnetic fields and evolution of relative concentration of Fe-containing crystalline phases within the surface layer and the volume of the nanocrystallized ribbons with annealing temperature. Differential scanning calorimetry revealed two crystallization stages at T{sub x1} ∼ 510 {sup ∘}C and T{sub x2} ∼ 640 {sup ∘}C, connected to precipitation of α-Fe and Fe(Mo,B) nanocrystals, respectively. The amorphous and partially crystalline state was obtained by annealing at several temperatures in the range 510-650 {sup ∘}C. The combination of conversion electron (CEMS) and transmission Mössbauer spectrometry (TMS) showed that annealing induces crystallization starting from both surfaces of the ribbons. For the as-quenched sample, scanning electron microscopy (SEM) and CEMS revealed significant differences in the “air” and “wheel” sides of the ribbons, crystallites were preferentially formed at the latter. While SEM micrographs of annealed samples showed various mean diameters of the crystals at opposite sides of the ribbons, the amounts of crystalline volume derived from the CEMS spectra approximately equaled. Mössbauer spectra of annealed samples contained narrow sextet ascribed to crystalline α-Fe phase, three sextets with distribution of hyperfine field assigned to the interface regions of the nanocrystals and the contribution of the amorphous phases. In-field TMS performed at 4.2 K with magnetic moments aligned by external magnetic field enabled to properly determine in particular the contribution of the amorphous phases in the samples. Resulting distributions of the hyperfine fields were compared with {sup 57}Fe({sup 10}B, {sup 11}B) nuclear magnetic resonance (NMR) spectra.

  5. Hyperfine splitting in positronium to O({alpha}{sup 7}m{sub e}). One-photon annihilation contribution

    Energy Technology Data Exchange (ETDEWEB)

    Baker, M. [Alberta Univ., Edmonton, AB (Canada). Dept. of Physics; Marquard, P. [Deutsches Elektronen-Synchrotron (DESY), Zeuthen (Germany); Penin, A.A. [Alberta Univ., Edmonton, AB (Canada). Dept. of Physics; Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik; Piclum, J. [Technische Univ. Muenchen, Garching (Germany). Physik-Department; RWTH Aachen (Germany). Inst. fuer Theoretische Teilchenphysik und Kosmologie; Steinhauser, M. [Karlsruher Institut fuer Technologie (Germany). Inst. fuer Theoretische Teilchenphysik

    2014-02-15

    We present the complete result for the O({alpha}{sup 7}m{sub e}) one-photon annihilation contribution to the hyperfine splitting of the ground state energy levels in positronium. Numerically it increases the prediction of quantum electrodynamics by 217{+-}1 kHz.

  6. Selection of support structure materials for irradiation experiments in the HFIR (High Flux Isotope Reactor) at temperatures up to 500 degrees C

    Energy Technology Data Exchange (ETDEWEB)

    Farrell, K.; Longest, A.W.

    1990-01-01

    The key factor in the design of capsules for irradiation of test specimens in the High Flux Isotope Reactor at preselected temperatures up to 500{degree}C utilizing nuclear heating is a narrow gas-filled gap which surrounds the specimens and controls the transfer of heat from the specimens through the wall of a containment tube to the reactor cooling water. Maintenance of this gap to close tolerances is dependent on the characteristics of the materials used to support the specimens and isolate them from the water. These support structure materials must have low nuclear heating rates, high thermal conductivities, and good dimensional stabilities under irradiation. These conditions are satisfied by certain aluminum alloys. One of these alloys, a powder metallurgy product containing a fine dispersion of aluminum oxide, is no longer manufactured. A new alloys of this type, with the trade name DISPAL, is determined to be a suitable substitute. 23 refs., 13 figs., 3 tabs.

  7. Energy-Level Related Nuclear-Spin Effects and Super-Hyperfine Spectral Patterns: how Molecules do Self-Nmr

    Science.gov (United States)

    Harter, William; Mitchell, Justin

    2009-06-01

    At several points in his defining works on molecular spectroscopy, Herzberg notes that ``because nuclear moments ldots are so very slight ldots transitions between species ldots are very strictly forbiddenldots '' Herzberg's most recent statement of such selection rules pertained to spherical top spin-species. It has since been shown that spherical top species (as well as those of lower symmetry molecules) converge exponentially with momentum quanta J and K to degenerate level clusters wherein even ``very slight'' nuclear fields and moments cause pervasive resonance and total spin species mixing. Ultra-high resolution spectra of Borde, et .al and Pfister et .al shows how SF_6 and SiF_4 Fluorine nuclear spin levels rearrange from total-spin multiplets to NMR-like patterns as their superfine structure converges. Similar super-hyperfine effects are anticipated for lower symmetry molecules exhibiting converging superfine level-clusters. Examples include PH_3 molecules and asymmetric tops. Following this we consider models that treat nuclear spins as coupled rotors undergoing generalized Hund-case transitions from spin-lab-momentum coupling to various spin-rotor correlations. G. A. Herzberg, Electronic Spectra of Polyatomic Molecules, (Von Norstrand Rheinhold 1966) p. 246. W G. Harter and C. W Patterson, Phys. Rev. A 19, 2277 (1979) W. G. Harter, Phys. Rev. A 24, 192 (1981). Ch. J. Borde, J. Borde, Ch. Breant, Ch. Chardonnet, A. Van Lerberghe, and Ch. Salomon, in Laser Spectroscopy VII, T. W Hensch and Y. R. Shen, eds. (Springer-Verlag, Berlin, 1985). O. Pfister, F. Guernet, G. Charton, Ch. Chardonnet, F. Herlemont, and J. Legrand, J. Opt. Soc. Am. B 10, 1521 (1993). O. Pfister, Ch. Chardonnet, and Ch. J. Bordè, Phys. Rev. Lett. 76, 4516 (1996) S. N. Yurchenko, W. Thiel, S. Patchkovskii, and P. Jensen, Phys. Chem. Chem. Phys.7, 573 (2005)

  8. The 35Cl/37Cl isotopic ratio in dense molecular clouds: HIFI observations of hydrogen chloride towards W3 A

    Science.gov (United States)

    Cernicharo, J.; Goicoechea, J. R.; Daniel, F.; Agúndez, M.; Caux, E.; de Graauw, T.; de Jonge, A.; Kester, D.; Leduc, H. G.; Steinmetz, E.; Stutzki, J.; Ward, J. S.

    2010-07-01

    We report on the detection with the HIFI instrument on board the Herschel satellite of the two hydrogen chloride isotopologues, H35Cl and H37Cl, towards the massive star-forming region W3 A. The J = 1-0 line of both species was observed with receiver 1b of the HIFI instrument at ~625.9 and ~624.9 GHz. The different hyperfine components were resolved. The observations were modeled with a non-local, non-LTE radiative transfer model that includes hyperfine line overlap and radiative pumping by dust. Both effects are found to play an important role in the emerging intensity from the different hyperfine components. The inferred H35Cl column density (a few times ~1014 cm-2), and fractional abundance relative to H nuclei (~7.5 × 10-10), supports an upper limit to the gas phase chlorine depletion of ≈200. Our best-fit model estimate of the H35Cl/H37Cl abundance ratio is ≈ 2.1 ± 0.5, slightly lower, but still compatible with the solar isotopic abundance ratio (≈3.1). Since both species were observed simultaneously, this is the first accurate estimation of the [35Cl] /[37Cl] isotopic ratio in molecular clouds. Our models indicate that even for large line opacities and possible hyperfine intensity anomalies, the H35Cl and H37Cl J = 1-0 integrated line-intensity ratio provides a good estimate of the 35Cl/37Cl isotopic abundance ratio. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important particiation from NASA.

  9. Toward the measurement of the hyperfine splitting in the ground state of muonic hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Bakalov, Dimitar, E-mail: dbakalov@inrne.bas.bg [Bulgarian Academy of Sciences, Institute for Nuclear Research and Nuclear Energy (Bulgaria); Adamczak, Andrzej [Polish Academy of Sciences, Institute of Nuclear Physics (Poland); Stoilov, Mihail [Bulgarian Academy of Sciences, Institute for Nuclear Research and Nuclear Energy (Bulgaria); Vacchi, Andrea [Istituto Nazionale di Fisica Nucleare, Sezione di Trieste (Italy)

    2015-08-15

    The recent Lamb shift experiment at PSI and the controversy about proton size revived the interest in measuring the hyperfine splitting in muonic hydrogen and extracting the proton Zemach radius. The efficiency of the experimental method depends on the energy dependence of the muon transfer rate to higher-Z gases in the near epithermal energy range. As long as the available experimental data only give the average transfer rate in the whole epithermal range, and the detailed theoretical calculations have not yet been verified, an experiment has been started for the measurement of the transfer rate in thermalized gas target at different temperatures and extracting from the data an estimate of the transfer rate for arbitrary energies. We outline the underlying mathematical method and estimate its accuracy.

  10. Hyperfine structure investigations of Pr-I lines in the region 4200-4450 A

    Energy Technology Data Exchange (ETDEWEB)

    Siddiqui, Imran; Khan, Shamim; Tanweer Iqbal, Syed; Windholz, Laurentius [Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A 8010 Graz (Austria)

    2012-07-01

    Praseodymium I spectral lines were investigated using laser induced fluorescence spectroscopy in a hollow cathode discharge lamp. The investigations led to the discovery of new Pr I energy levels of even and odd parity. A high resolution Fourier transform (FT) spectrum was used to extract promising excitation wavelengths. In the FT spectrum the investigated line 4375.53 A shows up as a narrow peak hfs with a weak SNR. Nevertheless, the line was excited and fluorescence signals were observed on 6 lines (4163 A, 4816 A, 5091 A, 5164 A, 5209 A, 5233 A). The hfs of the line was recorded by scanning the laser frequency and was fitted to obtain angular momentum J and hf constant A of the combining levels. We got J{sub up}=5/2, A{sub up}=1028.30 MHz, J{sub lo}=7/2 and A{sub lo}=861.46 MHz (the subscripts refer to upper and lower level). Assuming an unknown upper level, a known lower level was searched among the known levels having sufficient values of J and A. The level 7617.440 cm{sup -1}, even parity, J{sub lo}=7/2 and A{sub lo}=868 MHz fulfils these requirements. Using the center of gravity wave number of the line 4375.53 A and the energy of the lower level, the unknown upper level was calculated to have 30465.424 cm{sup -1}, odd parity, J{sub up}=5/2 and A{sub up}=1033(6) MHz.

  11. The Structure of the Heavy Calcium Isotopes and the Effective Interaction in the sd-fp Shell

    CERN Multimedia

    Dorvaux, O; Nowacki, F; Courtin, S; Marechal, F; Siiskonen, T M; Perrot, F; Pietri, S B

    2002-01-01

    Nuclei with 40 $<$ A $<$ 56, near the stability line, are very well described in the frame of the shell model. However, when the number of neutrons increases, the situation becomes more complex which explains why the interaction can be found very dissimilar within different calculations. Heavy Ca isotopes, because of the simplicity of their wave-functions, correspond to the optimal choice to fix unambiguously the interaction in this mass region.\\\\ It is proposed to measure the $\\beta$-decay of $^{51, 52, 53}$K with the help of an utmost performing neutron (TONNERRE array) and $\\gamma$- (Miniball clusters) detection, allowing efficient coincidence measurements. This will allow the lowest lying Gamow-Teller states to be located in $^{51, 52, 53}$Ca, and the still unknown properties of natural parity states to be investigated. The awaited results should allow to settle the n-n interaction in the fp shell and the Gnp matrix accross the sd and fp shells, one step farther from stability, by comparison with fu...

  12. cap alpha. -deuterium isotope effects and transition-state structure in an intramolecular model system for methyl-transfer enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Mihel, I.; Knipe, J.O.; Coward, J.K.; Schowen, R.L.

    1979-07-18

    The ..cap alpha..-deuterium isotope effects for the general base catalyzed ring-closure reaction of 2-(2-cis-hydroxycyclopentyl)ethylmethyl-4-nitrophenylsulfonium tetrafluoroborate (1) are k/sub 2H/K/sub 2D/ = 1.7 +- 0.02 (water catalysis), 1.104 +- 0.014 (carbonate buffer catalysis), and 0.998 +- 0.001 (hydroxide ion catalysis) in aqueous solution (..mu.. = 1.0) at 40.00 +- 0.05/sup 0/C. These are all considerably more normal (i.e., larger in the direction k/sub H/ > k/sub D/) than the effect for the catechol O-methyltransferase reaction (k/sub 3H//k/sub 3D/ = 0.83 +- 0.05) for which the reactions of 1 are a model. This indicates the model-reaction transition states to be looser (i.e., to possess a longer oxygen-to-sulfur distance) than the enzymic transition state and suggests that the enzyme may achieve all or part of its catalysis of methyl transfer from processes that are associated with compression of the transition state.

  13. Application and availability of stable isotopes on water research. Isotopic analysis of aquatic ecosystem structure; Mizu kankyo kenkyu ni okeru antei doitai no riyo to yukosei. Antei doitai hi niyoru suiken seitaikei kozo no kaimei

    Energy Technology Data Exchange (ETDEWEB)

    Minagawa, M. [Hokkaido Univ., Sapporo (Japan). Graduate School

    1997-05-10

    In case that our object of investigation does not lie in analysis of biological species and lies in clarification of substance circulation through the medium of organisms, the stable isotopic ratios {delta} of bioelements ({sup 13}C/{sup 12}C, {sup 15}N/{sup 14}N) distributing naturally are effective as approach. According to the food chain, heavy isotopes concentrating into animal tissues at a fixed rate, this phenomenon is brought about by the fact that there are many lighter isotopes in the matters exhausted from animal bodies. It is known that urine and ammonia exhausted from animal are lighter than somatic cells at {delta}{sup 15}N from about -8 to -2 (0/00). In result, somatic cells of animals coming to be more dense than feed by about 3 at {delta}{sup 15}N and about 1.5 at {delta}{sup 13}C, this concentration is called ``isotopic ratio effect in feeding`` and is held constant regardless of kind of animal, environment, age and difference of nitrogen metabolism system. An isotopic ratio {delta}{sub s} of an animal fed two kinds of feeds in the ratio f{sub 1} : f{sub 2} (= 1-f{sub 1}) is given by the following equation: {delta}{sub s} = f{sub 1}{delta}{sub 1} + (1-f{sub 1}){delta}{sub 2}. 6 refs., 7 figs.

  14. Nuclear moments and charge radii of argon isotopes between the neutron-shell closures N=20 and N=28

    CERN Document Server

    Blaum, K; Lassen, J; Lievens, P; Marinova, K; Neugart, R

    2008-01-01

    We report the measurement of optical isotope shifts for $^{40-44}\\!$Ar relative to $^{38}$Ar from which changes in the mean square nuclear charge radii across the 1$\\scriptstyle{f}_{7/2}$ neutron shell are deduced. In addition, the hyperfine structure of $^{41\\!}$Ar and $^{43}$Ar yields the spins, magnetic dipole and electric quadrupole moments, in particular the spin $\\,\\scriptstyle\\textrm{I}$ = 5/2 for $\\,^{43}\\!$Ar. The investigations were carried out by fast-beam collinear laser spectroscopy using highly sensitive detection based on optical pumping and state-selective collisional ionization. Mean square charge radii are now known from $^{32}$Ar to $^{46}$Ar, covering sd-shell as well as $\\scriptstyle{f}_{7/2}$-shell nuclei. They are discussed in the framework of spherical SGII Skyrme-type Hartree-Fock calculations, semi-empirically corrected for quadrupole core polarization. The Zamick-Talmi formula excellently describes the charge radii across the $\\scriptstyle{f}_{7/2}$ neutron shell, as it does for the...

  15. On-line nuclear orientation of the deformed neutron-deficient Eu, Sm and Pm isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Singleton, B.D.D.; Walker, P.M.; Bhagwat, A. (Univ. Surrey, Guildford (United Kingdom)); Al Ghamdi, S.S.; Barham, C.G.; Grant, I.S. (Univ. of Manchester (United Kingdom)); Griffiths, A.G.; Rikovska, J.; Stone, N.J. (Clarendon Lab., Oxford Univ. (United Kingdom))

    1992-11-01

    Low-temperature nuclear orientation measurements made on-line at the SERC Daresbury Laboratory on [sup 142m]Eu, [sup 141m]Sm, and [sup 141]Pm, with known magnetic dipole moments, have yielded the magnitude of the hyperfine fields of these isotopes in an iron host lattice. Thus measurements for the isotopes [sup 139,138]Eu, [sup 139m]Sm, and [sup 138]Pm yielded values for the respective magnetic moments. Limits on the thermal relaxation times of Eu and Sm isotopes in Fe were also deduced. The results for [sup 138]Eu appear to contradict the earlier [pi]h[sub 11/2]x[nu]h[sub 11/2] ground-state configuration assignment. (orig.).

  16. Charge radius change in the heavy tin isotopes until A=132 from laser spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Le Blanc, F.; Essabaa, S.; Obert, J.; Oms, J.; Ouchrif, A. [Institut de Physique Nucleaire, IN2P3-CNRS, 91406 Orsay cedex (France); Cabaret, L. [Laboratoire Aime Cotton, 91405 Orsay cedex (France); Crawford, J.E.; Lee, J.K.P. [Physics Department, Mc Gill University, H3A2T8 Montreal (Canada); Fedoseyev, V.; Mishin, V. [Institute for Spectroscopy, Troisk (Russian Federation); Geithner, W.; Horn, R.; Huber, G.; Kappertz, S.; Lassen, J.; Neugart, R. [Institut fuer Physik der Universitaet Mainz, 55099 Mainz (Germany); Genevey, J. [Institut des Sciences Nucleaires, Universite Joseph Fourier, 38026 Grenoble cedex (France); Girod, M.; Peru, S. [Service de Physique et Techniques Nucleaires, CEA, BP 12, 91680 Bruyeres-le-Chatel (France); Le Scornet, G. [CERN, 1211 Geneve 23 (Switzerland); Pinard, J.; Ravn, H.; Roussiere, B.; Sauvage, J.; Verney, D.

    2002-10-01

    Laser spectroscopy measurements have been carried out on the very neutron-rich tin isotopes with the COMPLIS experimental setup. Using the 5s{sup 2}5p{sup 23}P{sub 0} {yields} 5s{sup 2}5p6s{sup 3}P{sub 1} optical transition, hyperfine spectra of {sup 126-132}Sn and {sup 125m,127m,129m-131m}Sn where recorded for the first time. The variation of the mean-square charge radius ({delta} left angle r {sup 2} right angle) between these nuclei and nuclear moments of the isomers and the odd isotopes were thus measured. An odd-even staggering which inverts at A=130 is clearly observed. This indicates a small appearance of a plateau on the {delta} left angle r {sup 2} right angle which has to be confirmed by measuring the isotope shift beyond A=132. (orig.)

  17. Radiotracer diffusion in semiconductors and metallic compounds using short-lived isotopes

    CERN Multimedia

    Deicher, M; Kronenberg, J; Wagner, F E

    The transport of atoms in solids is of central importance for solid state physics, chemistry, metallurgy, and material sciences. Since the mobility of atoms in solids contributes to many physical phenomena the study of diffusion processes is of fundamental interest for solid state physics. Diffusion processes were frequently investigated using radioactive isotopes (radiotracers). The application of short-lived isotopes delivered at ISOLDE extends substantially the possibilities of investigating diffusion processes in solids. In particular, a new experimental set-up to be installed at ISOLDE in this year will enable the use of radioactive isotopes with half-lives down to minutes. Alternatively, in special cases diffusion processes can be investigated with help of hyperfine techniques on an atomic scale, like by perturbed $\\gamma \\gamma$-angular correlation (PAC). Here, the motion of the atom of interest becomes visible directly via characteristic changes in the measured PAC spectra.

  18. Stable isotope-based trophic structure of pelagic fish and jellyfish across natural and anthropogenic landscape gradients in a fjord estuary.

    Science.gov (United States)

    Naman, Sean M; Greene, Correigh M; Rice, Casimir A; Chamberlin, Joshua; Conway-Cranos, Letitia; Cordell, Jeffery R; Hall, Jason E; Rhodes, Linda D

    2016-11-01

    Identifying causes of structural ecosystem shifts often requires understanding trophic structure, an important determinant of energy flow in ecological communities. In coastal pelagic ecosystems worldwide, increasing jellyfish (Cnidaria and Ctenophora) at the expense of small fish has been linked to anthropogenic alteration of basal trophic pathways. However, this hypothesis remains untested in part because baseline description of fish-jellyfish trophic dynamics, and the environmental features that influence them are lacking. Using stable isotopes of carbon (δ(13)C) and nitrogen (δ(15)N), we examined spatiotemporal patterns of fish and jellyfish trophic structure in greater Puget Sound, an urbanizing fjord estuary in the NW United States. We quantified niche positions of constituent species, niche widths and trophic overlap between fish and jellyfish assemblages, and several community-level trophic diversity metrics (resource diversity, trophic length, and niche widths) of fish and jellyfish combined. We then related assemblage- and community-level measures to landscape gradients of terrestrial-marine connectivity and anthropogenic influence in adjacent catchments. Relative niche positions among species varied considerably and displayed no clear pattern except that fish generally had higher δ(15)N and lower δ(13)C relative to jellyfish, which resulted in low assemblage-level trophic overlap. Fish assemblages had larger niche widths than jellyfish in most cases and, along with whole community trophic diversity, exhibited contrasting seasonal patterns across oceanographic basins, which was positively correlated to landscape variation in terrestrial connectivity. In contrast, jellyfish niche widths were unrelated to terrestrial connectivity, but weakly negatively correlated to urban land use in adjacent catchments. Our results indicate that fish-jellyfish trophic structure is highly heterogeneous and that disparate processes may underlie the trophic ecology of

  19. Isotopic and geothermometric constraints on the structural and metamorphic evolution of Homestake gold deposit, Black Hills, South Dakota (USA)

    Science.gov (United States)

    Terry, M.; Dahl, P.; Frei, R.

    2003-04-01

    The Homestake Deposit, located in the northern Black Hills and host for 40 million ounces of gold, shows evidence for extensive remobilization of gold related to regional metamorphism deformation associated with the Early Proterozoic assembly of supercontinent Laurentia. Field and petrographic evidence for gold remobilization includes the occurrence of abundant quartz veins associated with selvages of chlorite-siderite-ankerite-pyrrhotite-arsenopyrite-gold in the Homestake Fm. The deposit is located on the western limb of a major anticlinorium that coincides with a vertical N-S-striking garnet isograd, and garnet-biotite geothermometry of metapelites sampled across the anticlinorium indicates a steep metamorphic field gradient of 150^oC/km (east side warmer). This gradient is mirrored by a pronounced fractionation of oxygen isotopes observed in the vein quartz, with δ18O ranging from 10 to 18 ppm. The isograd is parallel with a major N-S-striking shear zone, and kinematic indicators predominantly indicate oblique sinistral motion with east-side up. Garnet was separated from a subsurface sample of the Homestake Fm. collected from the nose of the so-called "main ledge" synform and subjected to Pb stepwise leaching (PbSL) to determine the age of garnet growth and thus metamorphism. PbSL analysis revealed a 207Pb/206Pb age of 1746 ± 10 Ma (± 2σ). Recent work in the southern Black Hills indicates that almandine does not contain sufficient Pb to be dated directly by this method; instead, the PbSL result represents the bulk age of abundant allanite inclusions observed in the garnet. Thus, 1746 Ma is interpreted as a maximum age of prograde garnet growth during regional thermotectonism. Mineral assemblages from selvages in Main Ledge indicate that mineralization occurred at or after peak metamorph, which indicates that 1746 Ma also represents a maximum age for gold remobilization. A minimum 1715 Ma age of these events is indicated by published ages of post

  20. Spectrally resolved hyperfine interactions between polaron and nuclear spins in organic light emitting diodes: Magneto-electroluminescence studies

    Energy Technology Data Exchange (ETDEWEB)

    Crooker, S. A.; Kelley, M. R.; Martinez, N. J. D.; Nie, W.; Mohite, A.; Nayyar, I. H.; Tretiak, S.; Smith, D. L. [Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States); Liu, F.; Ruden, P. P. [University of Minnesota, Minneapolis, Minnesota 55455 (United States)

    2014-10-13

    We use spectrally resolved magneto-electroluminescence (EL) measurements to study the energy dependence of hyperfine interactions between polaron and nuclear spins in organic light-emitting diodes. Using layered devices that generate bright exciplex emission, we show that the increase in EL emission intensity I due to small applied magnetic fields of order 100 mT is markedly larger at the high-energy blue end of the EL spectrum (ΔI/I ∼ 11%) than at the low-energy red end (∼4%). Concurrently, the widths of the magneto-EL curves increase monotonically from blue to red, revealing an increasing hyperfine coupling between polarons and nuclei and directly providing insight into the energy-dependent spatial extent and localization of polarons.

  1. Measurement of a strong atomic hyperfine field allowing the determination of nuclear g-factors in (sub)nanosecond states

    CERN Document Server

    Vyvey, K; Cottenier, S; Balabanski, D L; Coulier, N; Coussement, R; Georgiev, G; Lépine-Szily, A; Ternier, S; Teughels, S

    2001-01-01

    An extension of the time-integrated atomic decoupling technique to measure g-factors of (sub)nanosecond isomers and/or the magnetic hyperfine field induced by highly excited atomic electrons on nuclei recoiling into vacuum is discussed. A high average field B sub h sub f =1080 sub - sub 1 sub 7 sub 5 sup + sup 2 sup 7 sup 0 T and an average atomic spin J=2.7(2) is deduced using the known magnetic moment of a 4.05(7) mu s isomer in sup 6 sup 9 Ge. Such high magnetic fields allow g-factor measurements of (sub)nanosecond states. Ab initio calculations show that the combination of a high average magnetic hyperfine field and a high average atomic spin is only possible if a considerable fraction of the ions is in a metastable excited state.

  2. Linking Local Environments and Hyperfine Shifts: A Combined Experimental and Theoretical 31P and 7Li Solid–State NMR Study of Paramagnetic Fe(III) Phosphates

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Jonsik [Stony Brook Univ., NY (United States); Middlemiss, Derek S. [Stony Brook Univ., NY (United States); Chernova, Natasha [Univ. of Cambridge (United Kingdom); Zhu, Ben Y.H. [Stony Brook Univ., NY (United States); Masquelier, Christian [SUNY Binghamton, NY (United States); Grey, Clare P. [Stony Brook Univ., NY (United States); Universite de Picardie Jules Verne, Amiens (France)

    2010-11-05

    Iron phosphates (FePO4) are among the most promising candidate materials for advanced Li-ion battery cathodes. This work reports upon a combined nuclear magnetic resonance (NMR) experimental and periodic density functional theory (DFT) computational study of the environments and electronic structures occurring in a range of paramagnetic Fe(III) phosphates comprising FePO4 (heterosite), monoclinic Li3Fe2(PO4)3 (anti-NASICON A type), rhombohedral Li3Fe2(PO4)3 (NASICON B type), LiFeP2O7, orthorhombic FePO4·2H2O (strengite), monoclinic FePO4·2H2O (phosphosiderite), and the dehydrated forms of the latter two phases. Many of these materials serve as model compounds relevant to battery chemistry. The 31P spin-echo mapping and 7Li magic angle spinning NMR techniques yield the hyperfine shifts of the species of interest, complemented by periodic hybrid functional DFT calculations of the respective hyperfine and quadrupolar tensors. A Curie-Weiss-based magnetic model scaling the DFT-calculated hyperfine parameters from the ferromagnetic into the experimentally relevant paramagnetic state is derived and applied, providing quantitative finite temperature values for each phase. The sensitivity of the hyperfine parameters to the composition of the DFT exchange functional is characterized by the application of hybrid Hamiltonians containing admixtures 0%, 20%, and 35% of Fock exchange. Good agreement between experimental and calculated values is obtained, provided that the residual magnetic couplings persisting in the paramagnetic state are included. The potential applications of a similar combined experimental and theoretical NMR approach to a wider range of cathode materials are discussed.

  3. Hyperfine Interactions in the Electron Paramagnetic Resonance Spectra of Point Defects in Wide-Band-Gap Semiconductors

    Science.gov (United States)

    2014-09-18

    between the 5s electron and the silver nucleus. Breit and Rabi [5] described this hyperfine interaction in the context of the Stern-Gerlach...experiment, and Rabi et al. [6] were the first to directly measure nuclear magnetic moments with this beam technique [7]. 1 quantum angular momentum or spin...is an interruption in the periodicity of a crystal lattice that is localized within a few lattice sites. A crystal lattice is composed of a Bravais

  4. Transferred hyperfine interaction between the rare-earth ions and the fluorine nuclei in rare-earth trifluorides

    DEFF Research Database (Denmark)

    Hansen, P. E.; Nevald, Rolf; Guggenheim, H. G.

    1978-01-01

    The isotropic and anisotropic transferred hyperfine interactions between F ions in the two chemically inequivalent sites and the rare-earth ions (R) have been derived from 19F NMR measurements in the temperature region 100-300 K on single crystals of TbF3 and DyF3. The isotropic interactions are ...... to vary only slightly with temperature. They are further assigned to definite R's in the unit cell, which cannot be done from macroscopic magnetic measurements....

  5. Linking microbial community structure to biogeochemical function in coastal marine sediments: Stable isotope probing combined with magnetic bead capture

    NARCIS (Netherlands)

    Miyatake, T.

    2011-01-01

    Microbial community structure and its biogeochemical functions in marine sediments can be successfully linked by using the improved Mag-SIP method in combination with other approaches. In this thesis, we were able to provide detailed information on the microorganisms responsible for the utilization

  6. Experiment for the first direct measurement of the hyperfine splitting of positronium

    Energy Technology Data Exchange (ETDEWEB)

    Miyazaki, A; Ishida, A; Asai, S [Department of Physics, Graduate School of Science, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 133-0033 (Japan); Suehara, T; Namba, T; Kobayashi, T [International Center for Elementary Particle Physics (ICEPP), The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo, 113-0033 (Japan); Saito, H [Department of General Systems Studies, Graduate School of Arts and Sciences, University of Tokyo, 3-8-1 Komaba, Meguro-ku, Tokyo, 153-8902 (Japan); Yoshida, M [Accelerator Laboratory, High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba, Ibaraki, 305-0801 (Japan); Idehara, T; Ogawa, I; Urushizaki, Y [Research Center for Development of Far-Infrared Region, University of Fukui (FIR-FU), 3-9-1 Bunkyo, Fukui, Fukui, 910-8507 (Japan); Sabchevski, S, E-mail: miyazaki@icepp.s.u-tokyo.ac.j [Bulgarian Academy of Science, 1, 15 Noemvri Str., 1040 Sofia (Bulgaria)

    2010-04-01

    Positronium is an ideal system for the research of the bound state QED. The hyperfine splitting of positronium (Ps-HFS: about 203 GHz) is a good tool to test QED and also sensitive to new physics beyond the Standard Model via a quantum oscillation between an ortho-Ps and a virtual photon. Previous experimental results show 3.9 {sigma} (15 ppm) discrepancy from the QED calculation. All previous experiments used an indirect method with static magnetic field to cause Zeeman splitting (a few GHz) between triplet states of ortho-Ps, from which the HFS value was derived. One possible systematic error source of the indirect method is non-uniformity of the static magnetic field. We are developing a new direct Ps-HFS measurement system without static magnetic field. In this measurement we use a gyrotron, a novel sub-THz light source, with a high-finesse Fabry-Perot cavity to obtain enough radiation power at 203 GHz. The present status of the optimization studies and current design of the experiment are described.

  7. Leggett-Garg inequalities violation via the Fermi contact hyperfine interaction

    Energy Technology Data Exchange (ETDEWEB)

    Lobejko, Marcin; Dajka, Jerzy [Institute of Physics, University of Silesia, Katowice (Poland); Silesian Center for Education and Interdisciplinary Research, University of Silesia, Chorzow (Poland)

    2017-06-15

    In this paper we examine theoretically how the spin-spin interaction between a nuclei and an electron in the atom affects violation of the Leggett-Garg inequalities. We consider the simplest case of atoms in the {sup 2}S{sub 1/2} state that in the valence shell have just a single electron and the evolution in time of the spin is dictated only by the Fermi contact hyperfine interaction. We found that for special initial conditions and a particular measured observable the high spin nucleus couple to the valence electron such that violation of Leggett-Garg inequalities increases with total spin of states. Consequently, our results show that for the Hydrogen, the smallest atom in Nature, the violation of the Leggett-Garg inequalities is the smallest whereas for the largest atom, the Cesium, the violation is the largest. Moreover, this violation does not depend on a principal quantum number, thus our model can be used for Rydberg atoms in order to test macrorealism for 'almost macroscopic' objects. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  8. Isotopic and anatomical evidence of an herbivorous diet in the Early Tertiary giant bird Gastornis. Implications for the structure of Paleocene terrestrial ecosystems

    Science.gov (United States)

    Angst, D.; Lécuyer, C.; Amiot, R.; Buffetaut, E.; Fourel, F.; Martineau, F.; Legendre, S.; Abourachid, A.; Herrel, A.

    2014-04-01

    The mode of life of the early Tertiary giant bird Gastornis has long been a matter of controversy. Although it has often been reconstructed as an apex predator feeding on small mammals, according to other interpretations, it was in fact a large herbivore. To determine the diet of this bird, we analyze here the carbon isotope composition of the bone apatite from Gastornis and contemporaneous herbivorous mammals. Based on 13C-enrichment measured between carbonate and diet of carnivorous and herbivorous modern birds, the carbonate δ13C values of Gastornis bone remains, recovered from four Paleocene and Eocene French localities, indicate that this bird fed on plants. This is confirmed by a morphofunctional study showing that the reconstructed jaw musculature of Gastornis was similar to that of living herbivorous birds and unlike that of carnivorous forms. The herbivorous Gastornis was the largest terrestrial tetrapod in the Paleocene biota of Europe, unlike the situation in North America and Asia, where Gastornis is first recorded in the early Eocene, and the largest Paleocene animals were herbivorous mammals. The structure of the Paleocene terrestrial ecosystems of Europe may have been similar to that of some large islands, notably Madagascar, prior to the arrival of humans.

  9. Recent developments in production of radioactive ion beams with the selective laser ion source at the on-line isotope separator ISOLDE

    CERN Document Server

    Catherall, Richard; Köster, U; Lettry, Jacques; Suberlucq, Guy; Marsh, Bruce A; Tengborn, Elisabeth

    2004-01-01

    The production of radioactive ionization laser ion source (RILIS) of ISOLDE on-line isotope separation facility was investigated. The RILIS setup included three dye lasers and ionization schemes which employ three resonant transitions were also used. The RILIS efficiency could be reduced by nuclear effects such as hyperfine splitting and isotope shifts. The off-line resonance ionization spectroscopy determined optimal three-step ionization schemes for yttrium, scandium and antimony and antimony. The results show that best ionization schemes of Y provided gain factor of 15 with respect to surface ionization. (Edited abstract) 8 Refs.

  10. Herbivory of Omnivorous Fish Shapes the Food Web Structure of a Chinese Tropical Eutrophic Lake: Evidence from Stable Isotope and Fish Gut Content Analyses

    Directory of Open Access Journals (Sweden)

    Jian Gao

    2017-01-01

    Full Text Available Studies suggest that, unlike the situation in temperate lakes, high biomasses of omnivorous fish are maintained in subtropical and tropical lakes when they shift from a turbid phytoplankton-dominated state to a clear water macrophyte-dominated state, and the predation pressure on large-bodied zooplankton therefore remains high. Whether this reflects a higher degree of herbivory in warm lakes than in temperate lakes is debatable. We combined food web studies using stable isotopes with gut content analyses of the most dominant fish species to elucidate similarities and differences in food web structure between a clear water macrophyte-dominated basin (MDB and a turbid phytoplankton-dominated basin (PDB of Huizhou West Lake, a shallow tropical Chinese lake. The δ13C–δ15N biplot of fish and invertebrates revealed community-wide differences in isotope-based metrics of the food webs between MDB and PDB. The range of consumer δ15N (NR was lower in MDB than in PDB, indicating shorter food web length in MDB. The mean nearest neighbor distance (MNND and standard deviation around MNND (SDNND were higher in MDB than in PDB, showing a markedly low fish trophic overlap and a more uneven packing of species in niches in MDB than in PDB. The range of fish δ13C (CR of consumers was more extensive in MDB than in PDB, indicating a wider feeding range for fish in MDB. Mixing model results showed that macrophytes and associated periphyton constituted a large fraction of basal production sources for the fish in MDB, while particulate organic matter (POM contributed a large fraction in PDB. In MDB, the diet of the dominant fish species, crucian carp (Carassius carassius, consisted mainly of vegetal matter (macrophytes and periphyton and zooplankton, while detritus was the most important food item in PDB. Our results suggest that carbon from macrophytes with associated periphyton may constitute an important food resource for omnivorous fish, and this may strongly

  11. Chromatographic hydrogen isotope separation

    Science.gov (United States)

    Aldridge, Frederick T.

    1981-01-01

    Intermetallic compounds with the CaCu.sub.5 type of crystal structure, particularly LaNiCo.sub.4 and CaNi.sub.5, exhibit high separation factors and fast equilibrium times and therefore are useful for packing a chromatographic hydrogen isotope separation colum. The addition of an inert metal to dilute the hydride improves performance of the column. A large scale mutli-stage chromatographic separation process run as a secondary process off a hydrogen feedstream from an industrial plant which uses large volumes of hydrogen can produce large quantities of heavy water at an effective cost for use in heavy water reactors.

  12. Atomic spectroscopy study of nuclear properties of francium and cesium isotopes; Etude par spectroscopie atomique de proprietes nucleaires d'isotopes de francium et de cesium

    Energy Technology Data Exchange (ETDEWEB)

    Coc, A

    1986-04-15

    This work is based on the study of cesium ({sup 118,146}Cs) and francium ({sup 207-213}Fr,{sup 220-228}Fr) isotopes by hyperfine atomic spectroscopy and on the interpretation of these results from the nuclear physics point of view. The measured nuclear quantities are: the spin, the magnetic moment, the electric quadrupole moment and the mean square charge radius. The experimental method which is based on hyperfine optical pumping with a tunable laser, followed by magnetic analysis of the atoms is described in the first part. Results related to atomic physics are also presented. In the second part, these data are interpreted in the framework of nuclear models. The deformation of light cesium isomers are compared to values obtained from a theoretical self-consistent calculation. Heavy francium isotopes are situated in an area where the existence of static octupole deformations have been predicted. The odd-even staggering measured on the mean square radius is abnormal in this region. However, on the basis of experimental data, no definitive conclusion can be drawn regarding the nature of these deformations. (author)

  13. Hyperfine interaction measurements in biological compounds: the case of hydroxyapatite; Medidas de interacoes hiperfinas em compostos biologicos: o caso da hidroxiapatita

    Energy Technology Data Exchange (ETDEWEB)

    Leite Neto, Osmar Flavio da Silveira

    2014-07-01

    The use o nanoparticles in current medicine are under intense investigation. The possible advantages proposed by these systems are very impressive and the results may be quite schemer. In this scenario, the association of nanoparticles with radioactive materials (radionuclide) may be the most important step since the discovery of radioactive for nuclear medicine and radiopharmacy, especially for cancer targeting and therapy. The hyperfine interaction of the nuclear probe {sup 111}Cd in the Hydroxyapatite compounds has been investigated by perturbed angular correlation (PAC) spectroscopy in room temperature for the hydroxyapatite made in the temperatures of 90°C, 35°C and with Ho doped, both thermalized and not. The thermalized samples were heated to T= 1273 K for 6 h. The {sup 111}Cd was broadcast in the structure of the material by diffusion, closing in quartz tubes were heated – together with the radioactive PAC probe {sup 111}In/{sup 111}Cd to T = 1073 K for 12 h. In not thermalized samples the PAC spectra indicate a distribution of frequency, but in the thermalized samples, the PAC spectra shows the presence of β-tri calcium phosphate in the structure of this kind of Hydroxyapatite. (author)

  14. Hyperfine interactions in MnAs studied by perturbed angular correlations of $\\gamma$-rays using the probe $^{77}$Br $\\rightarrow ^{77}$Se and first principles calculations for MnAs and other Mn pnictides

    CERN Document Server

    Gonçalves, J N; Correia, J G; Lopes, A M L

    2011-01-01

    The MnAs compound shows a first-order transition at T$_{c}$≈ 42$^{\\circ}$C, and a second-order transition at T$_{t}$ ≈120$^{\\circ}$C. The first-order transition, with structural (hexagonal-orthorhombic), magnetic (FM-PM) and electrical conductivity changes, is associated to magnetocaloric, magnetoelastic, and magnetoresistance effects. We report a study in a large temperature range from −196$^{\\circ}$C up to 140$^{\\circ}$C, using the $\\gamma\\!-\\!\\gamma$ perturbed angular correlations method with the radioactive probe $^{77}$Br→$^{77}$Se, produced at the ISOLDE-CERN facility. The electric field gradients and magnetic hyperfine fields are determined across the first- and second-order phase transitions encompassing the pure and mixed phase regimes in cooling and heating cycles. The temperature irreversibility of the 1st order phase transition is seen locally, at the nanoscopic scale sensitivity of the hyperfine field, by its hysteresis, detailing and complementing information obtained with macroscopic me...

  15. Effect of triacylglycerol structure on absorption and metabolism of isotope-labeled palmitic and linoleic acids by humans.

    Science.gov (United States)

    Emken, E A; Adlof, R O; Duval, S M; Shane, J M; Walker, P M; Becker, C

    2004-01-01

    The effect of dietary TAG structure and fatty acid acyl TAG position on palmitic and linoleic acid metabolism was investigated in four middle-aged male subjects. The study design consisted of feeding diets containing 61 g/d of native lard (NL) or randomized lard (RL) for 28 d. Subjects then received an oral dose of either 1,3-tetradeuteriopalmitoyl-2-dideuteriolinoleoyl-rac-glycerol or a mixture of 1,3-dideuteriolinoleoyl-2-tetradeuteriopalmitoyl-rac-glycerol and 1,3-hexadeuteriopalmitoyl-2-tetradeuteriolinoleoyl-rac-glycerol. Methyl esters of plasma lipids isolated from blood samples drawn over a 2-d period were analyzed by GC-MS. Results showed that absorption of the 2H-fatty acids (2H-FA) was not influenced by TAG position. The 2H-FA at the 2-acyl TAG position were 85+/-4.6% retained after absorption. Substantial migration of 2H-16:0 (31.2+/-8.6%) from the sn-2 TAG position to the sn-1,3 position and 2H-18:2n-6 (52.8+/-6.4%) from the sn-1,3 position to the sn-2 position of chylomicron TAG occurred after initial absorption and indicates the presence of a previously unrecognized isomerization mechanism. Incorporation and turnover of the 2H-FA in chylomicron TAG, plasma TAG, and plasma cholesterol esters were not influenced by TAG acyl position. Accretion of 2H-16:0 from the sn-2 TAG position in 1-acylphosphatidylcholine was 1.7 times higher than 2H-16:0 from the sn-1,3 TAG positions. Acyl TAG position did not influence 2H-18:2n-6 incorporation in PC. The concentration of 2H-18:2n-6-derived 2H-20:4n-6 in plasma PC from subjects fed the RL diet was 1.5 times higher than for subjects fed the NL diet, and this result suggests that diets containing 16:0 located at the sn-2 TAG position may inhibit 20:4n-6 synthesis. The overall conclusion is that selective rearrangement of chylomicron TAG structures diminishes but does not totally eliminate the metabolic and physiological effects of dietary TAG structure.

  16. Modern Freshwater Microbialites of Cuatro Ciénegas, Mexico. I: Metagenomic and Stable Isotopic Analyses to Assess Microbial Community Structure and Function

    Science.gov (United States)

    Breitbart, M.; Hollander, D.; Nitti, A.; van Mooy, B.; Siefert, J.; Souza, V.

    2010-04-01

    This study utilized metagenomic and stable isotopic analyses to examine the microorganisms and chemical processes leading to carbonate precipitation in the actively-accreting freshwater microbialites from Rio Mesquites in Cuatro Ciénegas, Mexico.

  17. Charge radii of radium isotopes

    NARCIS (Netherlands)

    Wansbeek, L. W.; Schlesser, S.; Sahoo, B. K.; Dieperink, A. E. L.; Onderwater, C. J. G.; Timmermans, R. G. E.

    2012-01-01

    We present a combined analysis of the available isotope-shift data from the optical spectra of Ra atoms and Ra+ ions. Atomic structure calculations of the field-shift and specific mass-shift constants of the low-lying levels in Ra+ are used. The nuclear radial differences delta for the radium

  18. Absence of hyperfine effects in 13C-graphene spin-valve devices

    NARCIS (Netherlands)

    Wojtaszek, M.; Vera-Marun, I.J.; Whiteway, E.; Hilke, M.; Wees, B.J. van

    2014-01-01

    The carbon isotope 13C, in contrast to 12C, possesses a nuclear magnetic moment and can induce electron spin dephasing in graphene. This effect is usually neglected due to the low abundance of 13C in natural carbon allotropes (~1%). Chemical vapor deposition (CVD) allows for artificial synthesis of

  19. Hyperfine and magnetic properties of a Y{sub x}La{sub 1−x}FeO{sub 3} series (0 ≤ x ≤ 1)

    Energy Technology Data Exchange (ETDEWEB)

    Cristóbal, A.A.; Botta, P.M. [Instituto de Investigaciones en Ciencia y Tecnología de Materiales (INTEMA), CONICET-UNMdP, Av. J.B. Justo 4302, B7608FDQ Mar del Plata (Argentina); Bercoff, P.G., E-mail: bercoff@famaf.unc.edu.ar [Facultad de Matemática, Astronomía y Física (FaMAF), Universidad Nacional de Córdoba. IFEG (CONICET), Medina Allende s/n, Ciudad Universitaria, 5000 Córdoba (Argentina); Ramos, C.P. [CONICET and Centro Atómico Constituyentes (CAC), CNEA, Av. Gral. Paz 1499, 1650 San Martín (Argentina)

    2015-04-15

    Highlights: • Y{sub x}La{sub 1−x}FeO{sub 3} (0 ≤ x ≤ 1) was synthesized by mechanochemistry. • Two magnetic contributions were identified in the series. • A paramagnetic state is associated with a fraction of the smallest particles. • A ferromagnetic state is attributed to the larger particles. • Annealing of samples favored the formation of Y{sub 3}Fe{sub 5}O{sub 12} impurities. - Abstract: A series of orthoferrites Y{sub x}La{sub 1−x}FeO{sub 3} in the entire range of composition was synthesized at room temperature by mechanochemical activation of oxide mixtures. Phase composition, structure and microstructure of the obtained powder materials were characterized by X-ray diffraction and field-emission scanning electron microscopy. Hyperfine interactions and magnetic properties were determined by Mössbauer spectroscopy, SQUID and vibrating sample magnetometry. Two magnetic contributions could be identified in the series of materials: a paramagnetic state, associated with a fraction of the smallest particles and a ferromagnetic state, attributed to the larger particles. The results showed that the relative proportion of both contributions is very dependent on x, the Y content of samples. From M vs T measurements, it was possible to estimate the blocking temperature distribution for the end members of the series. Annealing of samples produced the elimination of the superparamagnetic behavior and the formation of Y{sub 3}Fe{sub 5}O{sub 12} impurities.

  20. Pulsed EPR investigations of systems modeling molybdenum enzymes: hyperfine and quadrupole parameters of oxo-17O in [Mo 17O(SPh)4]-.

    Science.gov (United States)

    Astashkin, Andrei V; Neese, Frank; Raitsimring, Arnold M; Cooney, J Jon A; Bultman, Eric; Enemark, John H

    2005-11-30

    Ka band ESEEM spectroscopy was used to determine the hyperfine (hfi) and nuclear quadrupole (nqi) interaction parameters for the oxo-17O ligand in [Mo 17O(SPh)4]-, a spectroscopic model of the oxo-Mo(V) centers of enzymes. The isotropic hfi constant of 6.5 MHz found for the oxo-17O is much smaller than the values of approximately 20-40 MHz typical for the 17O nucleus of an equatorial OH(2) ligand in molybdenum enzymes. The 17O nqi parameter (e2qQ/h = 1.45 MHz, eta approximately = 0) is the first to be obtained for an oxo group in a metal complex. The parameters of the oxo-17O ligand, as well as other magnetic resonance parameters of [Mo 17O(SPh)4]- predicted by quasi-relativistic DFT calculations, were in good agreement with those obtained in experiment. From the electronic structure of the complex revealed by DFT, it follows that the SOMO is almost entirely molybdenum d(xy) and sulfur p, while the spin density on the oxo-17O is negative, determined by spin polarization mechanisms. The results of this work will enable direct experimental identification of the oxo ligand in a variety of chemical and biological systems.

  1. Nuclear quadrupole hyperfine quantum beats in HCl and pyrimidine measured by the pump-probe method using REMPI/LIF detection

    Science.gov (United States)

    Lammer, H.; Carter, R. T.; Huber, J. R.

    2000-07-01

    Coherent time resolved IR-UV double resonance spectroscopy with REMPI and/or LIF detection has been used to measure the nuclear hyperfine structure of a diatomic and a polyatomic molecule. The pump-probe technique was applied and the experimental set up was optimized to achieve highest spectral resolution. Following excitation of the HCl fundamental vibrational transition by a nanosecond IR laser pulse, the nuclear quadrupole coupling constants were determined to be eQq = -69.51(22) MHz for H35Cl and eQq = -54.40(16) MHz for H37Cl in the J = 1 and J = 2 states of the υ = 1 level. Nuclear (Cl) spin-rotation interaction was shown to be active with the corresponding coupling constant being C I = 0.068(10) MHz for H35Cl and C I = 0.049(8) MHz for H37Cl. For pyrimidine a C-H stretch vibration ν 13 was excited and the quadrupole tensor elements for the rovibronic states J K a , K c = 110 and 101 of the υ 13 = 1 level were found to be χ aa = -3.095(10) MHz, χ bb = 0.227(10) MHz and χ cc = 3.322(10) MHz. In this case the residual frequency error was reduced to 8 kHz. The results of these jet experiments independently confirm those from millimeter wave and microwave measurements on static gas samples.

  2. Impact of silica environment on hyperfine interactions in ε-Fe{sub 2}O{sub 3} nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Kubíčková, Lenka, E-mail: sagittaria.64@gmail.com; Kohout, Jaroslav [Charles University in Prague, Faculty of Mathematics and Physics (Czech Republic); Brázda, Petr; Veverka, Miroslav [Institute of Physics of the AS CR, v.v.i. (Czech Republic); Kmječ, Tomáš; Kubániová, Denisa [Charles University in Prague, Faculty of Mathematics and Physics (Czech Republic); Bezdička, Petr [Institute of Inorganic Chemistry of the AS CR, v.v.i. (Czech Republic); Klementová, Mariana; Šantavá, Eva [Institute of Physics of the AS CR, v.v.i. (Czech Republic); Závěta, Karel [Charles University in Prague, Faculty of Mathematics and Physics (Czech Republic)

    2016-12-15

    Magnetic nanoparticles have found broad applications in medicine, especially for cell targeting and transport, and as contrast agents in MRI. Our samples of ε-Fe{sub 2}O{sub 3} nanoparticles were prepared by annealing in silica matrix, which was leached off and the bare particles were then coated with amorphous silica layers of various thicknesses. The distribution of particle sizes was determined from the TEM pictures giving the average size ∼20 nm and the thickness of silica coating ∼5; 8; 12; 19 nm. The particles were further characterized by the XRPD and DC magnetic measurements. The nanoparticles consisted mainly of ε-Fe{sub 2}O{sub 3} with admixtures of ∼1 % of the α phase and less than 1 % of the γ phase. The hysteresis loops displayed coercivities of ∼2 T at room temperature. The parameters of hyperfine interactions were derived from transmission Mössbauer spectra. Observed differences of hyperfine fields for nanoparticles in the matrix and the bare ones are ascribed to strains produced during cooling of the composite. This interpretation is supported by slight changes of their lattice parameters and increase of the elementary cell volume deduced from XRD. The temperature dependence of the magnetization indicated a two-step magnetic transition of the ε-Fe{sub 2}O{sub 3} nanoparticles spread between ∼85 K and ∼150 K, which is slightly modified by remanent tensile stresses in the case of nanoparticles in the matrix. The subsequent coating of the bare particles by silica produced no further change in hyperfine parameters, which indicates that this procedure does not modify magnetic properties of nanoparticles.

  3. Compilation of spectroscopic data of Radium (Ra I and Ra II)

    OpenAIRE

    Dammalapati, U.; Jungmann, K.; Willmann, L.

    2016-01-01

    Energy levels, wavelengths, lifetimes and hyperfine structure constants for the isotopes of the first and second spectra of radium, Ra I and Ra II have been compiled. Wavelengths and wave numbers are tabulated for 226Ra and for other Ra isotopes. Isotope shifts and hyperfine structure constants of even and odd-A isotopes of neutral radium atom and singly ionized radium are included. Experimental lifetimes of the states for both neutral and ionic Ra are also added, where available. The informa...

  4. METHOD OF ISOTOPE CONCENTRATION

    Science.gov (United States)

    Spevack, J.S.

    1957-04-01

    An isotope concentration process is described which consists of exchanging, at two or more different temperature stages, two isotopes of an element between substances that are physically separate from each other and each of which is capable of containing either of the isotopes, and withdrawing from a point between at least two of the temperatare stages one of the substances containing an increased concentration of the desired isotope.

  5. Statistical clumped isotope signatures

    NARCIS (Netherlands)

    Röckmann, T.; Popa, M.E.; Krol, M.C.; Hofmann, M.E.G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of

  6. Statistical clumped isotope signatures

    NARCIS (Netherlands)

    Röckmann, T.|info:eu-repo/dai/nl/304838233; Popa, M. E.|info:eu-repo/dai/nl/375806407; Krol, M. C.|info:eu-repo/dai/nl/078760410; Hofmann, M. E. G.|info:eu-repo/dai/nl/374642907

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a

  7. Statistical clumped isotope signatures

    Science.gov (United States)

    Röckmann, T.; Popa, M. E.; Krol, M. C.; Hofmann, M. E. G.

    2016-01-01

    High precision measurements of molecules containing more than one heavy isotope may provide novel constraints on element cycles in nature. These so-called clumped isotope signatures are reported relative to the random (stochastic) distribution of heavy isotopes over all available isotopocules of a molecule, which is the conventional reference. When multiple indistinguishable atoms of the same element are present in a molecule, this reference is calculated from the bulk (≈average) isotopic composition of the involved atoms. We show here that this referencing convention leads to apparent negative clumped isotope anomalies (anti-clumping) when the indistinguishable atoms originate from isotopically different populations. Such statistical clumped isotope anomalies must occur in any system where two or more indistinguishable atoms of the same element, but with different isotopic composition, combine in a molecule. The size of the anti-clumping signal is closely related to the difference of the initial isotope ratios of the indistinguishable atoms that have combined. Therefore, a measured statistical clumped isotope anomaly, relative to an expected (e.g. thermodynamical) clumped isotope composition, may allow assessment of the heterogeneity of the isotopic pools of atoms that are the substrate for formation of molecules. PMID:27535168

  8. Isotopes in heterogeneous catalysis

    CERN Document Server

    Hargreaves, Justin SJ

    2006-01-01

    The purpose of this book is to review the current, state-of-the-art application of isotopic methods to the field of heterogeneous catalysis. Isotopic studies are arguably the ultimate technique in in situ methods for heterogeneous catalysis. In this review volume, chapters have been contributed by experts in the field and the coverage includes both the application of specific isotopes - Deuterium, Tritium, Carbon-14, Sulfur-35 and Oxygen-18 - as well as isotopic techniques - determination of surface mobility, steady state transient isotope kinetic analysis, and positron emission profiling.

  9. Hyperfine interactions in dilute Se doped Fe{sub x}Sb{sub 1−x} bulk alloy

    Energy Technology Data Exchange (ETDEWEB)

    Sarkar, Mitesh, E-mail: miteshsarkar-msu@yahoo.com; Agrawal, Naveen [The M. S. University of Baroda, Department of Physics (India); Chawda, Mukesh [Polytechnic, The M. S. University of Baroda, Department of Applied Physics (India)

    2016-12-15

    Hyperfine Interaction technique like Moessbauer spectroscopy is a very sensitive tool to study the local probe interactions in Iron doped alloys and compounds. We report here the Moessbauer study of the effect of Fe concentration variations in dilute magnetic semiconducting Se{sub 0.004}Fe{sub x}Sb{sub 1−x} alloys for x = 0.002, 0.004 and 0.008. The materials were characterized using X-ray diffraction technique (XRD), Fourier Transform Infra-red spectroscopy (FTIR), Neutron depolarization and Moessbauer spectroscopy. The FTIR result shows the semiconducting behavior of the alloys with band gap of 0.18 eV. From Moessbauer spectroscopy two magnetic sites (A and B) were observed. The value of hyperfine magnetic fields (HMF) of ∼ 308 kOe (site A) and 270 kOe (site B) was constant with increase in Fe concentration. A nonmagnetic interaction was also observed with quadrupole splitting (QS) of 1.26 mm/sec (site C) for x = 0.004 and x = 0.008. The Neutron depolarization studies indicate that the clusters of Fe or Fe based compounds having net magnetic moments with a size greater than 100 Å is absent.

  10. Frequency tripled 1542 nm telecom laser diode stabilized to iodine hyperfine line in the 10-15 range

    CERN Document Server

    Philippe, Charles; Holleville, David; Lours, Michel; Minh-Pham, Tuam; Hrabina, Jan; Burck, Frederic Du; Wolf, Peter; Acef, Ouali

    2016-01-01

    We report on telecom laser frequency stabilization to narrow iodine hyperfine line in the green range of the optical domain, after a frequency tripling process using two nonlinear PPLN crystals. We have generated up to 300 mW optical power in the green (P3w), from 800 mW of infrared power (Pw). This result corresponds to an optical conversion efficiency eta= P3w/Pw ~ 36 %. To our knowledge, this is the best value ever demonstrated for a CW frequency tripling process. We have used a narrow linewidth iodine hyperfine line (component a1 of the 127I2 R 35 (44-0) line) to stabilize the IR laser yielding to frequency stability of 4.8x10-14 t-1/2 with a minimum of 6x10-15 reached after 50 s of integration time. The whole optical setup is very compact and mostly optically fibered. This approach opens the way for efficient and elegant architecture development for space applications as one of several potential uses.

  11. Chromium isotope variations

    DEFF Research Database (Denmark)

    D'Arcy, Joan Mary

    Chromium (Cr) stable isotopes are a useful tracer of changes in redox conditions because changes in its oxidation state are accompanied by an isotopic fractionation. For this reason the Cr isotope system is being developed as a potential tool for paleo-redox reconstruction. Dissolved Cr in seawater...... is incorporated into carbonates. Hence, ancient carbonates can potentially record the Cr isotopic composition (δ53Cr ‰) of seawater in the geological past. Reliable application and interpretation of this proxy requires a detailed knowledge about processes that fractionate Cr on the Earth’s surface......, and the quantification the Cr isotope composition of major Cr fluxes into and out of ocean. This thesis adds to the current knowledge of the Cr isotope system and is divided into two studies. The focus of the first study was to determine what processes control the Cr isotopic compositionof river water and to quantify...

  12. The Facility for Rare Isotope Beams

    Directory of Open Access Journals (Sweden)

    Wrede C.

    2015-01-01

    Full Text Available The Facility for Rare Isotope Beams (FRIB is a United States Department of Energy user facility currently under construction on the campus of Michigan State University. Based on a 400 kW, 200 MeV/u heavy-ion driver linac, FRIB will deliver high-quality fast, thermalized, and re-accelerated beams of rare isotopes with unprecedented intensities to a variety of experimental areas and equipment. New science opportunities at the frontiers of nuclear structure, nuclear astrophysics, fundamental symmetries, and societal applications will be enabled by this future world-leading rare-isotope beam facility.

  13. The Facility for Rare Isotope Beams

    Science.gov (United States)

    Wrede, C.

    2015-05-01

    The Facility for Rare Isotope Beams (FRIB) is a United States Department of Energy user facility currently under construction on the campus of Michigan State University. Based on a 400 kW, 200 MeV/u heavy-ion driver linac, FRIB will deliver high-quality fast, thermalized, and re-accelerated beams of rare isotopes with unprecedented intensities to a variety of experimental areas and equipment. New science opportunities at the frontiers of nuclear structure, nuclear astrophysics, fundamental symmetries, and societal applications will be enabled by this future world-leading rare-isotope beam facility.

  14. First observation of o-Ps to p-Ps transition and first direct measurement of positronium hyperfine splitting with sub-THz light

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, Takayuki, E-mail: yamazaki@icepp.s.u-tokyo.ac.jp; Miyazaki, Akira; Suehara, Taikan; Namba, Toshio; Asai, Shoji; Kobayashi, Tomio [University of Tokyo, Department of Physics, Graduate School of Science, and International Center for Elementary Particle Physics (Japan); Saito, Haruo [University of Tokyo, Graduate School of Arts and Sciences (Japan); Urushizaki, Yuichi; Ogawa, Isamu; Idehara, Toshitaka [University of Fukui, Research Center for Development of Far-Infrared Region (Japan); Sabchevski, Svilen [Bulgarian Academy of Sciences (Bulgaria)

    2012-12-15

    Positronium is an ideal system for the research of the bound state QED. The hyperfine splitting of positronium (Ps-HFS, about 203 GHz) is an important observable but all previous measurements of Ps-HFS had been measured indirectly using Zeeman splitting. There might be the unknown systematic errors on the uniformity of magnetic field. We are trying to measure Ps-HFS directly using sub-THz radiation. We developed an optical system to accumulate high power (about 10 kW) radiation in a Fabry-Perot resonant cavity and observed the positronium hyperfine transition for the first time.

  15. Isotope analysis in the transmission electron microscope

    OpenAIRE

    Susi, Toma; Hofer, Christoph; Argentero, Giacomo; Leuthner, Gregor T.; Pennycook, Timothy J.; Mangler, Clemens; Meyer, Jannik C.; Kotakoski, Jani

    2016-01-01

    The {\\AA}ngstr\\"om-sized probe of the scanning transmission electron microscope can visualize and collect spectra from single atoms. This can unambiguously resolve the chemical structure of materials, but not their isotopic composition. Here we differentiate between two isotopes of the same element by quantifying how likely the energetic imaging electrons are to eject atoms. First, we measure the displacement probability in graphene grown from either $^{12}$C or $^{13}$C and describe the proc...

  16. IUPAC Periodic Table of the Isotopes

    Science.gov (United States)

    Holden, N.E.; Coplen, T.B.; Böhlke, J.K.; Wieser, M.E.; Singleton, G.; Walczyk, T.; Yoneda, S.; Mahaffy, P.G.; Tarbox, L.V.

    2011-01-01

    For almost 150 years, the Periodic Table of the Elements has served as a guide to the world of elements by highlighting similarities and differences in atomic structure and chemical properties. To introduce students, teachers, and society to the existence and importance of isotopes of the chemical elements, an IUPAC Periodic Table of the Isotopes (IPTI) has been prepared and can be found as a supplement to this issue.

  17. Isotope Harvesting Opportunities at FRIB

    Science.gov (United States)

    Morrissey, David

    2017-01-01

    The fragmentation of fast heavy ion beams now at the National Superconducting Cyclotron Laboratory (NSCL) and in the future at the Facility for Rare Isotope Beams (FRIB) under construction produce an unprecedentedly broad spectrum of radionuclides but only a small fraction are used in the on-line rare-isotope program. Projectile fragmentation facilities provide an electromagnetically purified beam of a single projectile fragment for nuclear physics experiments ranging from low energy astrophysics, through nuclear structure studies, to probing fundamental symmetries. By augmenting the NSCL and FRIB production facilities with complimentary collection and purification of discarded ions, called isotope harvesting with chemical purification, many other nuclides will become available for off-line experiments in parallel with the primary experiment. A growing user community has established a list of key target isotopes and is working with the FRIB design team to allow inclusion of necessary equipment in the future. An overview of the possibilities and the techniques will be presented in this talk. Supported by Office of Science, US DOE and Michigan State University.

  18. Extended calculations of energy levels, radiative properties, AJ, BJ hyperfine interaction constants, and Landé gJ-factors for oxygen-like Kr XXIX

    Science.gov (United States)

    Wang, K.; Jönsson, P.; Ekman, J.; Si, R.; Chen, Z. B.; Li, Y. G.; Chen, C. Y.; Yan, J.

    2017-06-01

    Using the multiconfiguration Dirac-Fock method and the second-order many-body perturbation theory method, highly accurate calculations are performed for the lowest 344 fine-structure levels arising from the 2s2 2p4 , 2s2 2p5 , 2p6 , 2s2 2p3 3 s , 2s2 2p3 3 p , 2s2 2p3 3 d , 2s2 2p4 3 s , 2s2 2p4 3 p , 2s2 2p4 3 d , 2p5 3 s , 2p5 3 p , 2p5 3 d , 2s2 2p3 4 s , 2s2 2p3 4 p , 2s2 2p3 4 d , 2s2 2p3 4 f , and 2s 2p4 4 s configurations in O-like Kr XXIX. Complete and consistent atomic data, including excitation energies, lifetimes, wavelengths, hyperfine structures, Landé gJ-factors, and E1, M1, E2, M2 transition rates, line strengths, and oscillator strengths among these 344 levels are obtained. Comparisons are made between our two different sets of results, as well as with the other available experimental and theoretical values. For O-like Kr only a few levels have been experimentally established. The accuracy of our calculated energies is however high enough to facilitate identifications of observed lines involving the n=3,4 levels. The calculated data are also useful for modeling and diagnosing fusion plasmas.

  19. Hyperfine interaction and tuning of magnetic anisotropy of Cu doped CoFe{sub 2}O{sub 4} ferrite nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Batoo, Khalid Mujasam, E-mail: khalid.mujasam@gmail.com [King Abdullah Institute for Nanotechnology, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Salah, Dina [Department of Physics, Ain Shams University, Khalifa El-Maamon, Street, 11566 Cairo (Egypt); Kumar, Gagan; Kumar, Arun; Singh, Mahavir [Department of Physics, Himachal Pradesh University, Summer Hill, Shimla 171005 (India); Abd El-sadek, M. [Nanomaterials Lab, Physics Department, Faculty of Science, South Valley University, Qena 83523 (Egypt); Mir, Feroz Ahmad [University Science Instrumentation Centre, University of Kashmir, Srinagar 190006 (India); Imran, Ahamad [King Abdullah Institute for Nanotechnology, King Saud University, P.O. Box-2455, Riyadh 11451 (Saudi Arabia); Jameel, Daler Adil [School of Physics and Astronomy, Nottingham Nanotechnology and Nanoscience Center, University of Nottingham, NG7 2RD (United Kingdom)

    2016-08-01

    Ferrimagnetic oxides may contain single or multi domain particles which get converted into superparamagnetic state near a critical size. To explore the existence of these particles, we have made Mössbauer and magnetic studies of Cu{sup 2+} substitution effect in CoFe{sub 2−x}O{sub 4} Ferrites (0.0, 0.1, 0.2, 0.3, 0.4, and 0.5). All the samples have a cubic spinel structure with lattice parameters increasing linearly with increase in Cu content. The hysteresis loops yield a saturation magnetization, coercive field, and remanent magnetization that vary significantly with Cu content. The magnetic hysteresis curves shows a reduction in saturation magnetization and an increase in coercitivity with Cu{sup 2+} ion substitution. The anisotropy constant, K{sub 1,} is found strongly dependent on the composition of Cu{sup 2+} ions. The variation of saturation magnetization with increasing Cu{sup 2+} ion content has been explained in the light of Neel's molecular field theory. Mössbauer spectra at room temperature shows two ferrimagnetically relaxed Zeeman sextets. The dependence of Mössbauer parameters such as isomer shift, quadrupole splitting, line width and hyperfine magnetic field on Cu{sup 2+} ion concentration have been discussed. - Highlights: • Synthesis of the nanoparticles of Cu doped CoFe{sub 2}O{sub 4} ferrite nanoparticles. • The samples were characterized for the structural, morphological and magnetic studies using XRD, TEM, VSM and Mossbauer spectroscopy. • It has been found that the all the magnetic and Mossbauer parameters are diluted with the addition of Cu content in the CoFe{sub 2}O{sub 4} matrix. • The Mossbauer and magnetic properties were studied in the light of size of nanoparticles and also with respect to the doping composition.

  20. Transferred hyperfine interaction at 295 K between the rare-earth ions and the fluorine and lithium nuclei in lithium rare-earth fluorides

    DEFF Research Database (Denmark)

    Hansen, P. E.; Nevald, Rolf

    1977-01-01

    The nuclear-magnetic-resonance rotation spectra for the fluorine and lithium nuclei in LiTbF4, LiDyF4, LiHoF4, and LiErF4 have been obtained at 295 K. They are separated in contributions from the dipole and the transferred hyperfine interactions. In general, the latter consists of an isotropic part...

  1. Proceedings of the International Workshop on Nanomaterials, Magnetic Ions and Magnetic Semiconductors Studied Mostly by Hyperfine Interactions (IWNMS 2004) held in Baroda, India, 10–14 February 2004

    CERN Document Server

    Somayajulu, D. R. S; IWNMS 2004

    2005-01-01

    Proceedings of the Baroda Workshop IWNMS 2004, held in Baroda, India, 10-14 February, 2004 Researchers and graduate students interested in the Mössbauer Effect and its applications will find this volume indispensable. The volume presents the most recent developments in the methodology of Mössbauer spectroscopy. Reprinted from Hyperfine Interactions (HYPE) Volume 160, 1-4

  2. Direct measurement of excited-state dipole matrix elements using electromagnetically induced transparency in the hyperfine Paschen-Back regime

    CERN Document Server

    Whiting, Daniel J; Adams, Charles S; Hughes, Ifan G

    2016-01-01

    Applying large magnetic fields to gain access to the hyperfine Paschen-Back regime can isolate three-level systems in a hot alkali metal vapors, thereby simplifying usually complex atom-light interactions. We use this method to make the first direct measurement of the $|\\langle\\mathrm{5P}| er||\\mathrm{5D}\\rangle|$ matrix element in $^{87}$Rb. An analytic model with only three-levels accurately models the experimental electromagnetically induced transparency spectra and extracted Rabi-frequencies are used to determine the dipole matrix element. We measure $|\\langle\\mathrm{5P}_{3/2}|er||\\mathrm{5D}_{5/2}\\rangle| = (2.290\\pm0.002_{\\rm stat}\\pm0.05_{\\rm syst})~ea_{0}$ which is in excellent agreement with the theoretical calculations of Safronova, Williams and Clark, Phys. Rev. A 69(2), 022509 (2004).

  3. The {sup 57}Fe hyperfine interactions in the iron-bearing phases in some LL ordinary chondrites

    Energy Technology Data Exchange (ETDEWEB)

    Oshtrakh, M. I., E-mail: oshtrakh@gmail.com; Maksimova, A. A.; Grokhovsky, V. I.; Petrova, E. V.; Semionkin, V. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation)

    2016-12-15

    The study of several LL ordinary chondrites such as NWA 6286 LL6, NWA 7857 LL6 and Chelyabinsk LL5 fragments with different lithology was carried out using scanning electron microscopy with energy dispersion spectroscopy, X-ray diffraction and {sup 57}Fe Mössbauer spectroscopy with a high velocity resolution at 295 K. Small variations in the {sup 57}Fe hyperfine parameters were revealed for the M1 and M2 sites in olivine, orthopyroxene and clinopyroxene as well as for α-Fe(Ni, Co), α{sub 2}-Fe(Ni, Co) and γ-Fe(Ni, Co) phases, and for troilite in different samples of studied LL ordinary chondrites.

  4. Separating hyperfine from spin-orbit interactions in organic semiconductors by multi-octave magnetic resonance using coplanar waveguide microresonators

    Science.gov (United States)

    Joshi, G.; Miller, R.; Ogden, L.; Kavand, M.; Jamali, S.; Ambal, K.; Venkatesh, S.; Schurig, D.; Malissa, H.; Lupton, J. M.; Boehme, C.

    2016-09-01

    Separating the influence of hyperfine from spin-orbit interactions in spin-dependent carrier recombination and dissociation processes necessitates magnetic resonance spectroscopy over a wide range of frequencies. We have designed compact and versatile coplanar waveguide resonators for continuous-wave electrically detected magnetic resonance and tested these on organic light-emitting diodes. By exploiting both the fundamental and higher-harmonic modes of the resonators, we cover almost five octaves in resonance frequency within a single setup. The measurements with a common π-conjugated polymer as the active material reveal small but non-negligible effects of spin-orbit interactions, which give rise to a broadening of the magnetic resonance spectrum with increasing frequency.

  5. Separating hyperfine from spin-orbit interactions in organic semiconductors by multi-octave magnetic resonance using coplanar waveguide microresonators

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, G.; Miller, R.; Ogden, L.; Kavand, M.; Jamali, S.; Ambal, K.; Malissa, H.; Boehme, C., E-mail: boehme@physics.utah.edu [Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112 (United States); Venkatesh, S.; Schurig, D. [Department of Electrical and Computer Engineering, University of Utah, Salt Lake City, Utah 84112 (United States); Lupton, J. M. [Department of Physics and Astronomy, University of Utah, Salt Lake City, Utah 84112 (United States); Institut für Experimentelle und Angewandte Physik, Universität Regensburg, D-93040 Regensburg (Germany)

    2016-09-05

    Separating the influence of hyperfine from spin-orbit interactions in spin-dependent carrier recombination and dissociation processes necessitates magnetic resonance spectroscopy over a wide range of frequencies. We have designed compact and versatile coplanar waveguide resonators for continuous-wave electrically detected magnetic resonance and tested these on organic light-emitting diodes. By exploiting both the fundamental and higher-harmonic modes of the resonators, we cover almost five octaves in resonance frequency within a single setup. The measurements with a common π-conjugated polymer as the active material reveal small but non-negligible effects of spin-orbit interactions, which give rise to a broadening of the magnetic resonance spectrum with increasing frequency.

  6. Reversibility of the preferred hyperfine field direction in the electrochemically deposited Fe-Ni-P amorphous alloys

    Energy Technology Data Exchange (ETDEWEB)

    Zemcik, T. (Ceskoslovenska Akademie Ved, Brno (Czechoslovakia). Ustav Fyzikalni Metalurgie); Kuzmann, E. (Eoetvoes Lorand Tudomanyegyetem, Budapest (Hungary). Lab. of Nuclear Chemistry); Hemschik, H. (Akademie der Wissenschaften, Dresden (Germany, F.R.). Zentralinstitut fuer Festkoerperphysik und Werkstofforschung)

    1991-01-01

    Electrochemically deposited Fe(-Ni)-P alloys exhibit in the as-deposited state a strong magnetic anisotropy with the easy axis perpendicular to the foil plane. Using {sup 57}Fe Moessbauer measurements in three transmission directions and an evaluation procedure modified with respect to that reported previously, it is shown that the Fe{sub 43}Ni{sub 45}P{sub 12} alloy indeed possesses a pronounced normal orientation of the hyperfine field, i.e. the spontaneous magnetization. Application of an in-plane external field leads to an alignment of magnetic domains in field direction, whereas remanent-state results agree with those in the as-deposited state. (orig.).

  7. P ,T -odd and magnetic hyperfine-interaction constants and excited-state lifetime for HfF+

    Science.gov (United States)

    Fleig, Timo

    2017-10-01

    Parity- and time-reversal-symmetry violating interaction constants required for the interpretation of a recent measurement [W. B. Cairncross et al., Phys. Rev. Lett. 119, 153001 (2017), 10.1103/PhysRevLett.119.153001] of corresponding symmetry violations in the Ω =1 (3Δ1) science state of the HfF+ molecular ion are reported. Using a relativistic four-component all-electron multireference configuration interaction model the nucleon-electron scalar-pseudoscalar interaction constant is determined as WS=20.0 [kHz]. An updated result for the electron electric-dipole-moment effective electric field of | Eeff|=22.7 [GV/cm ] is obtained. Further results of relevance in the context of the search for leptonic charge-parity violation such as the 177Hf magnetic hyperfine interaction constant and electronic G tensor for HfF+ are presented.

  8. Hyperfine magnetic field on iron atoms as indication of stoichiometry in Co{sub 2}FeSi

    Energy Technology Data Exchange (ETDEWEB)

    Ksenofontov, Vadim; Balke, Benjamin; Felser, Claudia [Institute of Inorganic and Analytical Chemistry, Johannes Gutenberg-University, Mainz (Germany); Wojcik, Marek [Institute of Physics, Polish Academy of Sciences, Warszawa (Poland); Wurmehl, Sabine [Department of Applied Physics, Physics of Nanostructures, Eindhoven University of Technology (Netherlands); Schneider, Horst; Jakob, Gerhard [Institute of Physics, Johannes Gutenberg University, Mainz (Germany)

    2009-07-01

    The Heusler compound Co{sub 2}FeSi is a promising half-metallic material for thin films spintronic applications. Among the factors reducing spin-polarization, the defects and antisite disordering in such materials play a crucial role. To clarify effects of the non-stoichiometry, the continuous series of model solid solutions Co{sub 3-x}Fe{sub x}Si (0.96hyperfine magnetic fields on Fe can be used to monitor a non-stoichiometry in Co{sub 2}FeSi-based bulk samples and thin films.

  9. Hyperfine magnetic field on iron atoms and Co-Fe disordering in Co2FeSi

    Science.gov (United States)

    Ksenofontov, Vadim; Wójcik, Marek; Wurmehl, Sabine; Schneider, Horst; Balke, Benjamin; Jakob, Gerhard; Felser, Claudia

    2010-05-01

    The Heusler compound Co2FeSi is a prospective half-metallic material for spintronic applications. Defects and antisite disordering play a crucial role among the factors reducing spin polarization in such materials. To clarify effects of possible off-stoichiometry, a continuous series of model solid solutions Co3-xFexSi (0.6≤x≤1.4) was investigated by F57e Mössbauer spectroscopy and C59o nuclear magnetic resonance. It has been shown that the hyperfine magnetic fields on Fe can be used to monitor Co-Fe disordering in Co2FeSi-based bulk samples and thin films.

  10. Intercalation effect on hyperfine parameters of Fe in FeSe superconductor with Tc = 42 K

    Science.gov (United States)

    Shylin, Sergii I.; Ksenofontov, Vadim; Sedlmaier, Stefan J.; Clarke, Simon J.; Cassidy, Simon J.; Wortmann, Gerhard; Medvedev, Sergey A.; Felser, Claudia

    2015-03-01

    57Fe-Mössbauer spectra of superconducting β-FeSe, the Li/NH3 intercalate product and a subsequent sample of this intercalate treated with moist He gas have been measured in the temperature range 4.7-290 K. A correlation is established between hyperfine parameters and critical temperature T{c} in these phases. A strong increase of the isomer shift upon intercalation is explained by a charge transfer from the Li/NH3 intercalate to the FeSe layers resulting in an increase of T{c} up to 42 K. A significant decrease of the quadrupole splitting above 240 K has been attributed to diffusive motion of Li+ ions within the interlamellar space.

  11. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    titative measurements of equilibrium and kinetic isotope effects. In this part, we describe an ingenious way of studying ... is whether the structure obtained is the preferred one or just the superposition of some other equilibrating structures. ... Ammonia is a pyramidal molecule, but it undergoes rapid umbrella inversion. On the ...

  12. Discovery of the Indium Isotopes

    CERN Document Server

    Amos, S

    2010-01-01

    Thirty-eight indium isotopes (A = 98-135) have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.

  13. Oxygen isotope fractionation in double carbonates.

    Science.gov (United States)

    Zheng, Yong-Fei; Böttcher, Michael E

    2016-01-01

    Oxygen isotope fractionations in double carbonates of different crystal structures were calculated by the increment method. Synthesis experiments were performed at 60 °C and 100 °C to determine oxygen and carbon isotope fractionations involving PbMg[CO3]2. The calculations suggest that the double carbonates of calcite structure are systematically enriched in (18)O relative to those of aragonite and mixture structures. Internally consistent oxygen isotope fractionation factors are obtained for these minerals with respect to quartz, calcite and water at a temperature range of 0-1200 °C. The calculated fractionation factors for double carbonate-water systems are generally consistent with the data available from laboratory experiments. The experimentally determined fractionation factors for PbMg[CO3]2, BaMg[CO3]2 and CaMg[CO3]2 against H2O not only fall between fractionation factors involving pure carbonate end-members but are also close to the calculated fractionation factors. In contrast, experimentally determined carbon isotope fractionation factors between PbMg[CO3]2 and CO2 are much closer to theoretical predictions for the cerussite-CO2 system than for the magnesite-CO2 system, similar to the fractionation behavior for BaMg[CO3]2. Therefore, the combined theoretical and experimental results provide insights into the effects of crystal structure and exchange kinetics on oxygen isotope partitioning in double carbonates.

  14. Nuclear Spectroscopy with Copper Isotopes of Extreme N/Z Ratios

    CERN Multimedia

    La commara, M; Roeckl, E; Van duppen, P L E; Schmidt, K A; Lettry, J

    2002-01-01

    The collaboration aims to obtain detailed nuclear spectroscopy information on isotopes close to the magic proton number Z=28 Very neutron-rich and neutron-deficient copper isotopes are ionized with the ISOLDE resonance ionization laser ion source (RILIS) to provide beams with low cross contamination.\\\\ \\\\On the neutron-deficient side the high $Q_\\beta$-values of $^{56}$Cu (15~MeV) and $^{57}$Cu (8.8~MeV) allow to study levels at high excitation energies in the doubly magic nucleus $^{56}$Ni and the neighbouring $^{57}$Ni. On the neutron-rich side the spectroscopy with separated copper isotopes allows presently the closest approach to the doubly magic $^{78}$Ni at an ISOL facility. Up to now no suitable target material with a rapid release was found for nickel itself. A slow release behaviour has to be assumed also for the chemically similar elements iron and cobalt.\\\\ \\\\Using a narrow-bandwidth dye laser and tuning of the laser frequency allows to scan the hyperfine splittings of the copper isotopes and isome...

  15. Structure of the carbon isotope excursion in a high-resolution lacustrine Paleocene-Eocene Thermal Maximum record from central China

    Science.gov (United States)

    Chen, Zuoling; Wang, Xu; Hu, Jianfang; Yang, Shiling; Zhu, Min; Dong, Xinxin; Tang, Zihua; Peng, Ping'an; Ding, Zhongli

    2014-12-01

    The carbon isotope excursion (CIE) associated with the Paleocene-Eocene Thermal Maximum (PETM) has been recognized for the first time in the micritic carbonate, total organic carbon (TOC) and black carbon (BC) contained within the lacustrine sediments from the Nanyang Basin, central China. The remarkably large excursion (∼ - 6 ‰) in the δ13CTOC and δ13CBC values is possibly attributable to increased humidity and elevated pCO2 concentration. The ∼ - 4 ‰ CIE recorded in the δ13Ccalcite, reflecting the average isotope change of the watershed system, is consistent with that observed in planktonic foraminifera. This correspondence suggests that the true magnitude of the carbon isotope excursion in the ocean-atmosphere system is likely close to - 4 ‰. The ∼10 m excursion onset in our multi-proxy δ13C records demonstrates that the large input of 13C-depleted carbon into the ocean-atmosphere system was not geologically instantaneous. Despite difference and somewhat smoothness in detailed pattern of the CIE due to localized controls on different substrates, inorganic and organic δ13C data generally depict a gradual excursion onset at least over timescales of thousands of years. In addition, continental temperature reconstruction, based on the distribution of membrane lipids of bacteria, suggests a warming of ∼4 °C prior to the PETM and ∼7 °C increase in temperature during the PETM. The temperature data are overall similar in pattern and trend to the δ13C change across the PETM. These observations, combined with pre-CIE warming, are in line with the idea that 13C-depleted carbon release operated as a positive feedback to temperature, suggesting supply from one or more large organic carbon reservoirs on Earth's surface.

  16. Origin and tectonic implications of the Zhaxikang Pb-Zn-Sb-Ag deposit in northern Himalaya: evidence from structures, Re-Os-Pb-S isotopes, and fluid inclusions

    Science.gov (United States)

    Zhou, Qing; Li, Wenchang; Qing, Chengshi; Lai, Yang; Li, Yingxu; Liao, Zhenwen; Wu, Jianyang; Wang, Shengwei; Dong, Lei; Tian, Enyuan

    2017-08-01

    The Zhaxikang Pb-Zn-Sb-Ag-(Au) deposits, located in the eastern part of northern Himalaya, totally contain more than 1.146 million tonnes (Mt) of Pb, 1.407 Mt of Zn, 0.345 Mt of Sb, and 3 kilotonnes (kt) of Ag. Our field observations suggest that these deposits are controlled by N-S trending and west- and steep-dipping normal faults, suggesting a hydrothermal rather than a syngenetic sedimentary origin. The Pb-Zn-Sb-Ag-(Cu-Au) mineralization formed in the Eocene as indicated by a Re-Os isochron age of 43.1 ± 2.5 Ma. Sulfide minerals have varying initial Pb isotopic compositions, with (206Pb/204Pb)i of 19.04-19.68, (207Pb/204Pb)i of 15.75-15.88, and (208Pb/204Pb)i of 39.66-40.31. Sulfur isotopic values display a narrow δ34S interval of +7.8-+12.2‰. These Pb-S isotopic data suggest that the Zhaxikang sources of Pb and S should be mainly from the coeval felsic magmas and partly from the surrounding Mesozoic strata including metasedimentary rocks and layered felsic volcanic rocks. Fluid inclusion studies indicate that the hydrothermal fluids have medium temperatures (200-336 °C) but varying salinities (1.40-18.25 wt.% NaCl equiv.) with densities of 0.75-0.95 g/cm3, possibly suggesting an evolution mixing between a high salinity fluid, perhaps of magmatic origin, with meteoric water.

  17. Stable hydrogen and oxygen isotopes of tap water reveal structure of the San Francisco Bay Area's water system and adjustments during a major drought.

    Science.gov (United States)

    Tipple, Brett J; Jameel, Yusuf; Chau, Thuan H; Mancuso, Christy J; Bowen, Gabriel J; Dufour, Alexis; Chesson, Lesley A; Ehleringer, James R

    2017-08-01

    Water availability and sustainability in the Western United States is a major flashpoint among expanding communities, growing industries, and productive agricultural lands. This issue came to a head in 2015 in the State of California, when the State mandated a 25% reduction in urban water use following a multi-year drought that significantly depleted water resources. Water demands and challenges in supplying water are only expected to intensify as climate perturbations, such as the 2012-2015 California Drought, become more common. As a consequence, there is an increased need to understand linkages between urban centers, water transport and usage, and the impacts of climate change on water resources. To assess if stable hydrogen and oxygen isotope ratios could increase the understanding of these relationships within a megalopolis in the Western United States, we collected and analyzed 723 tap waters across the San Francisco Bay Area during seven collection campaigns spanning 21 months during 2013-2015. The San Francisco Bay Area was selected as it has well-characterized water management strategies and the 2012-2105 California Drought dramatically affected its water resources. Consistent with known water management strategies and previously collected isotope data, we found large spatiotemporal variations in the δ2H and δ18O values of tap waters within the Bay Area. This is indicative of complex water transport systems and varying municipality-scale management decisions. We observed δ2H and δ18O values of tap water consistent with waters originating from snowmelt from the Sierra Nevada Mountains, local precipitation, ground water, and partially evaporated reservoir sources. A cluster analysis of the isotope data collected in this study grouped waters from 43 static sampling sites that were associated with specific water utility providers within the San Francisco Bay Area and known management practices. Various management responses to the drought, such as source

  18. SHELL ISOTOPE GEOCHEMISTRY

    African Journals Online (AJOL)

    Valley. Although fossil specimens of this subspecies have been used in palaeoclimatic reconstruction, there have been no previous reports of living examples. Here We describe the local habitat, climate and some aspects of ecology and isotopic variation within the snail shell. If isotope data can be obtained for fossil shells, ...

  19. ICT: isotope correction toolbox.

    Science.gov (United States)

    Jungreuthmayer, Christian; Neubauer, Stefan; Mairinger, Teresa; Zanghellini, Jürgen; Hann, Stephan

    2016-01-01

    Isotope tracer experiments are an invaluable technique to analyze and study the metabolism of biological systems. However, isotope labeling experiments are often affected by naturally abundant isotopes especially in cases where mass spectrometric methods make use of derivatization. The correction of these additive interferences--in particular for complex isotopic systems--is numerically challenging and still an emerging field of research. When positional information is generated via collision-induced dissociation, even more complex calculations for isotopic interference correction are necessary. So far, no freely available tools can handle tandem mass spectrometry data. We present isotope correction toolbox, a program that corrects tandem mass isotopomer data from tandem mass spectrometry experiments. Isotope correction toolbox is written in the multi-platform programming language Perl and, therefore, can be used on all commonly available computer platforms. Source code and documentation can be freely obtained under the Artistic License or the GNU General Public License from: https://github.com/jungreuc/isotope_correction_toolbox/ {christian.jungreuthmayer@boku.ac.at,juergen.zanghellini@boku.ac.at} Supplementary data are available at Bioinformatics online. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com.

  20. The second spectrum of niobium: I. Accurate fine structure study of even-parity levels

    Science.gov (United States)

    Bouazza, Safa

    2013-03-01

    For the first time, a parametric analysis of the fine and hyperfine structure for even-parity levels of Nb II, involving 17 configurations, has been performed. The interpretation has been carried out based on a linked-parameter method of level-fitting calculations in a large multiconfiguration basis. The sets of fine structure parameters, the leading eigenvector percentages of levels, as well as their calculated magnetic Landé g-factors are newly given. Furthermore, we confirm on the whole the validity of the attributions to term designations, previously proposed. The single-electron hyperfine structure parameters are determined in their entirety for 93Nb II for the model space (4d + 5s)4 with a good accuracy and confirmed by ab initio calculations. Finally, a complete list of the predicted magnetic hyperfine structure constants A of all levels of this model space was generated.

  1. Stable isotope ratios of rain and vapor in 1995 hurricanes

    Science.gov (United States)

    Lawrence, James Robert; Gedzelman, Stanley David; Zhang, Xiaoping; Arnold, Robert

    1998-05-01

    Isotope ratios of rain and vapor samples collected at the surface from four tropical cyclones during the active 1995 Atlantic hurricane season were determined. A two-dimensional bulk microphysics isotope model was applied to steady symmetric tropical cyclones to explain the observed low mean values and inward decrease of isotope ratios of the rain and vapor. The low mean value is caused by the tropical cyclone's relatively large size, longevity, and deep clouds. The inward decrease is due to diffusive isotope exchange between falling rain and converging vapor in the atmospheric boundary layer. Dean, a minimal tropical storm, produced relatively high isotope ratios because of its small size and youth. Rains from the extreme outer edge of Felix, a category 3 hurricane, exhibited high isotope ratios similar to normal summer rain. Isotope ratios of rains and vapors from Hurricane Luis in Puerto Rico decreased as the storm approached. Isotope ratios of rain exhibited an abrupt jump from low values in the eastern half of Puerto Rico to high values farther west which is linked to the storm's rainbands. Isotope ratios of Hurricane Opal's rains reflected the storm's asymmetric structure, with lowest values west of the point of landfall. Record low isotope ratios from a squall line that struck eastern Texas two days before landfall are linked to low-level outflow from Opal and demonstrate that hurricanes can vent enormous quantities of vapor to the surroundings.

  2. Shallow dopants in nanostructered and in isotopically engineered silicon

    Energy Technology Data Exchange (ETDEWEB)

    Stegner, Andre Rainer

    2011-01-15

    This work addressed two major topics. The first part was dedicated to the investigation of the doping properties of Si nanostructures. There, we have reported our results on Si nanoparticles with particular focus on questions concerning the atomic incorporation efficiency of dopants, their compensation by surface defects, and the change of their localization due to confinement effects. In the second part of this thesis, we have addressed several open questions concerning the spin properties of shallow acceptor states in bulk Si crystals with different isotope compositions. As far as the first part is concerned, ESR and SIMS have been used to quantitatively investigate the P doping efficiency and the interrelationship of Si-db states and P doping in freestanding Si-NCs over a wide range of diameters. Two types of Si-db defect states, the P{sub b} center and the D center, were identified, where the P{sub b} centers are found at concentrations comparable to bulk Si/SiO{sub 2} interfaces. Moreover, the incorporation of P donors and B acceptors in amorphous Si nanoparticles was demonstrated via ESR. Employing EDMR, we investigated the spin-dependent transport through Si-NC networks. The selectivity and the high sensitivity of EDMR enabled the observation of isolated neutral donor states, which exhibit a characteristic hyperfine splitting in samples with very small diameters. This opened up a possibility for the direct study of the properties of the donor wave function in Si-NCs. To this end, we have used the hyperfine splitting as a spectroscopic measure to monitor the localization of donor wave functions when going from the bulk to the nanoscale. As far as the spin properties of shallow acceptors in Si are concerned, we have addressed a number of fundamental questions concerning the line shape, the magnitude of the residual broadening and the substructure of the boron resonances observed in low-temperature EPR experiments. Performing EPR measurements on different

  3. WWW Table of Radioactive Isotopes

    Science.gov (United States)

    Firestone, R. B.; Ekstrom, L. P.; Chu, S. Y. F.

    1999-10-01

    An electronic sequel to the Table of Radioactive Isotopes (John Wiley, 1986) is being developed for use on the WWW. Updated adopted and decay data from the Evaluated Nuclear Structure Decay File (ENSDF) and other sources have been combined and edited. Decay scheme normalizations are revised when necessary. Gamma-ray and alpha-particle energies can be searched interactively by energy or parent half-life, mass, and atomic or neutron number. Summary data including half-lives, Q-values, production mode(s), genetic feedings, and a list of references published since the last full evaluation are available. Users can display energy or intensity ordered tables of gamma-rays, K and L x-rays, alpha-particles, and beta endpoints. Spectra of betas and bremsstrahlung, and Auger/conversion electrons can be viewed with an interactive JAVA applet. Decay schemes can be displayed with the JAVA version of Isotope Explorer 3.0. The URL for the Table of Radioactive Isotopes is http://nucleardata.nuclear.lu.se/nucleardata/toi/.

  4. Defining fish community structure in Lake Winnipeg using stable isotopes (δ{sup 13}C, δ{sup 15}N, δ{sup 34}S): Implications for monitoring ecological responses and trophodynamics of mercury and other trace elements

    Energy Technology Data Exchange (ETDEWEB)

    Ofukany, Amy F.A. [Toxicology Centre, University of Saskatchewan, 44 Campus Drive, Saskatoon, Saskatchewan S7N 5B3 (Canada); Wassenaar, Leonard I. [Environment Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan S7N 3H5 (Canada); Bond, Alexander L., E-mail: alex.bond@rspb.org.uk [Environment Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan S7N 3H5 (Canada); Hobson, Keith A. [Environment Canada, 11 Innovation Boulevard, Saskatoon, Saskatchewan S7N 3H5 (Canada)

    2014-11-01

    The ecological integrity of freshwater lakes is influenced by atmospheric and riverine deposition of contaminants, shoreline development, eutrophication, and the introduction of non-native species. Changes to the trophic structure of Lake Winnipeg, Canada, and consequently, the concentrations of contaminants and trace elements measured in tissues of native fishes, are likely attributed to agricultural runoff from the 977,800 km{sup 2} watershed and the arrival of non-native zooplankters and fishes. We measured δ{sup 13}C, δ{sup 15}N, and δ{sup 34}S along with concentrations of 15 trace elements in 17 native fishes from the north and south basins of Lake Winnipeg in 2009 and 2010. After adjusting for differences in isotopic baseline values between the two basins, fishes in the south basin had consistently higher δ{sup 13}C and δ{sup 34}S, and lower δ{sup 15}N. We found little evidence of biomagnification of trace elements at the community level, but walleye (Sander vitreus) and freshwater drum (Aplodinotus grunniens) had higher mercury and selenium concentrations with increased trophic position, coincident with increased piscivory. There was evidence of growth dilution of cobalt, copper, manganese, molybdenum, thallium, and vanadium, and bioaccumulation of mercury, which could be explained by increases in algal (and consequently, lake and fish) productivity. We conclude that the north and south basins of Lake Winnipeg represent very different communities with different trophic structures and trace element concentrations. - Highlights: • Anthropogenic eutrophication and non-native species affect Lake Winnipeg’s ecosystem. • We measured stable isotopes and trace elements in 15 native fish species. • There was more evidence for growth dilution than biomagnification for most elements. • The trophic structures of the north and south basins were different. • These results will help determine the effects of recent arrival of zebra mussels.

  5. Zinc isotope fractionation during magmatic differentiation and the isotopic composition of the bulk Earth

    Science.gov (United States)

    Chen, Heng; Savage, Paul S.; Teng, Fang-Zehn; Helz, Rosalind T.; Moynier, Frédéric

    2013-01-01

    he zinc stable isotope system has been successfully applied to many and varied fields in geochemistry, but to date it is still not completely clear how this isotope system is affected by igneous processes. In order to evaluate the potential application of Zn isotopes as a proxy for planetary differentiation and volatile history, it is important to constrain the magnitude of Zn isotopic fractionation induced by magmatic differentiation. In this study we present high-precision Zn isotope analyses of two sets of chemically diverse, cogenetic samples from Kilauea Iki lava lake, Hawaii, and Hekla volcano, Iceland, which both show clear evidence of having undergone variable and significant degrees of magmatic differentiation. The Kilauea Iki samples display small but resolvable variations in Zn isotope composition (0.26‰66Zn66Zn defined as the per mille deviation of a sample's 66Zn/64Zn compositional ratio from the JMC-Lyon standard), with the most differentiated lithologies exhibiting more positive δ66Zn values. This fractionation is likely a result of the crystallization of olivine and/or Fe–Ti oxides, which can both host Zn in their crystal structures. Samples from Hekla have a similar range of isotopic variation (0.22‰66Zn66Zn=0.28±0.05‰ (2s.d.).

  6. Laser spectroscopy of neutron deficient Sn isotopes

    CERN Multimedia

    We propose to study the ground state properties of neutron-deficient Sn isotopes towards the doubly-magic nucleus $^{100}$Sn. Nuclear spins, changes in the rms charge radii and electromagnetic moments of $^{101-121}$Sn will be measured by laser spectroscopy using the CRIS experimental beam line. These ground-state properties will help to clarify the evolution of nuclear structure properties approaching the $\\textit{N = Z =}$ 50 shell closures. The Sn isotopic chain is currently the frontier for the application of state-of-the-art ab-initio calculations. Our knowledge of the nuclear structure of the Sn isotopes will set a benchmark for the advances of many-body methods, and will provide an important test for modern descriptions of the nuclear force.

  7. Recoil distance method lifetime measurement of the 21+ state in 94Sr and implications for the structure of neutron-rich Sr isotopes

    Science.gov (United States)

    Chester, A.; Ball, G. C.; Caballero-Folch, R.; Cross, D. S.; Cruz, S.; Domingo, T.; Drake, T. E.; Garnsworthy, A. B.; Hackman, G.; Hallam, S.; Henderson, J.; Henderson, R.; Korten, W.; Krücken, R.; Moukaddam, M.; Olaizola, B.; Ruotsalainen, P.; Smallcombe, J.; Starosta, K.; Svensson, C. E.; Williams, J.; Wimmer, K.

    2017-07-01

    A high precision lifetime measurement of the 21+ state in 94Sr was performed at TRIUMF's ISAC-II facility by coupling the recoil distance method implemented via the TIGRESS integrated plunger with unsafe Coulomb excitation in inverse kinematics. Due to limited statistics imposed by the use of a radioactive 94Sr beam, a likelihood ratio χ2 method was derived and used to compare experimental data to Geant4 simulations. The B (E 2 ;21+→01+) value extracted from the lifetime measurement of 7 .80-0.40+0.50(stat.)±0.07 (sys.) ps is approximately 25% larger than previously reported while the relative error has been reduced by a factor of approximately 8. A baseline deformation has been established for Sr isotopes with N ≤58 which is a necessary condition for the quantum phase transition interpretation of the onset of deformation in this region. A comparison to existing theoretical models is presented.

  8. Study on a pyrazine-modulated tetrapyridyltriamide and its complexes: Synthesis, structure and properties

    Science.gov (United States)

    Wang, Wen-Zhen; Ismayilov, Rayyat Huseyn; Lee, Gene-Hsiang; Wen, Yuh-Sheng; Peng, Shie-Ming

    2010-06-01

    A pyrazine-modulated oligo-α-pyridylamine ligand H 3pzpz and its mononuclear copper(II) and cobalt(II) complexes have been synthesized and structurally characterized. The protonated ligand cation 1 exhibits an anti-anti-anti-anti-syn-anti conformation. H 3pzpz can be a quadridentate ligand and coordinates to metal atoms with all- anti mode in both copper and cobalt mononuclear complexes. The copper(II) ion in 2 is five-coordinated in tetragonal pyramid geometry with one of the perchlorate anions being weakly coordinated in the apex position. The cobalt(II) ion in 3 and 4 is six-coordinated in octahedron geometry. Extensive hydrogen bonds are formed, and construct the complexes 1 and 2 into 2D networks and 3 and 4 into 3D networks. X-band EPR spectra of 2 showed well-resolved hyperfine structures resulting from the two paramagnetic isotopes 63Cu and 65Cu, yielding g = 2.16 and A0 = 67 × 10 -4 cm -1. Complexes 3 and 4 showed spin-orbital coupling and zero-field splitting that is reflected in the magnetic properties.

  9. Calcium stable isotope geochemistry

    Energy Technology Data Exchange (ETDEWEB)

    Gausonne, Nikolaus [Muenster Univ. (Germany). Inst. fuer Mineralogie; Schmitt, Anne-Desiree [Strasbourg Univ. (France). LHyGeS/EOST; Heuser, Alexander [Bonn Univ. (Germany). Steinmann-Inst. fuer Geologie, Mineralogie und Palaeontologie; Wombacher, Frank [Koeln Univ. (Germany). Inst. fuer Geologie und Mineralogie; Dietzel, Martin [Technische Univ. Graz (Austria). Inst. fuer Angewandte Geowissenschaften; Tipper, Edward [Cambridge Univ. (United Kingdom). Dept. of Earth Sciences; Schiller, Martin [Copenhagen Univ. (Denmark). Natural History Museum of Denmark

    2016-08-01

    This book provides an overview of the fundamentals and reference values for Ca stable isotope research, as well as current analytical methodologies including detailed instructions for sample preparation and isotope analysis. As such, it introduces readers to the different fields of application, including low-temperature mineral precipitation and biomineralisation, Earth surface processes and global cycling, high-temperature processes and cosmochemistry, and lastly human studies and biomedical applications. The current state of the art in these major areas is discussed, and open questions and possible future directions are identified. In terms of its depth and coverage, the current work extends and complements the previous reviews of Ca stable isotope geochemistry, addressing the needs of graduate students and advanced researchers who want to familiarize themselves with Ca stable isotope research.

  10. Isotope Production Facility (IPF)

    Data.gov (United States)

    Federal Laboratory Consortium — The Los Alamos National Laboratory has produced radioactive isotopes for medicine and research since the mid 1970s, when targets were first irradiated using the 800...

  11. Isotopes in Greenland Precipitation

    DEFF Research Database (Denmark)

    Faber, Anne-Katrine

    ) Constructing a new Greenland database of observations and present-day ice core measurements, and (3) Performance test of isotope-enabled CAM5 for Greenland. The recent decades of rapid Arctic sea ice decline are used as a basis for an observational-based model experiment using the isotope-enabled CAM model 3....... The simulation of Greenland isotopes is tested for the isotope-enabled model CAM5. Here the importance of model resolution is investigated. A positive bias of 6-10 ‰ is found for the annual mean δ18O on the central part of the Greenland Ice Sheet. The amplitude of the seasonal cycle of Greenland δ18O is highly...

  12. Study of the hyperfine properties of the nickel-zinc ferrite using coprecipitation process; Estudo das propriedades hiperfinas de ferrita de niquel e zinco obtida por coprecipitacao

    Energy Technology Data Exchange (ETDEWEB)

    Albuquerque, Adriana Silva de; Almeida Macedo, Waldemar Augusto de [Centro de Desenvolvimento da Tecnologia Nuclear (CDTN), Belo Horizonte, MG (Brazil)

    1996-09-01

    In this work were studied the synthesis by coprecipitation of the Ni Zn ferrite, Ni {sub 0,5} Zn{sub 0,5} Fe{sub 2} O{sub 4}``, and its hyperfine properties. The ferrite specimens were prepared using metallic nitrates in aqueous solutions as precursor agents and the precipitation processes were promoted by addition of ammonium or sodium hydroxide. The obtained powders were calcined and characterized by X-ray diffraction and fluorescence, and by {sup 57} Fe Moessbauer spectroscopy. The liquid phase was analysed by atomic absorption. The samples of stoichiometric Ni Zn ferrite were obtained using Na O H as precipitating agent. The ferrite powders presented different particles size related with changing in the preparation method,and then, different hyperfine properties. Moessbauer effect measurements reveled the superparamagnetic nature of the ferrite samples that presented particles size smaller than 30 nm. (author) 9 refs., 3 figs., 3 tabs.

  13. Isotope toolbox turns 10

    DEFF Research Database (Denmark)

    Wenander, Fredrik; Riisager, Karsten

    2012-01-01

    REX-ISOLDE, one of CERN’s most compact accelerators, has just celebrated its 10th anniversary. The machine’s versatility provides radioactive ion beams across the range of nuclear isotopes.......REX-ISOLDE, one of CERN’s most compact accelerators, has just celebrated its 10th anniversary. The machine’s versatility provides radioactive ion beams across the range of nuclear isotopes....

  14. Isotope research materials

    Energy Technology Data Exchange (ETDEWEB)

    Wilkinson, M. K.; Young, Jr, F. W.

    1977-10-01

    Preparation of research isotope materials is described. Topics covered include: separation of tritium from aqueous effluents by bipolar electrolysis; stable isotope targets and research materials; radioisotope targets and research materials; preparation of an 241Am metallurgical specimen; reactor dosimeters; ceramic and cermet development; fission-fragment-generating targets of 235UO2; and wire dosimeters for Westinghouse--Bettis. (GHT)

  15. Proceedings of the 13th International Conference on Hyperfine Interactions and 17th International Symposium on Nuclear Quadrupole Interactions (HFI/NQI 2004) Bonn, Germany, 22–27 August 2004

    CERN Document Server

    Maier, K; HFI/NQI 2004

    2005-01-01

    Proceedings of the 13th International Conference on Hyperfine Interactions and 17th International Symposium on Nuclear Quadrupole Interactions, HFI/NQI 2004, held in Bonn, Germany, 22-27 August, 2004 Researchers and graduate students interested in the Mössbauer Effect and its applications will find this volume indispensable. The volume presents the most recent developments in the methodology of Mössbauer spectroscopy. Reprinted from Hyperfine Interactions (HYPE) Volume 158/159.

  16. Differences of the {sup 57}Fe hyperfine parameters in both oxyhemoglobin and spleen from normal human and patient with primary myelofibrosis

    Energy Technology Data Exchange (ETDEWEB)

    Oshtrakh, M. I., E-mail: oshtrakh@mail.utnet.ru; Alenkina, I. V. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation); Vinogradov, A. V.; Konstantinova, T. S. [Ural State Medical Academy (Russian Federation); Semionkin, V. A. [Ural Federal University, Department of Physical Techniques and Devices for Quality Control, Institute of Physics and Technology (Russian Federation)

    2013-05-15

    Study of oxyhemoglobin in red blood cells and spleen tissues from normal human and patient with primary myelofibrosis was carried out using Moessbauer spectroscopy with a high velocity resolution. The {sup 57}Fe hyperfine parameters were evaluated and small variations in quadrupole splitting were revealed for both normal human and patient's oxyhemoglobin and both normal human and patient's spleen.

  17. Probing the Structure of Water Molecules at an Oil/Water Interface in the Presence of a Charged Soluble Surfactant Through Isotopic Dilution Studies

    National Research Council Canada - National Science Library

    Gragson, D

    1998-01-01

    .... By examining OH stretching modes that are highly sensitive to the local hydrogen bonding environment, we have been able to compare the structure of interfacial water molecules with the structure...

  18. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 2; Issue 10. Use of Isotopes for Studying Reaction Mechanisms Distinguishing between Single Minima and Rapidly Equilibrating Structures. Uday Maitra J Chandrasekhar. Series Article Volume 2 Issue 10 October 1997 pp 29-37 ...

  19. Use of Isotopes for Studying Reaction Mechanisms

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 16; Issue 12. Use of Isotopes for Studying Reaction Mechanisms - Distinguishing between Single Mimima and Rapidly Equilibrating Structures. Uday Maitra J Chandrasekhar. Volume 16 Issue 12 December 2011 pp 1315-1323 ...

  20. The magnetic structure on the ground state of the equilateral triangular spin tube

    Energy Technology Data Exchange (ETDEWEB)

    Matsui, Kazuki, E-mail: k703861@eagle.sophia.ac.jp; Goto, Takayuki [Sophia University, Physics Division (Japan); Manaka, Hirotaka [Kagoshima University, Graduate School of Science and Engineering (Japan); Miura, Yoko [Suzuka National College of Technology (Japan)

    2016-12-15

    The ground state of the frustrated equilateral triangular spin tube CsCrF{sub 4} is still hidden behind a veil though NMR spectrum broaden into 2 T at low temperature. In order to investigate the spin structure in an ordered state by {sup 19}F-NMR, we have determined the anisotropic hyperfine coupling tensors for each three fluorine sites in the paramagnetic state. The measurement field was raised up to 10 T to achieve highest resolution. The preliminary analysis using the obtained hyperfine tensors has shown that the archetypal 120°-type structure in ab-plane does not accord with the NMR spectra of ordered state.

  1. NMR investigation of domain wall dynamics and hyperfine field anisotropy in magnets by the magnetic video-pulse excitation method

    Science.gov (United States)

    Gavasheli, Ts A.; Mamniashvili, GI; Gegechkori, T. O.

    2017-04-01

    Two-pulse nuclear spin echoes were studied experimentally depending on the time of application and pulse amplitudes of the DC magnetic field-magnetic video-pulses (MVP) as well as on the value of the external magnetic field. The measurements were performed with nanopowders and polycrystals of metallic cobalt, in lithium ferrite and half metal Co2MnSi. Two types of dependences of these signals on time of application of MVP with respect to moments of application of exciting radio-frequency pulses were established, which were determined by the degree of anisotropy of local hyperfine fields. The mechanisms of influence of the pinning and mobility of domain walls on the revealed specific features of the signals under study are also discussed. It is shown that temporal spectra of the MVP effect on two-pulse echoes in multidomain magnets are determined by the parameters of domain walls and can be used for qualitative and quantitative characterization of the domain wall dynamics of magnets.

  2. Precision measurement of the 87Rb tune-out wavelength in the hyperfine ground state F =1 at 790 nm

    Science.gov (United States)

    Schmidt, Felix; Mayer, Daniel; Hohmann, Michael; Lausch, Tobias; Kindermann, Farina; Widera, Artur

    2016-02-01

    We report on a precision measurement of the D line tune-out wavelength of 87 in the hyperfine ground state |F =1 ,mF=0 ,±1 > manifold at 790 nm , where the scalar ac Stark shifts of the D1 and the D2 lines cancel. This wavelength is sensitive to usually neglected contributions from vector and tensor ac Stark shifts, transitions to higher principle quantum numbers, and core electrons. The ac Stark shift is probed by Kapitza-Dirac scattering of a rubidium Bose-Einstein condensate in a one-dimensional optical lattice in free space and controlled magnetic environment. The tune-out wavelength of the magnetically insensitive mF=0 state was determined to 790.01858 (23 )n m with sub-pm accuracy. An in situ absolute polarization, and magnetic background field measurement is performed by employing the ac vector Stark shift for the mF=±1 states. Comparing our findings to theory, we get quantitative insight into atomic physics beyond commonly used two-level atom approximations or the neglect of inner shell contributions.

  3. First-principles study of spin-state crossovers and hyperfine interactions of ferric iron in magnesium silicate perovskite

    Science.gov (United States)

    Hsu, Han; Blaha, Peter; Cococcioni, Matteo; Wentzcovitch, Renata

    2011-03-01

    The spin-state crossover in iron-bearing MgSi O3 perovskite, the most abundant mineral in the Earth, may significantly affect the properties of Earth's lower mantle. However, details of this phenomenon have been very unclear, owing to the complicated nature of this mineral, mainly the coexistence of ferrous and ferric iron. Using the density functional theory plus Hubbard U (DFT+ U) methods, we investigated the spin states and hyperfine interactions of ferric iron in this mineral. We show that a crossover from high-spin to low-spin state occurs within the lower-mantle pressure range, and it is accompanied by a noticeable volume reduction and an increase in iron nuclear quadrupole splitting (QS). These results are consistent with recent x-ray diffraction and Mössbauer spectroscopy measurements [K. Catalli et al., Earth Planet. Sci. Lett. 289, 68 (2010)]. This work is primarily supported by the MRSEC Program of NSF under DMR-0212302 and DMR-0819885, and partially supported by EAR-0810212 and EAR-1047629. P.B. was supported by the Austrian Science Fund (P20271-N17). Calculations were performed at MSI.

  4. Modeling nuclear volume isotope effects in crystals

    Science.gov (United States)

    Schauble, Edwin A.

    2013-01-01

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac–Hartree–Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor–crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from 119Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium

  5. Modeling nuclear volume isotope effects in crystals.

    Science.gov (United States)

    Schauble, Edwin A

    2013-10-29

    Mass-independent isotope fractionations driven by differences in volumes and shapes of nuclei (the field shift effect) are known in several elements and are likely to be found in more. All-electron relativistic electronic structure calculations can predict this effect but at present are computationally intensive and limited to modeling small gas phase molecules and clusters. Density functional theory, using the projector augmented wave method (DFT-PAW), has advantages in greater speed and compatibility with a three-dimensional periodic boundary condition while preserving information about the effects of chemistry on electron densities within nuclei. These electron density variations determine the volume component of the field shift effect. In this study, DFT-PAW calculations are calibrated against all-electron, relativistic Dirac-Hartree-Fock, and coupled-cluster with single, double (triple) excitation methods for estimating nuclear volume isotope effects. DFT-PAW calculations accurately reproduce changes in electron densities within nuclei in typical molecules, when PAW datasets constructed with finite nuclei are used. Nuclear volume contributions to vapor-crystal isotope fractionation are calculated for elemental cadmium and mercury, showing good agreement with experiments. The nuclear-volume component of mercury and cadmium isotope fractionations between atomic vapor and montroydite (HgO), cinnabar (HgS), calomel (Hg2Cl2), monteponite (CdO), and the CdS polymorphs hawleyite and greenockite are calculated, indicating preferential incorporation of neutron-rich isotopes in more oxidized, ionically bonded phases. Finally, field shift energies are related to Mössbauer isomer shifts, and equilibrium mass-independent fractionations for several tin-bearing crystals are calculated from (119)Sn spectra. Isomer shift data should simplify calculations of mass-independent isotope fractionations in other elements with Mössbauer isotopes, such as platinum and uranium.

  6. Geophysical, remote sensing, GIS, and isotopic applications for a better understanding of the structural controls on groundwater flow in the Mojave Desert, California

    Directory of Open Access Journals (Sweden)

    D. Dailey

    2015-03-01

    New hydrological insights for the region: The HF traces were mapped using LiDAR and Geoeye-1 imagery (surface and magnetic profiles (subsurface. Shallow basement parallel to and west of the HF was detected using the Vertical Electrical Soundings (VESs. Conductive water-saturated breccia was detected along the HF using the Very Low Frequency (VLF electromagnetic measurements. Isotopic analyses (δD and δ18O for groundwater samples from productive shallow wells, and springs sampled west of the HF and the basement uplift are less depleted (Group I: Fifteenmile Valley Groundwater sub-basin [FVGS]; average δD: −86.8‰; δ18O: −11.8‰ than samples east of the basement uplift (Group II: Lucerne Valley Groundwater sub-basin [LVGS]; average δD: −95.0‰; δ18O: −12.1‰, whereas samples proximal to, the fault have compositions similar to Group I but show evidence for mixing with Group II compositions (Group III; average δD: −88.8‰; δ18O: −11.5‰. Findings are consistent with the HF channeling groundwater from the San Bernardino Mountains with basement uplifts acting as barriers to lateral groundwater flow and could be applicable to similar settings across the Mojave Desert and elsewhere worldwide.

  7. Recoil Distance Method lifetime measurement of the 2 1 + state in 94Sr and implications for the structure of neutron rich Sr isotopes

    Science.gov (United States)

    Chester, Aaron; Starosta, Krzysztof; S1467 Experiment Collaboration

    2017-09-01

    A high precision lifetime measurement of the 21+ state in 94Sr was performed at TRIUMF's ISAC-II facility by coupling the Recoil Distance Method implemented via the TIGRESS Integrated Plunger with unsafe Coulomb excitation in inverse kinematics. Due to limited statistics imposed by the use of a radioactive 94Sr beam, a likelihood ratio χ2 method was derived and used to compare experimental data to Geant4-simulated lineshapes. The B (E 2 ;21+ ->01+) value extracted from the lifetime measurement of 7 .80-0.40 + 0.50 (stat .) +/- 0.07 (sys .) ps is approximately 25% larger than previously reported while the relative uncertainty has been reduced by a factor of approximately 8. A baseline deformation has been established for Sr isotopes with N <= 58 which is a necessary condition for the Quantum Phase Transition interpretation of the onset of deformation in this region. A summary of the experiment, description of the data analysis methods, and a comparison to existing theoretical models will be presented.

  8. Nuclear structure studies in the xenon and radon region and the discovery of a new radon isotope by Penning-trap mass spectrometry

    CERN Document Server

    Neidherr, Dennis

    2010-01-01

    Nowadays high-precision mass measurements based on Penning traps allow a deep insight into the fundamental properties of nucleonic matter. To this end, the cyclotron frequency of an ion confined in a strong, homogeneous magnetic field B is determined. At the ISOLTRAP mass spectrometer at ISOLDE / CERN the masses of short-lived radioactive nuclei with half-lives down to several ten ms can be measured with an uncertainty in the order of 10$^{-8}$and below. ISOLTRAP consists of an RFQ cooler and buncher to cool and accumulate the ions coming from ISOLDE and a double Penning-trap system to first clean the ion samples and finally perform the mass measurements. Within this thesis the masses of neutron rich xenon and radon isotopes, namely $^{138-146}$Xe and $^{223-229}$Rn were determined, eleven of them for the first time. $^{229}$Rn was even discovered in this experiment and its half-life could be determined to roughly 12$^{+1.2}_{-1.3}$ s. Since the mass reflects all interactions inside the nucleus it is a unique...

  9. Isotope analysis in the transmission electron microscope

    Science.gov (United States)

    Susi, Toma; Hofer, Christoph; Argentero, Giacomo; Leuthner, Gregor T.; Pennycook, Timothy J.; Mangler, Clemens; Meyer, Jannik C.; Kotakoski, Jani

    2016-10-01

    The Ångström-sized probe of the scanning transmission electron microscope can visualize and collect spectra from single atoms. This can unambiguously resolve the chemical structure of materials, but not their isotopic composition. Here we differentiate between two isotopes of the same element by quantifying how likely the energetic imaging electrons are to eject atoms. First, we measure the displacement probability in graphene grown from either 12C or 13C and describe the process using a quantum mechanical model of lattice vibrations coupled with density functional theory simulations. We then test our spatial resolution in a mixed sample by ejecting individual atoms from nanoscale areas spanning an interface region that is far from atomically sharp, mapping the isotope concentration with a precision better than 20%. Although we use a scanning instrument, our method may be applicable to any atomic resolution transmission electron microscope and to other low-dimensional materials.

  10. Isotopic quantum correction to liquid methanol at -30 C

    CERN Document Server

    Benmore, C J; Egelstaff, P A; Neuefeind, J

    2002-01-01

    Hydrogen/deuterium (H/D) substitution of molecular liquids in neutron diffraction is a powerful tool for structure determination. However, recent high-energy X-ray studies have found observable differences in the structures of many H and D liquids at the same temperature. In some cases this isotopic quantum effect can be corrected for by measuring the D sample at a slightly different temperature to the H sample. The example of hydroxyl isotopic substitution in liquid methanol at -30 C is presented. The magnitude of the quantum effect is shown to be significant when compared to the size of the first-order isotopic neutron-difference function. (orig.)

  11. Isotope and Nuclear Chemistry Division annual report, FY 1983

    Energy Technology Data Exchange (ETDEWEB)

    Heiken, J.H.; Lindberg, H.A. (eds.)

    1984-05-01

    This report describes progress in the major research and development programs carried out in FY 1983 by the Isotope and Nuclear Chemistry Division. It covers radiochemical diagnostics of weapons tests; weapons radiochemical diagnostics research and development; other unclassified weapons research; stable and radioactive isotope production, separation, and applications (including biomedical applications); element and isotope transport and fixation; actinide and transition metal chemistry; structural chemistry, spectroscopy, and applications; nuclear structure and reactions; irradiation facilities; advanced analytical techniques; development and applications; atmospheric chemistry and transport; and earth and planetary processes.

  12. Transportation of medical isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Nielsen, D.L.

    1997-11-19

    A Draft Technical Information Document (HNF-1855) is being prepared to evaluate proposed interim tritium and medical isotope production at the Fast Flux Test Facility (FFTF). This assessment examines the potential health and safety impacts of transportation operations associated with the production of medical isotopes. Incident-free and accidental impacts are assessed using bounding source terms for the shipment of nonradiological target materials to the Hanford Site, the shipment of irradiated targets from the FFTF to the 325 Building, and the shipment of medical isotope products from the 325 Building to medical distributors. The health and safety consequences to workers and the public from the incident-free transportation of targets and isotope products would be within acceptable levels. For transportation accidents, risks to works and the public also would be within acceptable levels. This assessment is based on best information available at this time. As the medical isotope program matures, this analysis will be revised, if necessary, to support development of a final revision to the Technical Information Document.

  13. Nuclear structure studies in the xenon and radon region and the discovery of a new radon isotope by Penning trap mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Neidherr, Dennis

    2010-04-28

    Nowadays high-precision mass measurements based on Penning traps allow a deep insight into the fundamental properties of nucleonic matter. To this end, the cyclotron frequency {nu}{sub c}=qB=(2{pi}m) of an ion confined in a strong, homogeneous magnetic field B is determined. At the ISOLTRAP mass spectrometer at ISOLDE / CERN the masses of short-lived radioactive nuclei with half-lives down to several ten ms can be measured with an uncertainty in the order of 10{sup -8} and below. ISOLTRAP consists of an RFQ cooler and buncher to cool and accumulate the ions coming from ISOLDE and a double Penning trap system to first clean the ion samples and finally perform the mass measurements. Within this thesis the masses of neutron rich xenon and radon isotopes, namely {sup 138-146}Xe and {sup 223-229}Rn were determined, eleven of them for the first time. {sup 229}Rn was even discovered in this experiment and its half-life could be determined to 12{sub -1.3}{sup +1.2} s. Since the mass reflects all interactions inside the nucleus it is a unique fingerprint of the nuclide of interest. One of these interactions, the proton-neutron interaction, leads for example to the onset of deformation. The aim of this thesis is to investigate a possible connection be- tween collective effects in nuclei, like the onset of deformation, and double-differences of binding energies, so called {delta}V{sub pn} values. Especially in the here presented areas these {delta}V{sub pn} values show a very unusual behavior and can not be explained with simple orbital overlapping arguments. One explanation could be the occurrence of octupolar deformation in these regions, which is usually probed with other experimental techniques. However, a quantitative description of the influence of such type of deformation on {delta}V{sub pn} is still not possible with modern theories. (orig.)

  14. Isotope geochemistry. Biological signatures in clumped isotopes of O₂.

    Science.gov (United States)

    Yeung, Laurence Y; Ash, Jeanine L; Young, Edward D

    2015-04-24

    The abundances of molecules containing more than one rare isotope have been applied broadly to determine formation temperatures of natural materials. These applications of "clumped" isotopes rely on the assumption that isotope-exchange equilibrium is reached, or at least approached, during the formation of those materials. In a closed-system terrarium experiment, we demonstrate that biological oxygen (O2) cycling drives the clumped-isotope composition of O2 away from isotopic equilibrium. Our model of the system suggests that unique biological signatures are present in clumped isotopes of O2—and not formation temperatures. Photosynthetic O2 is depleted in (18)O(18)O and (17)O(18)O relative to a stochastic distribution of isotopes, unlike at equilibrium, where heavy-isotope pairs are enriched. Similar signatures may be widespread in nature, offering new tracers of biological and geochemical cycling. Copyright © 2015, American Association for the Advancement of Science.

  15. Doping Properties of Ferromagnetic Semiconductors Investigated by the Hyperfine Interaction of Implanted Radioisotopes

    CERN Multimedia

    2002-01-01

    One of the most promising prospective applications of semiconductors will be in the field of spinelectronics. Thereby polarized spins must be injected into semiconductor structures. Ferromagnetic semiconductors (FMS) have a potential for such applications because of the coexistence of semiconducting and ferromagnetic properties. A special group of such FMS are the chromium chalcogenides of type AB$_{2}$C$_{4}$ with B = Cr. They crystallise in the structure of normal spinel. In this Proposal the application of the perturbed angular correlation technique (= PAC) for the investigation of nuclear probes in these substances is described. The radioactive probes will be implanted at the ISOLDE separator. We will start these investigations with the substances CdCr$_{2}$Se$_{4}$, CdCr$_{2}$S$_{4}$, HgCr$_{2}$Se$_{4}$, CuCr$_{2}$Se$_{4}$ and CuCr$_{2}$S$_{4}$ which are ferromagnetic with Curie temperatures between 84.5 and 460 K. In addition to the popular $^{111}$In($^{111}$Cd), which we get from other facilities, we ...

  16. Stable isotopes in Lithuanian bioarcheological material

    Science.gov (United States)

    Skipityte, Raminta; Jankauskas, Rimantas; Remeikis, Vidmantas

    2015-04-01

    Investigation of bioarcheological material of ancient human populations allows us to understand the subsistence behavior associated with various adaptations to the environment. Feeding habits are essential to the survival and growth of ancient populations. Stable isotope analysis is accepted tool in paleodiet (Schutkowski et al, 1999) and paleoenvironmental (Zernitskaya et al, 2014) studies. However, stable isotopes can be useful not only in investigating human feeding habits but also in describing social and cultural structure of the past populations (Le Huray and Schutkowski, 2005). Only few stable isotope investigations have been performed before in Lithuanian region suggesting a quite uniform diet between males and females and protein intake from freshwater fish and animal protein. Previously, stable isotope analysis has only been used to study a Stone Age population however, more recently studies have been conducted on Iron Age and Late medieval samples (Jacobs et al, 2009). Anyway, there was a need for more precise examination. Stable isotope analysis were performed on human bone collagen and apatite samples in this study. Data represented various ages (from 5-7th cent. to 18th cent.). Stable carbon and nitrogen isotope analysis on medieval populations indicated that individuals in studied sites in Lithuania were almost exclusively consuming C3 plants, C3 fed terrestrial animals, and some freshwater resources. Current investigation demonstrated social differences between elites and country people and is promising in paleodietary and daily life reconstruction. Acknowledgement I thank prof. dr. G. Grupe, Director of the Anthropological and Palaeoanatomical State Collection in Munich for providing the opportunity to work in her laboratory. The part of this work was funded by DAAD. Antanaitis-Jacobs, Indre, et al. "Diet in early Lithuanian prehistory and the new stable isotope evidence." Archaeologia Baltica 12 (2009): 12-30. Le Huray, Jonathan D., and Holger

  17. Isotope Production and Distribution Program`s Fiscal Year 1997 financial statement audit

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-03-27

    The Department of Energy Isotope Production and Distribution Program mission is to serve the national need for a reliable supply of isotope products and services for medicine, industry and research. The program produces and sells hundreds of stable and radioactive isotopes that are widely utilized by domestic and international customers. Isotopes are produced only where there is no U.S. private sector capability or other production capacity is insufficient to meet U.S. needs. The Department encourages private sector investment in new isotope production ventures and will sell or lease its existing facilities and inventories for commercial purposes. The Isotope Program reports to the Director of the Office of Nuclear Energy, Science and Technology. The Isotope Program operates under a revolving fund established by the Fiscal Year (FY) 1990 Energy and Water Appropriations Act and maintains financial viability by earning revenues from the sale of isotopes and services and through annual appropriations. The FY 1995 Energy and Water Appropriations Act modified predecessor acts to allow prices charged for Isotope Program products and services to be based on production costs, market value, the needs of the research community, and other factors. Although the Isotope Program functions as a business, prices set for small-volume, high-cost isotopes that are needed for research purposes may not achieve full-cost recovery. As a result, isotopes produced by the Isotope Program for research and development are priced to provide a reasonable return to the U.S. Government without discouraging their use. Commercial isotopes are sold on a cost-recovery basis. Because of its pricing structure, when selecting isotopes for production, the Isotope Program must constantly balance current isotope demand, market conditions, and societal benefits with its determination to operate at the lowest possible cost to U.S. taxpayers. Thus, this report provides a financial analysis of this situation.

  18. Isotopes in Condensed Matter

    CERN Document Server

    G Plekhanov, Vladimir

    2013-01-01

    This book provides a concise introduction to the newly created sub-discipline of solid state physics isotopetronics. The role of isotopes in materials and their properties are describe  in this book. The problem of the enigma of the atomic mass in microphysics is briefly discussed.  The range of the applications of isotopes is wide: from biochemical process in living organisms to modern technical applications in quantum information. Isotopetronics promises to improve nanoelectronic and optoelectronic devices. With numerous illustrations this book is useful to researchers, engineers and graduate students.

  19. Stable isotope?based trophic structure of pelagic fish and jellyfish across natural and anthropogenic landscape gradients in a fjord estuary

    OpenAIRE

    Naman, Sean M.; Greene, Correigh M.; Rice, Casimir A.; Chamberlin, Joshua; Conway?Cranos, Letitia; Cordell, Jeffery R.; Hall, Jason E.; Rhodes, Linda D.

    2016-01-01

    Abstract Identifying causes of structural ecosystem shifts often requires understanding trophic structure, an important determinant of energy flow in ecological communities. In coastal pelagic ecosystems worldwide, increasing jellyfish (Cnidaria and Ctenophora) at the expense of small fish has been linked to anthropogenic alteration of basal trophic pathways. However, this hypothesis remains untested in part because baseline description of fish?jellyfish trophic dynamics, and the environmenta...

  20. Discoveries of isotopes by fission

    Indian Academy of Sciences (India)

    About 3000 different isotopes have been discovered until now. A recent compilation sum- marized details of the discovery of all isotopes [1–4] including the year, laboratory and country of discovery as well as the production mechanism used to produce the isotopes. Fission, one of the largest contributing production ...

  1. Structure of the [M + H - H2O]+ ion from tetraglycine: a revisit by means of density functional theory and isotope labeling.

    Science.gov (United States)

    Verkerk, Udo H; Zhao, Junfang; Van Stipdonk, Michael J; Bythell, Benjamin J; Oomens, Jos; Hopkinson, Alan C; Siu, K W Michael

    2011-06-23

    Collision-induced dissociations of protonated (18)O-labeled tetraglycines labeled separately at either the first or the second amide bond established that water loss from the backbone occurs from the N-terminal residue. Density functional theory at B3LYP/6-311++G(d,p) predicted that the low-energy [G(4) + H - H(2)O](+) product ion is an N(1)-protonated 3,5-dihydro-4H-imidazol-4-one. The ion at the lowest energy, III, is 24.8 kcal mol(-1) lower than the protonated oxazole structure, II, proposed by Bythell et al. (J. Phys. Chem A2010, 114, 5076-5082). In addition, structure III has a predicted IR spectrum that provides a better match with the published experimental IRMPD spectrum than that of structure II.

  2. Expression and purification of 15N- and 13C-isotope labeled 40-residue human Alzheimer’s β-amyloid peptide for NMR-based structural analysis

    OpenAIRE

    Long, Fei; Cho, Wonhwa; Ishii, Yoshitaka

    2011-01-01

    Amyloid fibrils of Alzheimer’s β-amyloid peptide (Aβ) are a primary component of amyloid plaques, a hallmark of Alzheimer’s disease (AD). Enormous attention has been given to the structural features and functions of Aβ in amyloid fibrils and other type of aggregates in associated with development of AD. This report describes an efficient protocol to express and purify high-quality 40-residue Aβ(1–40), the most abundant Aβ in brains, for structural studies by NMR spectroscopy. Over-expression ...

  3. Ab-initio study of the hyperfine parameters in P2{sub 1}/c, P42nmc and Fm3m zirconia phases doped with Ta{sub zr} and the vacancy-Ta{sub zr} complex

    Energy Technology Data Exchange (ETDEWEB)

    Casali, R.A. [Facultad de Ciencias Exactas, y Nat. y Agr.-UNNE-Avenue Libertad 5600, Corrientes (Argentina)]. E-mail: rac@exa.unne.edu.ar; Caravaca, M.A. [Facultad de Ingenieria-UNNE, Avenue Las Heras 727, Resistencia (Argentina)

    2007-02-01

    In this work we develop selfconsistent calculations by means of the all-electron method NFP-LMTO. The electronic structure, quadrupolar frequencies and asymmetry parameters of ZrO{sub 2} polymorphs doped with Ta placed at substitutional site to Zr (Ta{sub Zr}), with and without vacancies are studied in the monoclinic, tetragonal and cubic phases. The calculated hyperfine parameters in neutral Ta{sub Zr} in the monoclinic phase are in agreement with hypine parameters measured with PAC and assigned to substitutional site in a wide range of temperatures. However, in the case of Ta{sub Zr} in the tetragonal P42nmc phase, the electric field gradient (EFG) is in large disagreement with the experimental assignment. Therefore we explored the incorporation of a near neighbor oxygen vacancy in several charged states. We found that the TaV{sup 0} and TaV{sup +1} pairs in the tetragonal symmetry with axis length ratio c/a=1.02 gives electric field gradients V{sub zz} and {eta} in agreement with low-temperature values of the experimentally assigned pure tetragonal, called t-form. Further, the pair Ta-V with a ratio c/a=1 gives EFG in close agreement with reported high-temperature values.

  4. Geographical variation and population structure in the White-rumped Sandpiper Calidris fuscicollis as shown by morphology, mitochondrial DNA and carbon isotope ratios

    NARCIS (Netherlands)

    Wennerberg, L.; Klaassen, M.R.J.; Lindström, A.

    2002-01-01

    We studied the population structure of a high arctic breeding wader bird species, the White-rumped Sandpiper Calidris fuscicollis. Breeding adults, chicks and juveniles were sampled at seven localities throughout the species' breeding range in arctic Canada in 1999. The mitochondrial control region

  5. Decay-assisted collinear resonance ionization spectroscopy: Application to neutron-deficient francium

    OpenAIRE

    K. M. Lynch; Billowes, J.; M. L. Bissell; Budinčević, I.; T. E. Cocolios; R. P. De Groote; de Schepper, S.; V. N. Fedosseev; K. T. Flanagan; Franchoo, S.; R. F. Garcia Ruiz; Heylen, H.; B. A. Marsh; Neyens, G.; T. J. Procter

    2014-01-01

    This paper reports on the hyperfine-structure and radioactive-decay studies of the neutron-deficient francium isotopes $^{202-206}$Fr performed with the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at the ISOLDE facility, CERN. The high resolution innate to collinear laser spectroscopy is combined with the high efficiency of ion detection to provide a highly-sensitive technique to probe the hyperfine structure of exotic isotopes. The technique of decay-assisted laser spectros...

  6. The 17O hyperfine interaction in V17O(H217O)52+ and Mn(H217O)62+ determined by high field ENDOR aided by DFT calculations.

    Science.gov (United States)

    Baute, Debbie; Goldfarb, Daniella

    2005-09-08

    The 17O hyperfine interaction of the water ligands and the V=O oxygen in the vanadyl aquo complex and of the water ligands in the Mn2+ aquo complex in a frozen solution were determined by W-band (95 GHz) electron-nuclear double resonance (ENDOR). Orientation selective ENDOR spectra of the vanadyl complex exhibited two distinct signals assigned to the vanadyl oxygen and the water ligands. The assignment of the signals was done based on the orientation of the principal axis system of the hyperfine interaction and through comparison with the hyperfine interaction predicted by DFT calculations. The latter showed good agreement with the experimental values thus providing clear evidence that the vanadyl oxygen is exchangeable. The interaction of the vanadyl oxygen, especially its anisotropic part, was significantly larger than that of the water oxygens due to a relatively large negative spin density on the oxygen p orbitals. The 17O hyperfine interaction of the water ligand in the Mn2+ complex was found to be similar to that of the water ligand in the vanadyl complex and was in good agreement with earlier single-crystal data. Here, due to the large thermal polarization, it was also possible to determine the absolute sign of the hyperfine coupling by selecting different EPR transitions.

  7. The influence of nitrogen inputs on biomass and trophic structure of ocean plankton: a study using biomass and stable isotope size-spectra

    KAUST Repository

    Mompeán, Carmen

    2016-08-18

    Large scale patterns in planktonic food web structure were studied by applying continuous size-scaled models of biomass and δ15N to plankton samples, collected at 145 stations during the Malaspina-2010 Expedition across three ocean basins and including major biomes. Carbon biomass and δ15N were determined in size-fractionated samples (40 to 5000 μm) collected by vertical hauls (0–200 m). Biomass-normalized size-spectra were constructed to summarize food web structure and spatial patterns in spectral parameters were analyzed using geographically-weighted regression analysis. Except in the northwestern Atlantic, size-spectra showed low variability, reflecting a homogeneity in nitrogen sources and food web structure for the central oceans. Estimated predator-to-prey mass ratios <104 and mean trophic transfer efficiency values between 16% (coastal biome) and >20% (Trades and Westerlies biomes) suggested that oceanic plankton food webs may support a larger number of trophic levels than current estimates based on high efficiency values. The largest changes in spectral parameters and nitrogen sources were related to inputs of atmospheric nitrogen, either from diazotrophic organisms or dust deposition. These results suggest geographic homogeneity in the net transfer of nitrogen up the food web.

  8. Solution structure of the two RNA recognition motifs of hnRNP A1 using segmental isotope labeling: how the relative orientation between RRMs influences the nucleic acid binding topology.

    Science.gov (United States)

    Barraud, Pierre; Allain, Frédéric H-T

    2013-01-01

    Human hnRNP A1 is a multi-functional protein involved in many aspects of nucleic-acid processing such as alternative splicing, micro-RNA biogenesis, nucleo-cytoplasmic mRNA transport and telomere biogenesis and maintenance. The N-terminal region of hnRNP A1, also named unwinding protein 1 (UP1), is composed of two closely related RNA recognition motifs (RRM), and is followed by a C-terminal glycine rich region. Although crystal structures of UP1 revealed inter-domain interactions between RRM1 and RRM2 in both the free and bound form of UP1, these interactions have never been established in solution. Moreover, the relative orientation of hnRNP A1 RRMs is different in the free and bound crystal structures of UP1, raising the question of the biological significance of this domain movement. In the present study, we have used NMR spectroscopy in combination with segmental isotope labeling techniques to carefully analyze the inter-RRM contacts present in solution and subsequently determine the structure of UP1 in solution. Our data unambiguously demonstrate that hnRNP A1 RRMs interact in solution, and surprisingly, the relative orientation of the two RRMs observed in solution is different from the one found in the crystal structure of free UP1 and rather resembles the one observed in the nucleic-acid bound form of the protein. This strongly supports the idea that the two RRMs of hnRNP A1 have a single defined relative orientation which is the conformation previously observed in the bound form and now observed in solution using NMR. It is likely that the conformation in the crystal structure of the free form is a less stable form induced by crystal contacts. Importantly, the relative orientation of the RRMs in proteins containing multiple-RRMs strongly influences the RNA binding topologies that are practically accessible to these proteins. Indeed, RRM domains are asymmetric binding platforms contacting single-stranded nucleic acids in a single defined orientation

  9. Power spectra and auto correlation analysis of hyperfine-induced long period oscillations in the tunneling current of coupled quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Harack, B.; Leary, A.; Coish, W. A.; Hilke, M. [Department of Physics, McGill University, Ernest Rutherford Building, 3600 rue University, Montreal, Quebec H3A 2T8 (Canada); Yu, G.; Gupta, J. A. [National Research Council of Canada, M50, Montreal Road, Ottawa, Ontario K1A 0R6 (Canada); Payette, C.; Austing, D. G. [Department of Physics, McGill University, Ernest Rutherford Building, 3600 rue University, Montreal, Quebec H3A 2T8, Canada and National Research Council of Canada, M50, Montreal Road, Ottawa, Ontario K1A 0R6 (Canada)

    2013-12-04

    We outline power spectra and auto correlation analysis performed on temporal oscillations in the tunneling current of coupled vertical quantum dots. The current is monitored for ∼2325 s blocks as the magnetic field is stepped through a high bias feature displaying hysteresis and switching: hallmarks of the hyperfine interaction. Quasi-periodic oscillations of ∼2 pA amplitude and of ∼100 s period are observed in the current inside the hysteretic feature. Compared to the baseline current outside the hysteretic feature the power spectral density is enhanced by up to three orders of magnitude and the auto correlation displays clear long lived oscillations about zero.

  10. Lithium Isotopic Fractionation in Subduction Zones: Clues From Clays

    Science.gov (United States)

    Williams, L. B.; Hervig, R. L.

    2003-12-01

    Lithium isotope ratios show such large variations in nature (>30 per mil), that many areas of geosciences are exploring the usefulness of this system in explaining the evolution of particular rocks. Here we show how the lithium isotope ratios change during the transformation of smectite clay minerals to illite during burial metamorphism. Such a transition may be a common feature in the shallow regions of subduction zones and may ultimately affect the Li isotope compositions of fluids contributing to arc magmatism. Lithium is a ubiquitous trace element in natural formation waters that, like B, shows large isotopic fractionation especially during interactions with clay minerals. Lithium is adsorbed in the interlayer region of expandable clay minerals but is easily exchanged. Lithium is also incorporated into the octahedral sites. The substitutions of Li in two crystallographic sites of clay minerals may complicate interpretations of bulk Li-isotope ratios. We suggest that the magnitude of the isotopic fractionation of Li between fluid and clay is different in the interlayer sites of clay minerals than in the octahedral sites of clay minerals. Examination of Li contents and isotope variations in experimental reactions of smectite to illite (300C, 100MPa) shows changes with structural re-arrangement of the clay layers. The Li-isotope trend declines (from ~+6 to -13 per mil, expressed as ratios of 7/6) throughout R1-ordering of the mixed-layered illite smectite (I/S). However, the equilibrium end products of the reaction have R3-ordering and show a heavier isotope ratio (~0 per mil). This observation is very similar to the trends we observed for B-isotopes, where the interlayer B initially overprinted the tetrahedral-layer B isotope composition, but as the interlayer sites were collapsed during illitization, the equilibrium isotope composition was approached. The significant Li and B isotopic changes that occur during ordering of I/S coincides with the temperatures

  11. Structure, magnetism, and interface properties of epitactical thin Fe and FePt films on GaAs(001) substrates; Struktur, Magnetismus und Grenzflaecheneigenschaften epitaktischer duenner Fe- und FePt-Filme auf GaAs(001)-Substraten

    Energy Technology Data Exchange (ETDEWEB)

    Schuster, Ellen Ursula

    2007-12-17

    The research in this thesis is focused on the study of the Fe spin structure and interface magnetism of thin epitaxial Fe layers or epitaxial FePt alloy films with chemical L1{sub 0} order on GaAs(001) surfaces. The main method of investigation was isotope-specific conversion electron Moessbauer spectroscopy (CEMS) combined with the {sup 57}Fe probe-layer technique in the temperature range of 4.2-300 K. The film structure was studied using electron diffraction (RHEED) and X-ray diffraction (XRD). The chemical order parameter S determined by XRD was found to increase with rising growth temperature, T{sub S}, to a maximum value of 0.71, until long range order is destroyed at T{sub S}>350 C by alloying with the substrate. As an important result a linear correlation between short-range order (revealed by the relative spectral area of the L1{sub 0} phase) and long-range order S was observed. The observed perpendicular Fe spin texture, characterized by the mean tilting angle left angle {theta} right angle of the Fe spins (relative to the film normal direction), was found to correlate with the L1{sub 0} phase content and with S. Furthermore, epitaxial Fe(001) films on GaAs(001)-(4 x 6) and on GaAs(001)-LED surfaces were grown successfully. In the initial stage of Fe film growth non-monotonous behavior of the in-plane lattice parameter was observed by RHEED. The magnetic hyperfine field distributions P(B{sub hf}) at the Fe/GaAs interface extracted from CEMS spectra for T{sub S}=-140 C or room temperature (RT) were found to be very similar. The observed large mean hyperfine fields of left angle B{sub hf} right angle {approx}25-27 T at the interface indicate the presence of high average Fe moments of 1.7-1.8 {mu}{sub B}. Nonmagnetic interface layers either can be excluded (Fe/GaAs) or are very thin (0.5 ML,Fe/GaAs-LED). Owing to its island structure an ultrathin (1.9 ML thick) uncoated Fe(001) film on GaAs(001)-(4 x 6) shows superparamagnetism with a blocking temperature of

  12. Seabird modulations of isotopic nitrogen on islands.

    Directory of Open Access Journals (Sweden)

    Stéphane Caut

    Full Text Available The transport of nutrients by migratory animals across ecosystem boundaries can significantly enrich recipient food webs, thereby shaping the ecosystems' structure and function. To illustrate the potential role of islands in enabling the transfer of matter across ecosystem boundaries to be gauged, we investigated the influence of seabirds on nitrogen input on islands. Basing our study on four widely differing islands in terms of their biogeography and ecological characteristics, sampled at different spatial and temporal intervals, we analyzed the nitrogen isotopic values of the main terrestrial ecosystem compartments (vascular plants, arthropods, lizards and rodents and their relationship to seabird values. For each island, the isotopic values of the ecosystem were driven by those of seabirds, which ultimately corresponded to changes in their marine prey. First, terrestrial compartments sampled within seabird colonies were the most enriched in δ(15N compared with those collected at various distances outside colonies. Second, isotopic values of the whole terrestrial ecosystems changed over time, reflecting the values of seabirds and their prey, showing a fast turnover throughout the ecosystems. Our results demonstrate that seabird-derived nutrients not only spread across the terrestrial ecosystems and trophic webs, but also modulate their isotopic values locally and temporally on these islands. The wealth of experimental possibilities in insular ecosystems justifies greater use of these model systems to further our understanding of the modalities of trans-boundary nutrient transfers.

  13. The investigation of structure, chemical composition, hydrogen isotope trapping and release processes in deposition layers on surfaces exposed to DIII-D divertor plasma

    Energy Technology Data Exchange (ETDEWEB)

    Buzhinskij, O.I.; Opimach, I.V.; Barsuk, V.A. [TRINITI, Troitsk (Russian Federation); Arkhipov, I.I. [Russian Academy of Science, Moscow (Russian Federation). Inst. of Physical Chemistry; West, W.P.; Wong, C.P.C. [General Atomics, San Diego, CA (United States); Whyte, D. [Univ. of California, San Diego, CA (United States); Wampler, W.R. [Sandia National Labs., Albuquerque, NM (United States)

    1998-05-01

    The exposure of ATG graphite sample to DIII-D divertor plasma was provided by the DiMES (Divertor Material Evaluation System) mechanism. The graphite sample arranged to receive the parallel heat flux on a small region of the surface was exposed to 600ms of outer strike point plasma. The sample was constructed to collect the eroded material directed downward into a trapping zone onto s Si disk collector. The average heat flux onto the graphite sample during the exposure was about 200W/cm{sup 2}, and the parallel heat flux was about 10 KW/cm{sup 2}. After the exposure the graphite sample and Si collector disk were analyzed using SEM, NRA, RBS, Auger spectroscopy. IR and Raman spectroscopy. The thermal desorption was studied also. The deposited coating on graphite sample is amorphous carbon layer. Just upstream of the high heat flux zone the redeposition layer has a globular structure. The deposition layer on Si disk is composed also from carbon but has a diamond-like structure. The areal density of C and D in the deposited layer on Si disk varied in poloidal and toroidal directions. The maximum D/C areal density ratio is about 0.23, maximum carbon density is about 3.8 {times} 10{sup 18}cm{sup {minus}2}, maximum D area density is about 3 {times} 10{sup 17}cm{sup 2}. The thermal desorption spectrum had a peak at 1,250K.

  14. First Principles Calculation on Equilibrium Si Isotope Fractionation Factors and its Implementation on Si Isotope Distributions in Earth Surface Environments

    Science.gov (United States)

    Liu, Y.; He, H. T.; Zhu, C.

    2014-12-01

    Several important equilibrium Si isotope fractionation factors are calculated here. We use a so-called volume-variable-cluster-model (VVCM) method for solids and the "water-droplet" method for aqueous species for isotope fractionation calculation at the same quantum chemistry level. The calculation results show that several silicate minerals, such as quartz, feldspar, kaolinite, etc., all enrich heavy Si isotopes relative to aqueous H4SiO4 and can be up to 3.3‰ at 25°C, different from most field observations. Meanwhile stable organosilicon complexes can enrich even lighter Si isotopes than aqueous H4SiO4. For explaining the difference between the calculation results and field observations, we calculate the kinetic isotope effect (KIE) associated with the formation of amorphous silica, and find that amorphous silica will enrich extremely light Si isotopes. From amorphous silica to crystalline quartz, the structural adjustment & transition needs getting rid of small amount of Si to re-organize the structure. Light Si isotopes will be preferentially lost and let the final crystalline quartz with a little bit more heavy Si isotopes. However, such late-stage Si heavy isotope enrichment cannot erase the total isotopic signal, crystalline quartz still inherit much light Si isotopic composition from amorphous quartz. That is the reason for the discrepancy between the calculation results and the field observations, because the formation of amorphous quartz is under a non-equilibrium process but theoretical calculations are for equilibrium isotope fractionations. With accurate equilibrium fractionation factors provided here, Si isotope distributions in earth surface environments including soil, groundwater and plants can be further interpreted. We find that δ30Si variations in soil are mainly driven by secondary minerals precipitation and adsorption. Also, bulk soil δ30Si maybe have a parabolic distribution with soil age, with a minimum value at where allophane is

  15. New Isotope 263Hs

    Energy Technology Data Exchange (ETDEWEB)

    Dragojevic, I.; Gregorich, K.E.; Dullmann, Ch.E.; Dvorak, J.; Ellison, P.A.; Gates, J.M.; Nelson, S.L.; Stavsetra, L.; Nitsche, H.

    2010-03-16

    A new isotope of Hs was produced in the reaction 208Pb(56Fe, n)263Hs at the 88-Inch Cyclotron of the Lawrence Berkeley National Laboratory. Six genetically correlated nuclear decay chains have been observed and assigned to the new isotope 263Hs. The measured cross section was 21+13-8.4 pb at 276.4 MeV lab-frame center-of-target beam energy. 263Hs decays with a half-life of 0.74 ms by alpha-decay and the measured alpha-particle energies are 10.57 +- 0.06, 10.72 +- 0.06, and 10.89 +- 0.06 MeV. The experimental cross section is compared to a theoretical prediction based on the Fusion by Diffusion model [W. J. Swiatecki et al., Phys. Rev. C 71, 014602 (2005)].

  16. Study of the hyperfine magnetic field acting on Ce probes substituting for the rare earth and the magnetic ordering in intermetallic compounds RAg (R=rare earth) by first principles calculations; Estudo do campo hiperfino magnetico na sonda de Ce colocada nos compostos intermetalicos do tipo RAg (R=terra rara) e do ordenamento magnetico desses compostos usando calculos de primeiros principios

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Luciano Fabricio Dias

    2006-07-01

    In this work the magnetic hyperfine field acting on Ce atoms substituting the rare-earths in R Ag compounds (R = Gd e Nd) was studied by means of first-principles electronic structure calculations. The employed method was the Augmented Plane Waves plus local orbitals (APW+lo), embodied in the WIEN2k program, within the framework of the Density Functional Theory (DFT) and with the Generalized Gradient Approximation (GGA) for the exchange and correlation potential. The super-cell approach was utilized in order to simulate for the Ce atoms acting as impurities in the R Ag matrix. In order to improve for correlation effects within the 4f shells, a Hubbard term was added to the DFT Hamiltonian, within a procedure called GGA+U. It was found that the magnetic hyperfine field (MHF) generated by the Ce 4f electron is the main component of the total MHF and that the Ce 4f ground state level is probably a combination of the m{sub l} = -2 and m{sub l} = -1 sub-levels. In addition, the ground-state magnetic structure was determined for Ho Ag and Nd Ag by observing the behavior of the total energy as a function of the lattice volume for several possible magnetic ordering in these compounds, namely, ferromagnetic, and the (0,0,{pi}), ({pi},{pi},0) and (({pi},{pi},{pi}) types of anti-ferromagnetic ordering of rare-earth atoms. It was found that the ground-state magnetic structure is anti-ferromagnetic of type ({pi},{pi},0) for both, the Ho Ag and Nd Ag compounds. The energy difference of the ferromagnetic and antiferromagnetic ordering is very small in the case of the Nd Ag compound. (author)

  17. ISOTOPE METHODS IN HOMOGENEOUS CATALYSIS.

    Energy Technology Data Exchange (ETDEWEB)

    BULLOCK,R.M.; BENDER,B.R.

    2000-12-01

    The use of isotope labels has had a fundamentally important role in the determination of mechanisms of homogeneously catalyzed reactions. Mechanistic data is valuable since it can assist in the design and rational improvement of homogeneous catalysts. There are several ways to use isotopes in mechanistic chemistry. Isotopes can be introduced into controlled experiments and followed where they go or don't go; in this way, Libby, Calvin, Taube and others used isotopes to elucidate mechanistic pathways for very different, yet important chemistries. Another important isotope method is the study of kinetic isotope effects (KIEs) and equilibrium isotope effect (EIEs). Here the mere observation of where a label winds up is no longer enough - what matters is how much slower (or faster) a labeled molecule reacts than the unlabeled material. The most careti studies essentially involve the measurement of isotope fractionation between a reference ground state and the transition state. Thus kinetic isotope effects provide unique data unavailable from other methods, since information about the transition state of a reaction is obtained. Because getting an experimental glimpse of transition states is really tantamount to understanding catalysis, kinetic isotope effects are very powerful.

  18. Large odd-even staggering in the very light platinum isotopes from laser spectroscopy

    CERN Document Server

    Le Blanc, F; Cabaret, L A; Crawford, J E; Duong, H T; Genevey, J; Girod, M; Huber, G; Krieg, M; Lee, J K P; Lettry, Jacques; Lunney, M D; Obert, J; Oms, J; Peru, S; Putaux, J C; Roussière, B; Sauvage, J; Sebastian, V; Zemlyanoi, S G

    1998-01-01

    Laser spectroscopy measurements have been carried out on very neutron-deficient platinum isotopes with the COMPLIS experimental set-up on line with the ISOLDE-Booster facility. For the first time, Hg alpha -decay was exploited to extend the very light platinum chain. Using the 5d/sup 9/6s /sup 3/D/sub 3/ to 5d/sup 9/6p /sup 3/P /sub 2/ optical transition, hyperfine spectra of /sup 182,181,180,179,178/Pt and /sup 183/Pt/sup m/ were recorded for the first time. The variation of the mean square charge radius between these nuclei, the magnetic moments of the odd isotopes and the quadrupole moment of /sup 183/Pt/sup m/ were thus measured. A large deformation change between /sup 183/Pt/sup 9/ and /sup 183/Pt/sup m/, an odd-even staggering of the charge radius and a deformation drop from A=179 are clearly observed. All these results are discussed and compared with microscopic theoretical predictions using Hartree-Fock- Bogolyubov calculations using the Gogny force. (20 refs).

  19. Nuclear moments and deformation changes in the lightest Pt isotopes measured by laser spectroscopy

    CERN Document Server

    Roussière, B; Crawford, J; Duong, H T; Genevey, J; Girod, M; Huber, G; Ibrahim, F; Krieg, M; Le Blanc, F; Lee, J K P; Obert, J; Oms, J; Peru, S; Pinard, J; Putaux, J C; Sauvage, J; Sebastian, V; Zemlyanoi, S G; Forkel-Wirth, Doris; Lettry, Jacques

    1999-01-01

    Laser spectroscopy measurements are performed with the lightest neutron-deficient platinum isotopes using the experimental setup COMPLIS installed at the ISOLDE-Booster facility. The hyperfine spectra of /sup 182-178/Pt and /sup 183m/Pt are recorded for the first time from the optical transition 5d/sup 9/6s/sup 3/D/sub 3/ to 5d/sup 9/6p/sup 3/P/sub 2/. The variation in the mean-square charge radius of these nuclei and the magnetic and quadrupole (for I>or=1) moments of the odd isotope nuclei are found. A large deformation change between the /sup 183g/Pt and /sup 183m/Pt nuclei, quite large inverted odd-even staggering of the charge radius around the neutron midshell N=104, and a nuclear deformation drop in the region A=179 are revealed. All the results are discussed in terms of nuclear shape variation and are compared with the results of Hartree-Fock- Bogoliubov calculations involving the Gogny force. Comparison of the deformation measured from /sup 183g, m/Pt to the odd-odd isotone /sup 184g, m/Au shows that...

  20. Investigation of hyperfine interactions in RMO{sub 3} (R = La, Nd; M = Cr, Fe) antiferromagnetic perovskite oxides using PAC spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Carbonari, A. W., E-mail: carbonar@ipen.br; Cavalcante, F. H. M.; Junqueira, A. C.; Leite, D. M. T.; Saxena, R. N.; Mestnik-Filho, J. [Instituto de Pesquisas Energeticas e Nucleares, IPEN-CNEN/SP (Brazil)

    2007-07-15

    The local magnetic interaction at the transition metal sites in RMO{sub 3} (R = La, Nd; M = Cr, Fe) compounds has been investigated by perturbed angular correlation (PAC) technique using {sup 181}Hf{yields}{sup 181}Ta probe nuclei. The present measurements cover a temperature range from 10 K to 1000 K. Above the respective Neel temperature, each compound shows a unique quadrupolar frequency that decreases linearly with temperature. These interactions were assigned to the radioactive probe substituting Cr or Fe sites. Below T{sub N}, a combined electric plus magnetic hyperfine interaction was observed. The magnetic interaction revealed that the super transferred hyperfine fields on {sup 181}Ta at the Cr sites in (La,Nd)CrO{sub 3} extrapolated to 0 K, are much smaller than the corresponding values at Fe sites in (La,Nd)FeO{sub 3}. This difference was attributed to different distribution of d electrons in Cr{sup 3+} (3d{sup 3}) and Fe{sup 3+} (3d{sup 5}) ions in each compound. As the fields for Nd compounds are smaller than those for La compounds, the role of rare-earth ions in the magnetism of these oxides is also discussed.

  1. Hyperfine field at Mn in the intermetallic compound LaMnSi2 measured by PAC using 111Cd nuclear probe

    Science.gov (United States)

    Domienikan, C.; Bosch-Santos, B.; Cabrera Pasca, G. A.; Saxena, R. N.; Carbonari, A. W.

    2015-04-01

    Magnetic hyperfine field at Mn site has been measured in the orthorhombic intermetallic compound LaMnSi2 with PAC spectroscopy using radioactive 111In- 111Cd nuclear probe. Samples of LaMnSi2 were prepared by melting pure metallic components in stoichiometric proportion in an arc furnace under argon atmosphere. The samples were sealed in a quartz tube under helium atmosphere, annealed at 1000 °C for 60 h and quenched in water. Samples were analyzed with X-ray diffraction method. 111In was introduced in the samples by thermal diffusion at 1000 °C for 60 h. PAC measurements were carried out with a six BaF2 detector spectrometer at several temperatures between 50 K and 410 K. Results show well defined quadrupole and magnetic interactions at all temperatures. The magnetic hyperfine field (Bhf) measured at 50 K is 7.1(1) T. The temperature dependence of Bhf follows the normal Brillouin-like behavior expected for a simple ferromagnetic ordering. The ferromagnetic transition temperature (Tc) was determined to be 401(1) K.

  2. Survey of large-scale isotope applications: nuclear technology field

    Energy Technology Data Exchange (ETDEWEB)

    Dewitt, R.

    1977-01-21

    A preliminary literature survey of potential large-scale isotope applications was made according to topical fields; i.e., nuclear, biological, medical, environmental, agricultural, geological, and industrial. Other than the possible expansion of established large-scale isotope applications such as uranium, boron, lithium, and hydrogen, no new immediate isotope usage appears to be developing. Over the long term a change in emphasis for isotope applications was identified which appears to be more responsive to societal concerns for health, the environment, and the conservation of materials and energy. For gram-scale applications, a variety of isotopes may be required for use as nonradioactive ''activable'' tracers. A more detailed survey of the nuclear field identified a potential need for large amounts (tons) of special isotopic materials for advanced reactor components and structures. At this need for special materials and the development of efficient separation methods progresses, the utilization of isotopes from nuclear wastes for beneficial uses should also progress.

  3. Optimizing isotope substitution in graphene for thermal conductivity minimization by genetic algorithm driven molecular simulations

    Science.gov (United States)

    Davies, Michael; Ganapathysubramanian, Baskar; Balasubramanian, Ganesh

    2017-03-01

    We present results from a computational framework integrating genetic algorithm and molecular dynamics simulations to systematically design isotope engineered graphene structures for reduced thermal conductivity. In addition to the effect of mass disorder, our results reveal the importance of atomic distribution on thermal conductivity for the same isotopic concentration. Distinct groups of isotope-substituted graphene sheets are identified based on the atomic composition and distribution. Our results show that in structures with equiatomic compositions, the enhanced scattering by lattice vibrations results in lower thermal conductivities due to the absence of isotopic clusters.

  4. Investigating the nuclear structure of the neutron-rich odd-mass Fe isotopes, in the $\\beta$-decay of their parent - Mn

    CERN Document Server

    AUTHOR|(CDS)2079133; Van Duppen, Piet

    For many years the shell structure of the nucleus, originally proposed by Mayer and Haxel, predicting certain energy gaps at specific proton and/or neutron numbers, has been consistent with the experimental findings at or near the line of stability. These nuclei exhibit a sequence of magic numbers – 2, 8, 20, 28, 50, 82, which is different from the one calculated using only a Harmonic Oscillator potential: 2, 8, 20, 40, 70... The strong spin-orbit term, added to the latter potential by Mayer and Haxel, is a necessary requirement for a successful description of these quantum systems, which lowers the energy orbitals with higher spins directly affecting the l = 4 (1$g_{9/2}$) orbit by reducing the gap at N = 40 and creating the N = 50 one. With the development of more exotic radioactive beams, however, it has been observed that for nuclei away from the stability line the traditional shell gaps have weakened, while new energy gaps have emerged instead. It has been further realized that the residual nucleon- nu...

  5. Therapeutic use of radioactive isotopes

    CERN Multimedia

    Caroline Duc

    2013-01-01

    In December, researchers from ISOLDE-CERN, the Paul Scherrer Institute (PSI) and the Institut Laue-Langevin (ILL) published the results of an in vivo study which successfully proved the effectiveness of four terbium isotopes for diagnosing and treating cancerous tumours.   Four terbium isotopes suitable for clinical purposes. “ISOLDE is the only installation capable of supplying terbium isotopes of such purity and intensity in the case of three out of the four types used in this study,” explains Karl Johnson, a physicist at ISOLDE.  “Producing over a thousand different isotopes, our equipment offers the widest choice of isotopes in the world!” Initially intended for fundamental physics research, ISOLDE has diversified its activities over time to invest in various projects in the materials science, biochemistry and nuclear medicine fields. The proof-of-concept study has confirmed that the four terbium isotopes 149Tb, 152Tb, 155Tb produ...

  6. The Valanginian terrestrial carbon-isotope record

    Science.gov (United States)

    Grocke, D. R.; Price, G. D.; Baraboshkin, E.; Mutterlose, J.; Ruffell, A. H.

    2003-04-01

    A stratigraphic, biostratigraphic and isotopic investigation has been performed on a Crimean section located on the Kacha River, Verkhorechie Village, SW Crimea. This clastic-dominated succession consists of a series of bioturbated inter-bedded shallow-marine silty sands, claystones and some oolitic sands. A published detailed study of the ammonite fauna has been undertaken and has revealed that the succession can be compared to standard Tethyan schemes. The lower part of the succession is dated on the basis of the ammonite fauna as Early Valanginian (otopeta-campylotoxus ammonite Zones), although this latter zone is highly condensed. A more expanded Late Valanginian is present (verrucosum, callidiscus and tauricum ammonite Zones), and is overlain by sand-dominated sediments of Early Hauterivian age. Throughout this section woody plant matter ranging in preservation from charcoal to coal has been collected and analyzed for stable carbon-isotope ratios. There is no correlation between state of preservation and carbon-isotope ratios. Carbon-isotope ratios range in the Early Valanginian from -24 ppm to -22 ppm, and in the mid-verrucosum Zone values shift abruptly towards more positive values and peak at -18 ppm in the lower callidiscus Zone. Wood carbon-isotope ratios decrease gradually through the remainder of the callidiscus Zone and return to pre-excursion values in the tauricum Zone. The remaining Hauterivian values fluctuate between -24 ppm to -21 ppm. The structure, magnitude and timing of the terrestrial carbon-isotope curve is very similar to the marine carbonate curve (from +1 ppm to +3 ppm) for the Valanginian. This would indicate, based on a delta-delta relationship between organic matter and carbonate, that there was very little change in atmospheric CO_2 concentrations during the Valanginian, and that the isotopic composition of the global carbon reservoir shifted. Future research on an Early Cretaceous (Valanginian-Hauterivian) interval from the Yatria

  7. The molecular mechanism of Mo isotope fractionation during adsorption to birnessite

    Science.gov (United States)

    Wasylenki, L.E.; Weeks, C.L.; Bargar, J.R.; Spiro, T.G.; Hein, J.R.; Anbar, A.D.

    2011-01-01

    Fractionation of Mo isotopes during adsorption to manganese oxides is a primary control on the global ocean Mo isotope budget. Previous attempts to explain what drives the surprisingly large isotope effect ??97/95Modissolved-??97/95Moadsorbed=1.8??? have not successfully resolved the fractionation mechanism. New evidence from extended X-ray absorption fine structure analysis and density functional theory suggests that Mo forms a polymolybdate complex on the surfaces of experimental and natural samples. Mo in this polynuclear structure is in distorted octahedral coordination, while Mo remaining in solution is predominantly in tetrahedral coordination as MoO42- Our results indicate that the difference in coordination environment between dissolved Mo and adsorbed Mo is the cause of isotope fractionation. The molecular mechanism of metal isotope fractionation in this system should enable us to explain and possibly predict metal isotope effects in other systems where transition metals adsorb to mineral surfaces. ?? 2011 Elsevier Ltd.

  8. Cold regions isotope applications

    Energy Technology Data Exchange (ETDEWEB)

    Perrigo, L.D.; Divine, T.E.

    1976-04-01

    Pacific Northwest Laboratories (PNL) started the Cold Regions Isotope Applications Program in FY-1975 to identify special conditions in the Arctic and similar geographic areas (Cold Regions) where radioisotope power, heater, or sterilization systems would be desirable and economically viable. Significant progress was made in the first year of this program and all objectives for this initial 12-month period were achieved. The major conclusions and recommendations resulting for this effort are described below. The areas of interest covered include: radiosterilization of sewage; heating of septic tanks; and radioisotope thermoelectric generators as power sources for meteorological instruments and navigational aids. (TFD)

  9. ISOTOPE FRACTIONATION PROCESS

    Science.gov (United States)

    Clewett, G.H.; Lee, DeW.A.

    1958-05-20

    A new method is described for isotopic enrichment of uranium. It has been found that when an aqueous acidic solution of ionic tetravalent uraniunn is contacted with chelate complexed tetravalent uranium, the U/sup 238/ preferentially concentrates in the complexed phase while U/sup 235/ concentrates in the ionic phase. The effect is enhanced when the chelate compound is water insoluble and is dissolved in a water-immiscible organic solvent. Cupferron is one of a number of sultable complexing agents, and chloroform is a suitable organic solvent.

  10. Decay-Assisted Laser Spectroscopy of Neutron-Deficient Francium

    CERN Document Server

    Lynch, K M; Bissell, M L; Budincevic, I; Cocolios, T E; De Groote, R P; De Schepper, S; Fedosseev, V N; Flanagan, K T; Franchoo, S; Garcia Ruiz, R F; Heylen, H; Marsh, B A; Neyens, G; Procter, T J; Rossel, R E; Rothe, S; Strashnov, I; Stroke, H H; Wendt, K D A

    2014-01-01

    This paper reports on the hyperfine-structure and radioactive-decay studies of the neutron-deficient francium isotopes $^{202-206}$Fr performed with the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at the ISOLDE facility, CERN. The high resolution innate to collinear laser spectroscopy is combined with the high efficiency of ion detection to provide a highly-sensitive technique to probe the hyperfine structure of exotic isotopes. The technique of decay-assisted laser spectroscopy is presented, whereby the isomeric ion beam is deflected to a decay spectroscopy station for alpha-decay tagging of the hyperfine components. Here, we present the first hyperfine-structure measurements of the neutron-deficient francium isotopes $^{202-206}$Fr, in addition to the identification of the low-lying states of $^{202,204}$Fr performed at the CRIS experiment.

  11. Decay-Assisted Laser Spectroscopy of Neutron-Deficient Francium

    Directory of Open Access Journals (Sweden)

    K. M. Lynch

    2014-03-01

    Full Text Available This paper reports on the hyperfine-structure and radioactive-decay studies of the neutron-deficient francium isotopes ^{202–206}Fr performed with the Collinear Resonance Ionization Spectroscopy (CRIS experiment at the ISOLDE facility, CERN. The high resolution innate to collinear laser spectroscopy is combined with the high efficiency of ion detection to provide a highly sensitive technique to probe the hyperfine structure of exotic isotopes. The technique of decay-assisted laser spectroscopy is presented, whereby the isomeric ion beam is deflected to a decay-spectroscopy station for alpha-decay tagging of the hyperfine components. Here, we present the first hyperfine-structure measurements of the neutron-deficient francium isotopes ^{202–206}Fr, in addition to the identification of the low-lying states of ^{202,204}Fr performed at the CRIS experiment.

  12. Decay-Assisted Laser Spectroscopy of Neutron-Deficient Francium

    Science.gov (United States)

    Lynch, K. M.; Billowes, J.; Bissell, M. L.; Budinčević, I.; Cocolios, T. E.; De Groote, R. P.; De Schepper, S.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Heylen, H.; Marsh, B. A.; Neyens, G.; Procter, T. J.; Rossel, R. E.; Rothe, S.; Strashnov, I.; Stroke, H. H.; Wendt, K. D. A.

    2014-01-01

    This paper reports on the hyperfine-structure and radioactive-decay studies of the neutron-deficient francium isotopes Fr202-206 performed with the Collinear Resonance Ionization Spectroscopy (CRIS) experiment at the ISOLDE facility, CERN. The high resolution innate to collinear laser spectroscopy is combined with the high efficiency of ion detection to provide a highly sensitive technique to probe the hyperfine structure of exotic isotopes. The technique of decay-assisted laser spectroscopy is presented, whereby the isomeric ion beam is deflected to a decay-spectroscopy station for alpha-decay tagging of the hyperfine components. Here, we present the first hyperfine-structure measurements of the neutron-deficient francium isotopes Fr202-206, in addition to the identification of the low-lying states of Fr202,204 performed at the CRIS experiment.

  13. Massively parallel implementations of coupled-cluster methods for electron spin resonance spectra. I. Isotropic hyperfine coupling tensors in large radicals

    Science.gov (United States)

    Verma, Prakash; Perera, Ajith; Morales, Jorge A.

    2013-11-01

    Coupled cluster (CC) methods provide highly accurate predictions of molecular properties, but their high computational cost has precluded their routine application to large systems. Fortunately, recent computational developments in the ACES III program by the Bartlett group [the OED/ERD atomic integral package, the super instruction processor, and the super instruction architecture language] permit overcoming that limitation by providing a framework for massively parallel CC implementations. In that scheme, we are further extending those parallel CC efforts to systematically predict the three main electron spin resonance (ESR) tensors (A-, g-, and D-tensors) to be reported in a series of papers. In this paper inaugurating that series, we report our new ACES III parallel capabilities that calculate isotropic hyperfine coupling constants in 38 neutral, cationic, and anionic radicals that include the 11B, 17O, 9Be, 19F, 1H, 13C, 35Cl, 33S,14N, 31P, and 67Zn nuclei. Present parallel calculations are conducted at the Hartree-Fock (HF), second-order many-body perturbation theory [MBPT(2)], CC singles and doubles (CCSD), and CCSD with perturbative triples [CCSD(T)] levels using Roos augmented double- and triple-zeta atomic natural orbitals basis sets. HF results consistently overestimate isotropic hyperfine coupling constants. However, inclusion of electron correlation effects in the simplest way via MBPT(2) provides significant improvements in the predictions, but not without occasional failures. In contrast, CCSD results are consistently in very good agreement with experimental results. Inclusion of perturbative triples to CCSD via CCSD(T) leads to small improvements in the predictions, which might not compensate for the extra computational effort at a non-iterative N7-scaling in CCSD(T). The importance of these accurate computations of isotropic hyperfine coupling constants to elucidate experimental ESR spectra, to interpret spin-density distributions, and to

  14. Method of separating boron isotopes

    Science.gov (United States)

    Jensen, Reed J.; Thorne, James M.; Cluff, Coran L.; Hayes, John K.

    1984-01-01

    A method of boron isotope enrichment involving the isotope preferential photolysis of (2-chloroethenyl)dichloroborane as the feed material. The photolysis can readily be achieved with CO.sub.2 laser radiation and using fluences significantly below those required to dissociate BCl.sub.3.

  15. Compilation of spectroscopic data of Radium (Ra I and Ra II)

    CERN Document Server

    Dammalapati, U; Willmann, L

    2016-01-01

    Energy levels, wavelengths, lifetimes and hyperfine structure constants for the isotopes of the first and second spectra of radium, Ra I and Ra II have been compiled. Wavelengths and wave numbers are tabulated for 226Ra and for other Ra isotopes. Isotope shifts and hyperfine structure constants of even and odd-A isotopes of neutral radium atom and singly ionized radium are included. Experimental lifetimes of the states for both neutral and ionic Ra are also added, where available. The information is beneficial for present and future experiments aimed at different physics motivations using neutral Ra and singly ionized Ra.

  16. Chromium isotope uptake in carbonates

    DEFF Research Database (Denmark)

    Rodler, Alexandra

    retain an isotopically light Cr signature. Cr(VI) enriched in heavy Cr isotopes is then transported via river waters to the oceans and sequestered into marine sediments. Marine chemical sediments such asbanded iron formations and modern marine carbonates have proven useful in recording the Cr isotope...... with calcium carbonate in order to test the reliability of the Cr carbonate compositions. Several experimental approaches have been employed to elucidate the fractionation behavior of Cr isotopes when Cr(VI) is incorporated into calcium carbonate phases. These results indicate that at lower Cr concentrations......Chromium (Cr) is a redox sensitive element potentially capable of tracing fine-scale fluctuations of the oxygenation of Earth’s early surface environments and seawater. The Cr isotope composition of carbonates could perhaps be used as paleo-redox proxy to elucidate changes in the geological past...

  17. Zinc isotope fractionation during adsorption on calcite

    Science.gov (United States)

    Dong, S.; Wasylenki, L. E.

    2013-12-01

    difference in coordination number between dissolved Zn and adsorbed Zn is drives the observed fractionation. Elzinga and Reeder[5] determined using EXAFS (Extended X-ray Absorption Fine Structure) that Zn adsorbed to calcite surfaces is tetrahedrally coordinated, sharing three oxygens with the calcite surface. Meanwhile density functional theory calculations[6] predicted that tetrahedral Zn-O species should be heavier than octahedral Zn-O species. Thus we infer that equilibrium between octahedrally coordinated, dissolved Zn and tetrahedrally coordinated, adsorbed Zn is the mechanism of fractionation in our experiments. Our further studies will determine whether the isotopically heavy pool of adsorbed Zn becomes the Zn incorporated within carbonates; if so, then we are closer to understanding the mechanism by which carbonate rocks in nature are enriched in heavier isotopes of zinc. [1] Bermin et al., 2006, Chem. Geol. 226, 280. [2] Maréchal et al., 2000, Geochem. Geophys. Geosyst. 1, 1999GC-000029. [3] Dong et al., 2013, Talanta 114, 103-109. [4] Pichat et al., 2003, Earth Planet. Sci. Lett. 210, 167-178. [5] Elzinga and Reeder, 2002, Geochim. Cosmochim. Acta 66, 3943-3954. [6] Schauble, 2003, EOS, Trans. AGU, Fall Meet. Suppl. 84(46), B12B-0781.

  18. Modeled and measured stable isotope data in Siberian tree rings

    Science.gov (United States)

    Sidorova, Olga; Siegwolf, Rolf; Kupzova, Anna; Launois, Thomas; Peylin, Philippe; Spahni, Renato; Bryukhanova, Marina; Roden, John; Saurer, Matthias; Shashkin, Aleksander

    2013-04-01

    Stable isotopes in tree-rings are widely used for the reconstruction of environmental conditions, but more information could be extracted when using mechanistic models for their interpretation. Tree-ring width, cell wall structure and stable carbon as well as oxygen isotope analyses in tree wood and cellulose were carried out for four larch trees (Larix cajanderi Mayr) from northeastern Yakutia (69°N, 148°E) during the period from 1945 to 2004 and these data compared with several models. Based on a biochemical model of photosynthesis and modified model of stomatal conductance our work provides intra-annual dynamics of carbon content in photoassimilates and isotope composition in tree-rings depending on climatic factors. The mechanistic Roden-Lin-Ehleringer model was used to quantify both the physical and biochemical fractionation events associated with hydrogen and oxygen isotope ratios in tree-ring cellulose. Simulation results were compared with measured data. Predictions of carbon isotope ratios from Fritts, ORCHIDEE and LPX models were consistent with measured data. The Roden-Lin-Ehleringer oxygen model allowed the prediction of humidity and source water enrichment as well as oxygen isotope effects associated with leaf water enrichment. This work was supported by Marie Curie Fellowships (EU-ISOTREC 235122; 909122) awarded to Sidorova Olga and a grant of Russian Scientific School 5327.2012.4.

  19. Stable isotopes of captive cetaceans (killer whales and bottlenose dolphins).

    Science.gov (United States)

    Caut, Stéphane; Laran, Sophie; Garcia-Hartmann, Emmanuel; Das, Krishna

    2011-02-15

    There is currently a great deal of interest in using stable isotope methods to investigate diet, trophic level and migration in wild cetaceans. In order to correctly interpret the results stemming from these methods, it is crucial to understand how diet isotopic values are reflected in consumer tissues. In this study, we investigated patterns of isotopic discrimination between diet and blood constituents of two species of cetaceans (killer whale, Orcinus orca, and bottlenose dolphin, Tursiops truncatus) fed controlled diets over 308 and 312 days, respectively. Diet discrimination factors (Δ; mean ± s.d.) for plasma were estimated to Δ(13)C=2.3±0.6‰ and Δ(15)N=1.8±0.3‰, respectively, for both species and to Δ(13)C=2.7±0.3‰ and Δ(15)N=0.5±0.1‰ for red blood cells. Delipidation did not have a significant effect on carbon and nitrogen isotopic values of blood constituents, confirming that cetacean blood does not serve as a reservoir of lipids. In contrast, carbon isotopic values were higher in delipidated samples of blubber, liver and muscle from killer whales. The potential for conflict between fisheries and cetaceans has heightened the need for trophic information about these taxa. These results provide the first published stable isotope incorporation data for cetaceans, which are essential if conclusions are to be drawn on issues concerning trophic structures, carbon sources and diet reconstruction.

  20. Mass Dependency of Isotope Fractionation of Gases Under Thermal Gradient and Its Possible Implications for Planetary Atmosphere Escaping Process

    Science.gov (United States)

    Sun, Tao; Niles, Paul; Bao, Huiming; Socki, Richard

    2014-01-01

    Physical processes that unmix elements/isotopes of gas molecules involve phase changes, diffusion (chemical or thermal), effusion and gravitational settling. Some of those play significant roles for the evolution of chemical and isotopic compositions of gases in planetary bodies which lead to better understanding of surface paleoclimatic conditions, e.g. gas bubbles in Antarctic ice, and planetary evolution, e.g. the solar-wind erosion induced gas escaping from exosphere on terrestrial planets.. A mass dependent relationship is always expected for the kinetic isotope fractionations during these simple physical processes, according to the kinetic theory of gases by Chapman, Enskog and others [3-5]. For O-bearing (O16, -O17, -O18) molecules the alpha O-17/ alpha O-18 is expected at 0.5 to 0.515, and for S-bearing (S32,-S33. -S34, -S36) molecules, the alpha S-33/ alpha S-34 is expected at 0.5 to 0.508, where alpha is the isotope fractionation factor associated with unmixing processes. Thus, one isotope pair is generally proxied to yield all the information for the physical history of the gases. However, we recently] reported the violation of mass law for isotope fractionation among isotope pairs of multiple isotope system during gas diffusion or convection under thermal gradient (Thermal Gradient Induced Non-Mass Dependent effect, TGI-NMD). The mechanism(s) that is responsible to such striking observation remains unanswered. In our past studies, we investigated polyatomic molecules, O2 and SF6, and we suggested that nuclear spin effect could be responsible to the observed NMD effect in a way of changing diffusion coefficients of certain molecules, owing to the fact of negligible delta S-36 anomaly for SF6.. On the other hand, our results also showed that for both diffusion and convection under thermal gradient, this NMD effect is increased by lower gas pressure, bigger temperature gradient and lower average temperature, which indicate that the nuclear spin effect may

  1. P31-NMR study of hyperfine interactions and magnetic fluctuations in the neptunium-based filled skutterudite NpFe4P12

    Science.gov (United States)

    Tokunaga, Y.; Kambe, S.; Sakai, H.; Chudo, H.; Matsuda, T. D.; Haga, Y.; Yasuoka, H.; Aoki, D.; Homma, Y.; Shiokawa, Y.; Ōnuki, Y.

    2009-02-01

    P31-NMR measurements have been performed on a single crystal of the neptunium-based filled skutterudite NpFe4P12 . The compound undergoes a ferromagnetic phase transition at TC=23K . From the field-orientation dependence of the P31-NMR line splitting, the angular dependence of the hyperfine interactions between Np5f spin and P31 nuclear moments has been investigated. We have observed anisotropic transferred hyperfine interactions at the P sites, which lead to an estimate of the local spin density in the P3p orbitals. It is shown that a fraction of the Np5f spin moments is transferred mostly into the P3p orbitals extending toward the inside of a P cage. The weak hybridization between Np5f and P3p orbitals suggests a localized character for Np5f electrons in NpFe4P12 . We have also measured the field and temperature dependences of the nuclear spin-lattice relaxation rate (1/T1) in several magnetic fields between 18.5 and 78.0 kOe. The 1/T1 data reveal that the low-energy spin fluctuations of Np5f spin moments are strongly suppressed by applied fields over a relatively wide temperature range up to 4TC . In this compound, a large and negative magnetoresistance has been known to occur in the same temperature range. The present NMR results demonstrate that the negative magnetoresistance comes from a reduction in the magnetic scattering from Np5f spin moments by an applied field.

  2. Hydrogen isotope fractionation in methane plasma

    Science.gov (United States)

    Robert, François; Derenne, Sylvie; Lombardi, Guillaume; Hassouni, Khaled; Michau, Armelle; Reinhardt, Peter; Duhamel, Rémi; Gonzalez, Adriana; Biron, Kasia

    2017-01-01

    The hydrogen isotope ratio (D/H) is commonly used to reconstruct the chemical processes at the origin of water and organic compounds in the early solar system. On the one hand, the large enrichments in deuterium of the insoluble organic matter (IOM) isolated from the carbonaceous meteorites are interpreted as a heritage of the interstellar medium or resulting from ion-molecule reactions taking place in the diffuse part of the protosolar nebula. On the other hand, the molecular structure of this IOM suggests that organic radicals have played a central role in a gas-phase organosynthesis. So as to reproduce this type of chemistry between organic radicals, experiments based on a microwave plasma of CH4 have been performed. They yielded a black organic residue in which ion microprobe analyses revealed hydrogen isotopic anomalies at a submicrometric spatial resolution. They likely reflect differences in the D/H ratios between the various CHx radicals whose polymerization is at the origin of the IOM. These isotopic heterogeneities, usually referred to as hot and cold spots, are commensurable with those observed in meteorite IOM. As a consequence, the appearance of organic radicals in the ionized regions of the disk surrounding the Sun during its formation may have triggered the formation of organic compounds.

  3. Microscopic study of low-lying yrast spectra in 100-108 Mo isotopes

    Indian Academy of Sciences (India)

    ... of inertia () and square of cranking frequency (2) for even–even Mo isotopes have been obtained. The results of the calculation give an indication that it is important to include the hexadecapole–hexadecapole component of the two-body interaction for obtaining various nuclear structure quantities in these Mo isotopes.

  4. Synthesis of isotopically labelled 2-isopropylthioxanthone from 2,2'-dithiosalicylic acid and deuterium cumene.

    Science.gov (United States)

    Fang, Chao; Yang, Weicheng; Yang, Chao; Wang, Haoran; Sun, Kai; Luo, Yong

    2016-06-30

    Two efficient synthetic routes of stable deuterium labelled 2-isopropylthioxanthone were presented with 98.1% and 98.8% isotopic abundance in acceptable yields and excellent chemical purities. Their structures and the isotope-abundance were confirmed according to proton nuclear magnetic resonance and liquid chromatography-mass spectrometry. Copyright © 2016 John Wiley & Sons, Ltd.

  5. Competition from Isotopic Modelling

    Directory of Open Access Journals (Sweden)

    Virginie Fabre

    2011-01-01

    Full Text Available During later MOIS3, in Europe two populations were present, autochthonous Neanderthals and modern humans. Ecological competition between these two populations has often been evoked but never demonstrated. Our aim is to establish whether resource competition occurred. In this paper, in order to examine the possibility of ecological competition between these two populations, 599 isotopic data were subjected to rigorous statistical treatment and analysis through mixing models. The aim of this paper was to compare dietary strategies of Neanderthals and modern humans over time. Our conclusions suggest that Neanderthals and modern humans shared dietary habits in the particular environmental context of MOIS3 characterised in Europe by climatic deterioration. In this environmental context, the resource competition between Neanderthals and modern humans may have accelerated the disappearance of the Neanderthal population.

  6. Microbes: Agents of Isotopic Change

    Science.gov (United States)

    Fogel, M. L.

    2012-12-01

    Microbes drive many of the important oxidation and reduction reactions on Earth; digest almost all forms of organic matter; and can serve as both primary and secondary producers. Because of their versatile biochemistry and physiology, they impart unique isotopic signatures to organic and inorganic materials, which have proven to be key measurements for understanding elemental cycling now and throughout Earth's history. Understanding microbial isotope fractionations in laboratory experiments has been important for interpreting isotopic patterns measured in natural settings. In fact, the pairing of simple experiment with natural observation has been the pathway for interpreting the fingerprint of microbial processes in ancient sediments and rocks. Examples of how key experiments have explained stable isotope fractionations by microbes and advanced the field of microbial ecology will be presented. Learning the isotopic signatures of Earth's microbes is a valuable exercise for predicting what isotopic signatures could be displayed by possible extant or extinct extraterrestrial life. Given the potential for discovery on Mars, Enceladus, and other solar system bodies, new methods and techniques for pinpointing what is unique about microbial isotope signatures is particularly relevant.

  7. Structural controls on fluid circulation at the Caviahue-Copahue Volcanic Complex (CCVC) geothermal area (Chile-Argentina), revealed by soil CO2 and temperature, self-potential, and helium isotopes

    Science.gov (United States)

    Roulleau, Emilie; Bravo, Francisco; Pinti, Daniele L.; Barde-Cabusson, Stéphanie; Pizarro, Marcela; Tardani, Daniele; Muñoz, Carlos; Sanchez, Juan; Sano, Yuji; Takahata, Naoto; de la Cal, Federico; Esteban, Carlos; Morata, Diego

    2017-07-01

    Natural geothermal systems are limited areas characterized by anomalously high heat flow caused by recent tectonic or magmatic activity. The heat source at depth is the result of the emplacement of magma bodies, controlled by the regional volcano-tectonic setting. In contrast, at a local scale a well-developed fault-fracture network favors the development of hydrothermal cells, and promotes the vertical advection of fluids and heat. The Southern Volcanic Zone (SVZ), straddling Chile and Argentina, has an important, yet unexplored and undeveloped geothermal potential. Studies on the lithological and tectonic controls of the hydrothermal circulation are therefore important for a correct assessment of the geothermal potential of the region. Here, new and dense self-potential (SP), soil CO2 and temperature (T) measurements, and helium isotope data measured in fumaroles and thermal springs from the geothermal area located in the north-eastern flank of the Copahue volcanic edifice, within the Caviahue Caldera (the Caviahue-Copahue Volcanic Complex - CCVC) are presented. Our results allowed to the constraint of the structural origin of the active thermal areas and the understanding of the evolution of the geothermal system. NE-striking faults in the area, characterized by a combination of SP, CO2, and T maxima and high 3He/4He ratios (up to 8.16 ± 0.21Ra, whereas atmospheric Ra is 1.382 × 10- 6), promote the formation of vertical permeability preferential pathways for fluid circulation. WNW-striking faults represent low-permeability pathways for hydrothermal fluid ascent, but promote infiltration of meteoric water at shallow depths, which dilute the hydrothermal input. The region is scattered with SP, CO2, and T minima, representing self-sealed zones characterized by impermeable altered rocks at depth, which create local barriers for fluid ascent. The NE-striking faults seem to be associated with the upflowing zones of the geothermal system, where the boiling process

  8. Rotational spectroscopy and molecular structure of the 1-chloro-1-fluoroethylene-acetylene complex.

    Science.gov (United States)

    Leung, Helen O; Marshall, Mark D; Grimes, David D

    2011-01-21

    Guided by ab initio calculations, Fourier transform microwave spectra in the 6-21 GHz region are obtained for seven isotopomers of the complex formed between 1-chloro-1-fluoroethylene and acetylene. These include the four possible combinations of (35)Cl- and (37)Cl-containing CH(2)CClF with the most abundant acetylene isotopic modification, HCCH, and its H(13)C(13)CH analogue, as well as three singly substituted deuterated isotopomers. Analysis of the spectra determines the rotational constants and additionally, the complete chlorine quadrupole hyperfine coupling tensors in both the inertial and principal electric field gradient axis systems, and where appropriate, the diagonal components of the deuterium quadrupole coupling tensors. The inertial information contained in the rotational constants provides the structure for CH(2)CClF-HCCH: a primary, hydrogen bonding interaction existing between the HCCH donor and the F atom acceptor on the 1-chloro-1-fluoroethylene moiety, while a secondary interaction occurs between the acetylenic bond on the HCCH molecule and the H atom cis to the hydrogen-bonded F atom on the substituted ethylene, which causes the hydrogen bond to deviate from linearity. This is similar to the structure obtained for 1,1-difluoroethylene-HCCH [H. O. Leung and M. D. Marshall, J. Chem. Phys. 126, 154301 (2006)], and indeed, to within experimental uncertainty, the intermolecular interactions in CH(2)CClF-HCCH and its 1,1-difluoroethylene counterpart are practically indistinguishable, even though ab initio calculations at the MP2∕6-311G++(2d, 2p) level suggest that the former complex is more strongly bound.

  9. Compelling Research Opportunities using Isotopes

    Energy Technology Data Exchange (ETDEWEB)

    None

    2009-04-23

    Isotopes are vital to the science and technology base of the US economy. Isotopes, both stable and radioactive, are essential tools in the growing science, technology, engineering, and health enterprises of the 21st century. The scientific discoveries and associated advances made as a result of the availability of isotopes today span widely from medicine to biology, physics, chemistry, and a broad range of applications in environmental and material sciences. Isotope issues have become crucial aspects of homeland security. Isotopes are utilized in new resource development, in energy from bio-fuels, petrochemical and nuclear fuels, in drug discovery, health care therapies and diagnostics, in nutrition, in agriculture, and in many other areas. The development and production of isotope products unavailable or difficult to get commercially have been most recently the responsibility of the Department of Energy's Nuclear Energy program. The President's FY09 Budget request proposed the transfer of the Isotope Production program to the Department of Energy's Office of Science in Nuclear Physics and to rename it the National Isotope Production and Application program (NIPA). The transfer has now taken place with the signing of the 2009 appropriations bill. In preparation for this, the Nuclear Science Advisory Committee (NSAC) was requested to establish a standing subcommittee, the NSAC Isotope Subcommittee (NSACI), to advise the DOE Office of Nuclear Physics. The request came in the form of two charges: one, on setting research priorities in the short term for the most compelling opportunities from the vast array of disciplines that develop and use isotopes and two, on making a long term strategic plan for the NIPA program. This is the final report to address charge 1. NSACI membership is comprised of experts from the diverse research communities, industry, production, and homeland security. NSACI discussed research opportunities divided into three areas: (1

  10. Isotopic characteristics of canopies in simulated leaf assemblages

    Science.gov (United States)

    Graham, Heather V.; Patzkowsky, Mark E.; Wing, Scott L.; Parker, Geoffrey G.; Fogel, Marilyn L.; Freeman, Katherine H.

    2014-11-01

    site where leaves were sampled. The model predicts a persistent ∼1‰ difference in δ13Clitter for the two sites which is consistent with higher water availability in the tropical forests. This work provides a new framework for linking contemporary ecological observations to the geochemical record using flux-weighted isotope data and lends insights to the effect of forest architecture on organic and isotopic records of ancient terrestrial ecosystems. How many leaves from a litter assemblage are necessary to distinguish the isotopic gradient characteristics of canopy closure? Are mean δ13Cleaf values for a litter assemblage diagnostic of a forest biome? Can we predict the δ13C values of cumulative litter, soil organic matter, and organic carbon in sedimentary archives using litter flux and isotope patterns in canopies? We determined the δ13C range and mean for different sized assemblages of leaves sampled from data for each forest. We re-sampled very high numbers of leaves in order to estimate the isotopic composition of cumulative carbon delivered to soils as litter, and compared these results to available data from forest soils. Modeled leaf and soil organic carbon isotope patterns in this study offer insights to how forest structure can be derived from carbon isotope measurements of fossil leaves, as well as secondary material - such as teeth, hair, paleosol carbonates, or organic soil carbon (van der Merwe and Medina, 1989; Koch, 1998; Secord et al., 2008; Levin et al., 2011).Distinct climate and seasonal difference in the Panamá and Maryland, USA forests are reflected in their canopy isotope gradients. In the tropical forest of Panamá, leaves are produced throughout the year within a canopy that is both extensively and persistently closed (Leigh, 1975; Lowman and Wittman, 1996). In the temperate forest of Maryland leaves are produced during the spring when canopy conditions are relatively open (Korner and Basler, 2010).

  11. Raman spectroscopic and mass spectrometric investigations of the hydrogen isotopes and isotopically labelled methane

    Energy Technology Data Exchange (ETDEWEB)

    Jewett, J.R., Fluor Daniel Hanford

    1997-02-24

    Suitable analytical methods must be tested and developed for monitoring the individual process steps within the fuel cycle of a fusion reactor and for tritium accountability. The utility of laser-Raman spectroscopy accompanied by mass spectrometry with an Omegatron was investigated using the analysis of all hydrogen isotopes and isotopically labeled methanes as an example. The Omegatron is useful for analyzing all hydrogen isotopes mixed with the stable helium isotopes. The application of this mass spectrometer were demonstrated by analyzing mixtures of deuterated methanes. In addition, it was employed to study the radiochemical Witzbach exchange reaction between tritium and methanes. A laser-Raman spectrometer was designed for analysis of tritium-containing gases and was built from individual components. A tritium-compatible, metal-sealed Raman cuvette having windows with good optical properties and additional means for measuring the stray light was first used successfully in this work. The Raman spectra of the hydrogen isotopes were acquired in the pure rotation mode and in the rotation-vibration mode and were used for on. The deuterated methanes were measured by Raman spectroscopy, the wavenumbers determined were assigned to the corresponding vibrations, and the wavenumbers for the rotational fine-structure were summarized in tables. The fundamental Vibrations of the deuterated methanes produced Witzbach reactions were detected and assigned. The fundamental vibrations of the molecules were obtained with Raman spectroscopy for the first time in this work. The @-Raman spectrometer assembled is well suited for the analysis of tritium- containing gases and is practical in combination with mass spectrometry using an Omegatron, for studying gases used in fusion.

  12. BOOK REVIEW: Computational Atomic Structure

    Science.gov (United States)

    Post, Douglass E.

    1998-02-01

    introduction to atomic structure. It covers single and many electron systems, how to set up a basis set of wavefunctions for a many electron system, LS coupling, single and multi-electron Hamiltonians, the elementary Hartree-Fock approximation and how variational methods are used to determine the ground state energy and wavefunctions. The computational methods used in the codes are outlined and there are exercises at the end of each chapter. For a number of candidate atomic configurations, explicit examples are given that illustrate the physics, the approximations and the computational methods involved, and which provide the reader with the opportunity to check that he is using the suite of codes correctly. Relativistic effects are covered as perturbations with Breit-Pauli Hamiltonians. Isotope and hyperfine level splitting are also covered. A summary chapter covers allowed and forbidden bound-bound transitions. It describes how to set up the matrix elements for transition operators, and the determination of selection rules and computational aspects of the methods for allowed and forbidden lines. The last chapter provides a brief introduction to continuum transitions, including how to compute the necessary wavefunctions to calculate photoionization or photodetachment and autoionization processes. Several appendices provide a summary of angular momentum theory, an introduction to the Dirac and Breit-Pauli theory for relativistic processes, and a description of the input parameters needed to run the programs. In summary, the book is an almost essential guide to anyone planning to use the Multi-Configuration Hartree-Fock suite of codes. With this guide, even someone not thoroughly familiar with the details of the subject or the codes should be able to use them to obtain energy levels, wavefunctions and transition rates for any atomic system of interest. This book serves as a model example for the general computational physics community of how to document an important suite of

  13. Carbon Isotope Chemistry in Molecular Clouds

    Science.gov (United States)

    Robertson, Amy N.; Willacy, Karen

    2012-01-01

    Few details of carbon isotope chemistry are known, especially the chemical processes that occur in astronomical environments like molecular clouds. Observational evidence shows that the C-12/C-13 abundance ratios vary due to the location of the C-13 atom within the molecular structure. The different abundances are a result of the diverse formation pathways that can occur. Modeling can be used to explore the production pathways of carbon molecules in an effort to understand and explain the chemical evolution of molecular clouds.

  14. Study of neutron deficient iridium isotopes by using laser spectroscopy; Etude des noyaux d'iridium deficients en neutrons par spectroscopie laser

    Energy Technology Data Exchange (ETDEWEB)

    Verney, D

    2000-12-19

    Resonance ionization spectroscopy was performed on neutron deficient iridium isotopes {sup 182-189}Ir, {sup 186}Ir{sup m} and stable isotopes {sup 191,193}Ir. Hyperfine spectra were recorded from the optical transition at 351,7 nm between the 5d{sup 7}6s{sup 2} {sup 4}F{sub 9/2} ground state and the 5d{sup 7}6s6p {sup 6}F{sub 11/2} excited state. Radioactive iridium isotopes were obtained from {beta}{sup +}/EC decay of radioactive mercury nuclei deposited on a graphite substrate. The radioactive mercury nuclei were produced at the ISOLDE facility at CERN through spallation reactions, by bombarding a molten lead target with the 1 GeV proton beam delivered by the PS-Booster. Magnetic dipole moments and spectroscopic quadrupole moments were extracted from the hyperfine spectra. The mean square charge radius variations, as deduced from the measured isotopic shift, show a sharp change between {sup 187}Ir and {sup 186}Ir{sup g}, accompanied by a sudden increase in deformation: from {beta}2 {approx} 0,16 to {beta}2 > 0, 2. These results were analysed in the framework of an axial rotor plus one or two quasiparticles. The wave functions of the osmium and platinum cores which are used in order to describe the iridium nuclei were calculated from the HF+BCS method with the Skyrme SIII effective interaction. The cores were constrained to take the deformation parameters extracted from the isotopic shift measurements. One shows then that this sudden deformation change corresponds also to a change in the proton state that describes the odd nuclei ground state or that participates in the coupling with the neutron in odd-odd nuclei. This state is identified with the {pi}3/2{sup +}[402] orbital for the smaller deformations nuclei and with the {pi}1/2{sup -}[541] orbital stemming from the h{sub 9/2} subshell for bigger deformations nuclei. (author)

  15. Isotope Geochronology: Models Versus Reality

    National Research Council Canada - National Science Library

    Jan Burchart

    2015-01-01

    Majority of the papers on isotopic dating of minerals and rocks have been devoted to some new geochronological data important for geology or to developments of apparatus and improvements of laboratory...

  16. Nuclear Data Compilation for Beta Decay Isotope

    Science.gov (United States)

    Olmsted, Susan; Kelley, John; Sheu, Grace

    2015-10-01

    The Triangle Universities Nuclear Laboratory nuclear data group works with the Nuclear Structure and Decay Data network to compile and evaluate data for use in nuclear physics research and applied technologies. Teams of data evaluators search through the literature and examine the experimental values for various nuclear structure parameters. The present activity focused on reviewing all available literature to determine the most accurate half-life values for beta unstable isotopes in the A = 3-20 range. This analysis will eventually be folded into the ENSDF (Evaluated Nuclear Structure Data File). By surveying an accumulated compilation of reference articles, we gathered all of the experimental half-life values for the beta decay nuclides. We then used the Visual Averaging Library, a data evaluation software package, to find half-life values using several different averaging techniques. Ultimately, we found recommended half-life values for most of the mentioned beta decay isotopes, and updated web pages on the TUNL webpage to reflect these evaluations. To summarize, we compiled and evaluated literature reports on experimentally determined half-lives. Our findings have been used to update information given on the TUNL Nuclear Data Evaluation group website. This was an REU project with Triangle Universities Nuclear Laboratory.

  17. Stable Chlorine Isotope Fractionation

    Science.gov (United States)

    Sharp, Z.

    2006-12-01

    Chlorine isotope partitioning between different phases is not well understood. Pore fluids can have δ37Cl values as low as -8‰, with neoform sediments having strongly positive values. Most strikingly, volcanic gases have δ37Cl values that cover a range in excess of 14‰ (Barnes et al., this meeting). The large range is difficult to explain in terms of equilibrium fractionation, which, although calculated to be very large for Cl in different oxidation states, should be less than 2‰ between chloride species (Schauble et al., 2003, GCA). To address the discrepancy between Nature and theory, we have measured Cl isotope fractionation for selected equilibrium and disequilibrium experiments in order to identify mechanisms that might lead to large fractionations. 1) NaCl (s,l) NaCl (v): NaCl was sealed in an evacuated silica tube and heated at one end, causing vaporization and reprecipitation of NaCl (v) at the cool end of the tube. The fractionation is 0.2‰ at 700°C (halite-vapor) and 0.7‰ at 800°C (liquid-vapor), respectively. The larger fractionation at higher temperature may be related to equilibrium fractionation between liquid and gas vs. `stripping' of the solid in the lower T experiments. 2) Sodalite NaCl(l): Nepheline and excess NaCl were sealed in a Pt crucible at 825°C for 48 hrs producing sodalite. The measured newly-formed sodalite-NaCl fractionation is -0.2‰. 3) Volatilization of HCl: Dry inert gas was bubbled through HCl solutions and the vapor was collected in a downstream water trap. There was no fractionation for 12.4M HCl (HCl fuming) vapor at 25°C. For a 1 M boiling HCl solution, the HCl-vapor fractionation was ~9‰. The difference is probably related to the degree of dissociation in the acid, with HCl dissolved in water for the highly acidic solutions, and dissociated H3O+ and Cl- for lower concentrations. The HCl volatilization experiments are in contrast to earlier vapor-liquid experiments in NaCl-H2O system, where fractionation was

  18. RIKEN radioactive isotope beam factory project–Present status and ...

    Indian Academy of Sciences (India)

    Abstract. Programs for studying nuclear reactions and structure of exotic nuclei available at the RIKEN radioactive isotope beam factory project are introduced and discussed by demonstrating recent highlights. Special emphasis is given to the present status and future plans of new devices.

  19. Isotope ratio analysis by Orbitrap mass spectrometry

    Science.gov (United States)

    Eiler, J. M.; Chimiak, L. M.; Dallas, B.; Griep-Raming, J.; Juchelka, D.; Makarov, A.; Schwieters, J. B.

    2016-12-01

    Several technologies are being developed to examine the intramolecular isotopic structures of molecules (i.e., site-specific and multiple substitution), but various limitations in sample size and type or (for IRMS) resolution have so far prevented the creation of a truly general technique. We will discuss the initial findings of a technique based on Fourier transform mass spectrometry, using the Thermo Scientific Q Exactive GC — an instrument that contains an Orbitrap mass analyzer. Fourier transform mass spectrometry is marked by exceptionally high mass resolutions (the Orbitrap reaches M/∆M in the range 250,000-1M in the mass range of greatest interest, 50-200 amu). This allows for resolution of a large range of nearly isobaric interferences for isotopologues of volatile and semi-volatile compounds (i.e., involving isotopes of H, C, N, O and S). It also provides potential to solve very challenging mass resolution problems for isotopic analysis of other, heavier elements. Both internal and external experimental reproducibilities of isotope ratio analyses using the Orbitrap typically conform to shot-noise limits down to levels of 0.2 ‰ (1SE), and routinely in the range 0.5-1.0 ‰, with similar accuracy when standardized to concurrently run reference materials. Such measurements can be made without modifications to the ion optics of the Q Exactive GC, but do require specially designed sample introduction devices to permit sample/standard comparison and long integration times. The sensitivity of the Q Exactive GC permits analysis of sub-nanomolar samples and quantification of multiply-substituted species. The site-specific capability of this instrument arises from the fact that mass spectra of molecular analytes commonly contain diverse fragment ion species, each of which samples a specific sub-set of molecular sites. We will present applications of this technique to the biological and abiological chemistry of amino acids, forensic identification of

  20. Geochemical characteristics and Sr-Nd-Hf isotope compositions of mantle xenoliths and host basalts from Assab, Eritrea: implications for the composition and thermal structure of the lithosphere beneath the Afar Depression

    Science.gov (United States)

    Teklay, Mengist; Scherer, Erik E.; Mezger, Klaus; Danyushevsky, Leonid

    2010-05-01

    The Afar Depression offers a rare opportunity to study the geodynamic evolution of a rift system from continental rifting to sea floor spreading. This study presents geochemical data for crustal and mantle xenoliths and their alkaline host basalts from the region. The basalts have enriched REE patterns, OIB-like trace element characteristics, and a limited range in isotopic composition (87Sr/86Sr = 0.70336-0.70356, ɛ Nd = +6.6 to +7.0, and ɛ Hf = +10.0 to +10.7). In terms of trace elements and Sr-Nd isotopes, they are similar to basalts from the Hanish and Zubair islands in the southern Red Sea and are thus interpreted to be melts from the Afar mantle. The gabbroic crustal xenoliths vary widely in isotope composition (87Sr/86Sr = 0.70437-0.70791, ɛ Nd = -8.1 to +2.5, and ɛ Hf = -10.5 to +4.9), and their trace element characteristics match those of Neoproterozoic rocks from the Arabian-Nubian Shield and modern arc rocks, suggesting that the lower crust beneath the Afar Depression contains Neoproterozoic mafic igneous rocks. Ultramafic mantle xenoliths from Assab contain primary assemblages of fresh ol + opx + cpx + sp ± pl, with no alteration or hydrous minerals. They equilibrated at 870-1,040°C and follow a steep geothermal gradient consistent with the tectonic environment of the Afar Depression. The systematic variations in major and trace elements among the Assab mantle xenoliths together with their isotopic compositions suggest that these rocks are not mantle residues but rather series of layered cumulate sills that crystallized from a relatively enriched picritic melt related to the Afar plume that was emplaced before the eruption of the host basalts.