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Sample records for 57fe hyperfine parameters

  1. The 57Fe hyperfine interactions in the iron-bearing phases in some LL ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Oshtrakh, M. I.; Maksimova, A. A.; Grokhovsky, V. I.; Petrova, E. V.; Semionkin, V. A.

    2016-12-01

    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 57Fe Mössbauer spectroscopy with a high velocity resolution at 295 K. Small variations in the 57Fe hyperfine parameters were revealed for the M1 and M2 sites in olivine, orthopyroxene and clinopyroxene as well as for α-Fe(Ni, Co), α 2-Fe(Ni, Co) and γ-Fe(Ni, Co) phases, and for troilite in different samples of studied LL ordinary chondrites.

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

    NASA Astrophysics Data System (ADS)

    Oshtrakh, M. I.; Alenkina, I. V.; Semionkin, V. A.

    2016-12-01

    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 57Fe hyperfine parameters for the studied samples.

  3. The 57Fe hyperfine interactions in iron storage proteins in liver and spleen tissues from normal human and two patients with mantle cell lymphoma and acute myeloid leukemia: a Mössbauer effect study

    NASA Astrophysics Data System (ADS)

    Oshtrakh, M. I.; Alenkina, I. V.; Vinogradov, A. V.; Konstantinova, T. S.; Semionkin, V. A.

    2015-04-01

    Study of human spleen and liver tissues from healthy persons and two patients with mantle cell lymphoma and acute myeloid leukemia was carried out using Mössbauer spectroscopy with a high velocity resolution. Small variations in the 57Fe hyperfine parameters for normal and patient's tissues were detected and related to small variations in the 57Fe local microenvironment in ferrihydrite cores. The differences in the relative parts of more crystalline and more amorphous core regions were also supposed for iron storage proteins in normal and patients' spleen and liver tissues.

  4. The 57Fe Mössbauer parameters of pyrite and marcasite with different provenances

    USGS Publications Warehouse

    Evans, B.J.; Johnson, R.G.; Senftle, F.E.; Cecil, C.B.; Dulong, F.

    1982-01-01

    The Mössbauer parameters of pyrite and marcasite exhibit appreciable variations, which bear no simple relationship to the geological environment in which they occur but appear to be selectively influenced by impurities, especially arsenic, in the pyrite lattice. Quantitative and qualitative determinations of pyrite/marcasite mechanical mixtures are straightforward at 298 K and 77 K but do require least-squares computer fittings and are limited to accuracies ranging from ±5 to ±15 per cent by uncertainties in the parameter values of the pure phases. The methodology and results of this investigation are directly applicable to coals for which the presence and relative amounts of pyrite and marcasite could be of considerable genetic significance.

  5. 57Fe Mössbauer study of Lu2Fe3Si5 iron silicide superconductor

    DOE PAGES

    Ma, Xiaoming; Ran, Sheng; Pang, Hua; ...

    2015-03-28

    With the advent of Fe–As based superconductivity it has become important to study how superconductivity manifests itself in details of 57Fe Mössbauer spectroscopy of conventional, Fe-bearing superconductors. The iron-based superconductor Lu2Fe3Si5 has been studied by 57Fe Mössbauer spectroscopy over the temperature range from 4.4 K to room temperature with particular attention to the region close to the superconducting transition temperature (Tc=6.1 K). Consistent with the two crystallographic sites for Fe in this structure, the observed spectra appear to have a pattern consisting of two doublets over the whole temperature range. Furthermore, the value of Debye temperature was estimated from temperaturemore » dependence of the isomer shift and the total spectral area and compared with the specific heat capacity data. Neither abnormal behavior of the hyperfine parameters at or near Tc, nor phonon softening were observed.« less

  6. A CEMS search for precipitate formation in 57Fe implanted ZnO

    NASA Astrophysics Data System (ADS)

    Bharuth-Ram, Krishanlal; Masenda, Hilary; Doyle, Terence B.; Geburt, Sebastian; Ronning, Carsten; Gunnlaugsson, Harald Palle

    2012-03-01

    Conversion electron Mössbauer Spectroscopy measurements have been made on ZnO single crystals implanted with 60 keV 57Fe to 4 and 8 at.% peak concentrations, and annealed up to 800°C. The spectra show quite strong changes with annealing, but no evidence of magnetic components, thus precluding the formation of large sized precipitates or secondary phases. Above an annealing temperature of 650°C, the dominant spectral component is a doublet with hyperfine parameters typical of Fe3 + , which is attributed to Fe3 + ions in nano-precipitates ˜5 nm in size.

  7. Transmission integral analysis of Mössbauer spectra displaying hyperfine parameter distributions with arbitrary profile

    SciTech Connect

    Klencsár, Zoltán

    2014-10-27

    Accurate quantitative analysis of Mössbauer spectra displaying thickness effects requires the consideration of the so-called transmission integral when modeling the spectral shape. Whereas this is straightforward when the correct model for the decomposition of the absorber's nuclear resonance absorption cross-section into individual components is a priori known, in the absence of such knowledge and notably in the presence of hyperfine parameter distributions with an unknown profile, the so-called model-independent evaluation methods could be used to fit the spectra. However, the methods available for this purpose were developed for the analysis of spectra for which the thin absorber approximation is valid, and thus they do not take the sample thickness and related effects into account. Consequently, in order to use them for spectra displaying thickness effects, their usage needs to be generalized by combining them with transmission integral fitting. A new algorithm realizing such a generalized version of the Hesse-Rübartsch model-independent evaluation method was developed recently as an integral part of the MossWinn program. In the present work, the working principle of the newly developed algorithm is described in details along with examples illustrating the capabilities of the method for the case of {sup 57}Fe Mössbauer spectroscopy.

  8. Transmission integral analysis of Mössbauer spectra displaying hyperfine parameter distributions with arbitrary profile

    NASA Astrophysics Data System (ADS)

    Klencsár, Zoltán

    2014-10-01

    Accurate quantitative analysis of Mössbauer spectra displaying thickness effects requires the consideration of the so-called transmission integral when modeling the spectral shape. Whereas this is straightforward when the correct model for the decomposition of the absorber's nuclear resonance absorption cross-section into individual components is a priori known, in the absence of such knowledge and notably in the presence of hyperfine parameter distributions with an unknown profile, the so-called model-independent evaluation methods could be used to fit the spectra. However, the methods available for this purpose were developed for the analysis of spectra for which the thin absorber approximation is valid, and thus they do not take the sample thickness and related effects into account. Consequently, in order to use them for spectra displaying thickness effects, their usage needs to be generalized by combining them with transmission integral fitting. A new algorithm realizing such a generalized version of the Hesse-Rübartsch model-independent evaluation method was developed recently as an integral part of the MossWinn program. In the present work, the working principle of the newly developed algorithm is described in details along with examples illustrating the capabilities of the method for the case of 57Fe Mössbauer spectroscopy.

  9. Theoretical study of the hyperfine parameters of OH

    NASA Technical Reports Server (NTRS)

    Chong, Delano P.; Langhoff, Stephen R.; Bauschlicher, Charles W., Jr.

    1991-01-01

    In the present study of the hyperfine parameters of O-17H as a function of the one- and n-particle spaces, all of the parameters except oxygen's spin density, b sub F(O), are sufficiently easily tractable to allow concentration on the computational requirements for accurate determination of b sub F(O). Full configuration-interaction (FCI) calculations in six Gaussian basis sets yield unambiguous results for (1) the effect of uncontracting the O s and p basis sets; (2) that of adding diffuse s and p functions; and (3) that of adding polarization functions to O. The size-extensive modified coupled-pair functional method yields b sub F values which are in fair agreement with FCI results.

  10. 237Np and 57Fe Mössbauer study of NpFeGa5

    NASA Astrophysics Data System (ADS)

    Homma, Y.; Nakada, M.; Nakamura, A.; Nasu, S.; Aoki, D.; Sakai, H.; Ikeda, S.; Yamamoto, E.; Haga, Y.; Ōnuki, Y.; Shiokawa, Y.

    2006-02-01

    57Fe and 237Np Mössbauer Ōmeasurements have been performed for NpFeGa5, which is one of the so-called neptunium 1-1-5 compounds. The 57Fe Mössbauer spectra below T N = 118 K show the magnetically ordered state. The magnitude of the hyperfine magnetic field at the 57Fe nucleus is determined to be 1.98 ± 0.05 T at 10 K. From the 237Np Mössbauer spectrum at 10 K, the hyperfine magnetic field at the 237Np nucleus is 203 T and the hyperfine coupling constant is determined to be 237 T/μB using the Np atomic magnetic moment of 0.86 μB determined by the neutron diffraction study.

  11. 237Np and 57Fe Mdssbauer study of NpFeGa5

    NASA Astrophysics Data System (ADS)

    Homma, Y.; Nakada, M.; Nakamura, A.; Nasu, S.; Aoki, D.; Sakai, H.; Ikeda, S.; Yamamoto, E.; Haga, Y.; Onuki, Y.; Shiokawa, Y.

    57Fe and 237Np Mössbauer Omeasurements have been performed for NpFeGa5, which is one of the so-called neptunium 1-1-5 compounds. The 57Fe Mössbauer spectra below T N=118 K show the magnetically ordered state. The magnitude of the hyperfine magnetic field at the 57Fe nucleus is determined to be 1.98 ± 0.05 T at 10K. From the 237Np Mössbauer spectrum at 10 K, the hyperfine magnetic field at the 237Np nucleus is 203 T and the hyperfine coupling constant is determined to be 237 T/μB using the Np atomic magnetic moment of 0.86 μB determined by the neutron diffraction study.

  12. 57Fe Mössbauer spectroscopy, X-ray single-crystal diffractometry, and electronic structure calculations on natural alexandrite

    NASA Astrophysics Data System (ADS)

    Weber, Sven-Ulf; Grodzicki, Michael; Lottermoser, Werner; Redhammer, Günther J.; Tippelt, Gerold; Ponahlo, Johann; Amthauer, Georg

    2007-09-01

    Natural alexandrite Al2BeO4:Cr from Malyshevo near Terem Tschanka, Sverdlovsk, Ural, Russia, has been characterized by 57Fe Mössbauer spectroscopy, electron microprobe, X-ray single-crystal diffractometry and by electronic structure calculations in order to determine oxidation state and location of iron. The sample contains 0.3 wt% of total iron oxide. The 57Fe Mössbauer spectrum can be resolved into three doublets. Two of them with hyperfine parameters typical for octahedrally coordinated high-spin Fe3+ and Fe2+, respectively, are assigned to iron substituting for Al in the octahedral M2-site. The third doublet is attributed to Fe3+ in hematite. Electronic structure calculations in the local spin density approximation are in reasonable agreement with experimental data provided that expansion and/or distortion of the coordination octahedra are presumed upon iron substitution. The calculated hyperfine parameters of Fe3+ are almost identical for the M1 and M2 positions, but the calculated ligand-field splitting is by far too large for high-spin Fe3+ on M1.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Mössbauer hyperfine parameters of iron species in the course of Geobacter-mediated magnetite mineralization

    NASA Astrophysics Data System (ADS)

    Li, Yi-Liang; Zhu, San-Yuan; Deng, Kun

    2011-10-01

    Amorphous ferric iron species (ferrihydrite or akaganeite of <5 nm in size) is the only known solid ferric iron oxide that can be reductively transformed by dissimilatory iron-reducing bacteria to magnetite completely. The lepidocrocite crystallite can be transformed into magnetite in the presence of abiotic Fe(II) at elevated pH or biogenic Fe(II) with particular growth conditions. The reduction of lepidocrocite by dissimilatory iron-reducing bacteria has been widely investigated showing varying results. Vali et al. (Proc Natl Acad Sci USA 101:16121-16126, 2004) captured a unique biologically mediated mineralization pathway where the amorphous hydrous ferric oxide transformed to lepidocrocite was followed by the complete reduction of lepidocrocite to single-domain magnetite. Here, we report the 57Fe Mössbauer hyperfine parameters of the time-course samples reported in Vali et al. (Proc Natl Acad Sci USA 101:16121-16126, 2004). Both the quadrupole splittings and linewidths of Fe(III) ions decrease consistently with the change of aqueous Fe(II) and transformations of mineral phases, showing the Fe(II)-mediated gradual regulation of the distorted coordination polyhedrons of Fe3+ during the biomineralization process. The aqueous Fe(II) catalyzes the transformations of Fe(III) minerals but does not enter the mineral structures until the mineralization of magnetite. The simulated abiotic reaction between Fe(II) and lepidocrocite in pH-buffered, anaerobic media shows the simultaneous formation of green rust and its gradual transformation to magnetite plus a small fraction of goethite. We suggested that the dynamics of Fe(II) supply is a critical factor for the mineral transformation in the dissimilatory iron-reducing cultures.

  15. Systematics of Mössbauer hyperfine parameters in Np intermetallics

    NASA Astrophysics Data System (ADS)

    Kalvius, G. M.; Gal, J.; Asch, L.; Potzel, W.

    1992-05-01

    Data for intermetallic compounds of neptunium obtained with the 60 keV Mössbauer resonance of237Np are reviewed. Measurements of temperature, pressure and field dependencies are available. The main questions addressed are: (a) the degree of delocalization of 5f-electrons, (b) the formal charge state of Np, and (c) the influence of the ligand on the neptunium electronic structure. For this purpose, we present an evaluation of systematic behavior concerning mainly the hyperfine field and isomer shift in the cubic Laves phase materials NpX2, the NaCl-type monochalcogenides and monopnictides, and intermetallics with AuCu3 and ThCr2Si2 structures. Analogies to corresponding rare-earth compounds will be pointed out.

  16. Magnetic properties of Al/57Fe/Cr multilayers

    NASA Astrophysics Data System (ADS)

    Jani, Snehal; Lakshmi, N.; Jain, Vishal; Reddy, V. R.; Gupta, Ajay; Venugopalan, K.

    2013-06-01

    Conversion Electron Mössbauer Spectroscopy (CEMS) and DC magnetization are used to compare magnetic properties of as-deposited multilayer (MLS) and Fe2CrAl thin film made from Al/57Fe/Cr MLS deposited by ion beam sputtering and then annealed in UHV. Interdiffusion of elements on annealing sample-1 at 500°C leads to formation of a single, disordered film of Fe2CrAl as evidenced by hyperfine field values obtained by CEMS in the film which compares well with that in bulk Fe2CrAl. CEMS also shows contributions from Fe, Fe/Cr and Fe/Al interfaces in the MLS. Saturation magnetization of as-deposited sample-1 is much less than pure Fe due to reduced Fe thickness because of interface formation and also reduction in Fe-Fe interaction due to intervening Al and Cr layers.

  17. Hyperfine interactions in magnetoelectric hexaferrite system

    NASA Astrophysics Data System (ADS)

    Kouřil, Karel; Chlan, Vojtěch; Štěpánková, Helena; Novák, Pavel; Knížek, Karel; Hybler, Jiří; Kimura, Tsuyoshi; Hiraoka, Yuji; Buršík, Josef

    2010-05-01

    Nuclear magnetic resonance (NMR) in Y-hexaferrite system (Ba 1-xSr x) 2Zn 2Fe 12O 22 was measured on both monocrystalline and polycrystalline samples at liquid helium temperature. Corresponding ab-initio calculation of the hyperfine parameters was also performed. The signal from 57Fe was detected in the frequency interval 65-76 MHz, while NMR spectrum of 67Zn nuclei occurs between 15 and 30 MHz. Due to the disorder in two tetrahedral sublattices occupied partly by Zn and partly by Fe, the NMR lines are broad and the spectra are poorly resolved. Comparison between the experimentally observed 67Zn spectra and the spectra modelled using the calculated hyperfine parameters was made. It indicates that the spectra of 67Zn can be used to determine the distribution of Zn and Fe between the two tetrahedral sublattices.

  18. Structures, hyperfine parameters, and inversion barriers of cyclopropyl and oxiranyl radicals

    NASA Astrophysics Data System (ADS)

    Barone, Vincenzo; Adamo, Carlo; Brunel, Yvon; Subra, Robert

    1996-08-01

    A comparative post-Hartree-Fock study has been performed on cyclopropyl and oxiranyl radicals in order to ascertain the role of the oxygen atom in modifying the hyperfine structure and height of the barrier governing inversion at the radical center. The structural parameters and harmonic force fields obtained for the parent molecules using second-order many-body perturbation theory with a large basis set are in good agreement with experiment. The same approach points out significant distortions upon breaking of a CH bond and a larger pyramidality for the radical center in oxiranyl with respect to cyclopropyl. Also inversion barriers of both radicals are in remarkable agreement with experimental estimates. Isotropic hyperfine parameters in good agreement with those obtained from electron spin resonance spectra can be computed only when using purposely tailored basis sets in the framework of a coupled cluster approach and taking into account vibrational averaging effects induced by the inversion motion. Interpretation of the results in terms of direct and spin polarization effects points out a number of general trends for germinal and vicinal atoms. Furthermore, it is well evidenced that replacement of a methylenic group by an oxygen atom modifies the hyperfine parameters through geometric rather than direct electronic effects.

  19. Comprehensive Wavelengths, Energy Levels, and Hyperfine Structure Parameters of Singly-Ionized Iron-Group Elements

    NASA Astrophysics Data System (ADS)

    Nave, Gillian

    We propose to measure wavelengths, energy levels, and hyperfine structure parameters of Ni II, Mn II, Sc II and other singly-ionized iron-group elements, covering the wavelength range 80 nm to 5500 nm. We shall use archival data from spectrometers at NIST and Kitt Peak National Observatory for spectra above 140 nm. Additional experimental observations will be taken if needed using Fourier transform spectrometers at NIST. Spectra will be taken using our normal incidence grating spectrograph to provide better sensitivity than the FT spectra and to extend the wavelength range down to 80 nm. We aim to produce a comprehensive description of the spectra of all singly-ionized iron- group elements. The wavelength uncertainty of the strong lines will be better than 1 part in 10^7. For most singly-ionized iron-group elements available laboratory data have uncertainties an order of magnitude larger than astronomical observations over wide spectra ranges. Some of these laboratory measurements date back to the 1960's. Since then, Fourier transform spectroscopy has made significant progress in improving the accuracy and quantity of data in the UV-vis-IR region, but high quality Fourier transform spectra are still needed for Mn II, Ni II and Sc II. Fourier transform spectroscopy has low sensitivity in the VUV region and is limited to wavelengths above 140 nm. Spectra measured with high-resolution grating spectrographs are needed in this region in order to obtain laboratory data of comparable quality to the STIS and COS spectrographs on the Hubble Space Telescope. Currently, such data exist only for Fe II and Cr II. Lines of Sc II, V II, and Mn II show hyperfine structure, but hyperfine structure parameters have been measured for relatively few lines of these elements. Significant errors can occur if hyperfine structure is neglected when abundances are determined from stellar spectra. Measurements of hyperfine structure parameters will be made using Fourier transform spectroscopy

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

    SciTech Connect

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

    2015-06-24

    Two specimens of copper ferrite, CuFe{sub 2}O{sub 4}, 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 (CuFeO{sub 2}) phase that is completely absent in quenched sample. The hyperfine interaction parameters are highly influenced by heat treatment employed.

  1. Interface and temperature dependent magnetic properties of 57Fe/Ti/Co multilayers

    NASA Astrophysics Data System (ADS)

    Jain, Vishal; Lakshmi, N.; Sudheesh, V. D.; Jain, Vivek Kumar; Reddy, V. R.; Venugopalan, K.; Gupta, Ajay

    2014-09-01

    The effect of thermal annealing on the interface of 57Fe/Ti/Co multilayer and associated changes in microstructure, hyperfine field and bulk magnetic properties such as saturation magnetization, coercivity and squareness has been studied by X-ray diffraction, X-ray reflectivity, conversion electron Mössbauer spectroscopy and vibrating sample magnetometry. With increase in annealing temperature, interdiffusion leads to an increase in the roughness, hyperfine fields and coercivity along with a decrease in saturation magnetization. Annealing at 823 K leads to the formation of a FeCo phase along with the precipitation of Ti. The electrical resistivity (ρ) of the as-deposited sample decreases on annealing and hence the thermal coefficient of resistance (TCR) goes from negative to positive on annealing the samples. All samples show Curie temperature in excess of 723 K.

  2. Single-Crystal 57Fe Q-Band ENDOR Study of the 4 Iron-4 Sulfur Cluster in its Reduced [4Fe-4S] 1+ State

    NASA Astrophysics Data System (ADS)

    Moriaud, Fabrice; Gambarelli, Serge; Lamotte, Bernard; Mouesca, Jean-Marie

    2001-12-01

    57Fe Q-band ENDOR has been used to study the [4Fe-4S]1+ state created by γ irradiation of single crystals of the synthetic model compound [N(C2H5)4]2[Fe4S4(SCH2C6H5)4] enriched in 57Fe. This compound is an excellent biomimetic model of the active sites of many 4 iron-4 sulfur proteins, enabling detailed and systematic studies of its oxidized [4Fe-4S]3+ and reduced [4Fe-4S]1+ paramagnetic states. Taking advantage of the fact that Q-band ENDOR, in contrast with X-Band ENDOR, allows for a very good separation of the 57Fe transitions from those of the protons, the complete hyperfine tensors of the four iron atoms for the [4Fe-4S]1+ species has been measured with precision. For each iron atom, the electron orbital and electron spin isotropic contributions have been determined separately. Moreover, it is remarkable that two 57Fe hyperfine tensors attributed to the ferrous pair of iron atoms are very different. In effect, one tensor presents a much larger anisotropic part and a much smaller isotropic part than those of the other. This difference has been interpreted in terms of a differential electron orbital hyperfine interaction among the two ferrous ions.

  3. Relativistic Calculating the Spectral Lines Hyperfine Structure Parameters for Heavy Ions

    SciTech Connect

    Khetselius, O. Yu.

    2008-10-22

    The energies and constants of the hyperfine structure, derivatives of the one-electron characteristics on nuclear radius, nuclear electric quadrupole, magnetic dipole moments for some Li-like multicharged ions are calculated.

  4. Study of 57 Fe Mössbauer effect in RFe2Zn20 ( R = Lu, Yb, Gd)

    DOE PAGES

    Bud’ko, Sergey L.; Kong, Tai; Ma, Xiaoming; ...

    2015-08-04

    In this document we report measurements of 57Fe Mössbauer spectra for RFe2Zn20 (R = Lu, Yb, Gd) from ~ 4.5 K to room temperature. The obtained isomer shift values are very similar for all three compounds, their temperature dependence was analyzed within the Debye model and resulted in an estimate of the Debye temperatures of 450-500 K. The values of quadrupole splitting at room temperature change with the cubic lattice constant a in a linear fashion. For GdFe2Zn20, ferromagnetic order is seen as an appearance of a sextet in the spectra. The 57Fe site hyperfine field for T → 0more » was evaluated to be ~ 2.4 T.« less

  5. Study of 57Fe Mössbauer effect in RFe2Zn20 ( R = Lu, Yb, Gd)

    DOE PAGES

    Bud’ko, Sergey L.; Kong, Tai; Ma, Xiaoming; ...

    2015-08-04

    In this document we report measurements of 57Fe Mössbauer spectra for RFe2Zn20 (R = Lu, Yb, Gd) from ~ 4.5 K to room temperature. The obtained isomer shift values are very similar for all three compounds, their temperature dependence was analyzed within the Debye model and resulted in an estimate of the Debye temperatures of 450-500 K. The values of quadrupole splitting at room temperature change with the cubic lattice constant a in a linear fashion. For GdFe2Zn20, ferromagnetic order is seen as an appearance of a sextet in the spectra. The 57Fe site hyperfine field for T → 0more » was evaluated to be ~ 2.4 T.« less

  6. Investigations of the g factors and hyperfine structure parameters for Er3+ ion in zircon-type compounds.

    PubMed

    Shao-Yi, Wu; Wen-Chen, Zheng

    2002-12-01

    The electron paramagnetic resonance (EPR) g factors g(parallel), g(perpendicular) and hyperfine structure parameters A(parallel), A(perpendicular) of the tetragonal Er3+ centers in zircon-type compounds YXO4 (X = As, P, V), ScVO4 and RSiO4 (R = Zr, Hf, Th) are calculated from the perturbation formulas of EPR parameters for 4f11 ion in tetragonal symmetry. In these formulas, the second-order perturbation contributions are included in addition to the first-order perturbation contributions considered in the previous papers. The crystal-field parameters used in the calculations are obtained by analyzing the optical spectral data from the superposition model. Although the superposition model intrinsic parameters An(R0) used in this paper for Er3+ in various zircon-type compounds are not as scattered as those in the previous paper, the calculated results of both the optical spectra and EPR parameters show better agreement than those in the previous paper with the observed values, suggesting that the above calculation method and parameters are more reasonable. The contributions of the second-order perturbation terms to EPR parameters are also discussed.

  7. 57Fe Mössbauer study of the chainpur meteorite

    NASA Astrophysics Data System (ADS)

    Elewa, Nancy N.; Cobas, R.; Cadogan, J. M.

    2016-12-01

    The Chainpur meteorite is one of 23 ordinary chondrites classified as LL3-type (low-Fe & low-metal). It was observed as a shower of stones falling on May 9, 1907 in Uttar Pradesh, India. We report here the characterization of the Fe-bearing phases in this chondrite using 57Fe Mössbauer spectroscopy carried out at 298 K, 120 K, 50 K and 13 K. The paramagnetic doublets of olivine and pyroxene dominate the room temperature spectrum, accounting for around 70 % of the spectral area. Moreover, a doublet present with a spectral area of 5 % and assigned to a superparamagnetic Fe 3+ phase is a consequence of terrestrial weathering. On the basis of the measured 57Fe electric quadrupole splitting of the olivine component at room temperature we estimate the mean Fe:Mg ratio in this meteoritic olivine to be around 35:65 % although there is clearly a wide range of composition. The effects of magnetic ordering of the major components olivine and pyroxene are observed at 13 K.

  8. 57Fe- and 119Sn-Moessbauer Studies of Tin Doped Chromium Iron Oxides of Composition {alpha}-Cr2-xFexO3

    SciTech Connect

    Helgason, Oern; Berry, Frank J.; Ren Xiaolin; Moyo, Thomas

    2005-04-26

    Tin-doped iron chromium oxides of composition {alpha}-Cr2-xFexO3 prepared by the calcination of precipitates adopt the corundum-related structure. 57Fe Moessbauer spectroscopy shows the materials to be composed of small superparamagnetic particles and no evidence for a Morin transition was observed above 80K. The supertransferred hyperfine magnetic field at the tin site is shown by 119Sn Moessbauer spectroscopy to be less than that experienced in tin-doped {alpha}-Fe2O3.

  9. First-principles study of boron oxygen hole centers in crystals: Electronic structures and nuclear hyperfine and quadrupole parameters

    SciTech Connect

    Li Zucheng; Pan Yuanming

    2011-09-15

    The electronic structures, nuclear hyperfine coupling constants, and nuclear quadrupole parameters of fundamental boron oxygen hole centers (BOHCs) in zircon (ZrSiO{sub 4}, I4{sub 1}/amd) and calcite (CaCO{sub 3}, R3c) have been investigated using ab initio Hartree-Fock (HF) and various density functional theory (DFT) methods based on the supercell models with all-electron localized basis sets. Both exact HF exchange and appropriate correlation functionals are important in describing the BOHCs, and the parameter-free hybrid method based on Perdew, Burke, and Ernzerhof density functionals (PBE0) turns out to be the best DFT method in reproducing the electron paramagnetic resonance (EPR) data. Our results reveal three distinct types of simple-spin (S = 1/2) [BO{sub 3}]{sup 2-} centers in calcite: (i) the classic [BO{sub 3}]{sup 2-} radical with the D{sub 3h} symmetry and the unpaired spin equally distributed on the three oxygen atoms (i.e. the O{sub 3}{sup 5-} type); (ii) the previously reported [BO{sub 2}]{sup 0} center with the unpaired spin equally distributed on two of the three oxygen atoms (O{sub 2}{sup 3-}); and (iii) a new variety with {approx}90% of its unpaired spin localized on one (O{sup -}) of the three oxygen atoms with a long B-O bond (1.44 A). Calculations confirm the unusual [BO{sub 4}]{sup 0} center in zircon and show it to arise from a highly distorted configuration with 90% of the unpaired spin on one oxygen atom that has a considerably longer B-O bond (1.68 A) than its three counterparts (1.45 A). The calculated magnitudes and directions of {sup 11}B and {sup 17}O hyperfine coupling constants and nuclear quadrupole constants for the [BO{sub 4}]{sup 0} center in zircon are in excellent agreement with the 15 K EPR experimental data. These BOHCs are all characterized by a small negative spin density on the central B atom arising from spin polarization. Our calculations also demonstrate that the spin densities on BOHCs are affected substantially by

  10. Mössbauer spectroscopic study of 57Fe metabolic transformations in the rhizobacterium Azospirillum brasilense Sp245

    NASA Astrophysics Data System (ADS)

    Kamnev, Alexander A.; Tugarova, Anna V.; Kovács, Krisztina; Biró, Borbála; Homonnay, Zoltán; Kuzmann, Ernő

    2014-04-01

    Preliminary 57Fe transmission Mössbauer spectroscopic data were obtained for the first time for live cells of the plant-growth-promoting rhizobacterium Azospirillum brasilense (wild-type strain Sp245) grown aerobically with 57FeIII-nitrilotriacetate (NTA) complex as a sole source of iron. The results obtained have shown that live cells actively reduce part of the assimilated iron(III) to iron(II), the latter amounting up to 33 % of total cellular iron after 18 h of growth, and 48 % after additional 3 days of storage of the dense wet cell suspension in nutrient-free saline solution in air at room temperature (measured at 80 K). The cellular iron(II) was found to be represented by two quadrupole doublets of different high-spin forms, while the parameters of the cellular iron(III) were close to those typical for bacterioferritins.

  11. Single-crystalline M-type Sr Hexaferrites studied by 57Fe Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Nagasawa, Nobumoto; Ikeda, Shugo; Shimoda, Aiko; Waki, Takeshi; Tabata, Yoshikazu; Nakamura, Hiroyuki; Kobayashi, Hisao

    2016-12-01

    The 57Fe Mössbauer spectra of the single crystalline and the finely ground Sr1- x La x Fe12- y Co y O19 ( x = 0 : y = 0, x = 0.192 : y = 0.152 and x = 0.456 : y = 0.225) samples have been measured to investigate the La-Co substitution effects. All observed spectra at 150 K were well fitted using the five subspectra which correspond to the five crystallographical nonequivalent Fe sites in the M-type hexaferrite, indicating that the valence changes to Fe2+ ions in the Fe3+ ions were not observed in our Sr1- x La x Fe12- y Co y O19 samples. In SrFe12O19, the relative absorption intensities in the five subspectra show the large anisotropies in the recoilless fractions at the five Fe sites whereas these anisotropies were not observed in Sr0.544La0.456Fe11.775Co0.225O19. These results indicate the chemical compositional dependence on the anisotropies of the recoilless fractions at the five Fe sites. The substitution of a Co2+ ion for the Fe3+ ion changes the center shifts of the Fe3+ ions near the Co2+ ion by the perturbation of the Fe-O-Co hybridizations. Therefore, the Co2+ ions occupy the 4 f 1 and the 4 f 2 sites due to the chemical compositional dependences of the refined magnetic hyperfine field and center shifts of the Fe3+ ions.

  12. Quantitative Measurement of Magnetic Hyperfine Parameters and the Physical Organic Chemistry of Supramolecular Systems

    NASA Astrophysics Data System (ADS)

    Bender, Christopher J.

    The physical principles that underlie organic reactions were established by a systematic study of chemical reaction dynamics that employed correlated measurements of reaction rates and a physical parameter that could be related of the electronic properties of the molecules in question (Hammett, 1970). Today, molecular science emphasizes the concept of molecular device, which connotes a supramolecular structure (the term "supramolecule" loosely means a molecule that has multiple functionalities associated with it; for example, an enzyme might be regarded as a supramolecule in the sense that it features a supported metal catalyst and a receptor site that recognizes a specific substrate upon which the catalyst acts) that acts in some specific fashion. A molecular device may be biological (e.g., enzymes, contractile proteins; cf. Tanford & Reynolds, 2001), or it may be produced by synthetic means (e.g., molecular wires, switches, machines, etc.; cf. Sauvage, 2001; Balzani et al., 2003). Current synthetic chemistry provides the technical means that enable one to create and modify molecular devices so that structure may elicit some specific function, and so physical organic chemists are interested in reactions that involve engineered and structurally complex systems such as supported catalysts, protein active sites, or nanostructures (cf. amilton, 1996; Tidwell et al., 1997).

  13. Mechanically-induced disorder in CaFe2As2: A 57Fe Mössbauer study

    DOE PAGES

    Ma, Xiaoming; Ran, Sheng; Canfield, Paul C.; ...

    2015-10-17

    57Fe Mössbauer spectroscopy was used to perform a microscopic study on the extremely pressure and strain sensitive compound, CaFe2As2, with different degrees of strain introduced by grinding and annealing. At the base temperature, in the antiferromagnetic/orthorhombic phase, compared to a sharp sextet Mössbauer spectrum of single crystal CaFe2As2, which is taken as an un-strained sample, an obviously broadened sextet and an extra doublet were observed for ground CaFe2As2 powders with different degrees of strain. The Mössbauer results suggest that the magnetic phase transition of CaFe2As2 can be inhomogeneously suppressed by the grinding induced strain to such an extent that themore » antiferromagnetic order in parts of the grains forming the powdered sample remain absent all the way down to 4.6 K. However, strain has almost no effect on the temperature dependent hyperfine magnetic field in the grains with magnetic order. Additional electronic and asymmetry information was obtained from the isomer shift and quadrupole splitting. Similar isomer shift values in the magnetic phase for samples with different degrees of strain, indicate that the stain does not bring any significant variation of the electronic density at 57Fe nucleus position. As a result, the absolute values of quadrupole shift in the magnetic phase decrease and approach zero with increasing degrees of strain, indicating that the strain reduces the average lattice asymmetry at Fe atom position.« less

  14. Pressure response of iron’s hyperfine parameters and solid state amorphism in (Mg0.87Fe0.13)SiO3 orthopyroxene

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Jackson, J. M.; Sturhahn, W.

    2009-12-01

    Iron-bearing orthopyroxene (opx) is an abundant mineral in the Earth’s crust and upper mantle. Understanding its structural response to relevant mantle conditions will provide important information for seismological and dynamical modeling of this region. Even though X-ray diffraction studies have been carried out at high pressure on iron-bearing opx, the specific site behavior of iron in the complex opx crystal structure at relevant mantle conditions are less understood. Mössbauer spectroscopy allows one to uniquely probe the site-specific behavior of iron in solid materials by direct determination of iron’s hyperfine fields, namely its quadrupole splitting (QS) and isomer shift (IS). Therefore, it is especially suitable for the exploration of iron’s site-specific behaviors in opx. We loaded a synthetic 57Fe-enriched (Mg0.87Fe0.13)SiO3 powdered opx sample into a diamond anvil cell using NaCl as a pressure-transmitting medium. Synchrotron Mössbauer Spectroscopy (SMS) was carried out at Sector 3-ID of the Advanced Photon Source at Argonne National Laboratory. The data were collected up to 36 GPa at room temperature using stainless steel as a reference absorber to accurately constrain the isomer shifts of the M1 and M2 sites in opx. In addition, X-ray powder diffraction spectra were collected in Advanced Light Source at Lawrence Berkeley National Laboratory. The SMS spectra were analyzed with the CONUSS software package. We used a two-site model below 9 GPa and a one-site model at higher pressures to analyze the spectra. In the two-site model, very good agreement was obtained when compared with conventional Mössbauer spectroscopic measurements at ambient pressure. We observed a smooth increase of the QS of the M1 and M2 sites below 9 GPa. Above 9 GPa, the QS remained nearly constant, but the distribution of field gradients overlapped. At low pressures, the IS of the M1 and M2 are distinct but begin to merge at P > 9 GPa. Our observations are suggestive of one

  15. Gebel Kamil Iron Meteorite: 57Fe Mössbauer Spectroscopy and Magnetic Properties Data

    NASA Astrophysics Data System (ADS)

    Dos Santos, E.; Munayco, P.; Gattacceca, J.; Rochette, P.; Scorzelli, R. B.; Folco, L.

    2014-09-01

    In this work, we present magnetic properties data along with mineralogical characterization by 57Fe Mössbauer spectroscopy for a shrapnel of Gebel Kamil meteorite, in order to evaluate the thermal/shock history revealed by these techniques.

  16. Mössbauer study 57Fe in ultrathin trilayer films with sharp and rough interfaces

    NASA Astrophysics Data System (ADS)

    Pogorily, A. N.; Bondarkova, G. V.; Razumov, O. N.; Shypil, E. V.

    2011-04-01

    Trilayer thin films Py/57Fe/Gd and Gd/57Fe/Py (Py: Fe20Ni80 permalloy) have been prepared by electron-beam evaporation and investigated using conversion-electron Mössbauer spectroscopy (CEMS), scanning tunneling microscopy (STM), polar magneto-optical Kerr effect (PMOKE), and ferromagnetic resonance (FMR). It was shown that the films deposited in the same vacuum and temperature runs but with the reverse order of the layers gave a different quality of interfaces: sharp (Py/57Fe/Gd) and rough (Gd/57Fe/Py). Different distribution of atoms in sharp and rough interfaces results in different magnetic properties: the Mössbauer spectra, FMR, and PMOKE data show the appearance of perpendicular magnetic anisotropy (PMA) and enhancement of magnetization in the samples with the rough Gd/Py interface.

  17. In-situ 57Fe Mössbauer characterization of iron oxides in pigments of a rupestrian painting from the Serra da Capivara National Park, in Brazil, with the backscattering Mössbauer spectrometer MIMOS II

    NASA Astrophysics Data System (ADS)

    Soares Meneses Lage, Maria Conceiç ao; Duarte Cavalcante, Luis Carlos; Klingelhöfer, Göstar; Fabris, José Domingos

    2016-12-01

    It is reported the use of the miniaturized portable 57Fe Mössbauer backscattering spectrometer MIMOS II to perform in situ measurements in the archaeological site known as Toca do Boqueirão do Sítio da Pedra Furada (BPF), in Serra da Capivara National Park, in order to specifically examine shades of dark red pigments and compare their differences relatively to the light red part of the same painting. The hyperfine Mössbauer parameters reveal that the dark red area of the rupestrian painting is composed of three populations of hematite and of a small proportion of maghemite, whereas the light red are of the same painting contain hematite mixed with a small proportion of maghemite and a (super)paramagnetic Fe 3+. The Fe content in the dark red area from the rupestrian painting is of approximately twice the amount in the light red of the same prehistoric graphism. The corresponding analysis of red ochre sample collected in the excavation of these archaeological site exhibited two populations of hematite and also a small proportion of maghemite.

  18. Iron nano-clusters in ytterbium films: a 57Fe Mössbauer spectroscopic study

    NASA Astrophysics Data System (ADS)

    Rojas-Ayala, C.; Herrera, W. T.; Dinóla, I. S.; Kraken, M.; Passamani, E. C.; Baggio-Saitovitch, E.; Litterst, F. J.

    2014-01-01

    We have performed a Mössbauer study on iron clusters that are formed in ytterbium films prepared by vapor co-deposition onto kapton substrates kept at room temperature. The film thicknesses were chosen in a range between 2.5 and 2.8 m. XRD of the films reveals a mixture of fcc- and hcp-like ytterbium. Iron concentrations were between 0.3 and 5 at %. All samples reveal hyperfine spectra attributed to only two types of iron clusters with well defined hyperfine parameters. The clusters are supposed to be formed at boundaries of hcp- and fcc-like grains. In addition there is found a small contribution from monomeric iron. Spectra taken at 4.2 K reveal a complex distribution of magnetic hyperfine fields. The dynamic origin of the spectral shape is supported by susceptibility data revealing spin-freezing at temperatures below ca. 10 K. This proves that the iron clusters have sizes on the order of nm.

  19. Sensitivity of 57Fe emission Mössbauer spectroscopy to Ar and C induced defects in ZnO

    NASA Astrophysics Data System (ADS)

    Bharuth-Ram, K.; Mølholt, T. E.; Langouche, G.; Geburt, S.; Ronning, C.; Doyle, T. B.; Gunnlaugsson, H. P.; Johnston, K.; Mantovan, R.; Masenda, H.; Naidoo, D.; Ncube, M.; Gislason, H.; Ólafsson, S.; Weyer, G.

    2016-12-01

    Emission Mössbauer Spectroscopy (eMS) measurements, following low fluence (<1012 cm-2) implantation of 57Mn (t 1/2 = 1.5 min.) into ZnO single crystals pre-implanted with Ar and C ions, has been utilized to test the sensitivity of the 57Fe eMS technique to the different types of defects generated by the different ion species. The dominant feature of the Mössbauer spectrum of the Ar implanted ZnO sample was a magnetic hyperfine field distribution component, attributed to paramagnetic Fe3+, while that of the C implanted sample was a doublet attributed to substitutional Fe2+ forming a complex with the C dopant ions in the 2- state at O vacancies. Magnetization measurements on the two samples, on the other hand, yield practically identical m(H) curves. The distinctly different eMS spectra of the two samples display the sensitivity of the probe nucleus to the defects produced by the different ion species.

  20. Mechanically - induced disorder in CaFe2As2: a 57Fe Mössbauer study

    NASA Astrophysics Data System (ADS)

    Ma, Xiaoming; Ran, Sheng; Canfield, Paul C.; Bud'Ko, Sergey L.

    57 Fe Mössbauer spectroscopy was used to study an extremely pressure and strain sensitive compound, CaFe2As2, with different degrees of strain introduced by grinding and annealing. At the base temperature, in the antiferromagnetic/orthorhombic phase, compared to a sharp sextet Mössbauer spectrum of single crystal CaFe2As2, which is taken as an un-strained sample, an obviously broadened sextet and an extra doublet were observed for ground CaFe2As2 powders with different degrees of strain. The Mössbauer results suggest that the magnetic phase transition of CaFe2As2 can be inhomogeneously suppressed by the grinding induced strain to such an extent that the antiferromagnetic order in parts of the grains forming the powdered sample remain absent all the way down to 4.6 K. However, strain has almost no effect on the temperature dependent hyperfine magnetic field in the grains with magnetic order. The quadrupole shift in the magnetic phase approachs zero with increasing degrees of strain, indicating that the strain reduces the average lattice asymmetry at Fe atom position. Supported by US DOE under the Contract No. DE-AC02-07CH11358 and by the China Scholarship Council.

  1. 57 Fe Mössbauer and magnetic studies of Nd3Fe24.5Cr4.5

    NASA Astrophysics Data System (ADS)

    Wang, J. L.; Md Din, M. F.; Campbell, S. J.; Kennedy, S. J.; Yang, F. M.; Wu, G. H.; Dou, S. X.

    2015-04-01

    The structural and magnetic properties of the rare earth transition metal compound Nd 3Fe 24.5Cr 4.5 have been investigated by variable temperature high resolution x-ray diffraction together with DC magnetization and 57Fe Mössbauer effect measurements. The magnetic ordering temperature has been found to be T C= 423(5) K with spin reorientation detected below room temperature around T sr= 158(5) K. Rietveld refinements indicate that Nd 3Fe 24.5Cr 4.5 crystallizes in the Nd 3(Fe,Ti) 29-type structure with the A2/m space group and a substantial magneto-volume effect is detected around T C. The Mössbauer spectra can be fitted well using five sub-spectra. The temperature dependence of the average hyperfine field has been analysed in terms of different power laws of the reduced temperature. The Debye temperature of Nd 3Fe 24.5Cr 4.5 has been determined as 𝜃 D= 400(± 30) K from a fit to the variable temperature isomer shift IS(T).

  2. Probe Mössbauer spectroscopy of mechanical alloying in binary Cr‐{sup 57}Fe(1 at%) system

    SciTech Connect

    Elsukov, Evgeny P. Kolodkin, Denis A. Ul'yanov, Alexander L. Porsev, Vitaly E.

    2014-10-27

    Solid state reactions during mechanical alloying (MA) in a binary mixture of powdered Cr and {sup 57}Fe in atomic ratio of 99:1 have been studied using {sup 57}Fe Mössbauer spectroscopy, X-ray diffraction and Auger spectrometry. The proposed model of MA includes formation of Cr(Fe){sub x}O{sub y} oxides at the contact places of Cr and Fe particles, formation of nanostructure with simultaneous dissolution of the oxides, penetration of Fe atoms along grain boundaries in close-to-boundary distorted zones of interfaces in a substitutional position, formation of the substitutional solid solution of Fe in Cr in the body of grains. It was shown that the increase in the BCC lattice parameter on increasing the milling time is due to the dissolution of oxides and formation of interstitial solid solution of O in Cr. There were established substantial differences in consumption of BCC Fe in a Mg → Al → Si → Cr sequence due to the major role of chemical interaction of Mg(Al,Si,Cr) with Fe.

  3. Evaluation of nitrogen nuclear hyperfine and quadrupole coupling parameters for the proximal imidazole in myoglobin-azide, -cyanide, and -mercaptoethanol complexes by electron spin echo envelope modulation spectroscopy.

    PubMed

    Magliozzo, R S; Peisach, J

    1993-08-24

    Electron spin echo envelope modulation (ESEEM) spectroscopy and computer simulation of spectra has been used to evaluate the nitrogen nuclear hyperfine and quadrupole coupling parameters for the proximal imidazole nitrogen directly coordinated to iron in three low-spin heme complexes, myoglobin-azide, -cyanide, and -mercaptoethanol (MbN3, MbCN, and MbRS). The variability in the weak electron-nuclear coupling parameters reveals the electronic flexibility within the heme group that depends on properties of the exogenous ligands. For example, the isotropic component of the nitrogen nuclear hyperfine coupling ranges from 4.4 MHz for MbN3 to 2.2 MHz for both MbCN and MbRS. The weaker coupling in MbCN and MbRS is taken as evidence for delocalization of unpaired electron spin from iron into the exogenous anionic ligands. The value of e2Qq, the nuclear quadrupole coupling constant for the axial imidazole nitrogen in MbCN and MbRS, was 2.5 MHz but was significantly larger, 3.2 MHz, in MbN3. This large value is considered evidence for a weakened sigma bond between the proximal imidazole and ferric iron in this form, and for a feature contributing to the origin of the high spin-low spin equilibrium exhibited by MbN3 [Beetlestone, J., & George, P. (1964) Biochemistry 5, 707-714]. The ESEEM results have allowed a correlation to be made between the orientation of the g tensor axes, the orientation of the p-pi orbital of the proximal imidazole nitrogen, and sigma- and pi-bonding features of the axial ligands. Furthermore, the proximal imidazole is suggested to act as a pi-acceptor in low-spin heme complexes in order to support strong sigma electron donation from the lone pair orbital to iron. An evaluation of the nitrogen nuclear hyperfine coupling parameters for the porphyrin pyrrole sites in MbRS reveals a large inequivalence in isotropic components consistent with an orientation of rhombic axes (and g tensor axes) that eclipses the Fe-Npyrrole vector directions.

  4. 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

    SciTech Connect

    Cazzoli, Gabriele; Lattanzi, Valerio; Puzzarini, Cristina; Alonso, José Luis; Gauss, Jürgen

    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.

  5. 57Fe quadrupole splitting and isomer shift in various oxyhemoglobins: study using Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Oshtrakh, M. I.; Berkovsky, A. L.; Kumar, A.; Kundu, S.; Vinogradov, A. V.; Konstantinova, T. S.; Semionkin, V. A.

    2010-04-01

    A comparative study of normal human, rabbit and pig oxyhemoglobins and oxyhemoglobin from patients with chronic myeloleukemia and multiple myeloma using Mössbauer spectroscopy with a high velocity resolution demonstrated small variations of the 57Fe quadrupole splitting and isomer shift. These variations may be a result of small structural differences in the heme iron stereochemistry of various hemoglobins.

  6. Determination of hyperfine fields orientation in nuclear probe techniques

    NASA Astrophysics Data System (ADS)

    Szymański, K.; Olszewski, W.; Satuła, D.; Gawryluk, D. J.; Krzton-Maziopa, A.; Kalska-Szostko, B.

    2017-02-01

    One of the most popular nuclear probes, 57Fe is used for the investigation of orientations of hyperfine fields and also for the determination of other important properties. In particular, the orientation of iron magnetic moments can be unambiguously determined, including its signs. Experiments with polarized radiation are presented with regard to selected systems. Orientation of electric field gradient is used for acquiring information about the shape of the texture-free spectra. Applications on the analysis of iron-based superconductors are presented.

  7. Determination of hyperfine fields orientation in nuclear probe techniques.

    PubMed

    Szymański, K; Olszewski, W; Satuła, D; Gawryluk, D J; Krzton-Maziopa, A; Kalska-Szostko, B

    2017-02-15

    One of the most popular nuclear probes, (57)Fe is used for the investigation of orientations of hyperfine fields and also for the determination of other important properties. In particular, the orientation of iron magnetic moments can be unambiguously determined, including its signs. Experiments with polarized radiation are presented with regard to selected systems. Orientation of electric field gradient is used for acquiring information about the shape of the texture-free spectra. Applications on the analysis of iron-based superconductors are presented.

  8. HfS, Hyperfine Structure Fitting Tool

    NASA Astrophysics Data System (ADS)

    Estalella, Robert

    2017-02-01

    Hyperfine Structure Fitting (HfS) is a tool to fit the hyperfine structure of spectral lines with multiple velocity components. The HfS_nh3 procedures included in HfS simultaneously fit the hyperfine structure of the NH3 (J, K) = (1, 1) and (2, 2) transitions, and perform a standard analysis to derive {T}{ex}, NH3 column density, {T}{rot}, and {T}{{k}}. HfS uses a Monte Carlo approach for fitting the line parameters. Special attention is paid to the derivation of the parameter uncertainties. HfS includes procedures that make use of parallel computing for fitting spectra from a data cube.

  9. Isotope shifts and hyperfine structure of the Fe I 372-nm resonance line

    SciTech Connect

    Krins, S.; Huet, N.; Bastin, T.; Oppel, S.; Zanthier, J. von

    2009-12-15

    We report measurements of the isotope shifts of the 3d{sup 6}4s{sup 2} a {sup 5}D{sub 4}-3d{sup 6}4s4p z {sup 5}F{sub 5}{sup o} Fe I resonance line at 372 nm between all four stable isotopes {sup 54}Fe, {sup 56}Fe, {sup 57}Fe, and {sup 58}Fe, as well as the complete hyperfine structure of that line for {sup 57}Fe, the only stable isotope having a nonzero nuclear spin. The field and specific mass shift coefficients of the transition have been derived from the data, as well as the experimental value for the hyperfine structure magnetic dipole coupling constant A of the excited state of the transition in {sup 57}Fe: A(3d{sup 6}4s4p z {sup 5}F{sub 5}{sup o})=81.69(86) MHz. The measurements were carried out by means of high-resolution Doppler-free laser saturated absorption spectroscopy in a Fe-Ar hollow cathode discharge cell using both natural and enriched iron samples. The measured isotope shifts and hyperfine constants are reported with uncertainties at the percent level.

  10. 57 Fe Mössbauer probe of spin crossover thin films on a bio-membrane

    NASA Astrophysics Data System (ADS)

    Naik, Anil D.; Garcia, Yann

    2012-03-01

    An illustrious complex [Fe(ptz)6](BF4)2 (ptz = 1-propyl-tetrazole) ( 1) which was produced in the form of submicron crystals and thin film on Allium cepa membrane was probed by 57Fe Mossbauer spectroscopy in order to follow its intrinsic spin crossover. In addition to a weak signal that corresponds to neat SCO compound significant amount of other iron compounds are found that could have morphed from 1 due to specific host-guest interaction on the lipid-bilayer of bio-membrane. Further complimentary information about biogenic role of membrane, was obtained from variable temperature Mossbauer spectroscopy on a ~5% enriched [57Fe(H2O)6](BF4)2 salt on this membrane.

  11. Thallium hyperfine anomaly

    NASA Astrophysics Data System (ADS)

    Gustavsson, Martin G. H.; Forssén, Christian; Mårtensson Pendrill, Ann Marie

    2000-08-01

    Measurements of the hyperfine structure in the highly charged hydrogen like systems 203Tl80+ and 205Tl80+ are underway at the Super EBIT at LLNL. This work considers the effects of the nuclear magnetization distribution on the hyperfine structure. The difference in energy splitting due to hyperfine structure for 203Tl and 205Tl, respectively, is found to be 0.031 04(1) eV, which corresponds to a transition wavelength difference of 3.640(1) nm.

  12. On the Observability of Optically Thin Coronal Hyperfine Structure Lines

    NASA Astrophysics Data System (ADS)

    Chatzikos, M.; Ferland, G. J.; Williams, R. J. R.; Fabian, A. C.

    2014-06-01

    We present CLOUDY calculations for the intensity of coronal hyperfine lines in various environments. We model indirect collisional and radiative transitions, and quantify the collisionally excited line emissivity in the density-temperature phase space. As an observational aid, we also express the emissivity in units of that in the 0.4-0.7 keV band. For most hyperfine lines, knowledge of the X-ray surface brightness and the plasma temperature is sufficient for rough estimates. We find that the radiation fields of both Perseus A and Virgo A can enhance the populations of highly ionized species within 1 kpc. They can also enhance line emissivity within the cluster core. This could have implications for the interpretation of spectra around bright active galactic nuclei. We find the intensity of the 57Fe XXIV λ3.068 mm line to be about two orders of magnitude fainter than previously thought, at ~20 μK. Comparably bright lines may be found in the infrared. Finally, we find the intensity of hyperfine lines in the Extended Orion Nebula to be low, due to the shallow sightline. Observations of coronal hyperfine lines will likely be feasible with the next generation of radio and submillimeter telescopes.

  13. On the observability of optically thin coronal hyperfine structure lines

    SciTech Connect

    Chatzikos, M.; Ferland, G. J.; Williams, R. J. R.; Fabian, A. C.

    2014-06-01

    We present CLOUDY calculations for the intensity of coronal hyperfine lines in various environments. We model indirect collisional and radiative transitions, and quantify the collisionally excited line emissivity in the density-temperature phase space. As an observational aid, we also express the emissivity in units of that in the 0.4-0.7 keV band. For most hyperfine lines, knowledge of the X-ray surface brightness and the plasma temperature is sufficient for rough estimates. We find that the radiation fields of both Perseus A and Virgo A can enhance the populations of highly ionized species within 1 kpc. They can also enhance line emissivity within the cluster core. This could have implications for the interpretation of spectra around bright active galactic nuclei. We find the intensity of the {sup 57}Fe XXIV λ3.068 mm line to be about two orders of magnitude fainter than previously thought, at ∼20 μK. Comparably bright lines may be found in the infrared. Finally, we find the intensity of hyperfine lines in the Extended Orion Nebula to be low, due to the shallow sightline. Observations of coronal hyperfine lines will likely be feasible with the next generation of radio and submillimeter telescopes.

  14. Different 57Fe microenvironments in the nanosized iron cores in human liver ferritin and its pharmaceutical analogues on the basis of temperature dependent Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Oshtrakh, M. I.; Alenkina, I. V.; Klencsár, Z.; Kuzmann, E.; Semionkin, V. A.

    2017-02-01

    Mössbauer spectra of human liver ferritin and its pharmaceutical analogues Ferrum Lek and Maltofer® measured at various temperatures within the range of 295-83 K were fitted using five quadrupole doublets related to different 57Fe microenvironments in various layers/regions of the ferrihydrite and akaganéite iron cores. The observed anomalous temperature dependences of some Mössbauer parameters were considered as a result of low temperature structural rearrangements in different layers/regions in the iron core.

  15. Microwave absorption and 57Fe Mössbauer properties of Ni-Ti doped barium hexaferrite

    NASA Astrophysics Data System (ADS)

    Harker, S. J.; Stewart, G. A.; Hutchison, W. D.; Amiet, A.; Tucker, D.

    2015-04-01

    The impact of doping the Fe component of barium hexaferrite with Ni0.5Ti0.5 is investigated using x-ray powder diffraction, 57Fe Mössbauer spectroscopy and microwave network analysis. The dopant ions exhibit a preference for the 2 b, 4 f 2 and 12 k-sites and the unit cell volume is observed to decrease. The ferromagnetic resonance frequency is reduced by about 11.5 GHz for each additional dopant ion per formula unit.

  16. Hyperfine interaction and magnetoresistance in organic semiconductors

    NASA Astrophysics Data System (ADS)

    Sheng, Y.; Nguyen, T. D.; Veeraraghavan, G.; Mermer, Ö.; Wohlgenannt, M.; Qiu, S.; Scherf, U.

    2006-07-01

    We explore the possibility that hyperfine interaction causes the recently discovered organic magnetoresistance (OMAR) effect. We deduce a simple fitting formula from the hyperfine Hamiltonian that relates the saturation field of the OMAR traces to the hyperfine coupling constant. We compare the fitting results to literature values for this parameter. Furthermore, we apply an excitonic pair mechanism model based on hyperfine interaction, previously suggested by others to explain various magnetic-field effects in organics, to the OMAR data. Whereas this model can explain a few key aspects of the experimental data, we uncover several fundamental contradictions as well. By varying the injection efficiency for minority carriers in the devices, we show experimentally that OMAR is only weakly dependent on the ratio between excitons formed and carriers injected, likely excluding any excitonic effect as the origin of OMAR.

  17. Effective Hyperfine-structure Functions of Ammonia

    NASA Astrophysics Data System (ADS)

    Augustovičová, L.; Soldán, P.; Špirko, V.

    2016-06-01

    The hyperfine structure of the rotation-inversion (v 2 = 0+, 0-, 1+, 1-) states of the 14NH3 and 15NH3 ammonia isotopomers is rationalized in terms of effective (ro-inversional) hyperfine-structure (hfs) functions. These are determined by fitting to available experimental data using the Hougen’s effective hyperfine-structure Hamiltonian within the framework of the non-rigid inverter theory. Involving only a moderate number of mass independent fitting parameters, the fitted hfs functions provide a fairly close reproduction of a large majority of available experimental data, thus evidencing adequacy of these functions for reliable prediction. In future experiments, this may help us derive spectroscopic constants of observed inversion and rotation-inversion transitions deperturbed from hyperfine effects. The deperturbed band centers of ammonia come to the forefront of fundamental physics especially as the probes of a variable proton-to-electron mass ratio.

  18. Magnetic behaviour and DCEMS study of SnO2 films implanted with 57Fe

    NASA Astrophysics Data System (ADS)

    Nomura, K.; Iio, S.; Hirose, Y.; Reuther, H.; Nakanishi, A.

    2013-04-01

    Fe implanted SnO2 films (5 × 1016 and 1 × 1017 57Fe ions/cm2) characterized by conversion electron Mossbauer spectroscopy (CEMS) are reviewed. The substrate temperatures affect the growth of precipitated iron oxides. The Fe ion implanted film at room temperature (RT) shows no Kerr effect and no magnetic sextet in CEM spectra. The SnO2 film implanted with 57Fe at the substrate temperature of 300 °C show a small Kerr effect although the magnetic sextet is not observed, but post-annealing results in the disappearance of the Kerr effect. This magnetism is considered to be due to defect induced magnetism. Some samples were measured by CEMS at 15 K. SnO2 (0.1 at %Sb and 3 at %Sb) films, implanted at 500 °C and the post-annealed samples, show RT ferromagnetism due to formation of clusters of magnetite and maghemite, respectively. The layer by layer analysis of these films within 100 nm in thickness has been done by depth sensitive CEMS (DCEMS) using a He + 5 % CH4 gas counter. The structures and compositions of Fe implanted SnO2 films, and the effects due to post-annealing were investigated.

  19. Interplay between magnetism and superconductivity in EuFe2-xCoxAs2 studied by 57Fe and 151Eu Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Błachowski, A.; Ruebenbauer, K.; Żukrowski, J.; Bukowski, Z.; Rogacki, K.; Moll, P. J. W.; Karpinski, J.

    2011-11-01

    The compound EuFe2-xCoxAs2 was investigated by means of 57Fe and 151Eu Mössbauer spectroscopy versus temperature (4.2-300 K) for x = 0 (parent), x = 0.34-0.39 (superconductor), and x = 0.58 (overdoped). It was found that the spin density wave (SDW) is suppressed by Co substitution; however, it survives in the region of superconductivity, but iron spectra exhibit some nonmagnetic components in the superconducting region. Europium orders magnetically, regardless of the cobalt concentration, with the spin reorientation from the a-axis in the parent compound toward the c-axis with increasing replacement of iron by cobalt. The reorientation takes place close to the a-c plane. Some trivalent europium appears in EuFe2-xCoxAs2 versus substitution due to the chemical pressure induced by Co atoms, and it experiences some transferred hyperfine field from Eu2+. Iron experiences some transferred field due to the europium ordering for substituted samples in the SDW and nonmagnetic state both, while the transferred field is undetectable in the parent compound. Superconductivity coexists with the 4f-europium magnetic order within the same volume. It seems that superconductivity has some filamentary character in EuFe2-xCoxAs2, and it is confined to the nonmagnetic component seen by the iron Mössbauer spectroscopy.

  20. Progressive Oxidation of Pyrite in Five Bituminous Coal Samples: An As XANES and 57Fe Mossbauer Spectroscopic Study

    SciTech Connect

    Kolker,A.; Huggins, F.

    2007-01-01

    Naturally occurring pyrite commonly contains minor substituted metals and metalloids (As, Se, Hg, Cu, Ni, etc.) that can be released to the environment as a result of its weathering. Arsenic, often the most abundant minor constituent in pyrite, is a sensitive monitor of progressive pyrite oxidation in coal. To test the effect of pyrite composition and environmental parameters on the rate and extent of pyrite oxidation in coal, splits of five bituminous coal samples having differing amounts of pyrite and extents of As substitution in the pyrite, were exposed to a range of simulated weathering conditions over a period of 17 months. Samples investigated include a Springfield coal from Indiana (whole coal pyritic S = 2.13 wt.%; As in pyrite = detection limit (d.l.) to 0.06 wt.%), two Pittsburgh coal samples from West Virginia (pyritic S = 1.32-1.58 wt.%; As in pyrite = d.l. to 0.34 wt.%), and two samples from the Warrior Basin, Alabama (pyritic S = 0.26-0.27 wt.%; As in pyrite = d.l. to 2.72 wt.%). Samples were collected from active mine faces, and expected differences in the concentration of As in pyrite were confirmed by electron microprobe analysis. Experimental weathering conditions in test chambers were maintained as follows: (1) dry Ar atmosphere; (2) dry O{sub 2} atmosphere; (3) room atmosphere (relative humidity {approx}20-60%); and (4) room atmosphere with samples wetted periodically with double-distilled water. Sample splits were removed after one month, nine months, and 17 months to monitor the extent of As and Fe oxidation using As X-ray absorption near-edge structure (XANES) spectroscopy and {sup 57}Fe Mossbauer spectroscopy, respectively. Arsenic XANES spectroscopy shows progressive oxidation of pyritic As to arsenate, with wetted samples showing the most rapid oxidation. {sup 57}Fe Mossbauer spectroscopy also shows a much greater proportion of Fe{sup 3+} forms (jarosite, Fe{sup 3+} sulfate, FeOOH) for samples stored under wet conditions, but much less

  1. Progressive oxidation of pyrite in five bituminous coal samples: An As XANES and 57Fe Mössbauer spectroscopic study

    USGS Publications Warehouse

    Kolker, Allan; Huggins, Frank E.

    2007-01-01

    Naturally occurring pyrite commonly contains minor substituted metals and metalloids (As, Se, Hg, Cu, Ni, etc.) that can be released to the environment as a result of its weathering. Arsenic, often the most abundant minor constituent in pyrite, is a sensitive monitor of progressive pyrite oxidation in coal. To test the effect of pyrite composition and environmental parameters on the rate and extent of pyrite oxidation in coal, splits of five bituminous coal samples having differing amounts of pyrite and extents of As substitution in the pyrite, were exposed to a range of simulated weathering conditions over a period of 17 months. Samples investigated include a Springfield coal from Indiana (whole coal pyritic S = 2.13 wt.%; As in pyrite = detection limit (d.l.) to 0.06 wt.%), two Pittsburgh coal samples from West Virginia (pyritic S = 1.32–1.58 wt.%; As in pyrite = d.l. to 0.34 wt.%), and two samples from the Warrior Basin, Alabama (pyritic S = 0.26–0.27 wt.%; As in pyrite = d.l. to 2.72 wt.%). Samples were collected from active mine faces, and expected differences in the concentration of As in pyrite were confirmed by electron microprobe analysis. Experimental weathering conditions in test chambers were maintained as follows: (1) dry Ar atmosphere; (2) dry O2 atmosphere; (3) room atmosphere (relative humidity ∼20–60%); and (4) room atmosphere with samples wetted periodically with double-distilled water. Sample splits were removed after one month, nine months, and 17 months to monitor the extent of As and Fe oxidation using As X-ray absorption near-edge structure (XANES) spectroscopy and 57Fe Mössbauer spectroscopy, respectively. Arsenic XANES spectroscopy shows progressive oxidation of pyritic As to arsenate, with wetted samples showing the most rapid oxidation. 57Fe Mössbauer spectroscopy also shows a much greater proportion of Fe3+ forms (jarosite, Fe3+ sulfate, FeOOH) for samples stored under wet conditions, but much less

  2. The 57Fe Synchrotron Mössbauer Source at the ESRF.

    PubMed

    Potapkin, Vasily; Chumakov, Aleksandr I; Smirnov, Gennadii V; Celse, Jean Philippe; Rüffer, Rudolf; McCammon, Catherine; Dubrovinsky, Leonid

    2012-07-01

    The design of a (57)Fe Synchrotron Mössbauer Source (SMS) for energy-domain Mössbauer spectroscopy using synchrotron radiation at the Nuclear Resonance beamline (ID18) at the European Synchrotron Radiation Facility is described. The SMS is based on a nuclear resonant monochromator employing pure nuclear reflections of an iron borate ((57)FeBO(3)) crystal. The source provides (57)Fe resonant radiation at 14.4 keV within a bandwidth of 15 neV which is tunable in energy over a range of about ±0.6 µeV. In contrast to radioactive sources, the beam of γ-radiation emitted by the SMS is almost fully resonant and fully polarized, has high brilliance and can be focused to a 10 µm × 5 µm spot size. Applications include, among others, the study of very small samples under extreme conditions, for example at ultrahigh pressure or combined high pressure and high temperature, and thin films under ultrahigh vacuum. The small cross section of the beam and its high intensity allow for rapid collection of Mössbauer data. For example, the measuring time of a spectrum for a sample in a diamond anvil cell at ∼100 GPa is around 10 min, whereas such an experiment with a radioactive point source would take more than one week and the data quality would be considerably less. The SMS is optimized for highest intensity and best energy resolution, which is achieved by collimation of the incident synchrotron radiation beam and thus illumination of the high-quality iron borate crystal within a narrow angular range around an optimal position of the rocking curve. The SMS is permanently located in an optics hutch and is operational immediately after moving it into the incident beam. The SMS is an in-line monochromator, i.e. the beam emitted by the SMS is directed almost exactly along the incident synchrotron radiation beam. Thus, the SMS can be easily utilized with all existing sample environments in the experimental hutches of the beamline. Owing to a very strong

  3. 57Fe Mössbauer spectroscopy used to develop understanding of a diamond preservation index model

    NASA Astrophysics Data System (ADS)

    Yambissa, M. T.; Forder, S. D.; Bingham, P. A.

    2016-12-01

    57Fe Mössbauer spectroscopy has provided precise and accurate iron redox ratios Fe2+/Fe3+ in ilmenite, FeTiO3, found within kimberlite samples from the Catoca and Camatxia kimberlite pipes from N.E. Angola. Ilmenite is one of the key indicator minerals for diamond survival and it is also one of the iron-bearing minerals with iron naturally occurring in one or both of the oxidation states Fe3+ and Fe2+. For this reason it is a good indicator for studying oxygen fugacities ( fO2) in mineral samples, which can then be related to iron redox ratios, Fe2+/Fe3+. In this paper we demonstrate that the oxidation state of the ilmenite mineral inclusion from sampled kimberlite rock is a key indicator of the oxidation state of the host kimberlite assemblage, which in turn determines the genesis of diamond, grade variation and diamond quality. Ilmenite samples from the two different diamondiferous kimberlite localities (Catoca and Camatxia) in the Lucapa graben, N.E. Angola, were studied using Mössbauer spectroscopy and X-Ray Diffractometry, in order to infer the oxidation state of their source regions in the mantle, oxygen partial pressure and diamond preservation conditions. The iron redox ratios, obtained using Mössbauer spectroscopy, show that the Catoca diamond kimberlite is more oxidised than kimberlite found in the Camatxia pipe, which is associated within the same geological tectonic structure. Here we demonstrate that57Fe Mössbauer spectroscopy can assist geologists and mining engineers to effectively evaluate and determine whether kimberlite deposits are economically feasible for diamond mining.

  4. Monte Carlo simulation of dose distribution in water around 57Fe3O4 magnetite nanoparticle in the nuclear gamma resonance condition

    NASA Astrophysics Data System (ADS)

    Gabbasov, R.; Polikarpov, M.; Safronov, V.; Sozontov, E.; Yurenya, A.; Panchenko, V.

    2016-12-01

    In this work was proposed a new radiotherapy enhancement method consisting of the administration of magnetic nanoparticles into the cells with further irradiation with a gamma-ray beam. As a result, adjusting the energy distribution of a gamma-ray beam and 57Fe abundance it is possible to achieve an extremely intensive electron emission because of a nuclear resonance. The produced conversion and Auger electrons can be used as an effective tool for DNA lesions production. We developed a Monte Carlo model for an electron and gamma emission by 57Fe nucleus using the Geant4 program package. The parameters of a resonant absorption were taken from Mössbauer spectra of magnetite nanoparticles synthesized for the administration into live cells. The space distribution of the radiation dose showed an increase in the dose of 2-2.5 times in the case of the natural abundance and more than 50 times in the case of the 66 % enrichment of the nanoparticles.

  5. A study of thermodynamic properties of dilute Fe-Ru alloys by 57Fe Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Idczak, R.; Konieczny, R.; Chojcan, J.

    2016-12-01

    The room temperature Mössbauer spectra of 57Fe were measured for Fe1- x Ru x solid solutions with x in the range 0.01 ≤ x ≤ 0.08. The obtained data were analysed in terms of short-range order parameter (SRO) and the binding energy E b between two ruthenium atoms in the studied materials using the extended Hrynkiewicz-Królas idea. The extrapolated value of E b for x = 0 was used to compute the enthalpy of solution H FeRu of Ru in Fe matrix. The result was compared with corresponding values given in the literature which were derived from experimental calorimetric data as well as with the value resulting from the cellular atomic model of alloys by Miedema. It was found that all the H FeRu values are negative or Ru atoms interact repulsively. At the same time, the Mössbauer data were used to determine values of the short-range order parameter α 1. For the as-obtained samples in which atoms are frozen-in high temperature state, close to the melting point, the negative α 1 values were found. The findings indicates ordering tendencies in such specimens. On the other hand, in the case of the annealed samples where the observed distributions of atoms should be frozen-in state corresponding to the temperature 700 K, the Fe1- x Ru x alloys with x ≥ 0.05 exhibit clustering tendencies (a predominance of Fe-Fe and Ru-Ru bonds), which manifest themselves by positive values of the calculated SRO parameter. The clustering process leads to a local increase in ruthenium concentration and nucleation of a new ruthenium-rich phase with the hcp structure.

  6. Hyperfine interactions in nanocrystallized NANOPERM-type metallic glass containing Mo

    NASA Astrophysics Data System (ADS)

    Cesnek, M.; Kubániová, D.; Kohout, J.; Křišťan, P.; Štěpánková, H.; Závěta, K.; Lančok, A.; Štefánik, M.; Miglierini, M.

    2016-12-01

    NANOPERM-type alloy with chemical composition Fe76Mo8CuB15 was studied by combination of 57Fe Mössbauer spectroscopy and 57Fe(10B, 11B) 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 x1 ˜ 510 ∘C and T x2 ˜ 640 ∘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 ∘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 57Fe(10B, 11B) nuclear magnetic resonance (NMR) spectra.

  7. The Mössbauer Parameters of the Proximal Cluster of Membrane-Bound Hydrogenase Revisited: A Density Functional Theory Study

    PubMed Central

    2015-01-01

    An unprecedented [4Fe-3S] cluster proximal to the regular [NiFe] active site has recently been found to be responsible for the ability of membrane-bound hydrogenases (MBHs) to oxidize dihydrogen in the presence of ambient levels of oxygen. Starting from proximal cluster models of a recent DFT study on the redox-dependent structural transformation of the [4Fe-3S] cluster, 57Fe Mössbauer parameters (electric field gradients, isomer shifts, and nuclear hyperfine couplings) were calculated using DFT. Our results revise the previously reported correspondence of Mössbauer signals and iron centers in the [4Fe-3S]3+ reduced-state proximal cluster. Similar conflicting assignments are also resolved for the [4Fe-3S]5+ superoxidized state with particular regard to spin-coupling in the broken-symmetry DFT calculations. Calculated 57Fe hyperfine coupling (HFC) tensors expose discrepancies in the experimental set of HFC tensors and substantiate the need for additional experimental work on the magnetic properties of the MBH proximal cluster in its reduced and superoxidized redox states. PMID:26598030

  8. /sup 57/Fe Mossbauer spectroscopy of U/sub 6/Fe

    SciTech Connect

    Lemon, G.; Boolchand, P.; Stevens, M.; DeLong, L.E.; Huber, J.G.; Marcuso, M.

    1986-04-01

    Samples of U/sub 6/Fe were prepared by arc melting U and enriched /sup 57/Fe. The samples display superconducting transitions which are sensitive to long-term exposure to air. Room temperature spectra of U/sub 6/Fe typically display a majority site A (quadrupole splitting ..delta.. = 0.749(3) mm/s, isomer shift delta = 0.482(6) mm/s relative to Cu) and a minority site B (..delta.. = 0.55(3) mm/s, sigma = 0.12(3) mm/s) with the site intensity ratio (I/sub B//I/sub A/) typically 0.05 to 0.10. The I/sub B//I/sub A/ intensity ratio increases upon air exposure of the samples. We have studied Moessbauer spectra as a function of temperature T in the range 15/sup 0/K less than or equal to T less than or equal to 310/sup 0/K paying particular attention to the T-variation of the isomer-shift and recoil-free-fraction of the majority site A. Results indicate a consistent softening of lattice vibrations of U/sub 6/Fe at T approx. = 170/sup 0/K.

  9. Iron-oxide aerogel and xerogel catalyst formulations: characterization by 57Fe Mössbauer and XAFS spectroscopies.

    PubMed

    Huggins, Frank E; Bali, Sumit; Huffman, Gerald P; Eyring, Edward M

    2010-06-01

    Iron in various iron-oxide aerogel and xerogel catalyst formulations (> or =85% Fe(2)O(3); < or =10% K, Co, Cu, or Pd) developed for possible use in Fischer-Tropsch synthesis (FTS) or the water-gas-shift (WGS) reaction has been examined by (57)Fe Mössbauer spectroscopy. The seventeen samples consisted of both as-prepared and calcined aerogels and xerogels and their products after use as catalysts for FTS or the WGS reaction. Complementary XAFS spectra were obtained on the occurrence of the secondary elements in some of the same materials. A broad, slightly asymmetric, two-peak Mössbauer spectrum was obtained from the different as-prepared and calcined catalyst formulations in the majority of cases. Such spectra could only be satisfactorily fit with three quadrupole doublet components, but no systematic trends in the isomer shift and quadrupole splitting parameters and area ratios of the individual components could be discerned that reflected variations in the composition or preparation of the aerogel or xerogel materials. However, significant reductions were noted in the Mössbauer effective thickness (recoilless absorption effect per unit mass of iron) parameter, chi(eff)/g, determined at room temperature, for aerogels and xerogels compared to bulk iron oxides, reflecting the openness and lack of rigidity of the aerogel and xerogel structures. Mössbauer measurements for two aerogels over the range from 15 to 292K confirmed the greatly diminished nature of this parameter at room temperature. Major increases in the effective thickness parameter were observed when the open structure of the aerogel or xerogel collapsed during calcination resulting in the formation of iron oxides (hematite, spinel ferrite). Similar structural changes were indicated by increases in this parameter after use of iron-oxide aerogels as catalysts for FTS or the WGS reaction, during which the iron-oxide aerogel was converted to a mixture of nonstoichiometric magnetite and the Hägg carbide

  10. Mössbauer and X-ray study of biodegradation of 57Fe3 O 4 magnetic nanoparticles in rat brain

    NASA Astrophysics Data System (ADS)

    Gabbasov, R. R.; Cherepanov, V. M.; Chuev, M. A.; Lomov, A. A.; Mischenko, I. N.; Nikitin, M. P.; Polikarpov, M. A.; Panchenko, V. Y.

    2016-12-01

    Biodegradation of a 57Fe3 O 4 - based dextran - stabilized ferrofluid in the ventricular cavities of the rat brain was studied by X-ray diffraction and Mössbauer spectroscopy. A two-step process of biodegradation, consisting of fast disintegration of the initial composite magnetic beads into separate superparamagnetic nanoparticles and subsequent slow dissolution of the nanoparticles has been found. Joint fitting of the couples of Mössbauer spectra measured at different temperatures in the formalism of multi-level relaxation model with one set of fitting parameters, allowed us to measure concentration of exogenous iron in the rat brain as a function of time after the injection of nanoparticles.

  11. Mineralogy, 57Fe Mössbauer spectra and magnetization of chalcolithic pottery

    NASA Astrophysics Data System (ADS)

    Keller, R.; Masch, L.; Pohl, J.; Schmidbauer, E.

    2005-06-01

    Three chalcolithic pottery sherds, paint removed from the surface of each sherd, and an unheated red pigment (Tell-Halaf culture, Turkey) were analysed within the frame of archaeometric studies using mineralogical methods, 57Fe Mössbauer spectroscopy, magnetization and rotational hysteresis data. From mineralogical results, the individual minerals forming the cores of the sherds were determined. It was found that the sherds are lime-rich. High temperature X-ray analysis on comparable Ca-rich material showed that the established composition is consistent with a firing temperature of 750-950°C. Apart from the pigment, each Mössbauer spectrum of Fe-bearing components consists of dominating paramagnetic doublets, arising mostly from silicate phases, and of a six-line pattern with reduced intensity, due to ferri- and/or antiferromagnetic Fe-oxide phases. For three samples, an Fe3+ silicate component of the spectra is clearly dominating, which points to oxidizing conditions during firing. For the others Fe2+ and Fe3+ components occur in about equal intensities. For the pigment, the magnetic sextet is of similar intensity to the Fe3+ silicate component. From magnetic analysis of ferrimagnetic phases it follows that a low percentage of particles of solid solutions γ-Fe2O3 Fe3O4 exist, probably in part ≤0.1 μm in diameter. The ferrimagnetic particles of at least one paint are probably covered by a thin layer of hematite as found from rotational hysteresis data. An attempt is made to draw conclusions from the experimental results, regarding the firing conditions of the sherds and paints.

  12. Hyperfine structure parametrisation in Maple

    NASA Astrophysics Data System (ADS)

    Gaigalas, G.; Scharf, O.; Fritzsche, S.

    2006-02-01

    In hyperfine structure examinations, routine high resolution spectroscopy methods have to be combined with exact fine structure calculations. The so-called magnetic A and electric B factor of the fine structure levels allow to check for a correct fine structure analysis, to find errors in the level designation, to find new levels and to probe the electron wavefunctions and its mixing coefficients. This is done by parametrisation of these factors into different contributions of the subshell electrons, which are split further into their radial and spin-angular part. Due to the routine with which hyperfine structure measurements are done, a tool for keeping the necessary information together, performing checks online with the experiment and deriving standard quantities is of great help. MAPLE [Maple is a registered trademark of Waterloo Maple Inc.] is a highly-developed symbolic programming language, often referred to as the pocket calculator of the future. Packages for theoretical atomic calculation exist ( RACAH and JUCYS) and the language meets all the requirements to keep and present information accessible for the user in a fast and practical way. We slightly extended the RACAH package [S. Fritzsche, Comput. Phys. Comm. 103 (1997) 51] and set up an environment for experimental hyperfine structure calculations, the HFS package. Supplying the fine structure and nuclear data, one is in the position to obtain information about the hyperfine spectrum, the different contributions to the splitting and to perform a least square fit of the radial parameters based on the semiempirical method. Experimentalist as well as theoretical physicist can do a complete hyperfine structure analysis using MAPLE. Program summaryTitle of program: H FS Catalogue number: ADXD Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADXD Program obtainable from: CPC Program Library, Queen's University of Belfast, N. Ireland Licensing provisions: none Computers for which the program is designed

  13. MODELING MOLECULAR HYPERFINE LINE EMISSION

    SciTech Connect

    Keto, Eric; Rybicki, George

    2010-06-20

    In this paper, we discuss two approximate methods previously suggested for modeling hyperfine spectral line emission for molecules whose collisional transition rates between hyperfine levels are unknown. Hyperfine structure is seen in the rotational spectra of many commonly observed molecules such as HCN, HNC, NH{sub 3}, N{sub 2}H{sup +}, and C{sup 17}O. The intensities of these spectral lines can be modeled by numerical techniques such as {Lambda}-iteration that alternately solve the equations of statistical equilibrium and the equation of radiative transfer. However, these calculations require knowledge of both the radiative and collisional rates for all transitions. For most commonly observed radio frequency spectral lines, only the net collisional rates between rotational levels are known. For such cases, two approximate methods have been suggested. The first method, hyperfine statistical equilibrium, distributes the hyperfine level populations according to their statistical weight, but allows the population of the rotational states to depart from local thermal equilibrium (LTE). The second method, the proportional method, approximates the collision rates between the hyperfine levels as fractions of the net rotational rates apportioned according to the statistical degeneracy of the final hyperfine levels. The second method is able to model non-LTE hyperfine emission. We compare simulations of N{sub 2}H{sup +} hyperfine lines made with approximate and more exact rates and find that satisfactory results are obtained.

  14. Nano-structure analysis of Fe implanted SnO2 films by 57Fe and 119Sn CEMS

    NASA Astrophysics Data System (ADS)

    Nomura, Kiyoshi; Reuther, Helfried

    2009-06-01

    SnO2 films were implanted with 57Fe at substrate temperatures of room temperature and 300°C. The chemical states of Fe and Sn were characterized by 57Fe CEMS and 119Sn CEMS, respectively. The implanted Fe species exist as Fe(II) and Fe(III) in SnO2 films, which also are reduced into Sn(II)on the implanted surface. The as prepared and post annealed at 500°C samples did not show Kerr effect, but the sample implanted with 1 × 1017 Fe ions/cm2 at 300°C showed Kerr effect although magnetic sextets were not clearly observed in the 57Fe CEM spectra. The Kerr effect disappeared after annealing. It suggests that the number of magnetic defects decreases by absorption of oxygen. Magnetic relaxation appeared in the case of low implantation of 5 × 1016 Fe ions/cm2, which is considered to be due to anti-ferromagnetism or paramagnetic relaxation.

  15. The magnetic transition in ε-Fe{sub 2}O{sub 3} nanoparticles: Magnetic properties and hyperfine interactions from Mössbauer spectroscopy

    SciTech Connect

    Kohout, J. Závěta, K.; Kubániová, D.; Kmječ, T.; Kubíčková, L.; Brázda, P.; Klementová, M.; Šantavá, E.; Lančok, A.

    2015-05-07

    The nanoparticles of ε-Fe{sub 2}O{sub 3} enriched with {sup 57}Fe isotope in amorphous silica matrix were prepared by sol-gel technique starting from a single molecular precursor for both Fe{sub 2}O{sub 3} and silica. From the X-ray powder diffraction pattern ε-Fe{sub 2}O{sub 3} was identified as the major phase and α-Fe{sub 2}O{sub 3} and β-Fe{sub 2}O{sub 3} were observed as minor iron oxide phases. Using the log-normal distribution for fitting the experimental data from the TEM micrographs, the characteristic size of particles d{sub 0} ∼ 25 nm was derived. The rather high coercivity of ∼2.1 T at room temperature was confirmed for our nanoparticle system. From the dependences of magnetization on temperature a two-step magnetic transition spread between 100 K and 153 K was indicated. From the {sup 57}Fe Mössbauer spectra measured in the temperature range of 4.2–300 K, the hyperfine parameters for one tetrahedral and three octahedral sites of ε-Fe{sub 2}O{sub 3} structure were identified. The in-field spectra in the external magnetic fields up to 6 T were taken both above and below the indicated two-step magnetic transition. Their dependence on temperature and external magnetic field suggests that the first step in the temperature range of 153 K–130 K is related to the spin reorientation of the local magnetic moments in the magnetic sublattices and the second step in temperatures 130 K–100 K may be associated with the intermediate spin–high spin state transition of Fe{sup 3+} cation in the tetrahedral sublattice expressed in the change of the hyperfine magnetic field.

  16. Hyperfine interaction in hydrogenated graphene

    NASA Astrophysics Data System (ADS)

    Garcia, Noel; Melle, Manuel; Fernandez-Rossier, Joaquin

    We study the hyperfine interaction of Hydrogen chemisorbed in graphene nanostructures with a gap in their spectrum, such as islands and ribbons. Chemisorption of Hydrogen on graphene results in a bound in-gap state that hosts a single electron localized around the adatom. Using both density functional theory and a four-orbital tight-binding model we study the hyperfine interaction between the hydrogen nuclear spin and the conduction electrons in graphene. We find that the strength of the hyperfine interaction decreases for larger nanostructures for which the energy gap is smaller. We then compare the results of the hyperfine interaction for large nanostructures with those of graphene 2D crystal with a periodic arrangement of chemisorbed Hydrogen atoms, obtaining very similar results. The magnitude of the hyperfine interaction is about 150 MHz, in line with that of Si:P. We acknowledge financial support by Marie-Curie-ITN 607904-SPINOGRAPH.

  17. High-Pressure-Hydrogen-Induced Spin Reconfiguration in GdFe2 Observed by 57Fe-Polarized Synchrotron Radiation Mössbauer Spectroscopy with Nuclear Bragg Monochromator

    NASA Astrophysics Data System (ADS)

    Mitsui, Takaya; Imai, Yasuhiko; Hirao, Naohisa; Matsuoka, Takahiro; Nakamura, Yumiko; Sakaki, Kouji; Enoki, Hirotoshi; Ishimatsu, Naoki; Masuda, Ryo; Seto, Makoto

    2016-12-01

    57Fe-polarized synchrotron radiation Mössbauer spectroscopy (PSRMS) with an X-ray phase plate and a nuclear Bragg monochromator was used to study ferrimagnetic GdFe2 in high-pressure hydrogen. The pressure-dependent spectra clearly showed a two-step magnetic transition of GdFe2. 57Fe-PSRMS with circular polarization gave direct evidence that the Fe moment was directed parallel to the net magnetization of the GdFe2 hydride at 20 GPa. This spin configuration was opposite to that of the initial GdFe2, suggesting an extreme weakening of the antiferromagnetic interaction between Fe and Gd. 57Fe-PSRMS enables the characterization of the nonuniform properties of iron-based polycrystalline powder alloys. The excellent applicability of 57Fe-PSRMS covers a wide range of scientific fields.

  18. Effects of the hyperfine interactions on the decay of the collective nuclear excited states in. alpha. -hematite

    SciTech Connect

    Faigel, G.; Berman, L.E.; Grover, J.R.; Hastings, J.B.; Haustein, P.E.; Siddons, D.P. . Central Research Inst. for Physics; Brookhaven National Lab., Upton, NY )

    1989-01-01

    In this paper the time dependence of the coherent decay of nuclear excited state in an {alpha}-{sup 57}Fe{sub 2}O{sub 3} single crystal is presented. The experiment was carried out in diffraction geometry. A highly monocromatized and collimated beam of synchrotron radiation was used for the excitation of nuclear levels. Quantum beat spectra taken below and above the (7,7,7) pure nuclear reflection of hematite show a characteristic pattern corresponding to the magnetic and quadrupole hyperfine interactions. 16 refs., 1 fig.

  19. In-field {sup 57}Fe Mössbauer spectroscopy below spin-flop transition in powdered troilite (FeS) mineral

    SciTech Connect

    Cuda, Jan Tucek, Jiri; Filip, Jan; Malina, Ondrej; Krizek, Michal; Zboril, Radek

    2014-10-27

    Powdered troilite (FeS), extracted from the Cape York IIIA octahedrite meteorite, was investigated employing in-field {sup 57}Fe Mössbauer spectroscopy. The study identified a typical behavior of polycrystalline antiferromagnetic material under external magnetic fields. The in-field evolution of the {sup 57}Fe Mössbauer spectra showed that the spin-flop transition in the FeS system occurs at a field higher than 5 T.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    2015-07-28

    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.

  2. An 57Fe Mössbauer study of three Australian L5 ordinary-chondrite meteorites: dating Kinclaven-001

    NASA Astrophysics Data System (ADS)

    Cadogan, J. M.; Rebbouh, L.; Mills, J. V. J.; Bland, P. A.

    2013-12-01

    Three L5-type ordinary chondrite meteorites recovered from the Nullarbor Region of Western Australia were studied by 57Fe Mössbauer spectroscopy: Kinclaven-001, Camel Donga-007 and Gunnadorah-002. The relative amounts of the various Fe-bearing phases including the primary minerals (Olivine, Pyroxene, Troilite and Fe-Ni metal) and the ferric alteration products (Goethite, Maghemite/Magnetite) were obtained to determine the percentage of iron converted to Fe3 + by weathering processes. These data allow us to estimate the terrestrial age of Kinclaven-001 at 1,700 ± 1,300 yrs.

  3. 57Fe75Mo8Cu1B16 metallic glass studied by CEMS, CXMS and HEXRD

    NASA Astrophysics Data System (ADS)

    Cesnek, Martin; Miglierini, Marcel; Bednarčík, Jozef

    2016-10-01

    57Fe75Mo8Cu1B16 metallic glass prepared by single roller melt spinning was investigated by conversion electron Mössbauer spectroscopy, conversion X-ray Mössbauer spectroscopy and high-energy X-ray diffraction. All methods confirmed presence of amorphous structure without traces of a crystalline phase. Results obtained by Mössbauer spectrometry suggest predominant appearance of magnetic regions on side of the ribbon which was in contact with the quenching wheel. In situ High-energy X-ray diffraction experiment revealed transition from ferromagnetic to paramagnetic state and it was even possible to estimate the Curie temperature.

  4. Fluctuating hyperfine interactions: computational implementation

    NASA Astrophysics Data System (ADS)

    Zacate, M. O.; Evenson, W. E.

    2010-04-01

    A library of computational routines has been created to assist in the analysis of stochastic models of hyperfine interactions. We call this library the stochastic hyperfine interactions modeling library (SHIML). It provides routines written in the C programming language that (1) read a text description of a model for fluctuating hyperfine fields, (2) set up the Blume matrix, upon which the evolution operator of the system depends, and (3) find the eigenvalues and eigenvectors of the Blume matrix so that theoretical spectra of experimental hyperfine interaction measurements can be calculated. Example model calculations are included in the SHIML package to illustrate its use and to generate perturbed angular correlation spectra for the special case of polycrystalline samples when anisotropy terms of higher order than A22 can be neglected.

  5. Large low-energy M1 strength for ^{56,57}Fe within the nuclear shell model.

    PubMed

    Brown, B Alex; Larsen, A C

    2014-12-19

    A strong enhancement at low γ-ray energies has recently been discovered in the γ-ray strength function of ^{56,57}Fe. In this work, we have for the first time obtained theoretical γ decay spectra for states up to ≈8  MeV in excitation for ^{56,57}Fe. We find large B(M1) values for low γ-ray energies that provide an explanation for the experimental observations. The role of mixed E2 transitions for the low-energy enhancement is addressed theoretically for the first time, and it is found that they contribute a rather small fraction. Our calculations clearly show that the high-ℓ(=f) diagonal terms are most important for the strong low-energy M1 transitions. As such types of 0ℏω transitions are expected for all nuclei, our results indicate that a low-energy M1 enhancement should be present throughout the nuclear chart. This could have far-reaching consequences for our understanding of the M1 strength function at high excitation energies, with profound implications for astrophysical reaction rates.

  6. Time differential 57Fe Mössbauer spectrometer with unique 4π YAP:Ce 122.06 keV gamma-photon detector

    NASA Astrophysics Data System (ADS)

    Novak, Petr; Pechousek, Jiri; Prochazka, Vit; Navarik, Jakub; Kouril, Lukas; Kohout, Pavel; Vrba, Vlastimil; Machala, Libor

    2016-10-01

    This paper presents a conceptually new design of the 57Fe Time Differential Mössbauer Spectrometer (TDMS) with the gamma-photon detector optimized for registration of a radiation emitted in a maximum solid angle. A high detection efficiency of 80% in 4π region was achieved for 122.06 keV photons emitted from 57Co source. Detector parameters have been optimized for the use in the Time Differential Mössbauer Spectroscopy where the high time resolution in range of 176-200 ns is highly required. Technical concept of the TDMS is based on the virtual instrumentation technique and uses fast digital oscilloscope. Performance and detector utilization have been clarified by decreasing the Mössbauer spectral line-width of K2MgFe(CN)6 reference sample from 0.33 mm/s (integral mode) to 0.23 mm/s (time differential mode). This report also describes characterization and utilization of the detector together with additional electronic blocks and two-channel fast data-acquisition system construction.

  7. Designing and characterization of Fe(III) complexes of oxydiacetate containing α-diimine as auxiliary ligand: 57Fe-Mössbauer and cyclic voltammetric studies

    NASA Astrophysics Data System (ADS)

    Shahid, M.; Sharma, Prashant K.; Siddiqi, Zafar A.; Sama, Farasha; Ansari, Istikhar A.; Khalid, Mohd.

    2014-04-01

    The newly prepared complexes with stoichiometries [Fe(oda)(phen)Cl] (1), [Fe(oda)(4-picNO)(H2O)Cl)] (2) and [Fe2(oda)2(H2O)2Cl2] (3) [H2oda = oxydiacetic acid, phen = 1,10‧-phenantroline and 4-picNO = 4-picoline-N-oxide] were synthesized under varying experimental conditions. The complexes were characterized by spectral (IR, FAB-MS and Mössbauer), electrochemical and thermal studies. 57Fe-Mössbauer spectral data for complexes exhibit a quadrupole splitting confirming the presence of iron nuclei in asymmetric environment. The relevant parameters like isomer shift (δ), quadruple splitting (ΔEQ), line widths and peak height ratio (HWh/HWl) are consistent with high spin state of Fe(III) centre with the presence of Kramer’s double degeneracy in distorted octahedral environment. The electrochemical studies indicate existence of quasi-reversible redox couples (FeII/III) in solution.

  8. Low temperature Raman and high field 57Fe Mossbauer study of polycrystalline GaFeO3.

    PubMed

    Sharma, Kavita; Raghavendra Reddy, V; Kothari, Deepti; Gupta, Ajay; Banerjee, A; Sathe, V G

    2010-04-14

    The magnetic and phonon properties of polycrystalline magnetoelectric/multiferroic GaFeO(3) are studied. Using high field (57)Fe Mossbauer spectroscopy, occupation of Fe is observed at four cation sites. A Fe population of about 6% is observed at the tetrahedral Ga1 site, which explains the observed pinched-like M-H curve and initial sharp increase of the magnetization. The calculated net magnetization value from Mossbauer data suggests that the Fe moment at the Ga1 site is parallel to Fe1 and opposite to that of Fe2 and Ga2 sites, resulting in ferrimagnetism. From low temperature Raman data, anomalous temperature variation in frequency at T(C) is observed for the mode at ∼700 cm(-1).

  9. The quantitative determination of FeS2 phases in coal by means of 57Fe Mössbauer spectroscopy

    USGS Publications Warehouse

    Evans, B.J.; King, Hobart M.; Renton, John J.; Stiller, A.

    1990-01-01

    A knowledge of the concentration of pyrite and marcasite in coals can provide important insight into the genesis of coal deposits. Determinations of the relative amounts of pyrite and marcasite by traditional methods of coal analysis are, however, beset with many difficulties. Using 57Fe Mössbauer spectroscopy and a mild chemical treatment with hydrofluoric acid, a technique has been devised for the quantitative determination of the relative concentrations of pyrite and marcasite in samples of whole coals or their low-temperature ashes. The sample preparation procedure is comparable to less accurate methods. Good qualitative agreement has been obtained between ore microscopic and Mössbauer spectroscopic techniques for a series of extensively investigated whole coal samples.

  10. Four Decades of Hyperfine Anomalies

    NASA Astrophysics Data System (ADS)

    Gustavsson, Martin G. H.; Mårtensson-Pendrill, Ann-Marie

    Isotopic differences in the distribution of nuclear charge and magnetization give rise to "hyperfine structure anomalies" which were observed already in the 1950s. More recently, the distribution of nuclear magnetization has been found to complicate the interpretation of the measured hyperfine splittings in highly charged hydrogen-like ions. In this paper, results of numerical calculations for a few hydrogen-like systems (133Cs, 165Ho, 185,187Re and 209Bi) of current experimental interest are presented in terms of moments of the nuclear charge and magnetization distribution, thereby displaying directly the sensitivity and emphasizing the need for a better understanding of nuclear wavefunctions. In addition, we also present results of many-body perturbation theory calculations for Cs hyperfine anomalies, in connection with experiments planned at ISOLDE.

  11. Stochastic hyperfine interactions modeling library

    NASA Astrophysics Data System (ADS)

    Zacate, Matthew O.; Evenson, William E.

    2011-04-01

    The stochastic hyperfine interactions modeling library (SHIML) provides a set of routines to assist in the development and application of stochastic models of hyperfine interactions. The library provides routines written in the C programming language that (1) read a text description of a model for fluctuating hyperfine fields, (2) set up the Blume matrix, upon which the evolution operator of the system depends, and (3) find the eigenvalues and eigenvectors of the Blume matrix so that theoretical spectra of experimental techniques that measure hyperfine interactions can be calculated. The optimized vector and matrix operations of the BLAS and LAPACK libraries are utilized; however, there was a need to develop supplementary code to find an orthonormal set of (left and right) eigenvectors of complex, non-Hermitian matrices. In addition, example code is provided to illustrate the use of SHIML to generate perturbed angular correlation spectra for the special case of polycrystalline samples when anisotropy terms of higher order than A can be neglected. Program summaryProgram title: SHIML Catalogue identifier: AEIF_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AEIF_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: GNU GPL 3 No. of lines in distributed program, including test data, etc.: 8224 No. of bytes in distributed program, including test data, etc.: 312 348 Distribution format: tar.gz Programming language: C Computer: Any Operating system: LINUX, OS X RAM: Varies Classification: 7.4 External routines: TAPP [1], BLAS [2], a C-interface to BLAS [3], and LAPACK [4] Nature of problem: In condensed matter systems, hyperfine methods such as nuclear magnetic resonance (NMR), Mössbauer effect (ME), muon spin rotation (μSR), and perturbed angular correlation spectroscopy (PAC) measure electronic and magnetic structure within Angstroms of nuclear probes through the hyperfine interaction. When

  12. Hyperfine Coherence in the Presence of Spontaneous Photon Scattering

    NASA Astrophysics Data System (ADS)

    Ozeri, R.; Langer, C.; Jost, J. D.; Demarco, B.; Ben-Kish, A.; Blakestad, B. R.; Britton, J.; Chiaverini, J.; Itano, W. M.; Hume, D. B.; Leibfried, D.; Rosenband, T.; Schmidt, P. O.; Wineland, D. J.

    2005-07-01

    The coherence of a hyperfine-state superposition of a trapped 9Be+ ion in the presence of off-resonant light is studied experimentally. It is shown that Rayleigh elastic scattering of photons that does not change state populations also does not affect coherence. We observe coherence times that exceed the average scattering time of 19 photons which is determined from measured Stark shifts. This result implies that, with sufficient control over its parameters, laser light can be used to manipulate hyperfine-state superpositions with very little decoherence.

  13. Thermal History of São João Nepomuceno (IVA) Iron Meteorite Inferred from Ganguly's Cooling Rate Model and 57Fe Mössbauer Spectroscopy Data

    NASA Astrophysics Data System (ADS)

    dos Santos, E.; Scorzelli, R. B.; Varela, M. E.

    2016-08-01

    The intracrystalline Fe-Mg distribution in orthopyroxenes, as measured by means of 57Fe Mössbauer spectroscopy and associated to Ganguly’s cooling rate numerical method, are used to infer the thermal history of São João Nepomuceno (IVA) meteorite.

  14. Hyperfine Structure in Rotational Spectra of Deuterated Molecules: the Hds and ND_3 Case Studies

    NASA Astrophysics Data System (ADS)

    Cazzoli, Gabriele; Puzzarini, Cristina

    2016-06-01

    The determination of hyperfine parameters (quadrupole-coupling, spin-spin coupling, and spin-rotation constants) is one of the aims of high-resolution rotational spectroscopy. These parameters are relevant not only from a spectroscopic point of view, but also from a physical and/or chemical viewpoint, as they might provide detailed information on the chemical bond, structure, etc. In addition, the hyperfine structure of rotational spectra is so characteristic that its analysis may help in assigning the spectra of unknown species. In astronomical observations, hyperfine structures of rotational spectra would allow us to gain information on column densities and kinematics, and the omission of taking them into account can lead to a misinterpretation of the line width of the molecular emission lines. Nevertheless, the experimental determination of hyperfine constants can be a challenge not only for actual problems in resolving hyperfine structures themselves, but also due to the lack of reliable estimates or the complexity of the hyperfine structure itself. It is thus important to be able to rely on good predictions for such parameters, which can nowadays be provided by quantum-chemical calculations. In fact, the fruitful interplay of experiment and theory will be demonstrated by means of two study cases: the hypefine structure of the rotational spectra of HDS and ND_3. From an experimental point of view, the Lamb-dip technique has been employed to improve the resolving power in themillimeter- and submillimeterwave frequency range by at least one order of magnitude, thus making it possible to perform sub-Doppler measurements as well as to resolve narrow hyperfine structures. Concerning theory, it will be demonstrated that high-level calculations can provide quantitative estimates for hyperfine parameters (quadrupole coupling constants, spin-rotation tensors, spin-spin couplings, etc.) and shown how theoretical predictions are often essential for a detailed analysis of

  15. Magnetic Properties and Hyperfine Interactions in Iron Containing Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Unruh, Karl Marlin

    Amorphous samples of Fe(,x)B(,100-x) (30 (LESSTHEQ) x (LESSTHEQ) 90), Fe(,x)Ag(,100-x) (40 (LESSTHEQ) x (LESSTHEQ) 50), and Fe(,x)Zr(,100-x) (20 (LESSTHEQ) x (LESSTHEQ) 93) have been prepared, and their magnetic properties and hyperfine interactions studied by ('57)Fe Mossbauer spectroscopy. Each system is representative of either Fe-metalloid (Fe-B), Fe-noble metal (Fe-Ag), or Fe-early transition metal (Fe -Zr) amorphous alloys. Therefore, by studying these three amorphous solids an overview is obtained, not only of the properties of the individual alloys, but also of the wider class of alloys of which they are representative. The amorphous Fe-B and Fe-Zr systems have been successfully fabricated over very wide ranges in composition, allowing the evolution of the magnetic properties and hyperfine interactions to be systematically studied. As a result it has been possible to determine the critical concentration for magnetic order (x(,c)). It has been shown that the loss of magnetic order below x(,c) is the result of the reduction and eventual disappearance of the Fe moment. The isomer shifts (IS) and quadrupole splittings (QS) have also been determined over wide composition ranges. This has led to the observation of a maximum in IS with decreasing Fe concentration in amorphous alloys of Fe and B. On the other hand, IS in the amorphous Fe-Zr alloys has been found to decrease monotonically over the same concentration range. In the paramagnetic region all the samples display quadrupole split doublets characteristic of site symmetries lower than cubic. It has been found that the observed asymmetry in the quadrupole spectra can be correlated with the relative changes in IS and QS as a function of composition. Amorphous alloys of Fe and Ag have been prepared for the first time and have been found to be stable at room temperature. The somewhat unusual magnetic properties of these alloys suggests that they may be simpler magnetically than previously studied magnetic

  16. Hyperfine magnetic fields in substituted Finemet alloys

    NASA Astrophysics Data System (ADS)

    Brzózka, K.; Sovák, P.; Szumiata, T.; Gawroński, M.; Górka, B.

    2016-12-01

    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.

  17. The role of alpha-iron and cementite phases in the growing mechanism of carbon nanotubes: a 57Fe Mössbauer spectroscopy study.

    PubMed

    Pérez-Cabero, M; Taboada, J B; Guerrero-Ruiz, A; Overweg, A R; Rodríguez-Ramos, I

    2006-03-14

    57Fe Mössbauer spectroscopy was used to study the reduction behavior at temperatures as high as 1073 K of an iron/silica catalyst, and also the carbonaceous materials isolated after acetylene decomposition over this catalyst at several temperatures (873-1073 K). The products were previously characterized by transmission electron microscopy and it was clearly proven that the concentration of carbon nanotubes increased when reaction reached highest temperatures. This was related with an increment in cementite concentration (generated from initial alpha-iron and the progressive reduction of the remnant Fe+2 caused by acetylene decomposition) as detected by 57Fe Mössbauer. These results undoubtedly revealed the role of alpha-iron as active center for acetylene decomposition and cementite as main carbide intermediate species in the catalytic growth of CNTs.

  18. Structure, phase transitions, 55Mn NMR, 57Fe Mössbauer studies and magnetoresistive properties of La0.6Sr0.3Mn1.1-xFexO3

    NASA Astrophysics Data System (ADS)

    Pashchenko, A. V.; Pashchenko, V. P.; Revenko, Yu. F.; Prokopenko, V. K.; Shemyakov, A. A.; Levchenko, G. G.; Pismenova, N. E.; Kitaev, V. V.; Gufan, Yu. M.; Sil'cheva, A. G.; Dyakonov, V. P.

    2014-11-01

    The influence of substitution of Fe ions for manganese on the structure, phase transitions, magnetoresistance, 55Mn NMR and 57Fe Mössbauer spectra in the ceramic La0.6Sr0.3Mn1.1-xFexO3 (x=0-0.15) samples has been studied by X-ray diffraction, electron microscopy, magnetic, 55Mn NMR and 57Fe Mössbauer methods. The real rhombohedral perovskite structure (R3barc) is established to contain the different valence manganese ions (Mn3+ and Mn4+), anion and cation vacancies as well as nanostructural clusters with Mn2+ located in the A-sites. Temperature dependences of the a lattice parameter, a(T), demonstrate the anomalies near the Curie temperature, Tc. Wide asymmetric 55Mn NMR spectra confirm the high frequency electron double exchange between Mn3+ and Mn4+ ions and irregularity of their surrounding by other ions and defects. According to the Mössbauer spectroscopy data, Fe3+ ions (~80%) substitute for Mn3+ and partially Mn4+ in the B-positions. The rest of Fe3+ (Fe2+) ions and clusters with Mn2+ are located in the A-positions. The temperatures of metal-semiconductor and ferromagnet-paramagnet phase transitions are reduced with increasing x, and the magnetic irregularity increases due to the weakening high-frequency Mn3+↔Mn4+ double exchange by Fe3+ ions. The amount of ferromagnetic phase is also reduced. The anomalous hysteresis is interpreted as a result of anisotropy of exchange interaction between the ferromagnetic matrix and antiferromagnetic cluster containing MnA2+ ions. The phase diagram demonstrates the strong correlated interrelation among magnetic, transport and magnetoresistance properties.

  19. Effect of 57Fe-goethite Amendment on Microbial Community Composition and Dynamics During the Transition from Iron to Sulfate Reduction

    NASA Astrophysics Data System (ADS)

    Moon, H.; McGuiness, L.; Kukkadapu, R. K.; Peacock, A.; Komlos, J.; Kerkhof, L.; Long, P. E.; Jaffe, P. R.

    2009-12-01

    Due to an increasing interest in microbial biostimulation for the purpose of U(VI) bioreduction, which proceeds via iron reduction, there is a growing need for a better understanding of the associated biogeochemical dynamics. This includes Fe(III) availability as well as the microbial community changes, including the activity of iron-reducers during the biostimulation period even after the onset of sulfate reduction. An up-flow column experiment was conducted with Old Rifle site sediments, where half of the columns had sediment that was augmented with 57Fe-goethite to track minute goethite changes after the onset of sulfate reduction, and to study the effects of increased Fe(III) levels on the overall biostimulation dynamics. The addition of the 57Fe-goethite did not delay the onset of sulfate reduction, but slightly suppressed the overall rate of sulfate reduction and hence acetate utilization. Mossbauer analyses confirmed that there was bioavailable iron present after the onset of sulfate reduction and that iron was still being reduced during sulfate reduction. Addition of the 57Fe-goethite to the sediment had a noticeable effect on the overall composition of the microbial population. 16S rRNA analyses of biostimulatd sediment using TRFLP showed that Geobacter sp. were still active and replicating after sulfate reduction had occurred for over 30 days. DNA fingerprints of the sediment-attached microbial communities were dominated by 5 TRFs, that comprised 25-57 % of the total profile. Augmentation of sediments with the 57Fe-goethite resulted in somewhat higher numbers of Geobacter-like species throughout the experiment, and during sulfate reduction slightly lower numbers of sulfate reducers. These columns also had a slightly improved U(VI) removal efficiency, which might be attributed to the higher Geobacter-like numbers.

  20. Hyperfine structure in the configuration 4 f 136 s7 s of Tm I

    NASA Astrophysics Data System (ADS)

    Kronfeldt, H.-D.; Kröger, S.

    1995-12-01

    Doppler-free saturation absorption spectroscopy was applied on an atomic thulium vapour in a see-through hollow cathode for the determination of precise values for the magnetic dipole hyperfine structure constants A of 6 levels of the configuration 4 f 13 6 s7 s. A parametric analysis of the hyperfine structure has been performed, using wave-functions from a fine structure calculation, which leads to one-electron hyperfine structure parameters a {4/f 01}=-500(6) MHz, a {6/s 10}=-5058(47) MHz, and a {7/s 10}=-1012 MHz.

  1. Noncollinear Fe spin structure in (Sm-Co)/Fe exchange-spring bilayers: Layer-resolved 57Fe Mössbauer spectroscopy and electronic structure calculations

    NASA Astrophysics Data System (ADS)

    Uzdin, V. M.; Vega, A.; Khrenov, A.; Keune, W.; Kuncser, V. E.; Jiang, J. S.; Bader, S. D.

    2012-01-01

    Magnetization reversal in nanoscale (Sm-Co)/Fe (hard/soft) bilayer exchange-spring magnets with in-plane uniaxial magnetic anisotropy was investigated by magnetometry, conversion-electron Mössbauer spectroscopy (CEMS) and atomistic Fe spin-structure calculations. Magnetization loops along the easy direction exhibit signatures typical of exchange-spring magnets. In-field CEMS at inclined γ-ray incidence onto thin (2 nm) 57Fe probe layers embedded at various depths in the 20-nm-thick natural (soft) Fe layer provides depth-dependent information (via the line-intensity ratio R23 as a function of the applied field H) about the in-plane rotation of Fe spins. A minimum in the R23-vs-H dependence at (Hmin, Rmin) determines the field where Fe magnetic moments roughly adopt an average perpendicular orientation during their reversal from positive to negative easy-axis orientation. A monotonic decrease of Hmin with distance from the hard/soft interface is observed. Rotation of Fe spins takes place even in the interface region in applied fields far below the field of irreversible switching, Hirr, of the hard phase. Formation of an Fe-Co alloy is detected in the interface region. For comparison, the noncollinear Fe spin structure during reversal and the resulting R23 ratio were obtained by electronic-structure calculations based on a quantum-mechanical Hamiltonian for itinerant electrons. The coupling at the hard/soft interface is described by the uniaxial exchange-anisotropy field, hint, as a parameter. Our calculated R23 ratios as a function of the (reduced) applied field h exhibit similar features as observed in the experiment, in particular a minimum at (hmin, Rmin). Rmin is found to increase with hint, thus providing a measure of the interface coupling. Evidence is provided for the existence of fluctuations of the interface coupling. The calculations also show that the Fe spin spiral formed during reversal is highly inhomogeneous. In general, our simulation of the Fe spin

  2. Noncollinear Fe spin structure in (Sm-Co)/Fe exchange-spring bilayers: layer-resolved {sup 57}Fe Mssbauer spectroscopy and electronic structure calculations.

    SciTech Connect

    Uzdin, V. M.; Vega, A.; Khrenov, A.; Keune, W.; Kuncser, V. E.; Jiang, J. S.; Bader, S. D.

    2012-01-01

    Magnetization reversal in nanoscale (Sm-Co)/Fe (hard/soft) bilayer exchange-spring magnets with in-plane uniaxial magnetic anisotropy was investigated by magnetometry, conversion-electron Moessbauer spectroscopy (CEMS) and atomistic Fe spin-structure calculations. Magnetization loops along the easy direction exhibit signatures typical of exchange-spring magnets. In-field CEMS at inclined {gamma}-ray incidence onto thin (2 nm) {sup 57}Fe probe layers embedded at various depths in the 20-nm-thick natural (soft) Fe layer provides depth-dependent information (via the line-intensity ratio R{sub 23} as a function of the applied field H) about the in-plane rotation of Fe spins. A minimum in the R{sub 23}-vs-H dependence at (H{sub min}, R{sub min}) determines the field where Fe magnetic moments roughly adopt an average perpendicular orientation during their reversal from positive to negative easy-axis orientation. A monotonic decrease of H{sub min} with distance from the hard/soft interface is observed. Rotation of Fe spins takes place even in the interface region in applied fields far below the field of irreversible switching, H{sub irr}, of the hard phase. Formation of an Fe-Co alloy is detected in the interface region. For comparison, the noncollinear Fe spin structure during reversal and the resulting R{sub 23} ratio were obtained by electronic-structure calculations based on a quantum-mechanical Hamiltonian for itinerant electrons. The coupling at the hard/soft interface is described by the uniaxial exchange-anisotropy field, hint, as a parameter. Our calculated R{sub 23} ratios as a function of the (reduced) applied field h exhibit similar features as observed in the experiment, in particular a minimum at (h{sub min}, R{sub min}). R{sub min} is found to increase with hint, thus providing a measure of the interface coupling. Evidence is provided for the existence of fluctuations of the interface coupling. The calculations also show that the Fe spin spiral formed

  3. Hadronic light-by-light scattering in muonium hyperfine splitting

    SciTech Connect

    Karshenboim, S. G.; Shelyuto, V. A.; Vainshtein, A. I.

    2008-09-15

    We consider an impact of hadronic light-by-light scattering on the muonium hyperfine structure. A shift of the hyperfine interval {delta}{nu}(Mu){sub HLBL} is calculated with the light-by-light scattering approximated by the exchange of pseudoscalar and pseudovector mesons. Constraints from the operator product expansion in QCD are used to fix parameters of the model similar to the one used earlier for the hadronic light-by-light scattering in calculations of the muon anomalous magnetic moment. The pseudovector exchange is dominant in the resulting shift, {delta}{nu}(Mu){sub HLBL}=-0.0065(10) Hz. Although the effect is tiny it is useful in understanding the level of hadronic uncertainties.

  4. 57Fe Mössbauer spectroscopy on disordered crystalline media with Ca-gallogermanate type structure. I. In the paramagnetic range

    NASA Astrophysics Data System (ADS)

    Barb, D.; Constantinescu, S.; Tarina, D.

    1995-12-01

    Polycrystalline strontium iron germanates of the type Sr3- y Ln y Fe2+ y Ge4- y O14(Ln=La, Nd; y=0, 1) were investigated by57Fe Mössbauer spectroscopy in the temperature range 4.2 300 K. The crystal chemistry and the distribution of Fe3+ ions in the structure, as well as the crystallographic inequivalence of the oxygen polyhedra occupied by iron, were studied over the whole paramagnetic temperature region. A correlation of the experimental data with a local environment computation is given.

  5. Molecular hyperfine fields in organic magnetoresistance devices

    NASA Astrophysics Data System (ADS)

    Giro, Ronaldo; Rosselli, Flávia P.; dos Santos Carvalho, Rafael; Capaz, Rodrigo B.; Cremona, Marco; Achete, Carlos A.

    2013-03-01

    We calculate molecular hyperfine fields in organic magnetoresistance (OMAR) devices using ab initio calculations. To do so, we establish a protocol for the accurate determination of the average hyperfine field Bhf and apply it to selected molecular ions: NPB, TPD, and Alq3. Then, we make devices with precisely the same molecules and perform measurements of the OMAR effect, in order to address the role of hole-transport layer in the characteristic magnetic field B0 of OMAR. Contrary to common belief, we find that molecular hyperfine fields are not only caused by hydrogen nuclei. We also find that dipolar contributions to the hyperfine fields can be comparable to the Fermi contact contributions. However, such contributions are restricted to nuclei located in the same molecular ion as the charge carrier (intramolecular), as extramolecular contributions are negligible.

  6. Hybrid density functional approach to the isotropic and anisotropic hyperfine couplings with 14N and 1H nuclei in the blue copper proteins

    NASA Astrophysics Data System (ADS)

    Jaszewski, Adrian R.; Jezierska, Julia

    2001-08-01

    We report UB1LYP hybrid density functional studies on the hyperfine parameters of wild-type azurin from Pseudomonas aeruginosa and M121Q mutant of azurin from Alcaligenes denitrificans. The large models of the copper site used in the calculations give quantitative insight into the spin density distribution and confirm highly delocalized character of the unpaired electron. Theoretically predicted isotropic and anisotropic hyperfine couplings are compared to the available EPR data and the assignment of the hyperfine splittings is verified.

  7. Scrutinizing Al-like 10+51V, 11+53Cr, 12+55Mn, 13+57Fe, 14+59Co, 15+61Ni, and 16+63Cu 1ions for atomic clocks with uncertainties below the 10-19 level

    NASA Astrophysics Data System (ADS)

    Yu, Yan-mei; Sahoo, B. K.

    2016-12-01

    We investigate the transition between the fine structure levels of the ground state, 3 p 2P1 /2→3 p 2P3 /2 , of the highly charged Al-like 10+51V, 11+53Cr, 12+55Mn, 13+57Fe, 14+59Co, 15+61Ni, and 16+63Cu ions for frequency standards. To comprehend them as prospective atomic clocks, we determine their transition wavelengths, quality factors, and various plausible systematics during the measurements. Since most of these ions have nuclear spin I =3 /2 , uncertainties due to dominant quadrupole shifts can be evaded in the F =0 hyperfine level of the 3 p 2P3 /2 state. Other dominant systematics such as quadratic Stark and black-body radiation shifts have been evaluated precisely demonstrating the feasibility of achieving high accuracy, below 10-19 fractional uncertainty, atomic clocks using the above transitions. Moreover, relativistic sensitivity coefficients are determined to find out the aptness of these proposed clocks to investigate possible temporal variation of the fine structure constant. To carry out these analysis, a relativistic coupled-cluster method considering Dirac-Coulomb-Breit Hamiltonian along with lower-order quantum electrodynamics interactions is employed and many spectroscopic properties are evaluated. These properties are also of immense interest for astrophysical studies.

  8. Exogenous iron redistribution between brain and spleen after the administration of the 57Fe3O4 ferrofluid into the ventricle of the brain

    NASA Astrophysics Data System (ADS)

    Gabbasov, Raul; Polikarpov, Dmitry; Cherepanov, Valery; Chuev, Michael; Mischenko, Ilya; Loginiva, Nadezhda; Loseva, Elena; Nikitin, Maxim; Panchenko, Vladislav

    2017-04-01

    Iron clearance pathways after the injection of 57Fe3O4-based dextran-stabilized ferrofluid into the brain ventricles were studied by Mössbauer spectroscopy and histologically. The nanoparticles appeared in spleen tissues within 3 h after transcranial injection. We separated and independently estimated concentrations of iron encapsulated in nanoparticles and iron encapsulated in proteins in the all rat organs. It was found that the dextran coated initial nanoparticles of the ferrofluid disintegrated in the brain into separate superparamagnetic nanoparticles within a week after the injection.The nanoparticles completely exited from the brain in a few weeks. The exogenous iron appeared in the spleen in 3 h after the injection and remained in the spleen for more than month. The appearance of additional component in Mössbauer spectra of spleen samples revealed a fundamental difference in the mechanisms of processing of iron nanoparticles in this organ, which was also confirmed by histological examination.

  9. Nuclear resonant scattering measurements on {sup 57}Fe by multichannel scaling with a 64-pixel silicon avalanche photodiode linear-array detector

    SciTech Connect

    Kishimoto, S. Haruki, R.; Mitsui, T.; Yoda, Y.; Taniguchi, T.; Shimazaki, S.; Ikeno, M.; Saito, M.; Tanaka, M.

    2014-11-15

    We developed a silicon avalanche photodiode (Si-APD) linear-array detector for use in nuclear resonant scattering experiments using synchrotron X-rays. The Si-APD linear array consists of 64 pixels (pixel size: 100 × 200 μm{sup 2}) with a pixel pitch of 150 μm and depletion depth of 10 μm. An ultrafast frontend circuit allows the X-ray detector to obtain a high output rate of >10{sup 7} cps per pixel. High-performance integrated circuits achieve multichannel scaling over 1024 continuous time bins with a 1 ns resolution for each pixel without dead time. The multichannel scaling method enabled us to record a time spectrum of the 14.4 keV nuclear radiation at each pixel with a time resolution of 1.4 ns (FWHM). This method was successfully applied to nuclear forward scattering and nuclear small-angle scattering on {sup 57}Fe.

  10. Search for 14.4 keV solar axions emitted in the M1-transition of {sup 57}Fe nuclei with CAST

    SciTech Connect

    Andriamonje, S.; Aune, S.; Dafni, T.; Ferrer-Ribas, E.; Autiero, D.; Barth, K.; Davenport, M.; Lella, L. Di; Belov, A.; Beltrán, B.; Carmona, J.M.; Cebrián, S.; Bräuninger, H.; Englhauser, J.; Friedrich, P.; Collar, J.I.; Eleftheriadis, C.; Fanourakis, G.; Fischer, H.; Franz, J.; Collaboration: CAST collaboration; and others

    2009-12-01

    We have searched for 14.4 keV solar axions or more general axion-like particles (ALPs), that may be emitted in the M1 nuclear transition of {sup 57}Fe, by using the axion-to-photon conversion in the CERN Axion Solar Telescope (CAST) with evacuated magnet bores (Phase I). From the absence of excess of the monoenergetic X-rays when the magnet was pointing to the Sun, we set model-independent constraints on the coupling constants of pseudoscalar particles that couple to two photons and to a nucleon g{sub aγ}|−1.19g{sub aN}{sup 0}+g{sub aN}{sup 3}| < 1.36 × 10{sup −16} GeV{sup −1} for m{sub a} < 0.03 eV at the 95% confidence level.

  11. Thermal decomposition and reconstruction of CaFe-layered double hydroxide studied by X-ray diffractometry and 57Fe Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Bugris, Valéria; Ádok-Sipiczki, Mónika; Anitics, Tamás; Kuzmann, Ernő; Homonnay, Zoltán; Kukovecz, Ákos; Kónya, Zoltán; Sipos, Pál; Pálinkó, István

    2015-06-01

    In spite of numerous investigations on the various processes of the thermal decomposition and rehydration of layered double hydroxides (LDHs) by a variety sophisticated experimental means, many details are still unexplored and some contradictions are still unresolved. In this work, our efforts were focussed on clarifying the composition, structure and properties of thermally decomposed metaphases originating from CaFe-LDH, heat treated in the 373-973 K temperature range. The structure reconstruction ability of mixed metal oxide phases obtained after heat treatments was also investigated, mainly concentrating on the changes in the microenvironment of Fe(III), in the presence of controlled amount of water vapour (i.e., at different relative humidities). All samples were characterised by X-ray diffractometry, and the iron-containing phases were studied by 57Fe Mössbauer spectroscopy.

  12. Structure and oscillational motion of /sup 57/Fe atoms in interstitial sites in Al as determined from interference of Moessbauer. gamma. radiation

    SciTech Connect

    Pauling, L.

    1981-12-01

    The first excited site of the /sup 57/Fe atom entrapped in an interstitial site in aluminum, as reported by W. Petry, G. Vogl, and W. Mansel (Phys. Rev. Lett. 45, 1862 (1980)) from a Moessbauer spectroscopic study of a single crystal, is analyzed by consideration of the value of the Hooke's law constant of the Fe-Al bonds obtained from the values for elemental Fe and Al. The eight wavefunctions for the eightfold nearly degenerate excited state are described as 2s1p1d1f hybrids of three-dimensional harmonic oscillator wavefunctions relative to the center of the undistorted Al/sub 6/ octahedron or as localized 1s functions relative to the center of the distorted octahedron. These considerations provide a qualitative understanding of the observations on this system.

  13. Effect of hyperfine splitting on light-induced drift

    NASA Astrophysics Data System (ADS)

    Parkhomenko, A. I.; Shalagin, A. M.

    1986-09-01

    The influence of the hyperfine structure (hfs) of the levels upon the light-induced drift (LID) effect is investigated. It is shown that hfs considerably affects the dependence of the LID velocity upon the radiation frequency. It is concluded that for decreasing separation between the hfs components the LID effect can both increase and decrease depending upon the relationship of the system parameters (collision frequencies in different levels, the pressure of a buffer gas, etc.). A considerable decrease of the effect however is highly unlikely. It is shown that a change in the buffer gas pressure can lead to reversal of the LID velocity direction.

  14. Fluctuating hyperfine interactions: an updated computational implementation

    NASA Astrophysics Data System (ADS)

    Zacate, M. O.; Evenson, W. E.

    2015-04-01

    The stochastic hyperfine interactions modeling library (SHIML) is a set of routines written in the C programming language designed to assist in the analysis of stochastic models of hyperfine interactions. The routines read a text-file description of the model, set up the Blume matrix, upon which the evolution operator of the quantum mechanical system depends, and calculate the eigenvalues and eigenvectors of the Blume matrix, from which theoretical spectra of experimental techniques can be calculated. The original version of SHIML constructs Blume matrices applicable for methods that measure hyperfine interactions with only a single nuclear spin state. In this paper, we report an extension of the library to provide support for methods such as Mössbauer spectroscopy and nuclear resonant scattering of synchrotron radiation, which are sensitive to interactions with two nuclear spin states. Examples will be presented that illustrate the use of this extension of SHIML to generate Mössbauer spectra for polycrystalline samples under a number of fluctuating hyperfine field models.

  15. Observation of molecular hyperfine structure in the extreme ultraviolet: The HF C-X spectrum.

    PubMed

    Philippson, Jeffrey N; Shiell, Ralph C; Reinhold, Elmar; Ubachs, Wim

    2008-11-07

    Clearly resolved hyperfine structure has been observed in the extreme ultraviolet (XUV) spectra of the C (1)Pi, v=0-X (1)Sigma(+), v=0 transition of H(19)F obtained through 1 XUV+1 UV resonance enhanced multiphoton ionization spectroscopy. The hyperfine splitting within the R-branch lines shows significant perturbations, which we attribute to mixing with the rotational levels of the nearby v=29 level of the B (1)Sigma(+) ion-pair state. A deperturbation analysis quantitatively explains the apparent variation of the fluorine magnetic hyperfine parameter a(F), for which a value of 4034(83) MHz was obtained by averaging over the values derived from the R(0)-R(4) lines, after correcting for the effects of the perturbations.

  16. Structure comparison between Th2Zn17-type and TbCu7-type Sm Fe intermetallic compounds and their nitrides by means of 57Fe-Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Sakai, Yoichi; Omatsuzawa, Ryo; Sakazaki, Iwao; Suzuki, Sayaka; Hashino, Hayato; Saito, Takanobu; Iriyama, Takahiko

    2005-11-01

    Samarium iron intermetallic compounds were prepared by a melt spinning method with low and high wheel speeds, which resulted in a Th2Zn17-type and a TbCu7-type structure, respectively. Structure comparison between these types was investigated for Sm Fe intermetallic compounds and their nitrides by 57Fe-Mössbauer spectroscopy.

  17. Hyperfine meson splittings: chiral symmetry versus transverse gluon exchange

    SciTech Connect

    Felipe J. Llanes-Estrada; Stephen R. Cotanch; Adam P. Szczepaniak; Eric S. Swanson

    2004-02-01

    Meson spin splittings are examined within an effective Coulomb gauge QCD Hamiltonian incorporating chiral symmetry and a transverse hyperfine interaction necessary for heavy quarks. For light and heavy quarkonium systems the pseudoscalar-vector meson spectrum is generated by approximate BCS-RPA diagonalizations. This relativistic formulation includes both S and D waves for the vector mesons which generates a set of coupled integral equations. A smooth transition from the heavy to the light quark regime is found with chiral symmetry dominating the /pi-/rho mass difference. A good, consistent description of the observed meson spin splittings and chiral quantities, such as the quark condensate and the /pi mass, is obtained. Similar comparisons with TDA diagonalizations, which violate chiral symmetry, are deficient for light pseudoscalar mesons indicating the need to simultaneously include both chiral symmetry and a hyperfine interaction. The /eta{sub b} mass is predicted to be around 9400 MeV consistent with other theoretical expectations and above the unconfirmed 9300 MeV candidate. Finally, for comparison with lattice results, the J reliability parameter is also evaluated.

  18. Transition to collapsed tetragonal phase in CaFe2As2 single crystals as seen by 57Fe Mössbauer spectroscopy

    DOE PAGES

    Bud'ko, Sergey L.; Ma, Xiaoming; Tomić, Milan; ...

    2016-01-21

    Temperature dependent measurements of 57Fe Mössbauer spectra on CaFe2As2 single crystals in the tetragonal and collapsed tetragonal phases are reported. Clear features in the temperature dependencies of the isomer shift, relative spectra area, and quadrupole splitting are observed at the transition from the tetragonal to the collapsed tetragonal phase. From the temperature dependent isomer shift and spectral area data, an average stiffening of the phonon modes in the collapsed tetragonal phase is inferred. The quadrupole splitting increases by ~25% on cooling from room temperature to ~100 K in the tetragonal phase and is only weakly temperature dependent at low temperaturesmore » in the collapsed tetragonal phase, in agreement with the anisotropic thermal expansion in this material. In order to gain microscopic insight about these measurements, we perform ab initio density functional theory calculations of the electric field gradient and the electron density of CaFe2As2 in both phases. By comparing the experimental data with the calculations we are able to fully characterize the crystal structure of the samples in the collapsed-tetragonal phase through determination of the As z coordinate. Furthermore, based on the obtained temperature dependent structural data we are able to propose charge saturation of the Fe-As bond region as the mechanism behind the stabilization of the collapsed-tetragonal phase at ambient pressure.« less

  19. High field magnetic transitions in the mixed holmium-yttrium iron garnet Ho(0.43)Y(2.57)Fe(5)O(12).

    PubMed

    Bouguerra, A; Khène, S; de Brion, S; Chouteau, G; Fillion, G

    2005-01-12

    High static magnetic field magnetization measurements have been performed up to 23 T on Ho(0.43)Y(2.57)Fe(5)O(12) single crystals at helium temperature (T = 4.2 K) with fields applied along the three main cubic axes: [Formula: see text], [Formula: see text] and [Formula: see text]. The change from the spontaneous ferrimagnetic structure in zero magnetic field to the fully ferromagnetic one in high field takes place through several intermediate phases separated by transitions with step-like magnetization behaviour, but without any observed hysteresis. Using the effective spin Hamiltonian approximation, we show that the general features of these transitions can be accounted for by a large magnetocristalline anisotropy of the Ho(3+) moments of the uniaxial type along the local z axis of each rare-earth site. The model is in better agreement with the experiments than its Ising limit, widely used before, but is still unsuccessful in predicting the 'umbrella' magnetic structures found by previous neutron and NMR experiments.

  20. Transition to collapsed tetragonal phase in CaFe2As2 single crystals as seen by 57Fe Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Bud'ko, Sergey L.; Ma, Xiaoming; Tomić, Milan; Ran, Sheng; Valentí, Roser; Canfield, Paul C.

    2016-01-01

    Temperature dependent measurements of 57Fe Mössbauer spectra on CaFe2As2 single crystals in the tetragonal and collapsed tetragonal phases are reported. Clear features in the temperature dependencies of the isomer shift, relative spectra area, and quadrupole splitting are observed at the transition from the tetragonal to the collapsed tetragonal phase. From the temperature dependent isomer shift and spectral area data, an average stiffening of the phonon modes in the collapsed tetragonal phase is inferred. The quadrupole splitting increases by ˜25 % on cooling from room temperature to ˜100 K in the tetragonal phase and is only weakly temperature dependent at low temperatures in the collapsed tetragonal phase, in agreement with the anisotropic thermal expansion in this material. In order to gain microscopic insight about these measurements, we perform ab initio density functional theory calculations of the electric field gradient and the electron density of CaFe2As2 in both phases. By comparing the experimental data with the calculations we are able to fully characterize the crystal structure of the samples in the collapsed-tetragonal phase through determination of the As z coordinate. Based on the obtained temperature dependent structural data we are able to propose charge saturation of the Fe-As bond region as the mechanism behind the stabilization of the collapsed-tetragonal phase at ambient pressure.

  1. Sensitivity of the CUORE detector to 14.4 keV solar axions emitted by the M1 nuclear transition of {sup 57}Fe

    SciTech Connect

    Li, Dawei; Creswick, Richard J.; III, Frank T. Avignone; Wang, Yuanxu E-mail: creswick.rj@sc.edu E-mail: wangyx@henu.edu.cn

    2016-02-01

    In this paper we present a calculation of the sensitivity of the CUORE detector to the monoenergetic 14.4 keV solar axions emitted by the M1 nuclear transition of {sup 57}Fe in the Sun and detected by inverse coherent Bragg-Primakoff conversion in single-crystal TeO{sub 2} bolometers. The expected counting rate is calculated using density functional theory for the electron charge density of TeO{sub 2} and realistic background and energy resolution of CUORE. Monte Carlo simulations for 5y × 741 kg=3705 kg y of exposure are analyzed using time correlation of individual events with the theoretical time-dependent counting rate. We find an expected model-independent limit on the product of the axion-photon coupling and the axion-nucleon coupling g{sub aγγ}g{sub aN}{sup eff} < 1.105 × 10{sup −16} /GeV for axion masses less than 500 eV with 95% confidence level.

  2. Magnetic hysteresis properties and 57Fe Mössbauer spectroscopy of iron and stony-iron meteorites: Implications for mineralogy and thermal history

    NASA Astrophysics Data System (ADS)

    Dos Santos, E.; Gattacceca, J.; Rochette, P.; Scorzelli, R. B.; Fillion, G.

    2015-05-01

    Since the solid matter in our solar system began to assemble 4.57 billion years ago, meteorites have recorded a large range of processes, including metamorphism, melting, irradiation and hypervelocity impacts. These processes as well as solar system magnetic fields can be accessed through the investigation of magnetic properties of meteorites. In this work, we present magnetic hysteresis properties, isothermal remanent magnetization acquisition curves and 57Fe Mössbauer spectra for nineteen iron and eleven stony-iron meteorites. These data will be the background for a discussion about the thermal and shock history of these meteorites. Although Mössbauer spectroscopy and hysteresis measurements are not able to provide cooling rates like the conventional metallographic method does, we show that the combination of the ordering degree of taenite phase measured by Mössbauer spectroscopy and hysteresis properties are useful for constraining the thermal and shock history of meteorites. In particular, strong shock and the associated thermal event that result in disordering of tetrataenite can be easily identified.

  3. Synthesis, structure of [H{sub 3} dien].(MF{sub 6}).H{sub 2}O (M=Cr, Fe) and {sup 57}Fe Moessbauer study of [H{sub 3} dien].(FeF{sub 6}).H{sub 2}O

    SciTech Connect

    Ben Ali, Amor Trang Dang, Minh; Greneche, Jean-Marc; Hemon-Ribaud, Annie; Leblanc, Marc; Maisonneuve, Vincent

    2007-06-15

    Single crystals of [H{sub 3} dien].(FeF{sub 6}).H{sub 2}O (I) and [H{sub 3} dien].(CrF{sub 6}).H{sub 2}O (II) are obtained by solvothermal synthesis under microwave heating. I is orthorhombic (Pna2{sub 1}) with a=11.530(2) A, b=6.6446(8) A, c=13.787(3) A, V=1056.3(2) A{sup 3} and Z=4. II is monoclinic (P2{sub 1} /c) with a=13.706(1) A, b=6.7606(6) A, c=11.3181(9) A, {beta}=99.38(1){sup o}, V=1034.7(1) A{sup 3} and Z=4. The structure determinations, performed from single crystal X-ray diffraction data, lead to the R {sub 1}/wR {sub 2} reliability factors 0.028/0.066 for I and 0.035/0.102 for II. The structures of I and II are built up from isolated FeF{sub 6} or CrF{sub 6} octahedra, water molecules and triprotonated amines. In both structures, each octahedron is connected by hydrogen bonds to six organic cations and two water molecules. The iron-based compound is also characterized by {sup 57}Fe Moessbauer spectrometry: the hyperfine structure confirms the presence of Fe{sup 3+} in octahedral coordination and reveals the existence of paramagnetic spin fluctuations. - Graphical abstract: Moessbauer spectra of [H{sub 3} dien].(FeF{sub 6}).H{sub 2}O.

  4. Glancing and Normal Incidence Cems Study of Hyperfine Interactions in IRON-57/GALLIUM ARSENIDE(110) Single-Crystal Films.

    NASA Astrophysics Data System (ADS)

    Wagner, Randall Paul

    CEMS spectra were gathered at room temperature for a series of Al overcoated ^{57 }Fe/GaAs(110) thin films (32-123 A) utilizing both normal and glancing incidence geometries. This research was conducted in order to investigate the effects which impurity diffusion, chemical reaction, and the Fe/substrate interface have on the hyperfine interactions within this system. All of the films were found to contain Fe nuclei with the same hyperfine field and isomer shift as is found in bulk Fe. Approximately 1-3 ML of paramagnetic Fe were also present, along with Fe atoms belonging to a solid mixture. None of the Mossbauer spectra of the bulk compounds FeAs, Fe_2As, or FeAs_2 were observed in the spectra of these films. Both the bulk-like Fe and mixture region were discovered to increase in thickness as the number of deposited Fe layers increased. In addition, the correlation between the average isomer shift and hyperfine field for part of the mixture in the thickest films was in good agreement with that found in dilute Fe-As alloys. This was not the case however, for the thinner films and that part of the mixture made up predominantly of Fe atoms which had lower hyperfine fields. Furthermore, the data revealed that the reduced magnetization previously measured in Fe/GaAs(110) thin films was not due exclusively to a decrease in the magnitude of the moment per Fe atom. Additional spectra were gathered for the 123 A film in applied magnetic fields with two different glancing geometries. The relative line intensities measured with the two geometries were compared at similar fields using a method which also incorporated the normal incidence results. From this comparison, it was discovered that 5.5% of the moment could be modeled oriented normal to the film plane with the rest confined to the film plane. Another model, which allowed for 16% of the moment to be randomly oriented while the remaining fraction was in-plane, also yielded better results than a model which assumed an

  5. Hyperfine Structure measurements of 45Sc

    NASA Astrophysics Data System (ADS)

    Jones, K. D.; Rossi, D. M.; Minamisono, K.; Miller, A. J.; Asberry, H.; Mantica, P. F.

    2015-10-01

    A chain of charge radii shows discontinuity at nucleon magic numbers. This signature of the shell closure, however, is missing at the neutron magic number N = 20 for Ar, Ca and K isotopes. A collinear laser spectroscopy experiment on the stable 45Sc isotope, which is one proton added to Ca, was performed as a prerequisite of radioactive beam experiments on Sc across N = 20 to further investigate the abnormal behavior. The experiment was performed at BEam COoling and LAser spectroscopy (BECOLA) facility at NSCL and a hyperfine spectrum was measured for the electronic transition of 3 d 4 s 3D1 --> 3 d 4 p 3F2 at λ = 364 . 3 nm in 45ScII. The magnetic dipole and electric quadrupole hyperfine coupling constants A and B of both the lower and upper states were obtained from the hyperfine structure by fitting a pseudo-Voigt profile. The results obtained from these data are in good agreement with previous values and have smaller statistical errors. The detail of experiment and analysis will be discussed. This work was supported in part by NSF Grant No. PHY-11-02511.

  6. Full hyperfine structure analysis of singly ionized molybdenum

    NASA Astrophysics Data System (ADS)

    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.

  7. Constraints on the oxidation state of the mantle: An electrochemical and sup 57 Fe Moessbauer study of mantle-derived ilmenites

    SciTech Connect

    Virgo, D.; Luth, R.W. ); Moats, M.A.; Ulmer, G.C. )

    1988-07-01

    Ilmenite samples from four kimberlite localities were studied using electrochemical, Moessbauer spectroscopic, and microprobe analytical techniques in order to infer the oxidation state of their source regions in the mantle. The values of Fe{sup 3+}/{Sigma}Fe calculated from analyses, using three different electron microanalytical instruments assuming ilmenite stoichiometry, are consistently higher than those derived from the Moessbauer data, by as much as 100%. Furthermore, the range in Fe{sup 3+}/{Sigma}Fe calculated using the analyses from different instruments and/or different correction schemes is nearly as large. Thus Fe{sup 3+}/{Sigma}Fe calculated from microprobe analyses should be taken with caution, even if the precision appears high. {sup 57}Fe Moessbauer spectroscopy on the electrochemical experiment run products demonstrates that Fe{sup 3+}/{Sigma}Fe is significantly lower than it is for the natural C-bearing ilmenites. In contrast, the ilmenite that lacked C did not change Fe{sup 3+}/{Sigma}Fe during the electrochemical experiment. Examination of the reduced samples with SEM established that the natural, single-phase ilmenites exsolved during the electrochemical experiment to form ilmenite{sub ss} + spinel{sub ss}. The initial, reduced trends in the electrochemical experiments for the C-bearing ilmenites are attributed to disequilibrium interactions between the decomposing sample and the evolved gas in the electrochemical cell and do not represent the quenched mantle memory nor the intrinsic f{sub O{sub 2}} of the sample prior to reduction. Furthermore, the oxidized f{sub O{sub 2}} trend is interpreted, for the carbon-bearing samples, are representing the f{sub O{sub 2}} of the ilmenite{sub ss} + spinel{sub ss} assemblage and not the intrinsic f{sub o{sub 2}} of the mantle-derived ilemnite{sub ss}.

  8. Magnetic and 57Fe Mössbauer study of the single molecule magnet behavior of a Dy3Fe7 coordination cluster.

    PubMed

    Abbas, Ghulam; Lan, Yanhua; Mereacre, Valeriu; Wernsdorfer, Wolfgang; Clérac, Rodolphe; Buth, Gernot; Sougrati, Moulay T; Grandjean, Fernande; Long, Gary J; Anson, Christopher E; Powell, Annie K

    2009-10-05

    The reaction between N-methydiethanolamine (mdeaH(2)), benzoic acid, FeCl(3), and DyCl(3) yields a decanuclear coordination cluster, [Dy(3)Fe(7)(mu(4)-O)(2)(mu(3)-OH)(2)(mdea)(7)(mu-benzoate)(4)(N(3))(6)] x 2 H(2)O x 7 CH(3)OH (1) whose single crystal structure exhibits three and seven crystallographically distinct Dy(III) and Fe(III) ions; six of the Fe(III) ions are pseudo-octahedrally coordinated, whereas the seventh has a trigonal-bipyramidal coordination geometry. Both direct current (dc) and alternating current (ac) magnetic susceptibility studies indicate that, upon cooling, intracluster antiferromagnetic interactions are dominant in 1, yielding a ferrimagnetic spin arrangement. The out-of-phase (chi'') ac susceptibility reveals that 1 undergoes a slow relaxation of its magnetization mainly resulting from the anisotropy of the Dy(III) ions. This slow relaxation has been confirmed both by magnetization measurements on an oriented single crystal of 1 and by the observation of hysteresis loops below 1.9 K. The macroscopic magnetic studies yield an effective energy barrier, U(eff), of 33.4 K for this relaxation, a barrier that is the highest yet reported for a lanthanide(III)-Fe(III) single molecule magnet. The (57)Fe Mössbauer spectra of 1 obtained between 3 and 35 K are consistent with the presence of Fe(III) intracluster antiferromagnetic coupling with slow magnetic relaxation relative to the Larmor precession time, thus confirming, on a microscopic scale, the presence of a barrier to the magnetic relaxation below 35 K. Between 55 and 295 K the Mössbauer spectra reveal paramagnetic behavior with six partially resolved quadrupole doublets, one for the trigonal-bipyramidal Fe(III) site and five for the six pseudo-octahedral Fe(III) sites.

  9. Redox condition of the late Neoproterozoic pelagic deep ocean: 57Fe Mössbauer analyses of pelagic mudstones in the Ediacaran accretionary complex, Wales, UK

    NASA Astrophysics Data System (ADS)

    Sato, Tomohiko; Sawaki, Yusuke; Asanuma, Hisashi; Fujisaki, Wataru; Okada, Yoshihiro; Maruyama, Shigenori; Isozaki, Yukio; Shozugawa, Katsumi; Matsuo, Motoyuki; Windley, Brian F.

    2015-11-01

    We report geological and geochemical analysis of Neoproterozoic pelagic deep-sea mudstones in an accretionary complex in Lleyn, Wales, UK. Ocean plate stratigraphy at Porth Felen, NW Lleyn, consists of mid-ocean ridge basalt (> 4 m), bedded dolostone (2 m), black mudstone (5 m), hemipelagic siliceous mudstone (1 m,) and turbiditic sandstone (15 m), in ascending order. The absence of terrigenous clastics confirms that the black and siliceous mudstone was deposited in a pelagic deep-sea. Based on the youngest U-Pb age (564 Ma) of detrital zircons separated from overlying sandstone, the deep-sea black mudstone was deposited in the late Ediacaran. The 5 m-thick black mudstone contains the following distinctive lithologies: (i) black mudstone with thin pyritic layers (0.8 m), (ii) alternation of black mudstone and gray/dark gray siliceous mudstone (2.4 m), (iii) thinly-laminated dark gray shale (1 m), and (iv) black mudstone with thin pyritic layers (1 m). 57Fe Mössbauer spectroscopy confirms that these black mudstones contain pyrite without hematite. In contrast, red bedded claystones (no younger than 542 Ma) in the neighboring Braich section contain hematite as their main iron mineral. These deep-sea mudstones in the Lleyn Peninsula record a change of redox condition on the pelagic deep-sea floor during the Ediacaran. The black mudstone at Porth Felen shows that deep-sea anoxia existed in the late Ediacaran. The eventual change from a reducing to an oxidizing deep-sea environment likely occurred in the late Ediacaran (ca. 564-542 Ma).

  10. HCN hyperfine ratio analysis of massive molecular clumps

    NASA Astrophysics Data System (ADS)

    Schap, W. J.; Barnes, P. J.; Ordoñez, A.; Ginsburg, A.; Yonekura, Y.; Fukui, Y.

    2017-03-01

    We report a new analysis protocol for HCN hyperfine data, based on the PYSPECKIT package, and results of using this new protocol to analyse a sample area of seven massive molecular clumps from the Census of High- and Medium-mass Protostars (CHaMP) survey, in order to derive maps of column density for this species. There is a strong correlation between the HCN integrated intensity, IHCN, and previously reported I_HCO+ in the clumps, but I_N_{2H+} is not well correlated with either of these other two 'dense gas tracers'. The four fitted parameters from PYSPECKIT in this region fall in the range of VLSR = 8-10 km s-1, σV = 1.2-2.2 km s-1, Tex = 4-15 K, and τ = 0.2-2.5. These parameters allow us to derive a column density map of these clouds, without limiting assumptions about the excitation or opacity. A more traditional (linear) method of converting IHCN to total mass column gives much lower clump masses than our results based on the hyperfine analysis. This is primarily due to areas in the sample region of low I, low Tex, and high τ. We conclude that there may be more dense gas in these massive clumps not engaged in massive star formation than previously recognized. If this result holds for other clouds in the CHaMP sample, it would have dramatic consequences for the calibration of the Kennicutt-Schmidt star formation laws, including a large increase in the gas depletion time-scale in such regions.

  11. Hyperfine field and magnetic structure in the B phase of CeCoIn5

    SciTech Connect

    Graf, Matthias J; Curro, Nicholas J; Young, Ben - Li; Urbano, Ricardo R

    2009-01-01

    We re-analyze Nuclear Magnetic Resonance (NMR) spectra observed at low temperatures and high magnetic fields in the field-induced B-phase of CeCoIn{sub 5}. The NMR spectra are consistent with incommensurate antiferromagnetic order of the Ce magnetic moments. However, we find that the spectra of the In(2) sites depend critically on the direction of the ordered moments, the ordering wavevector and the symmetry of the hyperfine coupling to the Ce spins. Assuming isotropic hyperfine coupling, the NMR spectra observed for H {parallel} [100] are consistent with magnetic order with wavevector Q = {pi}(1+{delta}/a, 1/a, 1/c) and Ce moments ordered antiferromagnetically along the [100] direction in real space. If the hyperfine coupling has dipolar symmetry, then the NMR spectra require Ce moments along the [001] direction. The dipolar scenario is also consistent with recent neutron scattering measurements that find an ordered moment of 0.15{micro}{sub B} along [001] and Q{sub n} = {pi}(1+{delta}/a, 1+{delta}c, 1/c) with incommensuration {delta} = 0.12 for field H {parallel} [1{bar 1}0]. Using these parameters, we find that the hyperfine field is consistent with both experiments. We speculate that the B phase of CeCoIn{sub 5} represents an intrinsic phase of modulated superconductivity and antiferromagnetism that can only emerge in a highly clean system.

  12. Measurement of a hyperfine-induced spin-exchange frequency shift in atomic hydrogen

    SciTech Connect

    Walsworth, R.L.; Silvera, I.F. ); Mattison, E.M.; Vessot, R.F.C. )

    1992-09-01

    We have measured a hyperfine-induced spin-exchange frequency shift in the atomic-hydrogen ground-state hyperfine transition. A recent quantum-mechanical treatment of low-energy hydrogen-hydrogen scattering by Koelman {ital et} {ital al}. (Phys. Rev. A 38, 3535 (1988)) predicts such frequency shifts to become large at low temperature, and to affect the performance of atomic clocks such as the cryogenic hydrogen maser. The experiment reported here was performed with a hydrogen maser operating near room temperature, where the reported hyperfine effects are predicted to be small, but measurable. Using an adiabatic fast passage (AFP) technique to vary the incoming atomic population in the masing states from approximately 100% (AFP on) to 50% (AFP off), we determined the change in the dimensionless hyperfine-induced frequency-shift parameter {Omega} to be {Omega}{sub on}{minus}{Omega}{sub off}=5.38 (1.06){times}10{sup {minus}4}. The theoretical prediction at this temperature is {Omega}{sub on}{minus}{Omega}{sub off}={minus}0.76{times}10{sup {minus}4} to {minus}1.12{times}10{sup {minus}4}, for the range of masing-state populations used in the present experiment. We review the relevant theory, report our experimental method and results, and discuss possible reasons for the discrepancy between experiment and theory.

  13. Observation of Enhancement of the Morin Transition Temperature in Iridium-Doped α-Fe2O3 Thin Film by 57Fe-Grazing Incidence Synchrotron Radiation Mössbauer Spectroscopy

    NASA Astrophysics Data System (ADS)

    Mitsui, Takaya; Mibu, Ko; Seto, Makoto; Kurokuzu, Masayuki; Pati, Satya Prakash; Nozaki, Tomohiro; Sahashi, Masashi

    2016-06-01

    The Morin transition of a (0001)-oriented iridium-doped α-Fe2O3 thin film deposited on an Al2O3(0001) substrate was studied by 57Fe-grazing incidence synchrotron radiation Mössbauer spectroscopy (GISRMS). Temperature-dependent spectra proved that the iridium doping markedly enhanced the Morin temperature of the α-Fe2O3 thin film; the iron spin directions were perpendicular to the film plane at temperatures below 100 °C, while they were in-plane at temperatures above 150 °C. The antiferromagnetic ordering was maintained far above 400 °C. The results demonstrated the availabilities of 57Fe-GISRMS, which enables a very quick evaluation of the magnetism in antiferromagnetic ultrathin films at high temperatures.

  14. Coexistence of magnetic fluctuations and superconductivity in SmFe0.95Co0.05AsO seen in 57Fe Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Long, G.; Demarco, M.; Chudyk, M.; Steiner, J.; Coffey, D.; Zeng, H.; Li, Y. K.; Cao, G. H.; Xu, Z. A.

    2011-08-01

    The Mössbauer spectra (MS) of powder samples of SmFe1-xCoxAsO (x = 0.0, 0.05, and 0.1) were measured in applied fields up to 9 T and at temperatures up to 298 K. SmFeAsO is magnetically ordered with TN = 137 K and has a hyperfine magnetic field of (4.98 ± 0.18) T at 4.2 K. In applied magnetic fields, the MS is consistent with a distribution of hyperfine magnetic fields of width Happlied+Hhyperfine. This arises because the angles between the direction of the ordered field in the crystallites making up the sample are randomly distributed about the direction of the applied field. The MS of the superconductors SmFe0.95Co0.05AsO (TC≃5 K) and SmFe0.9Co0.1AsO (TC≃17 K) are well described by a single peak from room temperature to 4.2 K indicating the absence of static magnetic order. However, the half width at half maximum, Γ, of the peak in SmFe0.95Co0.05AsO increases with decreasing temperature from its high temperature value, 0.13 mm/s at 25 K, to 0.25 mm/s at 10 K. No such temperature dependence is seen in SmFe0.9Co0.1AsO. We analyze this temperature dependence in terms of a fluctuating hyperfine magnetic field model whose frequency at 4.2 K is found to be ˜5-10 MHz, giving direct evidence of coexisting magnetic fluctuations and superconductivity at the interface in the phase diagram between the regions with magnetic and superconducting order. In a 5 T applied field, SmFe0.95Co0.05AsO is no longer superconducting; however, the temperature-dependent fluctuating magnetic field is still present and largely unchanged. The absence of fluctuations in superconducting SmFe0.9Co0.1AsO and their presence in superconducting SmFe0.95Co0.05AsO in zero applied field and in nonsuperconducting SmFe0.95Co0.05AsO at 5 T suggests that magnetic order is in competition with superconductivity in SmFe1-xCoxAsO.

  15. Nagaoka's atomic model and hyperfine interactions.

    PubMed

    Inamura, Takashi T

    2016-01-01

    The prevailing view of Nagaoka's "Saturnian" atom is so misleading that today many people have an erroneous picture of Nagaoka's vision. They believe it to be a system involving a 'giant core' with electrons circulating just outside. Actually, though, in view of the Coulomb potential related to the atomic nucleus, Nagaoka's model is exactly the same as Rutherford's. This is true of the Bohr atom, too. To give proper credit, Nagaoka should be remembered together with Rutherford and Bohr in the history of the atomic model. It is also pointed out that Nagaoka was a pioneer of understanding hyperfine interactions in order to study nuclear structure.

  16. Hyperfine structure of hydrogenlike thallium isotopes

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, Peter; Utter, Steven B.; Wong, Keith L.; Crespo López-Urrutia, José R.; Britten, Jerry A.; Chen, Hui; Harris, Clifford L.; Thoe, Robert S.; Thorn, Daniel B.; Träbert, Elmar; Gustavsson, Martin G. H.; Forssén, Christian; Mårtensson-Pendrill, Ann-Marie

    2001-09-01

    The hyperfine splitting of the 1s ground state of hydrogenlike Tl has been measured for the two stable isotopes using emission spectroscopy in the SuperEBIT electron-beam ion trap, giving 3858.22+/-0.30 Å for 203Tl80+ and 3821.84+/-0.34 Å for 205Tl80+ with a wavelength difference Δλ=36.38+/-0.35 Å. This difference is consistent with estimates based on hyperfine anomaly data for neutral Tl only if finite size effects are included in the calculation. By using previously determined nuclear magnetic moments, and applying appropriate corrections for the nuclear charge distribution and radiative effects, the experimental splittings can be interpreted in terms of nuclear magnetization radii 1/2=5.83(14) fm for 203Tl and 1/2=5.89(14) fm for 205Tl. These values are 10% larger than derived from single-particle nuclear magnetization models, and are slightly larger than the corresponding charge distributions.

  17. Interfacial magnetism of Ce/Fe and CeH ˜2/Fe multilayers studied by 57Fe Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Bauer, Ph.; Klose, F.; Schulte, O.; Felsch, W.

    1994-11-01

    The distribution of the magnetic hyperfine fields and the magnetic anisotropy of Ce/Fe and CeH ˜2/Fe multilayers have been studied by Mössbauer spectroscopy between 4.2 and 300 K. The extension of the Ce-Fe interaction defining a 'magnetic interface' exceeds the structural extension of the interface and is more than two times larger at the Ce/Fe than at the CeH ˜2/Fe interface. This is proposed to be a consequence of a strong hybridization between the Ce-5d and Fe-3d states that is suppressed by hydrogenation. From the relative intensity of the Mössbauer lines we show that for the CeH ˜2/Fe system with sufficiently thin Fe layers the orientation of the spontaneous magnetization is perpendicular to the film plane at low temperatures and switches to a parallel alignment at higher temperatures in a sharp transition. In contrast, the Ce/Fe system is spontaneously magnetized in the film plane.

  18. Hyperfine structure of S-states of muonic tritium

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    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.

  19. Elucidation of electronic structure by the analysis of hyperfine interactions: The MnH A 7Π-X 7Sigma + (0,0) band

    NASA Astrophysics Data System (ADS)

    Varberg, Thomas D.; Field, Robert W.; Merer, Anthony J.

    1991-08-01

    We present a complete analysis of the hyperfine structure of the MnH A 7Π-X 7Σ+ (0,0) band near 5680 Å, studied with sub-Doppler resolution by intermodulated fluorescence spectroscopy. Magnetic hyperfine interactions involving both the 55Mn (I=5/2) and 1H (I=1/2) nuclear spins are observed as well as 55Mn electric quadrupole effects. The manganese Fermi contact interaction in the X 7Σ+ state is the dominant contributor to the observed hyperfine splittings; the ΔF=0, ΔN=0, ΔJ=±1 matrix elements of this interaction mix the electron spin components of the ground state quite strongly at low N, destroying the ``goodness'' of J as a quantum number and inducing rotationally forbidden, ΔJ=±2 and ±3 transitions. The hyperfine splittings of over 50 rotational transitions covering all 7 spin components of both states were analyzed and fitted by least squares, allowing the accurate determination of 14 different hyperfine parameters. Using single electronic configurations to describe the A 7Π and X 7Σ+ states and Herman-Skillman atomic radial wave functions to represent the molecular orbitals, we calculated a priori values for the 55Mn and 1H hyperfine parameters which agree closely with experiment. We show that the five high-spin coupled Mn 3d electrons do not contribute to the manganese hyperfine structure but are responsible for the observed proton magnetic dipolar couplings. Furthermore, the results suggest that the Mn 3d electrons are not significantly involved in bonding and demonstrate that the molecular hyperfine interactions may be quantitatively understood using simple physical interpretations.

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

    ERIC Educational Resources Information Center

    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)

  1. Proton-structure corrections to hyperfine splitting in muonic hydrogen

    SciTech Connect

    Carlson, Carl E.; Nazaryan, Vahagn; Griffioen, Keith

    2011-04-15

    We present the derivation of the formulas for the proton structure-dependent terms in the hyperfine splitting of muonic hydrogen. We use compatible conventions throughout the calculations to derive a consistent set of formulas that reconcile differences between our results and some specific terms in earlier work. Convention conversion corrections are explicitly presented, which reduce the calculated hyperfine splitting by about 46 ppm. We also note that using only modern fits to the proton elastic form factors gives a smaller than historical spread of Zemach radii and leads to a reduced uncertainty in the hyperfine splitting. Additionally, hyperfine splittings have an impact on the muonic hydrogen Lamb shift and proton radius measurement, however the correction we advocate has a small effect there.

  2. Polarization operator contributions to the Lamb shift and hyperfine splitting

    SciTech Connect

    Eides, Michael I.; Shelyuto, Valery A.

    2003-10-01

    We calculate radiative corrections to the Lamb shift of order {alpha}{sup 3}(Z{alpha}){sup 5}m and radiative corrections to hyperfine splitting of order {alpha}{sup 3}(Z{alpha})E{sub F} generated by the diagrams with insertions of radiative photons and electron polarization loops in the graphs with two external photons. We also obtain the radiative-recoil correction to hyperfine splitting in muonium generated by the diagrams with the {tau} polarization loop.

  3. Hyperfine selectivity using multiquantum electron-nuclear-electron triple resonance

    NASA Astrophysics Data System (ADS)

    Christidis, T. C.; Mchaourab, Hassane S.; Hyde, James S.

    1996-06-01

    Hyperfine selectivity is demonstrated in a continuous wave electron-nuclear double resonance (ENDOR) experiment. A multiquantum electron-electron double resonance (ELDOR) signal is monitored as a function of the nuclear radio frequency. The signs and relative intensities of the ENDOR lines permit separating the case where both ELDOR and ENDOR frequencies match hyperfine couplings from the cases where this condition is not satisfied.

  4. Hyperfine Quantum Beat Spectroscopy of the Cs 8p level with Pulsed Pump-Probe Technique

    NASA Astrophysics Data System (ADS)

    Bayram, Burcin; Popov, Oleg; Kelly, Stephen; Boyle, Patrick; Salsman, Andrew

    2013-05-01

    Quantum beats arising from the hyperfine interaction were measured in a three-level excitation (lambda) scheme: pump for the 6s2S1 / 2 --> 8p2P3 / 2 and stimulated emission pump (probe) for the 8p2P3 / 2 --> 5d2D5 / 2 transitions of atomic cesium. In the technique, pump laser instantaneously excites the hot atomic vapor and creates anisotropy in the 8p2P3 / 2 level, and probe laser comes after some time delay. Delaying the probe time allows us to map out the motion of the polarized atoms like a stroboscope. According to the observed evolution of the hyperfine structure dependent parameters, e.g. alignment and atomic polarization, by delaying the arrival time of the stimulated emission pump laser (SEP), precise values of the magnetic dipole and electric quadrupole coefficients are obtained with an improved precision over previous results. The usefulness of the PUMP-SEP excitation scheme for the polarization hyperfine quantum beat measurements without complications from the Doppler effect will also be discussed. The financial support of the Research Corporation under the Grant number CC7133 and MiamiUniversity, College of the Arts and Sciences are acknowledged.

  5. Theory of hyperfine anomalies in muonic atoms

    SciTech Connect

    Freeman, A.J.; Mallow, J.V.; Desclaux, J.P.; Weinert, M.

    1983-01-01

    Negative muon spin precession experiments by Yamazaki, et al. have found giant hyperfine anomalies in muonic atoms ranging from a few percent up to 36%. In order to understand their results, we present Breit interaction calculations based on atomic self-consistent unrestricted Dirac-Fock solutions which explicitly include all electrons and the negative muon. The Breit interaction results (including the relativistic correction for the bound muon g-factor), vary from near zero for ..mu../sup -/ O/N to -5% for ..mu../sup -/Pd/Rh; this latter is much larger than the calculated muonic or nuclear Bohr-Weisskopf anomalies and much smaller than the 36% measured value. For ..mu../sup -/Ni/Co we find a calculated range of results (depending on assumed electronic configurations) of -2.3 to -2.7% in excellent agreement with recent measurements of the Yamazaki group. This excellent agreement in ..mu../sup -/Ni/Co provides strong support for the earlier suggestions that the discrepancy in the case of ..mu../sup -/Pd/Rh is due to experimental factors.

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

    SciTech Connect

    Belluzzi, Luca; Landi Degl’Innocenti, Egidio; Bueno, Javier Trujillo

    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.

  7. Isotropic Inelastic Collisions in a Multiterm Atom with Hyperfine Structure

    NASA Astrophysics Data System (ADS)

    Belluzzi, Luca; Landi Degl'Innocenti, Egidio; Trujillo Bueno, Javier

    2015-10-01

    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 D1 and D2 lines is presented.

  8. Anomalous hyperfine coupling and nuclear magnetic relaxation in Weyl semimetals

    NASA Astrophysics Data System (ADS)

    Okvátovity, Zoltán; Simon, Ferenc; Dóra, Balázs

    2016-12-01

    The electron-nuclear hyperfine interaction shows up in a variety of phenomena including, e.g., NMR studies of correlated states and spin decoherence effects in quantum dots. Here we focus on the hyperfine coupling and the NMR spin relaxation time T1 in Weyl semimetals. Since the density of states in Weyl semimetals varies with the square of the energy around the Weyl point, a naive power counting predicts a 1 /T1T ˜E4 scaling, with E the maximum of temperature (T ) and chemical potential. By carefully investigating the hyperfine interaction between nuclear spins and Weyl fermions, we find that while its spin part behaves conventionally, its orbital part diverges unusually, with the inverse of the energy around the Weyl point. Consequently, the nuclear spin relaxation rate scales in a graphenelike manner as 1 /T1T ˜E2ln(E /ω0) , with ω0 the nuclear Larmor frequency. This allows us to identify an effective hyperfine coupling constant, which is tunable by gating or doping. This is relevant for the decoherence effect in spintronics devices and double quantum dots, where hyperfine coupling is the dominant source of spin-blockade lifting.

  9. Stochastic hyperfine interactions modeling library-Version 2

    NASA Astrophysics Data System (ADS)

    Zacate, Matthew O.; Evenson, William E.

    2016-02-01

    The stochastic hyperfine interactions modeling library (SHIML) provides a set of routines to assist in the development and application of stochastic models of hyperfine interactions. The library provides routines written in the C programming language that (1) read a text description of a model for fluctuating hyperfine fields, (2) set up the Blume matrix, upon which the evolution operator of the system depends, and (3) find the eigenvalues and eigenvectors of the Blume matrix so that theoretical spectra of experimental techniques that measure hyperfine interactions can be calculated. The optimized vector and matrix operations of the BLAS and LAPACK libraries are utilized. The original version of SHIML constructed and solved Blume matrices for methods that measure hyperfine interactions of nuclear probes in a single spin state. Version 2 provides additional support for methods that measure interactions on two different spin states such as Mössbauer spectroscopy and nuclear resonant scattering of synchrotron radiation. Example codes are provided to illustrate the use of SHIML to (1) generate perturbed angular correlation spectra for the special case of polycrystalline samples when anisotropy terms of higher order than A22 can be neglected and (2) generate Mössbauer spectra for polycrystalline samples for pure dipole or pure quadrupole transitions.

  10. Neutral nitrogen acceptors in ZnO: The {sup 67}Zn hyperfine interactions

    SciTech Connect

    Golden, E. M.; Giles, N. C.; Evans, S. M.; Halliburton, L. E.

    2014-03-14

    Electron paramagnetic resonance (EPR) is used to characterize the {sup 67}Zn hyperfine interactions associated with neutral nitrogen acceptors in zinc oxide. Data are obtained from an n-type bulk crystal grown by the seeded chemical vapor transport method. Singly ionized nitrogen acceptors (N{sup −}) initially present in the crystal are converted to their paramagnetic neutral charge state (N{sup 0}) during exposure at low temperature to 442 or 633 nm laser light. The EPR signals from these N{sup 0} acceptors are best observed near 5 K. Nitrogen substitutes for oxygen ions and has four nearest-neighbor cations. The zinc ion along the [0001] direction is referred to as an axial neighbor and the three equivalent zinc ions in the basal plane are referred to as nonaxial neighbors. For axial neighbors, the {sup 67}Zn hyperfine parameters are A{sub ‖} = 37.0 MHz and A{sub ⊥} = 8.4 MHz with the unique direction being [0001]. For nonaxial neighbors, the {sup 67}Zn parameters are A{sub 1} = 14.5 MHz, A{sub 2} = 18.3 MHz, and A{sub 3} = 20.5 MHz with A{sub 3} along a [101{sup ¯}0] direction (i.e., in the basal plane toward the nitrogen) and A{sub 2} along the [0001] direction. These {sup 67}Zn results and the related {sup 14}N hyperfine parameters provide information about the distribution of unpaired spin density at substitutional neutral nitrogen acceptors in ZnO.

  11. Impact of silica environment on hyperfine interactions in 𝜖-Fe2O3 nanoparticles

    NASA Astrophysics Data System (ADS)

    Kubíčková, Lenka; Kohout, Jaroslav; Brázda, Petr; Veverka, Miroslav; Kmječ, Tomáš; Kubániová, Denisa; Bezdička, Petr; Klementová, Mariana; Šantavá, Eva; Závěta, Karel

    2016-12-01

    Magnetic nanoparticles have found broad applications in medicine, especially for cell targeting and transport, and as contrast agents in MRI. Our samples of 𝜖-Fe2O3 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-Fe2O3 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-Fe2O3 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.

  12. Hyperfine-mediated static polarizabilities of monovalent atoms and ions

    SciTech Connect

    Dzuba, V. A.; Flambaum, V. V.; Beloy, K.; Derevianko, A.

    2010-12-15

    We apply relativistic many-body methods to compute static differential polarizabilities for transitions inside the ground-state hyperfine manifolds of monovalent atoms and ions. Knowledge of this transition polarizability is required in a number of high-precision experiments, such as microwave atomic clocks and searches for CP-violating permanent electric dipole moments. While the traditional polarizability arises in the second order of interaction with the externally applied electric field, the differential polarizability involves an additional contribution from the hyperfine interaction of atomic electrons with nuclear moments. We derive formulas for the scalar and tensor polarizabilities including contributions from magnetic dipole and electric quadrupole hyperfine interactions. Numerical results are presented for Al, Rb, Cs, Yb{sup +}, Hg{sup +}, and Fr.

  13. Mössbauer study of exogenous iron redistribution between the brain and the liver after administration of 57Fe3O4 ferrofluid in the ventricle of the rat brain

    NASA Astrophysics Data System (ADS)

    Polikarpov, Dmitry; Gabbasov, Raul; Cherepanov, Valery; Loginova, Natalia; Loseva, Elena; Nikitin, Maxim; Yurenia, Anton; Panchenko, Vladislav

    2015-04-01

    Iron clearance pathways after the injection of 57Fe3O4-based ferrofluid into the brain ventricles were studied histologically and by Mössbauer spectroscopy. It was found that the dextran coated initial nanobeads of the ferrofluid disintegrated in the brain into separate superparamagnetic nanoparticles within a week after the injection. The exogenous iron completely exited all ventricular cavities of the brain within a week after the injection but remained in the white matter for months. Kupffer cells with the exogenous iron appeared in the rat liver 2 hours after the injection. Their concentration reached its maximum on the third day and dropped to zero within a week. The exogenous iron appeared in the spleen a week after the injection and remained in the spleen for months.

  14. Fe-implanted 6H-SiC: Direct evidence of Fe{sub 3}Si nanoparticles observed by atom probe tomography and {sup 57}Fe Mössbauer spectroscopy

    SciTech Connect

    Diallo, M. L.; Fnidiki, A. Lardé, R.; Cuvilly, F.; Blum, I.; Lechevallier, L.; Debelle, A.; Thomé, L.; Viret, M.; Marteau, M.; Eyidi, D.; Declémy, A.

    2015-05-14

    In order to understand ferromagnetic ordering in SiC-based diluted magnetic semiconductors, Fe-implanted 6H-SiC subsequently annealed was studied by Atom Probe Tomography, {sup 57}Fe Mössbauer spectroscopy and SQUID magnetometry. Thanks to its 3D imaging capabilities at the atomic scale, Atom Probe Tomography appears as the most suitable technique to investigate the Fe distribution in the 6H-SiC host semiconductor and to evidence secondary phases. This study definitely evidences the formation of Fe{sub 3}Si nano-sized clusters after annealing. These clusters are unambiguously responsible for the main part of the magnetic properties observed in the annealed samples.

  15. Effects of Al substitution and thermal annealing on magnetoelectric Ba0.5Sr1.5Zn2Fe12O22 investigated by the enhancement factor of 57Fe nuclear magnetic resonance.

    PubMed

    Kwon, Sangil; Kang, Byeongki; Kim, Changsoo; Jo, Euna; Lee, Soonchil; Chai, Yi Sheng; Chun, Sae Hwan; Kim, Kee Hoon

    2014-04-09

    The magnetoelectric properties of hexaferrite Ba0.5Sr1.5Zn2Fe12O22 are significantly improved by Al substitution and thermal annealing. Measuring the enhancement factor of 57Fe NMR, we found direct microscopic evidence that the magnetic moments of the L and S blocks are rotated by a magnetic field in such a way as to increase the net magnetic moment of a magnetic unit, even after the field is removed. Al substitution makes magnetoelectric property arise easily by suppressing the easy-plane anisotropy. The effect of thermal annealing is to stabilize the multiferroic state by reducing the number of pinning sites and the electron spin fluctuation. The transverse conic structure gradually changes to the alternating longitudinal conic structure where spins fluctuate more severely.

  16. All-orders Binding Corrections to Muonium Hyperfine Splitting

    NASA Astrophysics Data System (ADS)

    Sapirstein, Jonathan

    1997-04-01

    The use of exact Dirac-Coulomb propagators allows the evaluation of binding corrections to the Schwinger correction in ground state muonium hyperfine splitting to all orders (S.A. Blundell, K.T. Cheng, and J. Sapirstein, to appear in March issue of Physical Review A). The calculational method is described and used to verify recent perturbative calculations of higher order binding corrections and to estimate the residual terms of even higher order. Implications for the theory of muonium hyperfine splitting will be discussed.

  17. A computer program for analyzing unresolved Mossbauer hyperfine spectra

    NASA Technical Reports Server (NTRS)

    Schiess, J. R.; Singh, J. J.

    1978-01-01

    The program for analyzing unresolved Mossbauer hyperfine spectra was written in FORTRAN 4 language for the Control Data CYBER 170 series digital computer system with network operating system 1.1. With the present dimensions, the program requires approximately 36,000 octal locations of core storage. A typical case involving two innermost coordination shells in which the amplitudes and the peak positions of all three components were estimated in 25 iterations requires 30 seconds on CYBER 173. The program was applied to determine the effects of various near neighbor impurity shells on hyperfine fields in dilute FeAl alloys.

  18. Magnetic blackbody shift of hyperfine transitions for atomic clocks

    SciTech Connect

    Berengut, J. C.; Flambaum, V. V.; King-Lacroix, J.

    2009-12-15

    We derive an expression for the magnetic blackbody shift of hyperfine transitions such as the cesium primary reference transition which defines the second. The shift is found to be a complicated function of temperature, and has a T{sup 2} dependence only in the high-temperature limit. We also calculate the shift of ground-state p{sub 1/2} hyperfine transitions which have been proposed as new atomic clock transitions. In this case interaction with the p{sub 3/2} fine-structure multiplet may be the dominant effect.

  19. Doubly Magic Optical Trapping for Cs Atom Hyperfine Clock Transitions

    NASA Astrophysics Data System (ADS)

    Carr, A. W.; Saffman, M.

    2016-10-01

    We analyze doubly magic trapping of Cs hyperfine transitions including previously neglected contributions from the ground state hyperpolarizability and the interaction of the laser light and a static magnetic field. Extensive numerical searches do not reveal any doubly magic trapping conditions for any pair of hyperfine states. However, including the hyperpolarizability reveals light intensity insensitive traps for a wide range of wavelengths at specific intensities. We then investigate the use of bichromatic trapping light fields. Deploying a bichromatic scheme, we demonstrate doubly magic red and blue detuned traps for pairs of states separated by one or two single photon transitions.

  20. On the hyperfine structures in the m-type hexaferrite

    NASA Astrophysics Data System (ADS)

    Bahgat, A. A.; Fayek, M. K.

    1980-04-01

    Mössbauer measurements have been made on polycrystalline barium and strontium hexaferrite samples. The subspectra corresponding to the iron ion in the bypyramid lattice site in the temperature range 4.2 to 293 K with and without externally applied magnetic field up to 25 kG have been considered particularly. The quadrupole shift is vanishing, and the five magnetic hyperfine fields related to the magnetic sites are equal at low temperature. Values of the hyperfine fields for the pentahedral site are discussed.

  1. 7P1/2 hyperfine splitting in 206 , 207 , 209 , 213Fr and the hyperfine anomaly

    NASA Astrophysics Data System (ADS)

    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.

  2. Magnetic hyperfine interactions at the 51V nucleus in the pyrochlore Lu2V2O7

    NASA Astrophysics Data System (ADS)

    Agzamova, P. A.; Petrov, V. P.; Chernyshev, V. A.; Nikiforov, A. E.

    2015-01-01

    This is an ab initio calculation of the parameters of the magnetic hyperfine interactions at the 51V nucleus, in the Lu2V2O7 pyrochlore, in addition to a comparative analysis of the calculated values versus known experimental data. It is shown that the unrestricted Hartree-Fock method is more suitable when it comes to describing the magnetic properties at ion nuclei, in comparison to the density functional theory with hybrid functionals B3LYP and PBE0.

  3. Hyperfine Interactions for Hole Spins in Quantum Dots

    NASA Astrophysics Data System (ADS)

    Philippoppoulos, Pericles; Chesi, Sefano; Coish, William

    2014-03-01

    Due to the anisotropic nature of the hyperfine coupling for hole spins in semiconductor quantum dots, these systems may show significantly longer coherence times than electron spins given the correct quantum-dot geometry and magnetic field orientation. This advantage of hole spins relies on the hyperfine tensor taking-on an Ising-like form. This form of the hyperfine coupling has been recently called into question with experiments that have been interpreted to indicate a strong hybridization of p-like and d-like components in the valence band of III-V semiconductors. However, this interpretation relies on two assumptions: (1) That spin-orbit coupling is weak in these systems compared to the anisotropic crystal field, and (2) that higher-angular-momentum contributions are negligible. Assumption (1) may break down in light of the fact that the spin-orbit energy is even larger than the principle gap in InAs, and assumption (2) is difficult to justify in any crystal that breaks pure rotational symmetry. Using a generalization of the group-theoretic analysis in, we show here that relaxing either of these assumptions can restore the Ising-like nature of the hyperfine tensor, albeit for a particular choice of coupling constants.

  4. Hyperfine and nuclear quadrupole coupling in chlorine and fluorine dioxides

    NASA Astrophysics Data System (ADS)

    Fernández, Berta; Christiansen, Ove; Jørgensen, Poul; Byberg, Jørgen; Gauss, Jürgen; Ruud, Kenneth

    1997-02-01

    The hyperfine and nuclear quadrupole coupling tensors have been calculated for the two chlorine dioxide isomers OClO and ClOO and for fluorine dioxide FOO. The coupled-cluster singles and doubles (CCSD) approach with a perturbative treatment of triple excitations [CCSD(T)] has been used and basis saturation has been investigated. For the symmetric isomer OClO close agreement is obtained with the accurate and detailed experimental data. For FOO a geometry optimization as well as a comparison of calculated and experimental hyperfine coupling tensors suggest a shorter F-O bond length than that obtained experimentally. For the isomer ClOO, calculations have been carried out at the theoretical equilibrium geometry determined by Peterson and Werner and at the geometry proposed by Byberg for the matrix isolated molecule. The hyperfine coupling tensors obtained at these two geometries are substantially different, but the estimated accuracy of the calculations is not high enough to allow a determination of the geometry of ClOO from the hyperfine data.

  5. Isotope effects and proton hyperfine interactions in the lowest 3n pi * state of substituted benzaldehydes

    NASA Astrophysics Data System (ADS)

    Neugebauer-Crawford, S. M.; Tinti, D. S.

    1995-12-01

    The zero-field splittings, principal spin axes, kinetic parameters, and nuclear hyperfine interactions of the 3nπ* state of p-chloro- and p-methylbenzaldehyde and several of their deuterated derivatives are investigated by zero- and low-field optically detected magnetic resonance (ODMR) at 1.4 K in a p-dimethoxybenzene host. The zero-field splittings show large isotope effects. These are interpreted in terms of spin-orbit interaction with the nearby but higher lying 3ππ* state, yielding the energy gap between the two states in both benzaldehyde derivatives. The locations of the spin axes are approximately along the local symmetry axes of the carbonyl group and are insensitive to isotope. But, the spin axis most nearly normal to the plane of a host molecule deviates from the normal by an angle of 7°-13°. The kinetic parameters of the 3nπ* state also are relatively insensitive to isotope. The dominant hyperfine interactions are associated with the aldehyde hydrogen and indicate that the 3nπ* state is largely localized on the aldehyde moiety. Various properties of the 3nπ* and 3ππ* states are compared.

  6. Fine and hyperfine structure in three low-lying 3S+ states of molecular hydrogen

    NASA Astrophysics Data System (ADS)

    Minaev, Boris; Loboda, Oleksandr; Rinkevicius, Zilvinas; Vahtras, Olav; Ågren, Hans

    The fine structure constant (electron spin-spin coupling) and the hyperfine structure parameters (electron-nuclear spin coupling, including spin-rotation and electron-nuclear quadrupole coupling) in the low-lying triplet states and of molecular hydrogen and deuterium are calculated using a recently developed technique with full configu-ration interaction and multiconfiguration self-consistent field wave functions. The second-order spin-orbit coupling contribution to the 3Σ+ states splitting is negligible, and the calculations therefore provide a good estimate of the zero-field splitting based only on the electron spin-spin coupling values. For the bound state a negligible zero-field splitting is found, in qualitative agreement with the e-a spectrum. The zero-field splitting parameter is considerable for the repulsive state (≃1 cm-1) and of intermediate size for the bound state. The isotropic hyperfine coupling constant is very large not only for the valence state (1580 MHz) but also for the Rydberg a and e triplet states (≃1400 MHz). The quadrupole coupling constants for the deuterium isotopes are negligible (0.04-0.07 MHz) for all studied triplet states. The electric dipole activity of the spin sublevels in the triplet-singlet transitions to the ground state is estimated by means of the quadratic response technique.

  7. Hyperfine Resolved Pure Rotational Spectroscopy of ScN, yn, and BaNH (X1σ+): Insight Into Metal-Nitrogen Bonding

    NASA Astrophysics Data System (ADS)

    Zack, Lindsay N.; Bucchino, Matthew; Young, Justin; Binns, Marshall; Sheridan, Phillip M.; Ziurys, Lucy M.

    2015-06-01

    Fourier transform microwave spectroscopy coupled with a discharge-assisted laser ablation source (DALAS) has been used to record the J = 1 → 0 pure rotational transitions of Sc14N, Sc15N, Y14N, Y15N, and Ba14NH (X1σ+). Each species was synthesized by the reaction of the ablated metal with either NH3 or 15NH3 in the presence of a DC discharge. For each species hyperfine structure was resolved. In the case of ScN and YN hyperfine parameters (quadrupole and nuclear spin-rotation) for the metal and nitrogen were determined and for BaNH the nitrogen quadrupole coupling constant was measured. These hyperfine constants are interpreted to gain insight into the metal-nitrogen bonding in each species. In addition, DFT calculations were performed to assist with the assignment of each spectrum and the characterization of the metal-nitrogen bond.

  8. 57Fe Mössbauer spectroscopy and magnetization of cation deficient Fe2TiO4 and FeCr2O4. Part II: Magnetization data

    NASA Astrophysics Data System (ADS)

    Schmidbauer, E.

    1987-12-01

    Magnetic properties are reported for synthetic cation deficient Fe2TiO4 and FeCr2O4 particles (<1 μm). Cation deficiency, achieved by oxidation, is characterized by the oxidation parameter z which represents the fraction of Fe2+ ions converted to Fe3+ in the spinel lattice (0≤ z≤1). Fe2TiO4 ( z=0.85) has a Curie temperature T c that can only approximately be given with a value in the range 400 700 K and it has a magnetic moment per formula unit M≈0.50 μB (μB=Bohr's magneton) at 4.2 K, for FeCr2O4 it is T c≥520 K and M (4.2 K) ≈0.16 μB. Magnetic hysteresis parameters at various temperatures show in part characteristic features due to relaxation phenomena. In the Ti-spinel, the latter are caused by a superposition of superparamagnetism and spin relaxation and in the Cr-spinel by superparamagnetism, in agreement with Mössbauer data (part I of this paper). The cation and vacancy distribution and magnetic coupling are discussed in both compositions with respect to magnetic moment data considering magnetic dilution by incorporated vacancies, and in the Ti-spinel also by non magnetic Ti4+.

  9. Hyperfine Structure and Predissociation of the Odd TRIPLET-B-PI-PLUS(0) State of Bromine.

    NASA Astrophysics Data System (ADS)

    Booth, James Lawrence

    Investigations have been carried out in bromine of the hyperfine structure of the B ^3 prod_{0_sp{u}{+ }} and X ^1sum_sp {rm g}{+} electronic states and of the predissociation of the B ^3prod _{0_sp{rm u}{+} } state by the ^1prod _{rm 1u} dissociative level. The technique of laser induced fluoresence of a molecular beam was used. ^{79}rm Br^ {81}Br hyperfine spectra were recorded for various B-X vibrational bands (v^{ '}>=ts v^{'' }) with v^' = 11 through 17 and v^{' '} = 0, 1, and 2, and for various rotational transitions (rm J^' >=ts J^{''}) with J^' from 0 and 11 and J^{''} from 0 to 10. As well, the ^ {79}Br_2 and ^ {81}Br_2 hyperfine spectra of the (13^' - 0^{' '}) and (17^' - 2^{''}) bands over the same range of rotational states were measured. The spectra are well described using one X state parameter: the electric quadrupole coupling constant eqQ_ {rm X}; and two B state parameters: the electric quadrupole coupling constant eqQ_ {rm B} and the nuclear spin-rotation constant C_{rm sr}. The results show that eqQ_{rm B}( ^{79}rm Br) = (177.0+/- 0.6) MHz for v^{'} = 11 and increases by approximately 0.5 MHz per vibrational quantum up to (180.6 +/- 1.4) MHz for v^{'} = 17. Similarly the ground state electric quadrupole coupling constant, eqQ_{rm X}(^ {79}Br) = (808.1 +/- 1.4) MHz for v^{'' } = 0 and increases by about 1 MHz per vibrational quantum to (811.4 +/- 1.4) MHz for v^{''} = 2. The hyperfine data also provided a check on the accuracy of some of the published rovibronic constants ^1 for each isotopomer. In order to reproduce the observed relative spacings of the transitions for all three isotopomers, the published term values, T _{00}, have to be modified; this can be done by decreasing the published values of T_{00} for ^ {81}rm Br_2 and ^{79}Br^{81}Br by (177 +/- 8) MHz and (326 +/- 8) MHz, respectively. The phase shift technique was applied to the study of the predissociation of the v^' = 13 B ^3prod_{0 _sp{rm u}{+}} electronic state of bromine. The

  10. X-ray powder diffraction and 57Fe Mössbauer spectroscopy of synthetic trioctahedral micas {K}[Me3]

    NASA Astrophysics Data System (ADS)

    Redhammer, G. J.; Amthauer, G.; Lottermoser, W.; Bernroider, M.; Tippelt, G.; Roth, G.

    2005-11-01

    Trioctahedral 1 M micas have been synthesized along (pseudo)binary joins using hydrothermal techniques and controlled oxygen fugacities. Octahedrally coordinated iron in annite {K}[Fe3]parameters decrease almost linearly with decreasing average radius of the octahedral cation/average M O bond length within the octahedral sheet. With increasing substitution of Fe2+ the octahedral sheet becomes more flattened, the ditrigonal distortion of the tetrahedral sheet increases up to a maximum value of ≈10° for micas with tetrahedral sheet compositions close to 57Fe Mössbauer spectroscopy. With increasing substitution of iron by smaller divalent cations the quadrupole splitting distribution (QSD) evolves from a broad bimodal distribution in annite to a smaller unimodal distribution in Mg2+ and Ni2+-rich samples so that for high substitution rates more regular local environments are dominating. These results, however, can not be interpreted in terms of an octahedral cation ordering scheme. For none of the micas investigated reliable Fe2+ M2/M1 area ratios can be extracted. fMoreover, the complete QSD is shifted towards higher quadrupole splitting values. Similar observations were obtained for substituting Fe2+ by Mg2+ and Ni2+ in tetra-ferri-annite free of octahedral coordinated trivalent cations. Unlike in the Al3+ bearing micas a third QSD component is missing which supports the claim that the appearance of this third QSD component is closely related to the presence of trivalent cations (Al3+, Fe3+) in octahedra coordination.

  11. Frequency swept microwaves for hyperfine decoupling and time domain dynamic nuclear polarization.

    PubMed

    Hoff, Daniel E M; Albert, Brice J; Saliba, Edward P; Scott, Faith J; Choi, Eric J; Mardini, Michael; Barnes, Alexander B

    2015-11-01

    Hyperfine decoupling and pulsed dynamic nuclear polarization (DNP) are promising techniques to improve high field DNP NMR. We explore experimental and theoretical considerations to implement them with magic angle spinning (MAS). Microwave field simulations using the high frequency structural simulator (HFSS) software suite are performed to characterize the inhomogeneous phase independent microwave field throughout a 198GHz MAS DNP probe. Our calculations show that a microwave power input of 17W is required to generate an average EPR nutation frequency of 0.84MHz. We also present a detailed calculation of microwave heating from the HFSS parameters and find that 7.1% of the incident microwave power contributes to dielectric sample heating. Voltage tunable gyrotron oscillators are proposed as a class of frequency agile microwave sources to generate microwave frequency sweeps required for the frequency modulated cross effect, electron spin inversions, and hyperfine decoupling. Electron spin inversions of stable organic radicals are simulated with SPINEVOLUTION using the inhomogeneous microwave fields calculated by HFSS. We calculate an electron spin inversion efficiency of 56% at a spinning frequency of 5kHz. Finally, we demonstrate gyrotron acceleration potentials required to generate swept microwave frequency profiles for the frequency modulated cross effect and electron spin inversions.

  12. Frequency swept microwaves for hyperfine decoupling and time domain dynamic nuclear polarization

    PubMed Central

    Hoff, Daniel E.M.; Albert, Brice J.; Saliba, Edward P.; Scott, Faith J.; Choi, Eric J.; Mardini, Michael; Barnes, Alexander B.

    2015-01-01

    Hyperfine decoupling and pulsed dynamic nuclear polarization (DNP) are promising techniques to improve high field DNP NMR. We explore experimental and theoretical considerations to implement them with magic angle spinning (MAS). Microwave field simulations using the high frequency structural simulator (HFSS) software suite are performed to characterize the inhomogeneous phase independent microwave field throughout a 198 GHz MAS DNP probe. Our calculations show that a microwave power input of 17 W is required to generate an average EPR nutation frequency of 0.84 MHz. We also present a detailed calculation of microwave heating from the HFSS parameters and find that 7.1% of the incident microwave power contributes to dielectric sample heating. Voltage tunable gyrotron oscillators are proposed as a class of frequency agile microwave sources to generate microwave frequency sweeps required for the frequency modulated cross effect, electron spin inversions, and hyperfine decoupling. Electron spin inversions of stable organic radicals are simulated with SPINEVOLUTION using the inhomogeneous microwave fields calculated by HFSS. We calculate an electron spin inversion efficiency of 56% at a spinning frequency of 5 kHz. Finally, we demonstrate gyrotron acceleration potentials required to generate swept microwave frequency profiles for the frequency modulated cross effect and electron spin inversions. PMID:26482131

  13. Maraging-350 steel: Following the aging through diffractometric, magnetic and hyperfine analysis

    NASA Astrophysics Data System (ADS)

    Nunes, G. C. S.; Sarvezuk, P. W. C.; Alves, T. J. B.; Biondo, V.; Ivashita, F. F.; Paesano, A.

    2017-01-01

    Plates of solution annealed Maraging-350 steel were submitted to aging under an inert atmosphere, varying the time and temperature. The aged samples were characterized by X-ray diffraction and Mössbauer spectroscopy. The results revealed that the aging treatments induced the reversion of austenite, in amounts that vary with the time and the temperature of the heat treatment. The lattice parameters of the martensite and austenite phases, as well as their hyperfine parameters, were obtained at all aging conditions. No intermetallic compounds were identified in any of the aged samples, but a poorly crystallized phase fraction, the consequence of an incomplete martensite ⇒ austenite reversion transformation, was observed for some samples. The tetragonal distortion from cubic symmetry presented by the martensite in the solution annealed steel was not eliminated after aging.

  14. Hyperfine structures of the 2 (3)Sigma(g) (+), 3 (3)Sigma(g) (+), and 4 (3)Sigma(g) (+) states of Na(2).

    PubMed

    Liu, Yaoming; Li, Li; Lazarov, Guenadiy; Lazoudis, Angelos; Lyyra, A Marjatta; Field, Robert W

    2004-09-22

    The hyperfine structures of the 2 (3)Sigma(g) (+), 3 (3)Sigma(g) (+), and 4 (3)Sigma(g) (+) states of Na(2) have been resolved with sub-Doppler continuous wave perturbation facilitated optical-optical double resonance spectroscopy via A (1)Sigma(u) (+) approximately b (3)Pi(u) mixed intermediate levels. The hyperfine patterns of these three states are similar. The hyperfine splittings of the low rotational levels are all very close to the case b(betaS) limit. As the rotational quantum number increases, the hyperfine splittings become more complicated and the coupling cases become intermediate between cases b(betaS) and b(beta J) due to spin-rotation interaction. We present a detailed analysis of the hyperfine structures of these three (3)Sigma(g) (+) states, employing both case b(betaS) and b(beta J) coupling basis sets. The results show that the hyperfine splittings of the (3)Sigma(g) (+) states are mainly due to the Fermi-contact interaction. The Fermi contact constants for the two d sigma Rydberg states, the 2 (3)Sigma(g) (+) and 4 (3)Sigma(g) (+), are 245+/-5 MHz and 225+/-5 MHz, respectively, while the Fermi contact constant of the s sigma 3 (3)Sigma(g) (+) Rydberg state is 210+/-5 MHz. The diagonal spin-spin and spin-rotation constants, and nuclear spin-electronic spin dipolar interaction parameters of the 3 (3)Sigma(g) (+) and 4 (3)Sigma(g) (+) states are also obtained.

  15. Chlorine Nuclear Quadrupole Hyperfine Structure in the Vinyl - Chloride Complex

    NASA Astrophysics Data System (ADS)

    Leung, Helen O.; Marshall, Mark D.; Messinger, Joseph P.

    2015-06-01

    The microwave spectrum of the vinyl chloride--hydrogen chloride complex, presented at last year's symposium, is greatly complicated by the presence of two chlorine nuclei as well as an observed, but not fully explained tunneling motion. Indeed, although it was possible at that time to demonstrate conclusively that the complex is nonplanar, the chlorine nuclear quadrupole hyperfine splitting in the rotational spectrum resisted analysis. With higher resolution, Balle-Flygare Fourier transform microwave spectra, the hyperfine structure has been more fully resolved, but appears to be perturbed for some rotational transitions. It appears that knowledge of the quadrupole coupling constants will provide essential information regarding the structure of the complex, specifically the location of the hydrogen atom in HCl. Our progress towards obtaining values for these constants will be presented.

  16. Tuning hyperfine fields in conjugated polymers for coherent organic spintronics.

    PubMed

    Lee, Sang-Yun; Paik, Seo-Young; McCamey, Dane R; Yu, Justin; Burn, Paul L; Lupton, John M; Boehme, Christoph

    2011-02-23

    An appealing avenue for organic spintronics lies in direct coherent control of the spin population by means of pulsed electron spin resonance techniques. Whereas previous work has focused on the electrical detection of coherent spin dynamics, we demonstrate here the equivalence of an all-optical approach, allowing us to explore the influence of materials chemistry on the spin dynamics. We show that deuteration of the conjugated polymer side groups weakens the local hyperfine fields experienced by electron-hole pairs, thereby lowering the threshold for the resonant radiation intensity at which coherent coupling and spin beating occur. The technique is exquisitively sensitive to previously obscured material properties and offers a route to quantifying and tuning hyperfine fields in organic semiconductors.

  17. Hyperfine-field spectrum of epitaxially grown bcc cobalt

    NASA Astrophysics Data System (ADS)

    Riedi, P. C.; Dumelow, T.; Rubinstein, M.; Prinz, G. A.; Qadri, S. B.

    1987-09-01

    The hyperfine-field spectrum of the bcc phase of a 357-romanÅ-thick metallic cobalt film, epitaxially grown on a GaAs substrate, has been determined by spin-echo nuclear magnetic resonance. The peak of the distribution of hyperfine fields in bcc Co occurs at 167 MHz, much lower than the value found for fcc Co (217 MHz), suggesting that the moment in the bcc phase is lower than that of the fcc phase, in agreement with the measurements of Prinz, but in disagreement with recent theoretical calculations (assuming that no significant structural differences exist between theory and experiment). The full width of the distribution is 75 MHz, seven times greater than that found in thin fcc Co films. X-ray rocking-curve measurements yield a linewidth of 118 arc seconds, implying too low a dislocation density to explain the observed NMR line broadening.

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

    SciTech Connect

    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.

  19. {sup 57}Fe Moessbauer and x-ray magnetic circular dichroism study of magnetic compensation of the rare-earth sublattice in Nd{sub 2-x}Ho{sub x}Fe{sub 14}B compounds

    SciTech Connect

    Chaboy, J.; Piquer, C.; Plugaru, N.; Bartolome, F.; Laguna-Marco, M. A.

    2007-10-01

    We present here a study of the magnetic properties of the Nd{sub 2-x}Ho{sub x}Fe{sub 14}B series. The macroscopic properties of these compounds evolve continuously from those of Nd{sub 2}Fe{sub 14}B to those of Ho{sub 2}Fe{sub 14}B as Ho gradually replaces Nd. The system shows a compensation of the rare-earth sublattice magnetization for a critical concentration, x{sub c}=0.55, that is reflected into the anomalous behavior of both macroscopic and microscopic magnetic probes. The combined analysis of magnetization, {sup 57}Fe Moessbauer spectroscopy and Fe K-edge x-ray magnetic circular dichroism (XMCD) measurements suggests that the origin of the anomalous magnetic behavior found at x{sub c}=0.55 is mainly due to the Ho sublattice. Moreover, the analysis of the Fe K-edge XMCD signals reveal the presence of a rare-earth contribution, reflecting the coupling of the rare-earth and Fe magnetic moments, which can lead to the possibility of disentangling the magnetic behavior of both Fe and R atoms using a single absorption edge.

  20. Internal electron conversion of the isomeric {sup 57}Fe nucleus state with an energy of 14.4 keV excited by the radiation of the plasma of a high-power femtosecond laser pulse

    SciTech Connect

    Golovin, G V; Savel'ev-Trofimov, Andrei B; Uryupina, D S; Volkov, Roman V

    2011-03-31

    We recorded the spectrum of delayed secondary electrons ejected from the target, which was coated with a layer of iron enriched with the {sup 57}Fe isotope to 98%, under its irradiation by fluxes of broadband X-ray radiation and fast electrons from the plasma produced by a femtosecond laser pulse at an intensity of 10{sup 17} W cm{sup -2}. Maxima were identified at energies of 5.6, 7.2, and 13.6 keV in the spectrum obtained for a delay of 90 - 120 ns. The two last-listed maxima owe their origin to the internal electron conversion of the isomeric level with an energy of 14.4 keV and a lifetime of 98 ns to the K and L shells of atomic iron, respectively; the first-named level arises from a cascade K - L{sub 2}L{sub 3} Auger process. Photoexcitaion by the X-ray plasma radiation is shown to be the principal channel of the isomeric level excitation. (interaction of laser radiation with matter)

  1. Deuterium hyperfine structure in interstellar C3HD

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Astrophysics Data System (ADS)

    Eskin, A. V.; Martynenko, A. P.; Elekina, E. N.

    2016-12-01

    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.

  3. Weak-interaction contributions to hyperfine splitting and Lamb shift

    SciTech Connect

    Eides, M.I.

    1996-05-01

    Weak-interaction contributions to hyperfine splitting and the Lamb shift in hydrogen and muonium are discussed. The problem of sign of the weak-interaction contribution to HFS is clarified, and simple physical arguments that make this sign evident are presented. It is shown that weak-interaction contributions to HFS in hydrogen and muonium have opposite signs. A weak-interaction contribution to the Lamb shift is obtained. {copyright} {ital 1996 The American Physical Society.}

  4. First Optical Hyperfine Structure Measurement in an Atomic Anion

    SciTech Connect

    Fischer, A.; Canali, C.; Warring, U.; Kellerbauer, A.; Fritzsche, S.

    2010-02-19

    We have investigated the hyperfine structure of the transition between the 5d{sup 7}6s{sup 2} {sup 4}F{sub 9/2}{sup e} ground state and the 5d{sup 6}6s{sup 2}6p {sup 6}D{sub J}{sup o} excited state in the negative osmium ion by high-resolution collinear laser spectroscopy. This transition is unique because it is the only known electric-dipole transition in atomic anions and might be amenable to laser cooling. From the observed hyperfine structure in {sup 187}Os{sup -} and {sup 189}Os{sup -} the yet unknown total angular momentum of the bound excited state was found to be J=9/2. The hyperfine structure constants of the {sup 4}F{sub 9/2}{sup e} ground state and the {sup 6}D{sub 9/2}{sup o} excited state were determined experimentally and compared to multiconfiguration Dirac-Fock calculations. Using the knowledge of the ground and excited state angular momenta, the full energy level diagram of {sup 192}Os{sup -} in an external magnetic field was calculated, revealing possible laser cooling transitions.

  5. Mapping the magnetic hyperfine field in GdCo5

    NASA Astrophysics Data System (ADS)

    Krylov, V. I.; Bosch-Santos, B.; Cabrera-Pasca, G. A.; Delyagin, N. N.; Carbonari, A. W.

    2016-05-01

    The magnetic hyperfine field (Bhf) in ferrimagnetic GdCo5 compound has been investigated as a function of temperature by Mössbauer effect (ME) spectroscopy and perturbed angular correlation (PAC) spectroscopy using 119Sn and 111Cd probe nuclei, respectively. Results show that the non-magnetic probe atoms 119Sn and 111Cd substitute all three non-equivalent positions in GdCo5: Gd, CoI, and CoII. For 119Sn and 111Cd probes at Gd sites, the saturation magnetic hyperfine fields are very different with values of Bhf1 = 57.0(1) T and Bhf1= 20.7(1) T, respectively. For 119Sn and 111Cd atoms localized at CoI and CoII sites the magnetic hyperfine fields are practically identical and, in saturation, reach the values of Bhf2 = 11.6(1) T and Bhf2 = 11.1(2) T, and Bhf3 = 14.8(1) T and Bhf3 = 14.4(2) T, respectively.

  6. The hyperfine properties of iron-gallium alloys

    NASA Astrophysics Data System (ADS)

    Elzain, M.; Gismelseed, A.; Al-Rawas, A.; Yousif, A.; Widatallah, H.; Al-Azri, Maya; Al-Barwani, M.

    2016-12-01

    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 (Bhf) and isomer shift ( δ) at the Fe site versus the number of neighbouring Ga atoms. We found that Bhf decrease whereas δ increases with increasing number of neighbouring G atom. In addition we have calculated the hyperfine properties of FeGa system with DO3 structure, where various distributions of 4 the Ga atoms in the conventional unit cell are considered (including the regular DO3 structure). We found that the DO3 structure has the lowest energy as compared to the other configurations. The two distinct A and D sites of the ordered DO3 conventional unit cell have two distinct values for Bhf 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 DO3D site.

  7. Microwave spectra of O2-HF and O2-DF: Hyperfine interactions and global fitting with infrared data

    NASA Astrophysics Data System (ADS)

    Wu, Shenghai; Sedo, Galen; Grumstrup, Erik M.; Leopold, Kenneth R.

    2007-11-01

    Spectra of the open shell complexes O2-HF and O2-DF were recorded using Fourier transform microwave spectroscopy. A complete analysis of the hyperfine structure and a global fit including microwave and infrared frequencies [W. M. Fawzy, C. M. Lovejoy, D. J. Nesbitt, and J. T. Hougen, J. Chem. Phys. 117, 693 (2002)] are reported. The Fermi contact interaction between the electron and nuclear spins, the electron spin-nuclear spin dipolar interaction, the nuclear spin-nuclear spin dipolar interaction, and the nuclear electric quadrupole interaction (for O2-DF) were considered in the analysis. The correspondence between the magnetic hyperfine constants and the two nuclei of the H(D)F is unambiguously established. In both O2-HF and O2-DF, the Fermi contact parameter is larger for the fluorine than for the hydrogen, while for the nuclear spin-electron spin dipolar hyperfine constants, the reverse is true. The effective angle between the HF bond and the a axis of the complex, determined from the nuclear spin-nuclear spin interaction constant, is 38(4)°. The same angle for the DF complex, derived from the deuterium nuclear quadrupole coupling constant, is 31(4)°.

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

    PubMed

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

    2015-07-24

    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 nonconservation studies.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Self-energy correction to the hyperfine splitting for excited states

    SciTech Connect

    Wundt, B. J.; Jentschura, U. D.

    2011-05-15

    The self-energy corrections to the hyperfine splitting is evaluated for higher excited states in hydrogenlike ions using an expansion in the binding parameter Z{alpha}, where Z is the nuclear-charge number and {alpha} is the fine-structure constant. We present analytic results for D, F, and G states, and for a number of highly excited Rydberg states, with principal quantum numbers in the range 13{<=}n{<=}16, and orbital angular momenta l=n-2 and l=n-1. A closed-form analytic expression is derived for the contribution of high-energy photons, valid for any state with l{>=}2 and arbitrary n, l, and total angular momentum j. The low-energy contributions are written in the form of generalized Bethe logarithms and evaluated for selected states.

  11. Optimization of Yb{sup +} fluorescence and hyperfine-qubit detection

    SciTech Connect

    Ejtemaee, S.; Thomas, R.; Haljan, P. C.

    2010-12-15

    Fluorescence of single, trapped {sup 171}Yb{sup +} ions has been experimentally studied as a function of laser polarization, power, and detuning and as a function of magnetic field strength. The suppression of efficient fluorescence by coherent population trapping and the counteracting effect of the magnetic field are found to agree with theoretical predictions. For comparison, a fluorescence study has also been made of the isotope {sup 174}Yb{sup +} for which coherent population trapping is absent on the main fluorescence and laser cooling transition. Finally, state-sensitive fluorescence detection of the {sup 171}Yb{sup +} hyperfine qubit is studied, including the role of coherent population trapping in the optimization of detection parameters. A qubit detection fidelity of greater than 97% is achieved.

  12. Correlations between mass activity and physicochemical properties of Fe/N/C catalysts for the ORR in PEM fuel cell via 57Fe Mössbauer spectroscopy and other techniques.

    PubMed

    Kramm, Ulrike I; Lefèvre, Michel; Larouche, Nicholas; Schmeisser, Dieter; Dodelet, Jean-Pol

    2014-01-22

    The aim of this work is to clarify the origin of the enhanced PEM-FC performance of catalysts prepared by the procedures described in Science 2009, 324, 71 and Nat. Commun. 2011, 2, 416. Catalysts were characterized after a first heat treatment in argon at 1050 °C (Ar) and a second heat treatment in ammonia at 950 °C (Ar + NH3). For the NC catalysts a variation of the nitrogen precursor was also implemented. (57)Fe Mössbauer spectroscopy, X-ray photoelectron spectroscopy, neutron activation analysis, and N2 sorption measurements were used to characterize all catalysts. The results were correlated to the mass activity of these catalysts measured at 0.8 V in H2/O2 PEM-FC. It was found that all catalysts contain the same FeN4-like species already found in INRS Standard (Phys. Chem. Chem. Phys. 2012, 14, 11673). Among all FeN4-like species, only D1 sites, assigned to FeN4/C, and D3, assigned to N-FeN2+2 /C sites, were active for the oxygen reduction reaction (ORR). The difference between INRS Standard and the new catalysts is simply that there are many more D1 and D3 sites available in the new catalysts. All (Ar + NH3)-type catalysts have a much larger porosity than Ar-type catalysts, while the maximum number of their active sites is only slightly larger after a second heat treatment in NH3. The large difference in activity between the Ar-type catalysts and the Ar + NH3 ones stems from the availability of the sites to perform ORR, as many sites of the Ar-type catalysts are secluded in the material, while they are available at the surface of the Ar + NH3-type catalysts.

  13. Hyperfine Interactions of Narrow-line Trityl Radical with Solvent Molecules

    PubMed Central

    Trukhan, S.N.; Yudanov, V.F.; Tormyshev, V.M.; Rogozhnikova, O.Yu.; Trukhin, D.V.; Bowman, M.K.; Krzyaniak, M.D.; Chen, H.; Martyanov, O.N.

    2013-01-01

    The electron nuclear dipolar interactions responsible for some dynamic nuclear polarization (DNP) mechanisms also are responsible for the presence formally in CW EPR spectra of forbidden satellite lines in which both the electron spin and a nuclear spin flip. Such lines arising from 1H nuclei are easily resolved in CW EPR measurements of trityl radicals, a popular family of DNP reagents. The satellite lines overlap some of the hyperfine features from 13C in natural abundance in the trityl radical, but their intensity can be easily determined by simple simulations of the EPR spectra using the hyperfine parameters of the trityl radical. Isotopic substitution of 2H for 1H among the hydrogens of the trityl radical and/or the solvent allows the dipolar interactions from the 1H on the trityl radical and from the solvent to be determined. The intensity of the dipolar interactions, integrated over all the 1H in the system, is characterized by the traditional parameter called reff. For the so-called Finland trityl in methanol, the reff values indicate that collectively the 1H in the unlabeled solvent have a stronger integrated dipolar interaction with the unpaired electron spin of the Finland trityl than do the 1H in the radical and consequently will be a more important DNP route. Although reff has the dimensions of distance, it does not correspond to any simple physical dimension in the trityl radical because the details of the unpaired electron spin distribution and the hydrogen distribution are important in the case of trityls. PMID:23722184

  14. A search for the tritium hyperfine line from nearby stars

    NASA Astrophysics Data System (ADS)

    Valdes, F.; Freitas, R. A., Jr.

    1986-01-01

    A search for the tritium hyperfine line at 1516 MHz from 108 assorted astronomical objects, with emphasis on 53 nearby stars, was conducted in June 1983. All stars within 20 light-years visible from the 26-m telescope at Hat Creek Radio Observatory were examined using 256 4883-Hz channels. Twelve stars were also examined using 1024 76-Hz channels. The wideband- and narrow-band-channel observations achieved sensitivities of 5 - 14×10-24W/m2/channel and 0.7 - 2×10-24W/m2/channel, respectively. No detections were made. The tritium frequency is highly attractive for SETI work.

  15. Observation and analysis of the hyperfine structure of near-dissociation levels of the NaCs c +3Σ state below the dissociation limit 3 S1 /2+6 P3 /2

    NASA Astrophysics Data System (ADS)

    Liu, Wenliang; Wu, Jizhou; Ma, Jie; Li, Peng; Sovkov, Vladimir B.; Xiao, Liantuan; Jia, Suotang

    2016-09-01

    We report photoassociation (PA) of ultracold Na and Cs atoms in a dual-species magneto-optical trap. Trap loss spectroscopy of the ultracold polar NaCs molecules formed by PA, which carries information about relative PA transition strengths, has been experimentally obtained by using highly sensitive modulation spectroscopy technique. The fine and hyperfine effects at near-dissociation levels of NaCs molecular c +3Σ state are observed and modeled. The interaction Hamiltonian is described in terms of the Hund's case (a ) coupling scheme. The molecular hyperfine structure of near-dissociation levels is simulated within a simplified model of four interacting vibrational levels belonging to different initially unperturbed electronic states. The results of the simulation infer that the interaction parameters of the observed near-dissociation levels are close to the asymptotic parameters of the pair of atoms. The coupling of the electronic states is essential for forming the hyperfine structure.

  16. Self-interaction correction and contact hyperfine field

    NASA Astrophysics Data System (ADS)

    Novák, P.; Kuneš, J.; Pickett, W. E.; Ku, Wei; Wagner, F. R.

    2003-04-01

    The hyperfine field is a precise and essential probe of the magnetic state of a solid, and of the quality of theoretical core wave functions, but it’s accurate evaluation has proven challenging from first principles. In this work, the self-interaction free potential, suggested recently by Lundin and Eriksson, is applied to the core states in the calculation of the hyperfine field for 3d transition metal ferromagnets Fe, Co, and Ni, and for three Fe compounds. Compared to the local spin density approximation and to its conventional self-interaction corrected form, the new potential functional is found to increase substantially the core contribution to the Fermi contact term, leading to good agreement with measurements for Fe and Co, and significantly better results for iron compounds. Our results strongly suggest that the new functional is more suitable for generating realistic core wave functions to high accuracy for a wide range of materials. The subtle effects resulting from the change of potential functional are also addressed.

  17. A theoretical study of the fine and hyperfine interactions in the NCO and CNO radicals

    NASA Astrophysics Data System (ADS)

    Prasad, Rajendra

    2004-06-01

    The geometries, the harmonic vibrational frequencies, and the Renner-Teller parameter have been reported for the NCO+(X˜ 3Σ-), NCO(X˜ 2Π,Ã2Σ+,B˜ 2Π,2 2Σ+), NCO-(X˜ 1Σ+), CNO+(X˜), CNO(X˜ 2Π,Ã2Σ+,B˜ 2Π,2 2Σ+), and CNO-(X˜ 1Σ+) systems at the full valence-complete active space self-consistent-field (fv-CASSCF) level of theory. The 2Π electronic states of the NCO and CNO radicals have two distinct real vibrational frequencies for the bending modes and these states are subject to the type A Renner-Teller effect. The total energy of CNO+ without zero point energy correction of the linear geometry is ˜31 cm-1 higher than the bent geometry at the fv-CASSCF level and the inversion barrier vanishes after the zero point energy correction; therefore, the ground state of the CNO+ may possess a quasilinear geometry. The spin-orbit coupling constants estimated using atomic mean field Hamiltonian at the fv-CASSCF level of theory are in better agreement with the experimental values. The excitation energies, the electron affinity, and the ionization potential have been computed at the complete active space second order perturbation theory (CASPT2) and the multireference singles and doubles configuration (MRSD-CI) levels of theory. The computed values of the electric hyperfine coupling constants for the 14N atom in the ground state of the NCO radical agree well with the experimental data. The magnetic hyperfine coupling constants (HFCC's) have been estimated employing the configuration selected MRSD-CI and the multireference singles configuration interaction (MRS-CI) methods using iterative natural orbitals (ino) as one particle basis. Sufficiently accurate value of the isotropic contribution to the HFCC's can be obtained using an MRS-CI-ino procedure.

  18. Analytical calculation of radiative-recoil corrections to muonium hyperfine splitting: Muon-line contribution

    SciTech Connect

    Eides, M.I.; Karshenboim, S.G.; Shelyuto, V.A. )

    1991-02-01

    Analytic expression for radiative-recoil corrections to muonium ground-state hyperfine splitting induced by muon-line radiative insertions is obtained. This result completes the program of analytic calculation of all radiative-recoil corrections. The perspectives of further muonium hyperfine splitting investigations are also discussed.

  19. Muon loop light-by-light contribution to hyperfine splitting in muonium.

    PubMed

    Eides, Michael I; Shelyuto, Valery A

    2014-05-02

    Three-loop corrections to hyperfine splitting in muonium, generated by the gauge-invariant sets of diagrams with muon and tauon loop light-by-light scattering blocks, are calculated. These results complete calculations of all light-by-light scattering contributions to hyperfine splitting in muonium.

  20. Zeeman effects in the hyperfine structure of atomic iodine photodissociation laser emission.

    NASA Technical Reports Server (NTRS)

    Hwang, W. C.; Kasper, J. V. V.

    1972-01-01

    Observation of hyperfine structure in laser emission from CF3I and C2F5I photodissociation lasers. Constant magnetic fields affect the time behavior of the emission by changing the relative gains of the hyperfine transitions. Time-varying fields usually present in photodissociation lasers further complicate the emission.

  1. Magnetic hyperfine coupling of a methyl group undergoing internal rotation: a case study of methyl formate.

    PubMed

    Tudorie, M; Coudert, L H; Huet, T R; Jegouso, D; Sedes, G

    2011-02-21

    The hyperfine structure of methyl formate was recorded in the 2-20 GHz range. A molecular beam coupled to a Fourier transform microwave spectrometer having an instrumental resolution of 0.46 kHz and limited by a Doppler width of a few kHz was used. A-type lines were found split by the magnetic hyperfine coupling while no splittings were observed for E-type lines. Symmetry considerations were used to account for the internal rotation of the methyl top and to derive effective hyperfine coupling Hamiltonians. Neglecting the spin-rotation magnetic coupling, the vanishing splittings of the E-type lines could be understood and analyses of the hyperfine patterns of the A-type lines were performed. The results are consistent with a hyperfine structure dominated by the magnetic spin-spin coupling due to the three hydrogen atoms of the methyl group.

  2. Three-Loop Radiative-Recoil Corrections to Hyperfine Splitting in Muonium: Diagrams with Polarization Loops

    SciTech Connect

    Eides, Michael I.; Shelyuto, Valery A.

    2009-09-25

    We consider three-loop radiative-recoil corrections to hyperfine splitting in muonium generated by the diagrams with electron and muon vacuum polarizations. We calculate single-logarithmic and nonlogarithmic contributions of order alpha{sup 3}(m/M)E{sub F} generated by gauge invariant sets of diagrams with electron and muon polarization insertions in the electron and muon factors. Combining these corrections with the older results, we obtain total contribution to hyperfine splitting generated by all diagrams with electron and muon polarization loops. The calculation of this contribution completes an important stage in the implementation of the program of reduction of the theoretical uncertainty of hyperfine splitting below 10 Hz. The new results improve the theory of hyperfine splitting and affect the value of the electron-muon mass ratio extracted from experimental data on muonium hyperfine splitting.

  3. A study of magnetoresistance in organic semiconductors with varying strengths of hyperfine and spin-orbit coupling

    NASA Astrophysics Data System (ADS)

    Sheng, Yugang

    This thesis concerns itself with the scientific study of the recently discovered organic magnetoresistance (OMAR) whose underlying mechanism is currently not known with certainty. As an introduction, we briefly review the major findings from prior work done by my colleagues. They found that OMAR can be as large as ≈10% magnetoresistance at 10 mT magnetic fields at room temperature. Both OMAR and other kinds of magnetic field effect data in organics can be fitted using the empirical laws B2/B2+B20 or B2/(|B| + B0)2, dependent on material. The fitting parameter B0 is a measure of the characteristic magnetic field strength of OMAR. We explore the dependence of B0 on material parameters to clarify the origin of OMAR. Various pi-conjugated semiconductor OMAR devices were studied to explore the possibility that hyperfine interaction causes OMAR. For a quantitative analysis of the experiments, we developed a theoretical fitting formula to relate B0 to the hyperfine coupling strength. In addition, organic materials with different spin-orbit coupling strengths were also measured. Fluorescence and phosphorescence spectroscopies were used to estimate the spin-orbit coupling strength from the measured spectra. For analyzing our measurements, we developed a fitting formula from the time-dependent Schrodinger equation that takes into account the combined effect of hyperfine and spin-orbit coupling on spin-dynamics. We found that in the case of strong spin-orbit coupling, it dominates the behavior, resulting in magnetic field effect traces that are much wider than those in ordinary organics. However, a small cone remains at zero field with a width equal to the hyperfine coupling strength. We find qualitative agreement between the experimental results and the model. We also investigated the question whether OMAR is related to an excitonic effect, or is primarily a transport effect. We measured the magnetic field effects on current, photocurrent and electroluminescence to address

  4. Opto-Electronic Oscillator Stabilized By A Hyperfine Atomic Transition

    NASA Technical Reports Server (NTRS)

    Strekalov, Dmitry; Aveline, David; Matsko, Andrey B.; Thompson, Robert; Yu, Nan

    2004-01-01

    Opto-electronic oscillator (OEO) is a closed-loop system with part of the loop is implemented by an optical beam, and the rest by RF circuitry. The technological advantage of this approach over traditional all-RF loops in the gigahertz range comes from the that frequency filtering can be done far more efficiently in the optical range with compact, low power, and have superior stability. In this work, we report our preliminary results on using the phenomenon of coherent population trapping in (87) Rb vapor as an optical filter. Such a filter allows us to stabilize the OEO at the hyperfine splitting frequency of rubidium, thus implementing a novel type of frequency standard.

  5. Coulomb artifacts and bottomonium hyperfine splitting in lattice NRQCD

    NASA Astrophysics Data System (ADS)

    Liu, T.; Penin, A. A.; Rayyan, A.

    2017-02-01

    We study the role of the lattice artifacts associated with the Coulomb binding effects in the analysis of the heavy quarkonium within lattice NRQCD. We find that a "na¨ıve" perturbative matching generates spurious linear Coulomb artifacts, which result in a large systematic error in the lattice predictions for the heavy quarkonium spectrum. This effect is responsible, in particular, for the discrepancy between the recent determinations of the bottomonium hyperfine splitting in the radiatively improved lattice NRQCD [1, 2]. We show that the correct matching procedure which provides full control over discretization errors is based on the asymptotic expansion of the lattice theory about the continuum limit, which gives M Y(1 S) - M ηb (1 S) = 52.9 ± 5.5 MeV [1].

  6. Isotope shift and hyperfine structure measurements in titanium I

    NASA Astrophysics Data System (ADS)

    Luc, P.; Vetter, R.; Bauche-Arnoult, C.; Bauche, J.

    1994-09-01

    High accuracy measurements of hyperfine structure due to47Ti and49Ti in the 3 d 2 4 s 2 a 3 F 2-3 d 2 4 s4 p z 5 D 1 absorption line at σ=18482.772 cm-1 have been performed by use of a Doppler-free experiment, where a beam of titanium atoms is crossed by a CW single mode tunable dye laser. They have allowed for the determination of isotope shifts between46Ti,47Ti,48Ti,49Ti and50Ti. By use of accurate values of mean square nuclear charge radii for the even isotopes, it has been possible to separate mass shifts from field shifts and to determine accurate values for the mean square nuclear charge radii of47Ti and49Ti. The field shift presents a marked odd-even staggering.

  7. Nagaoka’s atomic model and hyperfine interactions

    PubMed Central

    INAMURA, Takashi T.

    2016-01-01

    The prevailing view of Nagaoka’s “Saturnian” atom is so misleading that today many people have an erroneous picture of Nagaoka’s vision. They believe it to be a system involving a ‘giant core’ with electrons circulating just outside. Actually, though, in view of the Coulomb potential related to the atomic nucleus, Nagaoka’s model is exactly the same as Rutherford’s. This is true of the Bohr atom, too. To give proper credit, Nagaoka should be remembered together with Rutherford and Bohr in the history of the atomic model. It is also pointed out that Nagaoka was a pioneer of understanding hyperfine interactions in order to study nuclear structure. PMID:27063182

  8. Multispectral plasmon-induced transparency in hyperfine terahertz meta-molecules

    NASA Astrophysics Data System (ADS)

    Yang, Shengyan; Xia, Xiaoxiang; Liu, Zhe; Yiwen, E.; Wang, Yujin; Tang, Chengchun; Li, Wuxia; Li, Junjie; Wang, Li; Gu, Changzhi

    2016-11-01

    We experimentally and theoretically demonstrated an approach to achieve multispectral plasmon-induced transparency (PIT) by utilizing meta-molecules that consist of hyperfine terahertz meta-atoms. The feature size of such hyperfine meta-atoms is 400 nm, which is one order smaller than that of normal terahertz metamaterials. The hyperfine meta-atoms with close eigenfrequencies and narrow resonant responses introduce different metastable energy levels, which makes the multispectral PIT possible. In the triple PIT system, the slow light effect is further confirmed as the effective group delay at three transmission windows can reach 7.3 ps, 7.4 ps and 4.5 ps, respectively. Precisely controllable manipulation of the PIT peaks in such hyperfine meta-molecules was also proven. The new hyperfine planar design is not only suitable for high-integration applications, but also exhibits significant slow light effect, which has great potential in advanced multichannel optical information processing. Moreover, it reveals the possibility to construct hyperfine N-level energy systems by artificial hyperfine plasmonic structures, which brings a significant prospect for applications on miniaturized plasmonic devices.

  9. Tungsten monocarbide, WC: Pure rotational spectrum and 13C hyperfine interaction

    NASA Astrophysics Data System (ADS)

    Wang, Fang; Steimle, Timothy C.

    2012-01-01

    The J = 1 → 2 pure rotational transitions in the X3Δ1(v = 0) state of 186W12C and 184W12C were recorded using a pump/probe microwave optical double resonance (PPMODR) technique and analyzed to give fine structure parameters. The field-free [17.6]2← X3Δ1 (1, 0) bands of the W13C isotopologues were recorded using laser induced fluorescence and analyzed to produce the 13C(I = 1/2) magnetic hyperfine parameter. Bonding in the [17.6]2(v = 1) and X3Δ1(v = 0) states is discussed and a comparison of the experimentally determined properties of the X3Δ1(v = 0) state with those predicted as a prelude to the electron electric dipole moment (eEDM) measurements [J. Lee, E. R. Meyer, R. Paudel, J. L. Bohn, and A. E. Leanhardt, J. Mod. Opt. 56, 2005 (2009), 10.1080/09500340903349930] is given.

  10. Re-appraisal of the hyperfine-structure constants in YbF: relativistic configuration interaction approach

    NASA Astrophysics Data System (ADS)

    Naik, Deepali; Sikarwar, Manu; Nayak, Malaya K.; Ghosh, Swapan K.

    2014-11-01

    Ab initio calculation of the spin rotational Hamiltonian parameters A and Ad has been performed using a fully-relativistic restricted active space (RAS) configuration interaction (CI) method for the YbF molecule. These calculations lead to the results for the hyperfine-structure constants as A = 6725 MHz, and Ad = 86 MHz, which agree favorably well with some previous correlated calculations and experimental findings. The convergence behavior of the parameters A and Ad with respect to the size of the active space and basis set has been tested satisfactorily for the reliability of the present results (within an uncertainty of ˜7%). Further, we believe that the theoretical estimates of some symmetry violating interaction constants like Wd can also be predicted with similar accuracy using the RASCI method.

  11. Nonequilibrium nuclear polarization and induced hyperfine and dipolar magnetic fields in semiconductor nanostructures

    NASA Astrophysics Data System (ADS)

    Ţifrea, Ionel; Flatté, Michael E.

    2011-10-01

    We investigate the dynamic nuclear polarization (DNP) caused by hyperfine coupling between nonequilibrium electronic spins and nuclear spins in semiconductor nanostructures. We derive the time and position dependence of the resulting hyperfine and dipolar magnetic fields. In GaAs quantum wells the induced nuclear spin polarization greatly exceeds the polarization of the electronic system that causes the DNP. The induced magnetic fields vary between tens of tesla for the electronic hyperfine field acting on nuclei, to hundreds of gauss for the nuclear hyperfine field acting on electrons, to a few gauss for the induced nuclear dipolar fields that act on both nuclei and electrons. The field strengths should be measurable via optically induced nuclear magnetic resonance or time-resolved Faraday rotation experiments. We discuss the implications of our calculations for low-dimensional semiconductor nanostructures.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    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.

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

    SciTech Connect

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

    1987-05-01

    We have rigorously included hyperfine interactions during electron-spin-exchange collisions between ground-state hydrogen atoms and find additional frequency shifts which are significant for low-temperature atomic hydrogen maser oscillators.

  14. Polarized 3He− ion source with hyperfine state selection

    SciTech Connect

    Dudnikov, V.; Morozov, Vasiliy; Dudnikov, A.

    2015-04-01

    High beam polarization is essential to the scientific productivity of a collider. Polarized 3He ions are an essential part of the nuclear physics programs at existing and future ion-ion and electron-ion colliders such as BNL's RHIC and eRHIC and JLab's ELIC. Ion sources with performance exceeding that achieved today are a key requirement for the development of these next generation high-luminosity high-polarization colliders. The development of high-intensity high-brightness arc-discharge ion sources at the Budker Institute of Nuclear Physics (BINP) has opened up an opportunity for realization of a new type of a polarized 3He− ion source. This report discusses a polarized 3He− ion source based on the large difference of extra-electron auto-detachment lifetimes of the different 3He− ion hyperfine states. The highest momentum state of 5/2 has the largest lifetime of τ ∼ 350 µs while the lower momentum states have lifetimes of τ ~ 10 µs. By producing 3He− ion beam composed of only the |5/2, ±5/2> hyperfine states and then quenching one of the states by an RF resonant field, 3He− beam polarization of 90% can be achieved. Such a method of polarized 3He− production has been considered before; however, due to low intensities of the He+ ion sources existing at that time, it was not possible to produce any interesting intensity of polarized 3He− ions. The high-brightness arc-discharge ion source developed at BINP can produce a high-brightness 3He+ beam with an intensity of up to 2 A allowing for selection of up to ∼1-4 mA of 3He− ions with ∼90% polarization. The high gas efficiency of an arc-discharge source is important due to the high cost of 3He gas. Some features of such a PIS as well as prototype designs are considered. An integrated 3He− ion source design providing high beam polarization could be prepared using existing BNL equipment with incorporation of new designs of the 1) arc discharge plasma generator, 2) extraction system, 3) charge

  15. Calculation of the hyperfine structure of the superheavy elements Z=119 and Z=120{sup +}

    SciTech Connect

    Dinh, T. H.; Dzuba, V. A.; Flambaum, V. V.

    2009-10-15

    The hyperfine-structure constants of the lowest s and p{sub 1/2} states of superheavy elements Z=119 and Z=120{sup +} are calculated using ab initio approach. Core polarization and dominating correlation effects are included to all orders. Breit and quantum electrodynamic effects are also considered. Similar calculations for Cs, Fr, Ba{sup +}, and Ra{sup +} are used to control the accuracy. The dependence of the hyperfine-structure constants on the nuclear radius is discussed.

  16. Hyperfine interactions in titanates: Study of orbital ordering and local magnetic properties

    SciTech Connect

    Agzamova, P. A. Leskova, Yu. V.; Nikiforov, A. E.

    2013-05-15

    Hyperfine magnetic fields induced on the nuclei of nonmagnetic ions {sup 139}La and {sup 89}Y in LaTiO{sub 3} and YTiO{sub 3}, respectively, have been microscopically calculated. The dependence of the hyperfine fields on the orbital and magnetic structures of the compounds under study has been analyzed. The comparative analysis of the calculated and known experimental data confirms the existence of the static orbital structure in lanthanum and yttrium titanates.

  17. 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.

    PubMed

    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)].

  18. Theoretical study of the nitrogen atom hyperfine coupling constant

    NASA Technical Reports Server (NTRS)

    Bauschlicher, Charles W., Jr.; Langhoff, Stephen R.; Partridge, Harry; Chong, Delano P.

    1988-01-01

    The nitrogen-atom isotropic hyperfine coupling constant A(iso) is studied as a function of improvements in both the one-particle and n-particle basis sets. The study underscores the importance of diffuse basis functions. For example, the (9s 5p) primitive set of Huzinaga (1965) augmented with an even-tempered diffuse s function yields values for A(iso) that are virtually identical to an energy-optimized (23s 12p) even-tempered set. The A(iso) constant is found to converge relatively quickly with increasing l quantum numbers: d, f, and g functions are estimated to contribute 2.5 + or - 0.2, 0.4 + or - 0.1, and 0.05 + or - 0.05 MHz, respectively. Full CI calibration calculations indicate that very high levels of correlation treatment are required for quantitative results. In addition, a strong coupling is observed between the one-particle and n-particle requirements. The best result, 10.4 MHz, is in excellent agreement with the accurate experimental value of 10.4509 MHz.

  19. Hyperfine anomalies of HCN in cold dark clouds

    SciTech Connect

    Walmsley, C.M.; Churchwell, E.; Nash, A.; Fitzpatrick, E.

    1982-07-15

    We report observations of the J = 1..-->..0 line of HCN measured toward six positions in nearby low-temperature dark clouds. The measured relative intensities of the hyperfine components of the J = 1..-->..0 line are anomalous in that the F = 0..-->..1 transition is stronger than would be expected if all three components (F = 2..-->..1, F = 1..-->..1, F = 0..-->..1) had equal excitation temperatures. Differences of approximately 20% in the populations per sublevel of J = 1 could account for the observations. The results are in contrast to the situation observed in warmer molecular clouds associated with H II regions where the F = 1..-->..1 line is anomalously weak. The apparent overpopulation of J = 1, F = 0 in dark clouds may be related to the phenomenon observed in the J = 1..-->..0 transitions of HCO/sup +/ and HNC in the same objects where /sup 13/C substituted version of these species is found to be stronger than the /sup 12/C species.

  20. New Precise Measurement of the Hyperfine Splitting of Positronium

    SciTech Connect

    Ishida, A.

    2015-09-15

    Positronium (Ps) is an ideal system for precision test of bound state quantum electrodynamics. The hyperfine splitting (HFS) of the ground state of Ps, which is one of the most precisely tested quantity, has a large discrepancy of 16 ppm (4.5 σ) between previous experiments and theoretical calculation up to O(α{sup 3}lnα{sup −1}) and part of O(α{sup 3}) corrections. A new experiment which reduces possible systematic uncertainties of Ps thermalization effect and nonuniformity of magnetic field was performed. It revealed that the Ps thermalization effect was as large as 10 ± 2 ppm. Treating the thermalization effect correctly, a new result of 203.3942 ± 0.0016(stat., 8.0 ppm) ± 0.0013(sys., 6.4 ppm) GHz was obtained. This result is consistent with theory within 1.1 σ, whereas it disfavors the previous experimental result by 2.6 σ. It shows that the Ps thermalization effect is crucial for precision measurement of HFS. Future prospects for improved precision are briefly discussed.

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

    NASA Astrophysics Data System (ADS)

    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

  2. Charge distribution and hyperfine interactions in the vicinity of impurity sites in In2O3 doped with Fe, Co, and Ni

    NASA Astrophysics Data System (ADS)

    Sena, C.; Costa, M. S.; Muñoz, E. L.; Cabrera-Pasca, G. A.; Pereira, L. F. D.; Mestnik-Filho, J.; Carbonari, A. W.; Coaquira, J. A. H.

    2015-08-01

    In this paper, first-principles calculations based on density functional theory (DFT) were used to determine TM (TM=Fe, Ni, Co) and Cd impurity locations in the In2O3 host structure, their charge states, the electronic and structural relaxations induced in the host lattice as well as to interpret previous and supplementary experimental results of hyperfine interactions. Different techniques were carried out to characterize TM-doped In2O3 bulk samples prepared by the sol-gel method starting from very pure metals. Perturbed angular correlation (PAC) spectroscopy, a sensitive nuclear technique capable of measuring interactions from electronic charge and spins within an atomic distance, was used to experimentally determine hyperfine interactions at cation sites of In2O3 doped with Co and Ni using 111In →111Cd as probe nuclei. Room temperature results of magnetization measurements in In2O3 doped with Fe, Co and Ni show ferromagnetic ordering coexisting with a paramagnetic behavior for all samples. Results of PAC spectroscopy and DFT calculations show that TM atoms locate as second nearest neighbors of Cd probes preferentially occupy symmetric sites of the doped In2O3 crystal structure with lattice parameters slightly different from that of pure In2O3. Moreover, while a major population of 111Cd probes observes almost the same hyperfine interactions measured for pure In2O3, a small population detects magnetic dipole interactions with magnetic hyperfine field at Cd probes of 2.6 T, 3.1 T, and 4.6 T, respectively for Ni, Co, and Fe doping presenting an almost linear dependence on the number of unpaired 3d electrons of the transition metal impurity.

  3. Analytic calculation of radiative-recoil corrections to muonium hyperfine splitting: Electron-line contribution

    SciTech Connect

    Eides, M.I.; Karshenboim, S.G.; Shelyuto, V.A. )

    1991-02-01

    The detailed account of analytic calculation of radiative-recoil correction to muonium hyperfine splitting, induced by electron-line radiative insertions, is presented. The consideration is performed in the framework of the effective two-particle formalism. A good deal of attention is paid to the problem of the divergence cancellation and the selection of graphs, relevant to radiative-recoil corrections. The analysis is greatly facilitated by use of the Fried-Yennie gauge for radiative photons. The obtained set of graphs turns out to be gauge-invariant and actual calculations are performed in the Feynman gauge. The main technical tricks, with the help of which we have effectively utilized the existence in the problem of the small parameter-mass ratio and managed to perform all calculations in the analytic form are described. The main intermediate results, as well as the final answer, {delta}E{sub rr} = ({alpha}({Zeta}{alpha})/{pi}{sup 2})(m/M)E{sub F}(6{zeta}(3) + 3{pi}{sup 2} In 2 + {pi}{sup 2}/2 + 17/8), are also presented.

  4. Hidden sector hydrogen as dark matter: Small-scale structure formation predictions and the importance of hyperfine interactions

    NASA Astrophysics Data System (ADS)

    Boddy, Kimberly K.; Kaplinghat, Manoj; Kwa, Anna; Peter, Annika H. G.

    2016-12-01

    We study the atomic physics and the astrophysical implications of a model in which the dark matter is the analog of hydrogen in a secluded sector. The self-interactions between dark matter particles include both elastic scatterings as well as inelastic processes due to a hyperfine transition. The self-interaction cross sections are computed by numerically solving the coupled Schrödinger equations for this system. We show that these self-interactions exhibit the right velocity dependence to explain the low dark matter density cores seen in small galaxies while being consistent with all constraints from observations of clusters of galaxies. For a viable solution, the dark hydrogen mass has to be in the 10-100 GeV range and the dark fine-structure constant has to be larger than 0.01. This range of model parameters requires the existence of a dark matter-antimatter asymmetry in the early universe to set the relic abundance of dark matter. For this range of parameters, we show that significant cooling losses may occur due to inelastic excitations to the hyperfine state and subsequent decays, with implications for the evolution of low-mass halos and the early growth of supermassive black holes. Cooling from excitations to higher n levels of dark hydrogen and subsequent decays is possible at the cluster scale, with a strong dependence on halo mass. Finally, we show that the minimum halo mass is in the range of 1 03.5 to 1 07M⊙ for the viable regions of parameter space, significantly larger than the typical predictions for weakly interacting dark matter models. This pattern of observables in cosmological structure formation is unique to this model, making it possible to rule in or rule out hidden sector hydrogen as a viable dark matter model.

  5. Magnetic hyperfine interactions on Cd sites of the rare-earth cadmium compounds R Cd (R =Ce , Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er)

    NASA Astrophysics Data System (ADS)

    Cavalcante, F. H. M.; Leite Neto, O. F. L. S.; Saitovitch, H.; Cavalcante, J. T. P. D.; Carbonari, A. W.; Saxena, R. N.; Bosch-Santos, B.; Pereira, L. F. D.; Mestnik-Filho, J.; Forker, M.

    2016-08-01

    This paper reports the investigation of the magnetic hyperfine field Bh f in a series of rare-earth (R ) cadmium intermetallic compounds R Cd and GdCd2 measured by perturbed angular correlation (PAC) spectroscopy using 111In/111Cd as probe nuclei at Cd sites as well as first-principles calculations of Bh f at Cd sites in the studied compounds. Vapor-solid state reaction of R metals with Cd vapor and the 111In radioisotope was found to be an appropriate route of doping rare-earth cadmium compounds with the PAC probe 111In/111Cd. The observation that the hyperfine parameters depend on details of the sample preparation provides information on the phase preference of diffusing 111In in the rare-earth cadmium phase system. The 111Cd hyperfine field has been determined in the compounds R Cd for the R constituents Ce, Pr, Nd, Sm, Gd, Tb, Dy, Ho, and Er, in several cases as a function of temperature. For most R constituents, the temperature dependence Bh f(T ) of 111Cd:R Cd is consistent with ferromagnetic order of the compound. DyCd, however, presents a remarkable anomaly: a finite magnetic hyperfine field is observed only in the temperature interval 35 K ≤ T ≤ 80 K which indicates a transition from ferromagnetic order to a spin arrangement where all 4 f -induced contributions to the magnetic hyperfine field at the Cd site cancel. First-principles calculation results for DyCd show that the (π , π , 0) antiferromagnetic configuration is energetically more favorable than the ferromagnetic. The approach used in the calculations to simulate the R Cd system successfully reproduces the experimental values of Bh f at Cd sites and shows that the main contribution to Bh f comes from the valence electron polarization. The de Gennes plot of the hyperfine field Bh f of 111Cd:R Cd vs the 4 f -spin projection (g -1 )J reflects a decrease of the strength of indirect 4 f -4 f exchange across the R series. Possible mechanisms are discussed and the experimental results indicate that

  6. Measurement of hyperfine splitting and determination of hyperfine structure constant of cesium 8S1/2 state by using of ladder-type EIT

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Wang, Junmin; Liu, Huifeng; Yang, Baodong; He, Jun

    2013-05-01

    The narrow electromagnetically-induced transparency (EIT) resonance peaks are observed with two low-power counter-propagating diode lasers in cesium (Cs) 6S1/2 - 6P1/2 - 8S1/2 ladder-type atomic system. To precisely determine the centers of resonance peaks, multiple background-free EIT signals are achieved using a novel scanning scheme in which the coupling laser driving Cs 6P1/2 - 8S1/2 transition is scanned and the probe laser driving Cs 6S1/2 - 6P1/2 is frequency locked. A temperature-stabilized fiber-pigtailed waveguide-type phase electro-optical modulator (EOM) and a stable confocal Fabry-Perot cavity are used as a precise frequency marker to measure the hyperfine splitting of Cs 8S1/2 state. The impact of the external magnetic field on the measurement is also investigated. Furthermore, the hyperfine structure constant (here it is the hyperfine magnetic dipole constant, A) of Cs 8S1/2 state is determined to be A = 219.06 MHz +/- 0.12 MHz based on the measured hyperfine splitting (Δhfs = 876.24 MHz +/- 0.50 MHz).

  7. Hyperfine Splittings in the Near-Infrared Spectrum of 14NH_3

    NASA Astrophysics Data System (ADS)

    Twagirayezu, Sylvestre; Sears, Trevor; Hall, Gregory

    2016-06-01

    Sub-Doppler, saturation dip, measurements of transitions in the ν_1 + ν_3 band of 14NH_3 have been made by frequency comb-referenced diode laser absorption spectroscopy. The observed spectra exhibit either resolved or partially-resolved hyperfine splittings that are primarily determined by the 14N quadrupole coupling in the molecule. Modeling of the line shapes based on the known hyperfine level structure of the ground state of the molecule shows that, in nearly all cases, the upper state level has splittings similar to that of the same rotational level in the ground state. The data provide accurate frequencies for the line positions and the observed hyperfine splittings can be used to make or confirm rotational assignments. Of all the measurements, one transition, pP(5,4)_a at 195 994.73457 GHz, exhibits hyperfine structure which does not conform to that expected based on extrapolation from the known lower state hyperfine splittings. Examination of the known vibration-rotation level structure near the upper state energy shows that there exists a near degeneracy between this level and one in the ν_1 + 2ν_4 manifold which is of the appropriate symmetry to be mixed by magnetic hyperfine terms that couple ortho- and para- modifications of the molecule. It is possible that the unusual hyperfine splittings are a consequence of ortho-paro mixing, which has been predicted, but not previously seen in ammonia and further experimental measurements to investigate this possibility are ongoing. Acknowledgments: Work at Brookhaven National Laboratory was carried out under Contract No. DE-SC0012704 with the U.S. Department of Energy, Office of Science, and supported by its Division of Chemical Sciences, Geosciences and Biosciences within the Office of Basic Energy Sciences.

  8. Hyperfine structures, isotope shifts, and transition rates of C II, N III, and O IV from relativistic configuration interaction calculations

    SciTech Connect

    Joensson, Per Li Jiguang; Gaigalas, Gediminas; Dong Chenzhong

    2010-05-15

    Energy levels, specific mass shift parameters, hyperfine interaction constants, Landeg{sub J} factors, and transition probabilities between computed levels are reported for C II, N III, and O IV. Results include levels belonging to 2s{sup 2}2p,2s2p{sup 2},2p{sup 3},2s{sup 2}3s,2s{sup 2}3p,2s{sup 2}3d,2s2p3s and, in the case of C II, the 2s{sup 2}4s and 2s{sup 2}4p configurations. Wavefunctions were determined using the multiconfiguration Dirac-Hartree-Fock method and account for valence, core-valence, and core-core correlation effects.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Calculation of radiative corrections to hyperfine splittings in the neutral alkali metals

    SciTech Connect

    Sapirstein, J.; Cheng, K.T.

    2003-02-01

    The radiative correction to hyperfine splitting in hydrogen is dominated by the Schwinger term, {alpha}/2{pi} E{sub F}, where E{sub F} is the lowest-order hyperfine splitting. Binding corrections to this term, which enter as powers and logarithms of Z{alpha}, can be expected to be increasingly important in atoms with higher nuclear charge Z. Methods that include all orders of Z{alpha}, developed first to study highly charged ions, are adapted to the study of the neutral alkali metals, lithium through francium. It is shown that the use of the Schwinger term alone to account for radiative corrections to hyperfine splittings becomes qualitatively incorrect for the heavier alkali metals.0.

  11. 2s Hyperfine splitting in light hydrogen-like atoms: Theory and experiment

    SciTech Connect

    Karshenboim, S. G. Kolachevsky, N. N.; Ivanov, V. G.; Fischer, M.; Fendel, P.; Haensch, T. W.

    2006-03-15

    Since the combination D{sub 21} = 8f{sub HFS}(2s)-f{sub HFS}(1s) of hyperfine intervals in hydrogen and light two-body hydrogen-like atomic systems weakly depends on the nuclear structure, comparison between theory and experiment can be sensitive to high order QED corrections. New theoretical and experimental results are presented. Calculations have been performed for the hydrogen and deuterium atoms and for the helium-3 ion. Experiments on the 2s hyperfine splitting (responsible for the dominant contribution to the error in D{sub 21}) have been conducted for hydrogen and deuterium. The theory and experiment are in good agreement, and their accuracy is comparable to that attained in verifying the QED theory of the hyperfine splitting in leptonic atoms (muonium and positronium)

  12. Appraising nuclear-octupole-moment contributions to the hyperfine structures in 211Fr

    NASA Astrophysics Data System (ADS)

    Sahoo, B. K.

    2015-11-01

    Hyperfine structures of 211Fr due to the interactions of magnetic dipole (μ ), electric quadrupole (Q ), and magnetic octupole (Ω ) moments with the electrons are investigated using the relativistic coupled-cluster theory with the single, double, and important valence triple excitations approximations. The validity of our calculations is substantiated by comparing these values with the available experimental results. Its Q value has also been elevated by combining the measured hyper-fine-structure constant of the 7 p 2P3 /2 state with our improved calculation. Considering the preliminary value of Ω from the nuclear shell model, its contributions to the hyperfine structures up to the 7 d 2D5 /2 low-lying states in 211Fr are estimated. Hyperfine energy-level splittings of many states have been assessed to find the suitability for carrying out their precise measurements so that Ω of 211Fr can be inferred from them unambiguously.

  13. Hyperfine structure constants for singly ionized manganese (Mn II) using Fourier transform spectroscopy

    NASA Astrophysics Data System (ADS)

    Townley-Smith, Keeley; Nave, Gillian; Pickering, Juliet C.; Blackwell-Whitehead, Richard J.

    2016-09-01

    We expand on the comprehensive study of hyperfine structure (HFS) in Mn II conducted by Holt et al. (1999) by verifying hyperfine magnetic dipole constants (A) for 20 levels previously measured by Holt et al. (1999) and deriving A constants for 47 previously unstudied levels. The HFS patterns were measured in archival spectra from Fourier transform (FT) spectrometers at Imperial College London and the National Institute of Standards and Technology. Analysis of the FT spectra was carried out in XGREMLIN. Our A constant for the ground level has a lower uncertainty by a factor of 6 than that of Blackwell-Whitehead et al.

  14. Hyperfine field of einsteinium in iron and nuclear magnetic moment of {sup 254}Es

    SciTech Connect

    Severijns, N.; Kraev, I. S.; Phalet, T.; Tandecki, M.; Traykov, E.; Gorp, S. Van; Wauters, F.; Belyaev, A. A.; Lukhanin, A. A.; Noga, V. I.; Erzinkyan, A. L.; Parfenova, V. P.; Eversheim, P.-D.; Herzog, P.; Tramm, C.; Filimonov, V. T.; Toporov, Yu. G.; Zotov, E.; Golovko, V. V.; Gurevich, G. M.

    2009-06-15

    The angular distributions of {gamma} rays and {alpha} particles from oriented {sup 250}Bk, {sup 253,254}Es, and {sup 255}Fm nuclei were investigated to extract hyperfine interaction information for these actinide impurities in an iron host lattice. The hyperfine field of einsteinium in iron was found to be |B{sub hf}(EsFe{sub lowbar|})=396(32) T. With this value the magnetic moment of {sup 254}Es was then determined as |{mu}|=4.35(41) {mu}{sub N}.

  15. Suppression of ultracold ground-state hyperfine-changing collisions with laser light

    SciTech Connect

    Sanchez-Villicana, V.; Gensemer, S.D.; Tan, K.Y.N.; Kumarakrishnan, A.; Dinneen, T.P.; Sueptitz, W.; Gould, P.L.

    1995-06-05

    Using laser light tuned to a repulsive molecular potential, we have been able to suppress inelastic ground-state hyperfine-changing collisions between ultracold {sup 87}Rb atoms. Adiabatic excitation to the repulsive curve alters the atomic trajectories and prevents the atoms from approaching close enough for the hyperfine change to occur. Experimental results show suppressions up to {similar_to}50% and are in reasonable agreement with a simple Landau-Zener model. Our ability to control collisional trap loss processes may have important implications for the achievement of high densities in laser cooled samples.

  16. 57Fe NMR study of the magnetoelectric hexaferrite Ba0.5Sr1.5Zn2Fe12O22 and Ba0.5Sr1.5Zn2(Fe0.92Al0.08)12O22

    NASA Astrophysics Data System (ADS)

    Kwon, Sangil; Yoon, Dong Young; Lee, Soonchil; Chai, Yi Sheng; Chun, Sae Hwan; Kim, Kee Hoon

    2013-08-01

    Magnetoelectric hexaferrite Ba0.5Sr1.5Zn2Fe12O22 (BSZFO) and Ba0.5Sr1.5Zn2(Fe0.92Al0.08)12O22 (BSZFAO) were investigated by 57Fe nuclear magnetic resonance (NMR). The spin-canting angles of all NMR peaks were measured to assign each peak to corresponding Fe3+ sites. It was revealed that the spin-canting angle of Fe3+ ions at off-centered octahedra is fixed and Al3+ ions substitute for Fe3+ ions at those sites. The temperature dependence of the NMR frequency indicates that the low-temperature excitation is spin wave in ferromagnetic phase.

  17. Effect of particle size distribution on the structure, hyperfine, and magnetic properties of Ni0.5Zn0.5Fe2O4 nanopowders

    NASA Astrophysics Data System (ADS)

    Bhattacharjee, Kaustav; Pati, Satya P.; Das, G. C.; Das, D.; Chattopadhyay, K. K.

    2014-12-01

    Ni0.5Zn0.5Fe2O4 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 (⟨ɛ2⟩1/2), oxygen positional parameter (u), metal-oxygen bond lengths ( RO A and RO B ), and the band positions (ν1and ν2) 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 Ni0.5Zn0.5Fe2O4 nanoparticles was investigated herein which hitherto has not been discussed in the literature.

  18. Theoretical and electron paramagnetic resonance studies of hyperfine interaction in nitrogen doped 4H and 6H SiC

    SciTech Connect

    Szász, K.; Gali, A.

    2014-02-21

    Motivated by recent experimental findings on the hyperfine signal of nitrogen donor (N{sub C}) in 4 H and 6 H SiC, we calculate the hyperfine tensors within the framework of density functional theory. We find that there is negligible hyperfine coupling with {sup 29}Si isotopes when N{sub C} resides at h site both in 4 H and 6 H SiC. We observe measurable hyperfine coupling to a single {sup 29}Si at k site in 4 H SiC and k{sub 1} site in 6 H SiC. Our calculations unravel that such {sup 29}Si hyperfine coupling does not occur at k{sub 2} site in 6 H SiC. Our findings are well corroborated by our new electron paramagnetic resonance studies in nitrogen doped 6 H SiC.

  19. {sup 87}Rb hyperfine-transition dephasing in mixed buffer-gas systems

    SciTech Connect

    Huang, M.; Coffer, J. G.; Camparo, J. C.

    2007-05-15

    Elucidating the mechanisms of dephasing in the alkali-metal ground state hyperfine transition has remained an unsatisfactorily resolved problem since the mid-1960s, even though its solution has relevance to next-generation atomic clocks. Recently, however, measurements of electronic spin relaxation in strong magnetic fields have resolved a number of outstanding ambiguities, and the situation has greatly improved. Unfortunately, while these studies have illuminated the processes contributing to hyperfine transition dephasing, they only allow one to infer actual dephasing rates, {gamma}. The direct measurement of dephasing rates remains problematic, primarily as a result of temperature gradient inhomogeneous broadening, which makes it nearly impossible to distinguish systematic from physical effects. Here, we demonstrate that by measuring {gamma} as a function of mole fraction in mixed buffer-gas systems we can isolate temperature gradient effects, thereby allowing a direct comparison between theory and experiment. In the present work, we examine the linewidth of the {sup 87}Rb hyperfine transition in Ar-N{sub 2} mixed buffer-gas systems. We obtain good agreement between theory and experiment so long as we include the full dephasing contribution from RbAr van der Waals molecules: the spin-rotation contribution, {gamma}{sub SR}, and the contribution from the change in {sup 87}Rb hyperfine coupling, {gamma}{sub B}, which we refer to as the Bouchiat rate. We have been able to measure {gamma}{sub B}, obtaining {gamma}{sub B}=87{+-}6 s{sup -1} for RbAr.

  20. Measurement of rubidium ground-state hyperfine transition frequency using atomic fountains

    NASA Astrophysics Data System (ADS)

    Ovchinnikov, Yuri B.; Szymaniec, Krzysztof; Edris, Soliman

    2015-08-01

    The results of precision measurements of the 87Rb ground-state hyperfine transition frequency, which were conducted at NPL from 2009 to 2013, are reported. The resulting frequency, measured using NPL’s Cs and Rb atomic frequency standards, demonstrates reasonable agreement with the most recent measurements reported by LNE-SYRTE.

  1. Towards measuring the ground state hyperfine splitting of antihydrogen - a progress report

    NASA Astrophysics Data System (ADS)

    Sauerzopf, C.; Capon, A. A.; Diermaier, M.; Dupré, P.; Higashi, Y.; Kaga, C.; Kolbinger, B.; Leali, M.; Lehner, S.; Rizzini, E. Lodi; Malbrunot, C.; Mascagna, V.; Massiczek, O.; Murtagh, D. J.; Nagata, Y.; Radics, B.; Simon, M. C.; Suzuki, K.; Tajima, M.; Ulmer, S.; Vamosi, S.; Gorp, S. van; Zmeskal, J.; Breuker, H.; Higaki, H.; Kanai, Y.; Kuroda, N.; Matsuda, Y.; Venturelli, L.; Widmann, E.; Yamazaki, Y.

    2016-12-01

    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.

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

    SciTech Connect

    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.

  3. Strain and electric field control of hyperfine interactions for donor spin qubits in silicon

    NASA Astrophysics Data System (ADS)

    Usman, M.; Hill, C. D.; Rahman, R.; Klimeck, G.; Simmons, M. Y.; Rogge, S.; Hollenberg, L. C. L.

    2015-06-01

    Control of hyperfine interactions is a fundamental requirement for quantum computing architecture schemes based on shallow donors in silicon. However, at present, there is lacking an atomistic approach including critical effects of central-cell corrections and nonstatic screening of the donor potential capable of describing the hyperfine interaction in the presence of both strain and electric fields in realistically sized devices. We establish and apply a theoretical framework, based on atomistic tight-binding theory, to quantitatively determine the strain and electric-field-dependent hyperfine couplings of donors. Our method is scalable to millions of atoms, and yet captures the strain effects with an accuracy level of DFT method. Excellent agreement with the available experimental data sets allow reliable investigation of the design space of multiqubit architectures, based on both strain only as well as hybrid (strain + field) control of qubits. The benefits of strain are uncovered by demonstrating that a hybrid control of qubits based on (001) compressive strain and in-plane (100 or 010) fields results in higher gate fidelities and or faster gate operations, for all of the four donor species considered (P, As, Sb, and Bi). The comparison between different donor species in strained environments further highlights the trends of hyperfine shifts, providing predictions where no experimental data exists. While faster gate operations are realizable with in-plane fields for P, As, and Sb donors, only for the Bi donor, our calculations predict faster gate response in the presence of both in-plane and out-of-plane fields, truly benefiting from the proposed planar field control mechanism of the hyperfine interactions.

  4. Spin dynamics of polarons and polaron pairs in a random hyperfine field

    NASA Astrophysics Data System (ADS)

    Roundy, Robert C.

    Spin-dependent recombination of polaron pairs and spin relaxation of a single polaron are the most fundamental processes are responsible for the performance of organic spintronics-based devices such as light-emitting diodes and organic spin valves. In organic materials, with no spin-orbit coupling, both processes are due to random hyperfine fields created by protons neighboring the polaron sites. The essence of spin-dependent recombination is that in order to recombine the pair must be in the singlet state. Hyperfine fields acting on the electron and hole govern the spin-dynamics of localized pairs during the waiting time for recombination. We demonstrate that for certain domain of trapping configurations of hyperfine fields, crossover to the singlet state is quenched. This leads to the blocking of current. The phenomenon of organic magnetoresistance (OMAR) is described by counting the weights of trapping configurations as a function of magnetic field. This explains the universality of the lineshapes of the OMAR curves. In finite samples incomplete averaging over the hyperfine fields gives rise to mesoscopic fluctuations of the current response. We also demonstrate that under the condition of magnetic resonance, new trapping configurations emerge. This leads to nontrivial evolution of current through the sample with microwave power. When discussing spin-relaxation two questions can be asked: (a) How does the local spin polarization decay as a function of distance from the spin-polarized injector? (b) How does the injected spin decay as a function of time after spatial averaging? With regard to (a), we demonstrate that, while decaying exponentially on average, local spin-polarization exhibits giant fluctuations from point to point. Concerning (b), we find that for a spin-carrier which moves diffusively in low dimensions the decay is faster than a simple exponent. The underlying physics for both findings is that in describing spin evolution it is necessary to add up

  5. Strong hyperfine-induced modulation of an optically driven hole spin in an InAs quantum dot

    NASA Astrophysics Data System (ADS)

    Carter, S. G.; Economou, Sophia E.; Greilich, A.; Barnes, Edwin; Sweeney, T.; Bracker, A. S.; Gammon, D.

    2014-02-01

    Compared to electrons, holes in InAs quantum dots have a significantly weaker hyperfine interaction that leads to less dephasing from nuclear spins. Thus many recent studies have suggested that nuclear spins are unimportant for hole-spin dynamics compared to electric-field fluctuations. We show that the hole hyperfine interaction can have a strong effect on hole-spin coherence measurements through a nuclear feedback effect. The nuclear polarization is generated through a unique process that is dependent on the anisotropy of the hole hyperfine interaction and the coherent precession of nuclear spins, giving rise to strong modulation at the nuclear precession frequency.

  6. Electronic spectroscopy of jet-cooled HCP+: molecular structure, phosphorus hyperfine structure, and Renner-Teller analysis.

    PubMed

    Sunahori, Fumie X; Zhang, Xiaopeng; Clouthier, Dennis J

    2007-09-14

    Laser-induced fluorescence spectra of jet-cooled HCP(+) and DCP(+) have been obtained with the pulsed discharge technique using HCPDCP and argon precursor mixtures. Transitions involving all of the excited state vibrations have been observed and a set of vibrational constants has been obtained. High-resolution spectra of the (2)Pi(32) components of the 0(0) (0) bands of both isotopomers have been recorded, and these spectra show resolved phosphorus hyperfine structure which allowed the determination of the excited state Fermi contact parameter. The B values were used to obtain the ground and excited state effective geometric parameters as r(0) (")(CH)=1.077(2) A, r(0) (")(CP)=1.6013(3) A, r(0) (')(CH)=1.082(2) A, and r(0) (')(CP)=1.5331(3) A. A Renner-Teller analysis of the ground state vibrational energy levels obtained from the literature was attempted. All of the observed levels of DCP(+) and the majority of those of HCP(+) were satisfactorily fitted with a standard Renner-Teller model, but three HCP(+) levels showed large systematic deviations which could not be accommodated by reassignments or improvements in the Fermi resonance Hamiltonian. Further improvements in the theory or in the experimental data will be needed to resolve this discrepancy.

  7. The rotational spectra, potential function, Born-Oppenheimer breakdown, and hyperfine structure of GeSe and GeTe

    NASA Astrophysics Data System (ADS)

    Giuliano, Barbara M.; Bizzocchi, Luca; Sanchez, Raquel; Villanueva, Pablo; Cortijo, Vanessa; Sanz, M. Eugenia; Grabow, Jens-Uwe

    2011-08-01

    The pure rotational spectra of 18 and 21 isotopic species of GeSe and GeTe have been measured in the frequency range 5-24 GHz using a Fabry-Pérot-type resonator pulsed-jet Fourier-transform microwave spectrometer. Gaseous samples of both chalcogenides were prepared by a combined dc discharge/laser ablation technique and stabilized in supersonic jets of Ne. Global multi-isotopologue analyses of the derived rotational data, together with literature high-resolution infrared data, produced very precise Dunham parameters, as well as rotational constant Born-Oppenheimer breakdown (BOB) coefficients (δ01) for Ge, Se, and Te. A direct fit of the same datasets to an appropriate radial Hamiltonian yielded analytic potential-energy functions and BOB radial functions for the X1Σ+ electronic state of both GeSe and GeTe. Additionally, the electric quadrupole and magnetic hyperfine interactions produced by the nuclei 73Ge, 77Se, and 125Te were observed, yielding much improved quadrupole coupling constants and first determinations of the spin-rotation parameters.

  8. Hyperfine interaction and tuning of magnetic anisotropy of Cu doped CoFe2O4 ferrite nanoparticles

    NASA Astrophysics Data System (ADS)

    Batoo, Khalid Mujasam; Salah, Dina; Kumar, Gagan; Kumar, Arun; Singh, Mahavir; Abd El-sadek, M.; Mir, Feroz Ahmad; Imran, Ahamad; Jameel, Daler Adil

    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 Cu2+ substitution effect in CoFe2-xO4 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 Cu2+ ion substitution. The anisotropy constant, K1, is found strongly dependent on the composition of Cu2+ ions. The variation of saturation magnetization with increasing Cu2+ 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 Cu2+ ion concentration have been discussed.

  9. Torsionally mediated spin-rotation hyperfine splittings at moderate to high J values in methanol.

    PubMed

    Belov, S P; Golubiatnikov, G Yu; Lapinov, A V; Ilyushin, V V; Alekseev, E A; Mescheryakov, A A; Hougen, J T; Xu, Li-Hong

    2016-07-14

    This paper presents an explanation based on torsionally mediated proton-spin-overall-rotation interaction for the observation of doublet hyperfine splittings in some Lamb-dip sub-millimeter-wave transitions between ground-state torsion-rotation states of E symmetry in methanol. These unexpected doublet splittings, some as large as 70 kHz, were observed for rotational quantum numbers in the range of J = 13 to 34, and K = - 2 to +3. Because they increase nearly linearly with J for a given branch, we confined our search for an explanation to hyperfine operators containing one nuclear-spin angular momentum factor I and one overall-rotation angular momentum factor J (i.e., to spin-rotation operators) and ignored both spin-spin and spin-torsion operators, since they contain no rotational angular momentum operator. Furthermore, since traditional spin-rotation operators did not seem capable of explaining the observed splittings, we constructed totally symmetric "torsionally mediated spin-rotation operators" by multiplying the E-species spin-rotation operator by an E-species torsional-coordinate factor of the form e(±niα). The resulting operator is capable of connecting the two components of a degenerate torsion-rotation E state. This has the effect of turning the hyperfine splitting pattern upside down for some nuclear-spin states, which leads to bottom-to-top and top-to-bottom hyperfine selection rules for some transitions, and thus to an explanation for the unexpectedly large observed hyperfine splittings. The constructed operator cannot contribute to hyperfine splittings in the A-species manifold because its matrix elements within the set of torsion-rotation A1 and A2 states are all zero. The theory developed here fits the observed large doublet splittings to a root-mean-square residual of less than 1 kHz and predicts unresolvable splittings for a number of transitions in which no doublet splitting was detected.

  10. Level density inputs in nuclear reaction codes and the role of the spin cutoff parameter

    DOE PAGES

    Voinov, A. V.; Grimes, S. M.; Brune, C. R.; ...

    2014-09-03

    Here, the proton spectrum from the 57Fe(α,p) reaction has been measured and analyzed with the Hauser-Feshbach model of nuclear reactions. Different input level density models have been tested. It was found that the best description is achieved with either Fermi-gas or constant temperature model functions obtained by fitting them to neutron resonance spacing and to discrete levels and using the spin cutoff parameter with much weaker excitation energy dependence than it is predicted by the Fermi-gas model.

  11. Sub-Doppler two-photon-excitation Rydberg spectroscopy of atomic xenon: mass-selective studies of isotopic and hyperfine structure

    NASA Astrophysics Data System (ADS)

    Kono, Mitsuhiko; He, Yabai; Baldwin, Kenneth G. H.; Orr, Brian J.

    2016-03-01

    Mass-selective sub-Doppler two-photon excitation (TPE) spectroscopy is employed to resolve isotopic contributions for transitions to high-energy Rydberg levels of xenon in an atomic beam, using narrowband pulses of coherent ultraviolet light at 205-213 nm generated by nonlinear-optical conversion processes. Previous research (Kono et al 2013 J. Phys. B: At. Mol. Opt. Phys. 46 35401), has determined isotope energy shifts and hyperfine structure for 33 high-energy Rydberg levels of gas-phase xenon and accessed Rydberg levels at TPE energies in the range of 94 100-97 300 cm-1 with unprecedented spectroscopic resolution. The new isotopic-mass-resolved results were obtained by adding a pulsed free-jet atomic-beam source and a mass-selective time-of-flight detector to the apparatus in order to discern individual xenon isotopes and extract previously unresolved spectroscopic information. Resulting isotope energy shifts and hyperfine-coupling parameters are examined with regard to trends in principal quantum number n and in atomic angular-momentum quantum numbers, together with empirical and theoretical precedents for such trends.

  12. Hyperfine frequency shift and Zeeman relaxation in alkali-metal-vapor cells with antirelaxation alkene coating

    NASA Astrophysics Data System (ADS)

    Corsini, Eric P.; Karaulanov, Todor; Balabas, Mikhail; Budker, Dmitry

    2013-02-01

    An alkene-based antirelaxation coating for alkali-metal vapor cells exhibiting Zeeman relaxation times up to 77 s was recently identified by Balabas The long relaxation times, two orders of magnitude longer than in paraffin- (alkane-) coated cells, motivate revisiting the question of what the mechanism is underlying wall-collision-induced relaxation and renew interest in applications of alkali-metal vapor cells to secondary frequency standards. We measure the width and frequency shift of the ground-state hyperfine mF=0→mF'=0 transition (clock resonance) in vapor cells with 85Rb and 87Rb atoms, with an alkene antirelaxation coating. We find that the frequency shift is slightly larger than for paraffin-coated cells and that the Zeeman linewidth scales linearly with the hyperfine frequency shift.

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

    PubMed

    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.

  14. Magnetic Hyperfine Fields in Lu_2V_2O_7: A Model Approach

    NASA Astrophysics Data System (ADS)

    Agzamova, Polina; Nikiforov, Anatoliy; Nazipov, Dmitriy

    2016-12-01

    We report a theoretical approach to the investigation of the magnetic hyperfine interaction on the ^{51}V nucleus in Lu_2V_2O_7 with the view of understanding the orbital ordering pattern in this compound. First, we have evaluated the vanadium 3d^1-level splitting (Δ ) under the crystal field with the D _{3d}-symmetry using the point charges approximation. Second, we have calculated the exchange interaction constant ( J) using the ab initio approach. It is shown that the crystal field energy is much stronger than the exchange interaction one and hence the orbital liquid state cannot occur in Lu_2V_2O_7. Finally we have analyzed the magnetic hyperfine field affecting the vanadium nucleus leaning upon these results.

  15. Defect induced magnetism in highly oriented pyrolytic graphite: bulk magnetization and 19F hyperfine interaction studies.

    PubMed

    Mohanta, S K; Mishra, S N; Davane, S M; Srivastava, S K

    2012-02-29

    We have made bulk and local investigations on defect induced magnetism in highly oriented pyrolytic graphite (HOPG) irradiated with a 40 MeV carbon beam. The local magnetic response of irradiated HOPG was studied by measuring the hyperfine field of recoil implanted (19)F using γ-ray time differential perturbed angular distribution (TDPAD) measurements. While the bulk magnetic properties of the irradiated sample show features characteristic of room temperature ferromagnetism, the hyperfine field data reflect enhanced paramagnetism with no indication of long range magnetic ordering. The experimental studies are further supported by ab initio density functional calculations. We believe that the ferromagnetic response in irradiated HOPG arises mostly from defect induced magnetic moments of carbon atoms in the near surface region, while those deep inside the host matrix remain paramagnetic.

  16. Cross-talk compensation of hyperfine control in donor-qubit architectures

    NASA Astrophysics Data System (ADS)

    Kandasamy, G.; Wellard, C. J.; Hollenberg, L. C. L.

    2006-09-01

    We theoretically investigate cross-talk in hyperfine gate control of donor-qubit quantum computer architectures, in particular the Kane proposal. By solving the Poisson and Schrödinger equations numerically for the gated donor system, we calculate the change in hyperfine coupling and thus the error in spin-rotation for the donor nuclear-electron spin system, as the gate-donor distance is varied. We thus determine the effect of cross-talk—the inadvertent effect on non-target neighbouring qubits—which occurs due to closeness of the control gates (20-30 nm). The use of compensation protocols is investigated, whereby the extent of cross-talk is limited by the application of compensation bias to a series of gates. In the light of these factors, architectural implications are then considered.

  17. Ro-vibrational averaging of the isotropic hyperfine coupling constant for the methyl radical

    SciTech Connect

    Adam, Ahmad Y.; Jensen, Per; Yachmenev, Andrey; Yurchenko, Sergei N.

    2015-12-28

    We present the first variational calculation of the isotropic hyperfine coupling constant of the carbon-13 atom in the CH{sub 3} radical for temperatures T = 0, 96, and 300 K. It is based on a newly calculated high level ab initio potential energy surface and hyperfine coupling constant surface of CH{sub 3} in the ground electronic state. The ro-vibrational energy levels, expectation values for the coupling constant, and its temperature dependence were calculated variationally by using the methods implemented in the computer program TROVE. Vibrational energies and vibrational and temperature effects for coupling constant are found to be in very good agreement with the available experimental data. We found, in agreement with previous studies, that the vibrational effects constitute about 44% of the constant’s equilibrium value, originating mainly from the large amplitude out-of-plane bending motion and that the temperature effects play a minor role.

  18. Three-loop radiative-recoil corrections to hyperfine splitting generated by one-loop fermion factors

    SciTech Connect

    Eides, Michael I.; Grotch, Howard; Shelyuto, Valery A.

    2004-10-01

    We consider three-loop radiative-recoil corrections to hyperfine splitting in muonium generated by diagrams with one-loop radiative photon insertions both in the electron and muon lines. An analytic result for these nonlogarithmic corrections of order {alpha}(Z{sup 2}{alpha})(Z{alpha})(m/M)E{sub F} is obtained. This result constitutes a next step in the implementation of the program of reduction of the theoretical uncertainty of hyperfine splitting below 10 Hz.

  19. Test of many-electron QED effects in the hyperfine splitting of heavy high-Z ions.

    PubMed

    Volotka, A V; Glazov, D A; Andreev, O V; Shabaev, V M; Tupitsyn, I I; Plunien, G

    2012-02-17

    A rigorous evaluation of the two-photon exchange corrections to the hyperfine structure in lithiumlike heavy ions is presented. As a result, the theoretical accuracy of the specific difference between the hyperfine splitting values of H- and Li-like Bi ions is significantly improved. This opens a possibility for the stringent test of the many-electron QED effects on a few percent level in the strongest electromagnetic field presently available in experiments.

  20. Isotope shifts and hyperfine structure in polonium isotopes by atomic-beam laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Kowalewska, D.; Bekk, K.; Göring, S.; Hanser, A.; Kälber, W.; Meisel, G.; Rebel, H.

    1991-08-01

    Laser-induced fluorescence spectroscopy in a collimated atomic beam has been applied to determine isotope shifts and the hyperfine structure of an isotopic chain of the radioactive element polonium (200Po, 202Po, 204-210Po). The relative isotope shifts show a striking similarity with results for other elements in the vicinity of Pb, even reproducing details of the odd-even staggering.

  1. Optical isolator using an atomic vapor in the hyperfine Paschen-Back regime.

    PubMed

    Weller, L; Kleinbach, K S; Zentile, M A; Knappe, S; Hughes, I G; Adams, C S

    2012-08-15

    A light, compact optical isolator using an atomic vapor in the hyperfine Paschen-Back regime is presented. Absolute transmission spectra for experiment and theory through an isotopically pure 87Rb vapor cell show excellent agreement for fields of 0.6 T. We show π/4 rotation for a linearly polarized beam in the vicinity of the D2 line and achieve an isolation of 30 dB with a transmission >95%.

  2. Hyperfine specific heats of PrX 2 ( X = Ir, Pt, Rh, Ru) laves phase compounds

    NASA Astrophysics Data System (ADS)

    Greidanus, F. J. A. M.; de Jongh, L. J.; Huiskamp, W. J.; Buschow, K. H. J.

    1980-01-01

    Specific heat data below 1 K for the C-15 compounds PrX 2 (X = Ir, Pt, Rh, Ru) reveal Schottky-type anomalies, ascribed to hyperfine interactions. Apparently the 4f-moments are magnetically ordered. The values deduced for these moments are only ≈ 70% of that for J = 4, indicating that the Pr 3+ moment is partially quenched by the crystal field.

  3. Leading logarithmic corrections to the muonium hyperfine splitting and to the hydrogen Lamb shift

    SciTech Connect

    Karshenboim, S.G.

    1994-12-31

    Main leading corrections with recoil logarithm log(M/m) and low-energy logarithm log(Za) to the Muonium hyperfine splitting axe discussed. Logarithmic corrections have magnitudes of 0.1 {divided_by} 0.3 kHz. Non-leading higher order corrections axe expected to be not larger than 0.1 kHz. Leading logarithmic correction to the Hydrogen Lamb shift is also obtained.

  4. Three-loop reducible radiative photon contributions to Lamb shift and hyperfine splitting

    SciTech Connect

    Eides, Michael I.; Shelyuto, Valery A.

    2004-08-01

    Corrections of order {alpha}{sup 3}(Z{alpha}){sup 5}m to the Lamb shift and corrections of order {alpha}{sup 3}(Z{alpha})E{sub F} to the hyperfine splitting, generated by insertion of the three-loop one-particle reducible diagrams with radiative photons in the electron line, are calculated. The calculations are performed in the Yennie gauge.

  5. Radiative-recoil corrections to hyperfine splitting: Polarization insertions in the muon factor

    SciTech Connect

    Eides, Michael I.; Shelyuto, Valery A.

    2009-09-01

    We consider three-loop radiative-recoil corrections to hyperfine splitting in muonium due to insertions of a one-loop polarization operator in the muon factor. The contribution produced by electron polarization insertions is enhanced by the large logarithm of the electron-muon mass ratio. We obtained all single-logarithmic and nonlogarithmic radiative-recoil corrections of order {alpha}{sup 3}(m/M)E{sub F} generated by the diagrams with electron and muon polarization insertions.

  6. Optical nuclear polarization via hyperfine relaxation. Polarization mechanism in anthracene/tetracyanobenzene charge-transfer crystals

    NASA Astrophysics Data System (ADS)

    Allgeier, J.; Macho, V.; Stehlik, D.; Vieth, H. M.; Auch, W.; Von Schütz, J. U.

    1982-03-01

    The large optical nuclear polarization (ONP) found in A/TCNB crystals is due to relaxation caused by the mobility of triplet excitons. The ONP field dependence gives an excitonic hopping rate of 3 × 10 9 s -1 (at 300 K). Exclusion of ONP by static hyperfine interaction (LAC ONP) is based on results of rf ONP experiments which allow an unambiguous distinction between the two processes.

  7. Storage-ring measurements of hyperfine induced transition rates in berylliumlike ions

    SciTech Connect

    Schippers, Stefan

    2013-07-11

    The status of experimental measurements and theoretical calculations of the hyperfine induced 2s2p{sup 3}P{sub 0}{yields}2s{sup 21}S{sub 0} transition rate in Be-like ions is reviewed. Possible reasons, such as external electromagnetic fields and competing E1M1 two-photon transitions, for presently existing significant discrepancies between experiment and theory are discussed. Finally, directions for future research are outlined.

  8. Frequency tuning of the optical delay in cesium D{sub 2} line including hyperfine structure

    SciTech Connect

    Anderson, Monte D.; Perram, Glen P.

    2010-03-15

    The frequency dependence of optical delays in both the wings and core of the cesium 6 {sup 2}S{sub 1/2}-6 {sup 2}P{sub 3/2} transition have been observed and modeled with a Voigt line shape convolved with the six hyperfine components. Tunable delays of 0-37 ns are achieved by tuning the laser frequency through resonance at various vapor pressures of 0.15-5.28 mTorr.

  9. Vacuum polarization and quadrupole corrections to the hyperfine splitting of P-states in muonic deuterium

    NASA Astrophysics Data System (ADS)

    Martynenko, A. P.; Sorokin, V. V.

    2017-02-01

    On the basis of the quasipotential approach in quantum electrodynamics, we calculate vacuum polarization and quadrupole corrections in the first and second orders of perturbation theory in the hyperfine structure of P-states in muonic deuterium. All corrections are presented in integral form and are evaluated analytically and numerically. The obtained results can be used for the improvement of the transition frequencies between levels 2P and 2S.

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

    NASA Astrophysics Data System (ADS)

    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).

  11. New electron levels and classified lines in Pr II from hyperfine structure measurements

    SciTech Connect

    Furmann, B. . E-mail: furman@phys.put.poznan.pl; Stefanska, D.; Dembczynski, J.; Stachowska, E.

    2007-01-15

    Classification of 75 spectral lines (hitherto not classified) in singly ionized praseodymium (Pr II) with the use of 31 new electron levels belonging to odd configurations 4f{sup 3}5d and 4f{sup 3}6s and 14 new levels belonging to even configurations is presd. Hyperfine structure constant A and B for each new level were determined by using the method of laser-induced fluorescence in a hollow cathode discharge.

  12. Hyperfine structure and isotope shifts of transitions in neutral and singly ionized ytterbium

    NASA Technical Reports Server (NTRS)

    Berends, R. W.; Maleki, L.

    1992-01-01

    The present experimental investigation of the hyperfine structure and isotopic shifts of transitions in neutral and singly-ionized Yb, which constitute a system of some interest to microwave-frequency standards, used counterpropagating pump and probe laser beams directed through a hollow-cathode discharge lamp. The results obtained are in agreement with previous measurements except in the case of the Yb-173(+) 6 2P0 sub 3/2 state, which is more accurately determined.

  13. Raman scattering in a four-level atomic system with hyperfine structure

    NASA Astrophysics Data System (ADS)

    Li, Jia-Hua; Yang, Wen-Xing; Peng, Ju-Cun

    2005-04-01

    We propose and analyse an efficient Raman scheme for suppressing the absorption of a weak probe beam in a typical four-level atomic system with a nearly hyperfine doublet structure of two higher-lying excited levels for the two cases of transient regime and steady-state process. For the transient process, using the numerical calculations by a nice MATHEMATICA code, we find that the magnitude of the probe absorption at line centre of the probe transition is small compared to the standard three-level atomic system based on electromagnetically induced transparency (EIT). In particular, our results show that the probe absorption can be completely eliminated under the condition of Raman resonance, i.e. we only require that two-photon detuning is zero within the range of the hyperfine two-level frequency gap for the case of the steady state. In contrast to the standard three-level EIT scheme, one of the key advantages of our four-level Raman scheme is that under the Raman resonance condition we can observe one transparency window without the need of exact vanishing of one- and two-photon detuning. As a consequence, the atomic hyperfine structure cannot be a hindrance for obtaining EIT.

  14. Calculation of Radiative Corrections to Hyperfine Splitting in p1/2 States

    SciTech Connect

    Sapirstein, J; Cheng, K T

    2006-09-20

    Techniques to calculate one-loop radiative corrections to hyperfine splitting including binding corrections to all orders have been developed in the last decade for s states of atoms and ions. In this paper these methods are extended to p{sub 1/2} states for three cases. In the first case, the point-Coulomb 2p{sub 1/2} hyperfine splitting is treated for the hydrogen isoelectronic sequence, and the lowest order result, {alpha}/4{pi} E{sub F}, is shown to have large binding corrections at high Z. In the second case, neutral alkalis are considered. In the third case, hyperfine splitting of the 2p{sub 1/2} state of lithium-like bismuth is treated. In the latter two cases, correlation corrections are included and, in addition, the point is stressed that uncertainties associated with nuclear structure, which complicate comparison with experiment for s states, are considerably reduced because of the smaller overlap with the nucleus.

  15. Calculation of radiative corrections to hyperfine splitting in p{sub 1/2} states

    SciTech Connect

    Sapirstein, J.; Cheng, K. T.

    2006-10-15

    Techniques to calculate one-loop radiative corrections to hyperfine splitting including binding corrections to all orders have been developed in the last decade for s states of atoms and ions. In this paper these methods are extended to p{sub 1/2} states for three cases. In the first case, the point-Coulomb 2p{sub 1/2} hyperfine splitting is treated for the hydrogen isoelectonic sequence, and the lowest order result ({alpha}/4{pi})E{sub F}, is shown to have large binding corrections at high Z. In the second case, neutral alkali-metal atoms are considered. In the third case, hyperfine splitting of the 2p{sub 1/2} state of lithiumlike bismuth is treated. In the latter two cases, correlation corrections are included and, in addition, the point is stressed that uncertainties associated with nuclear structure, which complicate comparison with experiment for s states, are considerably reduced because of the smaller overlap with the nucleus.

  16. HYPERFINE STRUCTURE CONSTANTS OF ENERGETICALLY HIGH-LYING LEVELS OF ODD PARITY OF ATOMIC VANADIUM

    SciTech Connect

    Güzelçimen, F.; Yapıcı, B.; Demir, G.; Er, A.; Öztürk, I. K.; Başar, Gö.; Kröger, S.; Tamanis, M.; Ferber, R.; Docenko, D.; Başar, Gü. E-mail: sophie.kroeger@htw-berlin.de

    2014-09-01

    High-resolution Fourier transform spectra of a vanadium-argon plasma have been recorded in the wavelength range of 365-670 nm (15,000-27,400 cm{sup –1}). Optical bandpass filters were used in the experimental setup to enhance the sensitivity of the Fourier transform spectrometer. In total, 138 atomic vanadium spectral lines showing resolved or partially resolved hyperfine structure have been analyzed to determine the magnetic dipole hyperfine structure constants A of the involved energy levels. One of the investigated lines has not been previously classified. As a result, the magnetic dipole hyperfine structure constants A for 90 energy levels are presented: 35 of them belong to the configuration 3d {sup 3}4s4p and 55 to the configuration 3d {sup 4}4p. Of these 90 constants, 67 have been determined for the first time, with 23 corresponding to the configuration 3d {sup 3}4s4p and 44 to 3d {sup 4}4p.

  17. How Bonding in Manganous Phosphates Affects their Mn(II)-(31)P Hyperfine Interactions.

    PubMed

    Un, Sun; Bruch, Eduardo M

    2015-11-02

    Manganous phosphates have been postulated to play an important role in cells as antioxidants. In situ Mn(II) electron-nuclear double resonance (ENDOR) spectroscopy has been used to measure their speciation in cells. The analyses of such ENDOR spectra and the quantification of cellular Mn(II) phosphates has been based on comparisons to in vitro model complexes and heuristic modeling. In order to put such analyses on a more physical and theoretical footing, the Mn(II)-(31)P hyperfine interactions of various Mn(II) phosphate complexes have been measured by 95 GHz ENDOR spectroscopy. The dipolar components of these interactions remained relatively constant as a function of pH, esterification, and phosphate chain length, while the isotropic contributions were significantly affected. Counterintuitively, although the manganese-phosphate bonds are weakened by protonation and esterification, they lead to larger isotropic values, indicating higher unpaired-electron spin densities at the phosphorus nuclei. By comparison, extending the phosphate chain with additional phosphate groups lowers the spin density. Density functional theory calculations of model complexes quantitatively reproduced the measured hyperfine couplings and provided detailed insights into how bonding in Mn(II) phosphate complexes modulates the electron-spin polarization and consequently their isotropic hyperfine couplings. These results show that various classes of phosphates can be identified by their ENDOR spectra and provide a theoretical framework for understanding the in situ (31)P ENDOR spectra of cellular Mn(II) complexes.

  18. Hyperfine Sublevel Correlation (HYSCORE) Spectra for Paramagnetic Centers with Nuclear Spin I = 1 Having Isotropic Hyperfine Interactions

    SciTech Connect

    Maryasov, Alexander G.; Bowman, Michael K.

    2004-07-08

    It is shown that HYSCORE spectra of paramagnetic centers having nuclei of spin I=1 with isotropic hfi and arbitrary NQI consist of ridges having zero width. A parametric presentation of these ridges is found which shows the range of possible frequencies in the HYSCORE spectrum and aids in spectral assignments and rapid estimation of spin Hamiltonian parameters. An alternative approach for the spectral density calculation is presented that is based on spectral decomposition of the Hamiltonian. Only the eigenvalues of the Hamiltonian are needed in this approach. An atlas of HYSCORE spectra is given in the Supporting Information. This approach is applied to the estimation of the spin Hamiltonian parameters of the oxovanadium-EDTA complex.

  19. 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

    SciTech Connect

    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 {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)].

  20. 33S hyperfine interactions in H2S and SO2 and revision of the sulfur nuclear magnetic shielding scale

    NASA Astrophysics Data System (ADS)

    Helgaker, Trygve; Gauss, Jürgen; Cazzoli, Gabriele; Puzzarini, Cristina

    2013-12-01

    Using the Lamb-dip technique, the hyperfine structure in the rotational spectra of H233S and 33SO2 has been resolved and the corresponding parameters—that is, the sulfur quadrupole-coupling and spin-rotation tensors—were determined. The experimental parameters are in good agreement with results from high-level coupled-cluster calculations, provided that up to quadruple excitations are considered in the cluster operator, sufficiently large basis sets are used, and vibrational corrections are accounted for. The 33S spin-rotation tensor for H2S has been used to establish a new sulfur nuclear magnetic shielding scale, combining the paramagnetic part of the shielding as obtained from the spin-rotation tensor with a calculated value for the diamagnetic part as well as computed vibrational and temperature corrections. The value of 716(5) ppm obtained in this way for the sulfur shielding of H2S is in good agreement with results from high-accuracy quantum-chemical calculations but leads to a shielding scale that is about 28 ppm lower than the one suggested previously in the literature, based on the 33S spin-rotation constant of OCS.

  1. Donor hyperfine Stark shift and the role of central-cell corrections in tight-binding theory

    NASA Astrophysics Data System (ADS)

    Usman, Muhammad; Rahman, Rajib; Salfi, Joe; Bocquel, Juanita; Voisin, Benoit; Rogge, Sven; Klimeck, Gerhard; Hollenberg, Lloyd L. C.

    2015-04-01

    Atomistic tight-binding (TB) simulations are performed to calculate the Stark shift of the hyperfine coupling for a single arsenic (As) donor in silicon (Si). The role of the central-cell correction is studied by implementing both the static and the non-static dielectric screenings of the donor potential, and by including the effect of the lattice strain close to the donor site. The dielectric screening of the donor potential tunes the value of the quadratic Stark shift parameter (η2) from -1.3 × 10-3 µm2 V-2 for the static dielectric screening to -1.72 × 10-3 µm2 V-2 for the non-static dielectric screening. The effect of lattice strain, implemented by a 3.2% change in the As-Si nearest-neighbour bond length, further shifts the value of η2 to -1.87 × 10-3 µm2 V-2, resulting in an excellent agreement of theory with the experimentally measured value of -1.9 ± 0.2 × 10-3 µm2 V-2. Based on our direct comparison of the calculations with the experiment, we conclude that the previously ignored non-static dielectric screening of the donor potential and the lattice strain significantly influence the donor wave function charge density and thereby leads to a better agreement with the available experimental data sets.

  2. Effect of Jahn-Teller ion in zinc sodium sulphate hexahydrate: a case of low hyperfine coupling constant for Cu(II) ion

    NASA Astrophysics Data System (ADS)

    Naidu, K. C.; Shiyamala, C.; Mithira, S.; Natarajan, B.; Venkatesan, R.; Rao, P. S.

    2005-06-01

    Single crystal electron paramagnetic resonance (EPR) studies of Cu(II) doped zinc sodium sulphate hexahydrate are carried out from room temperature (RT) to 123 K. The RT spectra show unresolved hyperfine lines and hence angular variation studies are also carried out at 123 K to obtain spin Hamiltonian parameters. The spin Hamiltonian parameters calculated from the 123 K spectra are: g(11)=2.039, g(22)=2.232, g(33)=2.394, A(11)=5.64 mT, A(22)=4.20 mT, and A(33)=7.94 mT. The g-matrix values at RT and 123 K have matched fairly well with each other. The low hyperfine value (A(33)), obtained at 123 K, has been explained by considering considerable admixture of d(x 2-y 2) ground state with d(z 2) excited state and the delocalization of the unpaired spin density onto the ligands. The admixture coefficients of ground state wave function are: a=0.346, b=0.935, c=0.055, d=0.040, e=-0.040, where a and b correspond to admixture coefficients for d(z 2) and d(x 2-y 2), respectively. Angular variation of Cu(II) resonances in the three orthogonal axes shows that the impurity has entered a substitutional site in the host lattice in place of Zn(II). Bonding parameters, kappa=0.295, P=245.4x10(-4), alpha(2)=0.709, alpha=0.8421 and alpha'=0.6034, have also been calculated to fully characterize the EPR.

  3. Magnetic properties of PrX 2 compounds (X = Pt, Rh, Ru, Ir) studied by hyperfine specific heat, magnetization and neutron-diffraction measurements

    NASA Astrophysics Data System (ADS)

    Greidanus, F. J. A. M.; de Jongh, L. J.; Huiskamp, W. J.; Fischer, P.; Furrer, A.; Buschow, K. H. J.

    1983-04-01

    Magnetic ordering phenomena in rare-earth intermetallic compounds can be unravelled most advantageously in the case of simple crystallographic structure and when a combination of microscopic techniques is applied. Here we shall present the temperature and magnetic field dependence of the magnetic moment of the cubic PrX 2 compounds (X = Pt, Rh, Ru, Ir), as inferred from hyperfine specific-heat, magnetization and neutron-diffraction measurements. The results are compared with a mean-field calculation, taking crystalline electric field and bilinear (dipolar) exchange interactions into account. Adopting experimental values of the Lea, Leask and Wolf parameters x and W from inelastic neutron scattering results, we find satisfactory agreement between our magnetic data and the mean-field theory. An observed discrepancy of about 15% between the calculated and measured saturation values of the spontaneous magnetization can be explained by the presence of quadrupolar interactions.

  4. Enhanced NMR Relaxation of Tomonaga-Luttinger Liquids and the Magnitude of the Carbon Hyperfine Coupling in Single-Wall Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Kiss, A.; Pályi, A.; Ihara, Y.; Wzietek, P.; Simon, P.; Alloul, H.; Zólyomi, V.; Koltai, J.; Kürti, J.; Dóra, B.; Simon, F.

    2011-10-01

    Recent transport measurements [Churchill et al. Nature Phys.NPAHAX1745-2473 5, 321 (2009)10.1038/nphys1247] found a surprisingly large, 2-3 orders of magnitude larger than usual C13 hyperfine coupling (HFC) in C13 enriched single-wall carbon nanotubes. We formulate the theory of the nuclear relaxation time in the framework of the Tomonaga-Luttinger liquid theory to enable the determination of the HFC from recent data by Ihara et al. [Europhys. Lett. 90, 17 004 (2010)EULEEJ0295-507510.1209/0295-5075/90/17004]. Though we find that 1/T1 is orders of magnitude enhanced with respect to a Fermi-liquid behavior, the HFC has its usual, small value. Then, we reexamine the theoretical description used to extract the HFC from transport experiments and show that similar features could be obtained with HFC-independent system parameters.

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

    PubMed

    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.

  6. 119Sn Mössbauer parameters as predictive tool for future Sn-based negative electrode materials

    NASA Astrophysics Data System (ADS)

    Naille, S.; Jumas, J.-C.; Lippens, P.-E.; Olivier-Fourcade, J.

    Thanks to the 119Sn Mössbauer hyperfine parameters, it is possible to analyze and predict Li reaction mechanisms with Sn-based negative electrodes for Li-ion batteries. The present approach is based on the interpretation of the 119Sn Mössbauer hyperfine parameters: isomer shift (δ) and quadrupole splitting (Δ) by considering: (i) the analysis of the 119Sn Mössbauer hyperfine parameters of the Li-Sn alloys used as model compounds, (ii) their interpretation from some physicochemical parameters (Li/Sn ratio, crystal structure, electronic density as defined by Hume-Rothery), and (iii) the proposition of an experimental based model to understand Li lithiation/delithiation mechanisms and predict electrochemical performances for Sn-based compounds including the effects of volume variations, particle coalescence or SEI formation.

  7. Inherent interface defects in thermal (211)Si/SiO{sub 2}:{sup 29}Si hyperfine interaction

    SciTech Connect

    Iacovo, Serena E-mail: andre.stesmans@fys.kuleuven.be; Stesmans, Andre E-mail: andre.stesmans@fys.kuleuven.be

    2014-10-21

    Low temperature electron spin resonance (ESR) studies were carried out on ‘higher index’ (211)Si/SiO{sub 2} interfaces thermally grown in the temperature range T{sub ox} = 400–1066°C. The data reveal the presence of two species of a P{sub b}-type interface defect, exhibiting a significant difference in defect density. On the basis of the pertinent ESR parameters and interface symmetry, the basic defect is typified as P{sub b0}{sup (211)}, close to the Pb0 center observed in standard (100)Si/SiO{sub 2}. The dominant type is found to pertain to defected Si atoms at (111)Si-face terraces with the dangling bond along the [111] direction at ∼19.5°C with the interface normal, these sites thus apparently predominantly accounting for interface mismatch adaptation. The total of the P{sub b}-type defect appearance clearly reflects the higher-index nature of the interface. It is found that T{sub ox} = 750°C is required to minimize the P{sub b0}{sup (211)} defect density through relaxation of the oxide (interface). Q-band ESR saturation spectroscopy reveals an anisotropic {sup 29}Si (nuclear spin I=1/2) hyperfine (hf) doublet associated with the central P{sub b0}{sup (211)} Zeeman signal, with hf parameters closest to those of the similar hf structure of the P{sub b0}{sup (110)} defect in thermal (110)Si/SiO{sub 2}, adducing independent support to the P{sub b0}{sup (211)} typification.

  8. 2D TRIPLE in orientationally disordered samples—a means to resolve and determine relative orientation of hyperfine tensors

    NASA Astrophysics Data System (ADS)

    Goldfarb, D.; Epel, B.; Zimmermann, H.; Jeschke, G.

    2004-05-01

    The two-dimensional (2D) TRIPLE experiment provides correlations between electron-nuclear double resonance (ENDOR) frequencies that belong to the same electron-spin manifold, MS, and therefore allows to assign ENDOR lines to their specific paramagnetic centers and MS manifolds. This, in turn, also provides the relative signs of the hyperfine couplings. So far this experiment has been applied only to single crystals, where the cross-peaks in the 2D spectrum are well resolved with regular shapes. Here we introduce the application of the 2D TRIPLE experiment to orientationally disordered systems, where it can resolve overlapping powder patterns. Moreover, analysis of the shape of the cross-peaks shows that it is highly dependent on the relative orientation of the hyperfine tensors of the two nuclei contributing to this particular peak. This is done initially through a series of simulations and then demonstrated experimentally at a high field (W-band, 95 GHz). The first example concerned the 1H hyperfine tensors of the stable radical α,γ-bisdiphenylene-β-phenylallyl (BDPA) immobilized in a polystyrene matrix. Then, the experiment was applied to a more complex system, a frozen solution of Cu(II)-bis(2,2 ':6 ',2″ terpyridine) complex. There, the 2D TRIPLE experiment was combined with the variable mixing time (VMT) ENDOR experiment, which determined the absolute sign of the hyperfine couplings involved, and orientation selective ENDOR experiments. Analysis of the three experiments gave the hyperfine tensors of a few coupled protons.

  9. Measurement of the dmud quartet-to-doublet molecular formation rate ratio (lambdaq : lambdad) and the mu d hyperfine rate (lambdaqd) using the fusion neutrons from mu- stops in D2 gas

    NASA Astrophysics Data System (ADS)

    Raha, Nandita

    with rates lambdad and lambdaq and yield 2.45 MeV mono-energetic fusion neutrons. Encoded in the time dependence of the fusion neutrons are the dmicrod formation rates lambda d, lambdaq and hyperfine rate lambda qd. Consequently, the investigation of the fusion neutron time spectrum enables the determination of these kinetics parameters that are important in the extraction of Lambdad from the decay electron time spectrum. The final results of this work yield lambda q : lambdad = 85.51 +/- 3.25 and lambdaqd = 38.49 +/- 0.21 micros -1.

  10. New approach to hyperfine structure - Application to the Li ground state

    NASA Technical Reports Server (NTRS)

    Bhatia, A. K.; Sucher, J.

    1980-01-01

    Global identities for delta functions, given by Hiller, Sucher and Feinberg (HSF) are applied to the calculation of the hyperfine structure (HFS) of the ground state of Li. It is shown that use of the HSF identity together with configuration interaction type wavefunctions can yield values of the HFS constant f which are comparable in accuracy to that obtained by Larsson with a 100-term Hylleraas-type wavefunction. The implications of this result for HFS calculations for atoms with many electrons are discussed.

  11. Isotope shift and hyperfine splitting of the 4s{yields}5p transition in potassium

    SciTech Connect

    Behrle, Alexandra; Koschorreck, Marco; Koehl, Michael

    2011-05-15

    We have investigated the 4s {sup 2}S{sub 1/2}{yields}5p {sup 2}P{sub 1/2} transition (D{sub 1} line) of the potassium isotopes {sup 39}K, {sup 40}K, and {sup 41}K using Doppler-free laser saturation spectroscopy. Our measurements reveal the hyperfine splitting of the 5p {sup 2}P{sub 1/2} state of {sup 40}K, and we have determined the specific mass shift and the nuclear field shift constants for the blue (405 nm) D{sub 1} line.

  12. Radiative recoil corrections to hyperfine splitting: Polarization insertions in the electron factor

    SciTech Connect

    Eides, M. I.; Shelyuto, V. A.

    2010-01-15

    We consider three-loop radiative recoil corrections to hyperfine splitting in muonium due to insertions of the one-loop polarization operator in the electron factor. The contribution generated by electron polarization insertions is a cubic polynomial in the large logarithm of the electron-muon mass ratio. The leading logarithm cubed and logarithm squared terms are well known for some time. We calculate all single-logarithmic and nonlogarithmic radiative recoil corrections of the order {alpha}{sup 3}(m/M)E{sub F} generated by diagrams with the electron and muon polarization insertions.

  13. Hyperfine structure measurement of rubidium atom and tunable diode laser stabilization by using Sagnac interferometer.

    PubMed

    Kim, Jin-Tae; Zhen, Liu; Kapitanov, Venedikt; Kim, Hyun Su; Park, Jong Rak; Park, Si-Hyun

    2006-11-01

    The Rubidium saturated absorption spectra for D2 transition lines are used to measure the Fabry-Perot interferometer free spectral range (FSR). The scale linearity of the laser frequency tuning is determined. The Sagnac interferometer has been used for the laser stabilization. The result shows that the laser frequency is stabilized upto sub-mega Herz level. Also the hyperfine structure [5(2)S(1/2) F = 3 --> F' = 2, 3, 4 5(2)P(3/2) 85Rb] of the rubidium atom has been measured by using the tilt locking method, which shows the same result as the conventional saturation spectroscopy.

  14. Spin noise of localized electrons: Interplay of hopping and hyperfine interaction

    NASA Astrophysics Data System (ADS)

    Glazov, M. M.

    2015-05-01

    The theory of spin fluctuations is developed for an ensemble of localized electrons, taking into account both the hyperfine interaction of electron and nuclear spins and electron hopping between the sites. The analytical expression for the spin noise spectrum is derived for an arbitrary relation between the electron spin precession frequency in a field of nuclear fluctuations and the hopping rate. An increase in the hopping rate results in a drastic change in the spin noise spectrum. The effect of an external magnetic field is briefly addressed.

  15. Negative muon spin precession measurement of the hyperfine states of muonic sodium

    NASA Astrophysics Data System (ADS)

    Brewer, J. H.; Ghandi, K.; Froese, A. M.; Fryer, B. A.

    2005-05-01

    Both hyperfine states of muonic 23Na and the rate R of conversion between them have been observed directly in a high field negative muon spin precession experiment using a backward muon beam with transverse spin polarization. The result in metallic sodium, R=13.7±2.2μs-1, is consistent with Winston's prediction in 1963 based on Auger emission of core electrons, and with the measurements of Gorringe et al. in Na metal, but not with their smaller result in NaF. In NaOH we find R=23.5±8μs-1, leaving medium-dependent effects ambiguous.

  16. Microstructure, hyperfine interaction and magnetic transition of Fe-25%Ni-5%Si-x%Co alloys

    NASA Astrophysics Data System (ADS)

    Gungunes, H.

    2016-12-01

    Morphological and magnetic properties in Fe-25%Ni-5%Si-x%Co (x = 0, 10, 15) alloys are investigated. Scanning electron microscopy (SEM), Mössbauer spectroscopy and AC magnetic susceptibility measurements are used to determine the physical properties of alloys. The martensite morphology changed depending on the Co content. The Mössbauer study shows that the volume fraction and hyperfine field of martensite increases while isomer shift values decrease with increasing Co content. On the other hand; AC susceptibility results showed that; Co is an effective element which can be used to control both the magnetic transition and martensitic transformation temperatures.

  17. Limitation of electron mobility from hyperfine interaction in ultraclean quantum wells and topological insulators

    NASA Astrophysics Data System (ADS)

    Tarasenko, S. A.; Burkard, Guido

    2016-07-01

    The study of electron transport and scattering processes limiting electron mobility in high-quality semiconductor structures is central to solid-state electronics. Here, we uncover an unavoidable source of electron scattering which is caused by fluctuations of nuclear spins. We calculate the momentum relaxation time of electrons in quantum wells governed by the hyperfine interaction between electrons and nuclei and show that this time depends greatly on the spatial correlation of nuclear spins. Moreover, the scattering processes accompanied by a spin flip are a source of the backscattering of Dirac fermions at conducting surfaces of topological insulators.

  18. High resolution laser spectroscopy studies of perturbations in sodium: Hyperfine interaction and global analysis of the A(1)sigma(+) and b(3)pi(u) coupled states

    NASA Astrophysics Data System (ADS)

    Qi, Peng

    This thesis mainly consists of two parts. The focus of first part is on the study of the hyperfine interaction in the Na2 23 productg electronic state. Many new Na 2 23productg v = 0-43, O = 0,1, and 2 levels have been observed by continuous wave (CW) sub-Doppler Perturbation Facilitated Optical-Optical Double Resonance (PFOODR) fluorescence excitation spectroscopy and the hyperfine structures of the O = 0 and O = 2 levels have been resolved. New molecular constants for the less perturbed v = 0-43 levels have been obtained with these new and the previously reported data. The hyperfine coupling scheme of the observed 23product g levels is close to Hund's case (abeta ) coupling scheme with a Fermi contact constant b F = 160 +/- 5 MHz, which is smaller than the Fermi contact constants of other Na2 triplet Rydberg states, bF = 200-245 MHz. The second part of this thesis is on the global analysis of the Na 2 lowest excited electronic states, A1S+u and b3productu. These coupled states are of interest as intermediarie in the excitation of higher electronic states and in the development of methods for producing cold molecules. We have compiled previously obtained spectroscopic data on the A1S+u and b3productu states of Na2 from about 20 sources, both published and unpublished, together with the sub-Doppler linewidth measurements of about 15,000 A ← X transitions using the polarization spectroscopic technique. In addition, new ab initio results for the diagonal and off-diagonal spin-orbit functions by Svetlana Kotochigova are also included in the global deperturbation analysis. The discrete variable representation (DVR) method is used together with Hund's case (a) potentials plus spin-orbit effects to model data extending from v = 0 to very close to the 32S + 32 P1/2 dissociation limit. The overall variance of the fit of the present A1S+u and b3productu data to potential and spin-orbit parameters is 2.85. The final rms residual for the polarization spectroscopy data is 0

  19. Hyperfine structure in the J = 1-0 transitions of DCO^+, DNC, and HN13C: astronomical observations and quantum-chemical calculations

    NASA Astrophysics Data System (ADS)

    van der Tak, F. F. S.; Müller, H. S. P.; Harding, M. E.; Gauss, J.

    2009-11-01

    Context: Knowledge of the hyperfine structure of molecular lines is useful for estimating reliable column densities from observed emission, and essential for the derivation of kinematic information from line profiles. Aims: Deuterium bearing molecules are especially useful in this regard, because they are good probes of the physical and chemical structure of molecular cloud cores on the verge of star formation. However, the necessary spectroscopic data are often missing, especially for molecules which are too unstable for laboratory study. Methods: We have observed the ground-state (J = 1{-}0) rotational transitions of DCO^+, HN13C and DNC with the IRAM 30 m telescope toward the dark cloud LDN 1512 which has exceptionally narrow lines permitting hyperfine splitting to be resolved in part. The measured splittings of 50-300 kHz are used to derive nuclear quadrupole and spin-rotation parameters for these species. The measurements are supplemented by high-level quantum-chemical calculations using coupled-cluster techniques and large atomic-orbital basis sets. Results: We find eQq = + 151.12 (400) kHz and CI = -1.12 (43) kHz for DCO^+, eQq = 272.5 (51) kHz for HN13C, and eQq(D) =265.9 (83) kHz and eQq(N) = 288.2 (71) kHz for DNC. The numbers for DNC are consistent with previous laboratory data, while our constants for DCO+ are somewhat smaller than previous results based on astronomical data. For both DCO+ and DNC, our results are more accurate than previous determinations. Our results are in good agreement with the corresponding best theoretical estimates, which amount to eQq = 156.0 kHz and CI = -0.69 kHz for DCO^+, eQq = 279.5 kHz for HN13C, and eQq(D) = 257.6 kHz and eQq(N) = 309.6 kHz for DNC. We also derive updated rotational constants for HN13C: B = 43 545.6000 (47) MHz and D = 93.7 (20) kHz. Conclusions: The hyperfine splittings of the DCO^+, DNC and HN13C J = 1{-}0 lines range over 0.47-1.28 km s-1, which is comparable to typical line widths in pre

  20. Optical pumping and readout of bismuth hyperfine states in silicon for atomic clock applications

    PubMed Central

    Saeedi, K.; Szech, M.; Dluhy, P.; Salvail, J.Z.; Morse, K.J.; Riemann, H.; Abrosimov, N.V.; Nötzel, N.; Litvinenko, K.L.; Murdin, B.N.; Thewalt, M.L.W.

    2015-01-01

    The push for a semiconductor-based quantum information technology has renewed interest in the spin states and optical transitions of shallow donors in silicon, including the donor bound exciton transitions in the near-infrared and the Rydberg, or hydrogenic, transitions in the mid-infrared. The deepest group V donor in silicon, bismuth, has a large zero-field ground state hyperfine splitting, comparable to that of rubidium, upon which the now-ubiquitous rubidium atomic clock time standard is based. Here we show that the ground state hyperfine populations of bismuth can be read out using the mid-infrared Rydberg transitions, analogous to the optical readout of the rubidium ground state populations upon which rubidium clock technology is based. We further use these transitions to demonstrate strong population pumping by resonant excitation of the bound exciton transitions, suggesting several possible approaches to a solid-state atomic clock using bismuth in silicon, or eventually in enriched 28Si. PMID:25990870

  1. Electron-impact rotational and hyperfine excitation of HCN, HNC, DCN and DNC

    NASA Astrophysics Data System (ADS)

    Faure, Alexandre; Varambhia, Hemal N.; Stoecklin, Thierry; Tennyson, Jonathan

    2007-12-01

    Rotational excitation of isotopologues of HCN and HNC by thermal electron-impact is studied using the molecular R-matrix method combined with the adiabatic-nuclei-rotation approximation. Rate coefficients are obtained for electron temperatures in the range 5-6000 K and for transitions among all levels up to J = 8. Hyperfine rates are also derived using the infinite-order-sudden scaling method. It is shown that the dominant rotational transitions are dipole-allowed, that is, those for which ΔJ = 1. The hyperfine propensity rule ΔJ = ΔF is found to be stronger than that in the case of He-HCN collisions. For dipole-allowed transitions, electron-impact rates are shown to exceed those for excitation of HCN by He atoms by six orders of magnitude. As a result, the present rates should be included in any detailed population model of isotopologues of HCN and HNC in sources where the electron fraction is larger than 10-6, for example, in interstellar shocks and comets.

  2. Applications of the two-photon doppler-free method: Hyperfine interactions and isotope shift measurements

    NASA Astrophysics Data System (ADS)

    Cagnac, B.

    1985-08-01

    The hyperfine structures are generally of the same order of magnitude as the Doppler broadening of optical transitions and so are the isotopic shifts in the case of heavy elements. When these structures are too small, one must use Doppler-free methods. Among these methods, the two-photon spectroscopy has obtained good results in highly excited levels. In our laboratory in Paris, we did measurements on neon and helium by two-photon excitation from metastable levels. The precision of the measurements is of the order of one MHz, which permits a precise comparison with theory. We compare the measurements on neon with the theory by Liberman and we obtain a good fit in the first approximation, but must introduce mixing of wave functions for an exact explanation. In the case of helium, we obtain a good fit with the theoretical values obtained from the wave functions by Accad, Pekeris and Schiff. We also give an example where another technique by polarization measurements permits us to obtain experimentally a hyperfine structure smaller than the natural width. We also present a short review of the measurements done by the two-photon method in other laboratories on other elements, Pb, Tl, In and alkaline earths Ca, Sr. Ba.

  3. Landauer-Büttiker approach for hyperfine mediated electronic transport in the integer quantum Hall regime

    NASA Astrophysics Data System (ADS)

    Singha, Aniket; Fauzi, M. H.; Hirayama, Y.; Muralidharan, Bhaskaran

    2017-03-01

    The interplay of spin-polarized electronic edge states with the dynamics of the host nuclei in quantum Hall systems presents rich and nontrivial transport physics. Here, we develop a Landauer-Büttiker approach to understand various experimental features observed in the integer quantum Hall setups featuring quantum point contacts. The approach developed here entails a phenomenological description of spin-resolved interedge scattering induced via hyperfine assisted electron-nuclear spin flip-flop processes. A self-consistent simulation framework between the nuclear spin dynamics and edge state electronic transport is presented in order to gain crucial insights into the dynamic nuclear polarization effects on electronic transport and in turn the electron-spin polarization effects on the nuclear spin dynamics. In particular, we show that the hysteresis noted experimentally in the conductance-voltage trace as well as in the resistively detected NMR line-shape results from a lack of quasiequilibrium between electronic transport and nuclear polarization evolution. In addition, we present circuit models to emulate such hyperfine mediated transport effects to further facilitate a clear understanding of the electronic transport processes occurring around the quantum point contact. Finally, we extend our model to account for the effects of quadrupolar splitting of nuclear levels and also depict the electronic transport signatures that arise from single and multiphoton processes.

  4. Electronic Structure and the Magnetic Hyperfine Interactions in Heme Unit of Metmyoglobin

    NASA Astrophysics Data System (ADS)

    Maharjan, N. B.; Badu, S. R.; Dubey, Archana; Scheicher, R. H.; Pink, R. H.; Chow, Lee; Schulte, A.; Saha, H. P.; Das, T. P.

    2008-03-01

    The ^14N and ^57mFe hyperfine interactions in the heme unit of metmyoglobin are available experimentally by electron-nuclear double resonance (ENDOR) and Mossbauer spectroscopic techniques. We have carried out electronic structure investigations on the heme system including the H2O and proximal imidazole ligands by the first-principles Hartree-Fock procedure and studied the magnetic hyperfine and nuclear quadrupole coupling constants for the ^57mFe nucleus and all the six ^14N nuclei on the four pyrrole and imidazole ligands as well as the ^17O nucleus on the H2O ligand. Comparison will be made with available experimental data [1, 2] and earlier theoretical investigations [3] by the approximate self-consistent charge Extended Huckel procedure. Results will also be presented for the optical frequencies and intensities from transitions between ligand-like and iron d-like states and the Fe-Nɛ vibrational frequency [1] G. Lang, Q. Rev. Biophys. 3, 1 (1970) [2] C.P. Scholes, R.A. Isaacson and G Feher, Biochim. Biophys. Acta 263,448(1972) [3] S.K. Mun, Jane C. Chang and T.P. Das J. Am. Chem. Soc. 101, 5562(1979)

  5. Prediction of nitroxide hyperfine coupling constants in solution from combined nanosecond scale simulations and quantum computations

    NASA Astrophysics Data System (ADS)

    Houriez, Céline; Ferré, Nicolas; Masella, Michel; Siri, Didier

    2008-06-01

    We present a combined theoretical approach based on analyzing molecular dynamics trajectories (at the nanosecond scale) generated by use of classical polarizable force fields and on quantum calculations to compute averaged hyperfine coupling constants. That method is used to estimate the constant of a prototypical nitroxide: the dimethylnitroxide. The molecule is embedded during the simulations in a cubic box containing about 500 water molecules and the molecular dynamics is generated using periodic conditions. Once the trajectories are achieved, the nitroxide and its first hydration shell molecules are extracted, and the coupling constants are computed by considering the latter aggregates by means of quantum computations. However, all the water molecules of the bulk are also accounted for during those computations by means of the electrostatic potential fitted method. Our results exhibit that in order to predict accurate and reliable coupling constants, one needs to describe carefully the out-of-plane motion of the nitroxide nitrogen and to sample trajectories with a time interval of 400 fs at least to generate an uncorrelated large set of nitroxide structures. Compared to Car-Parrinello molecular dynamics techniques, our approach can be used readily to compute hyperfine coupling constants of large systems, such as nitroxides of great size interacting with macromolecules such as proteins or polymers.

  6. Femtosecond frequency comb measurement of absolute frequencies and hyperfine coupling constants in cesium vapor

    SciTech Connect

    Stalnaker, Jason E.; Mbele, Vela; Gerginov, Vladislav; Fortier, Tara M.; Diddams, Scott A.; Hollberg, Leo; Tanner, Carol E.

    2010-04-15

    We report measurements of absolute transition frequencies and hyperfine coupling constants for the 8S{sub 1/2}, 9S{sub 1/2}, 7D{sub 3/2}, and 7D{sub 5/2} states in {sup 133}Cs vapor. The stepwise excitation through either the 6P{sub 1/2} or 6P{sub 3/2} intermediate state is performed directly with broadband laser light from a stabilized femtosecond laser optical-frequency comb. The laser beam is split, counterpropagated, and focused into a room-temperature Cs vapor cell. The repetition rate of the frequency comb is scanned and we detect the fluorescence on the 7P{sub 1/2,3/2{yields}}6S{sub 1/2} branches of the decay of the excited states. The excitations to the different states are isolated by the introduction of narrow-bandwidth interference filters in the laser beam paths. Using a nonlinear least-squares method we find measurements of transition frequencies and hyperfine coupling constants that are in agreement with other recent measurements for the 8S state and provide improvement by 2 orders of magnitude over previously published results for the 9S and 7D states.

  7. Measurement of the 1s Hyperfine Transition of Two Tl^80+ Isotopes

    NASA Astrophysics Data System (ADS)

    Beiersdorfer, P.; Utter, S. B.; Wong, K. L.; Crespo López-Urrutia, J. R.; Britten, J. A.; Chen, H.; Thoe, R. S.; Thorn, D. B.; Träbert, E.; Gustavsson, M. G. H.; Forssén, C.; Mårtenson-Pendrill, A.-M.; Harris, C. L.

    2001-05-01

    The hyperfine splitting of the 1s ground state has been measured for the two stable isotopes of hydrogen-like Tl using emission spectroscopy in the SuperEBIT electron beam ion trap. The results are 3858.22± 0.30 Åfor ^203Tl^80+ and 3821.84± 0.34 Åfor ^205Tl^80+. These differ by about 60 Å from recent and about 19 Å from very recent calculations, illustrating unsolved issues affecting these transitions in hydrogen-like ions. The wavelength difference Δλ = 36.38± 0.35 Å is consistent with estimates based on hyperfine anomaly data for neutral Tl. By using previously determined nuclear magnetic moments and applying appropriate corrections for the nuclear charge distribution and radiative effects, the experimental splittings can be interpreted in terms of nuclear magnetization radii < r^2_m>^1/2= 5.83(14) fm for ^203Tl and < r^2_m>^1/2= 5.89(14) fm for ^205Tl. These values are 10% larger than derived from single-particle nuclear magnetization models, and are slightly larger than the corresponding charge distributions. *Work performed under the auspices of DOE by UCLLNL under contract W-7405-ENG-48 and supported by the Office of Basic Energy Sciences.

  8. Determination of the hyperfine coupling constant of the cesium 7S1/2 state

    NASA Astrophysics Data System (ADS)

    Yang, Guang; Wang, Jie; Yang, Baodong; Wang, Junmin

    2016-08-01

    We report the hyperfine splitting (HFS) measurement of the cesium (Cs) 7S1/2 state by optical-optical double-resonance spectroscopy with the Cs 6S1/2-6P3/2-7S1/2 (852 nm  +  1470 nm) ladder-type system. The HFS frequency calibration is performed by employing a phase-type waveguide electro-optic modulator together with a stable confocal Fabry-Perot cavity. From the measured HFS between the F″  =  3 and F″  =  4 manifolds of the Cs 7S1/2 state (HFS  =  2183.273  ±  0.062 MHz), we have determined the magnetic dipole hyperfine coupling constant (A  =  545.818  ±  0.016 MHz), which is in good agreement with the previous work but much more precise.

  9. Diamagnetic correction to the {sup 9}Be{sup +} ground-state hyperfine constant

    SciTech Connect

    Shiga, N.; Itano, W. M.; Bollinger, J. J.

    2011-07-15

    We report an experimental determination of the diamagnetic correction to the {sup 9}Be{sup +} ground state hyperfine constant A. We measured A = -625 008 837.371(11) Hz at a magnetic field B of 4.4609 T. Comparison with previous results, obtained at lower values of B (0.68 T and 0.82 T), yields the diamagnetic shift coefficient k = 2.63(18)x10{sup -11} T{sup -2}, where A(B)=A{sub 0}(1+kB{sup 2}). The zero-field hyperfine constant A{sub 0} is determined to be -625 008 837.044(12) Hz. The g-factor ratio g{sub I}{sup '}/g{sub J} is determined to be 2.134 779 852 7(10)x10{sup -4}, which is equal to the value measured at lower B to within experimental error. Upper limits are placed on some other corrections to the Breit-Rabi formula. The measured value of k agrees with theoretical estimates.

  10. Hyperfine coupling of hole and nuclear spins in symmetric (111)-grown GaAs quantum dots

    NASA Astrophysics Data System (ADS)

    Vidal, M.; Durnev, M. V.; Bouet, L.; Amand, T.; Glazov, M. M.; Ivchenko, E. L.; Zhou, P.; Wang, G.; Mano, T.; Kuroda, T.; Marie, X.; Sakoda, K.; Urbaszek, B.

    2016-09-01

    In self-assembled III-V semiconductor quantum dots, valence holes have longer spin coherence times than the conduction electrons, due to their weaker coupling to nuclear spin bath fluctuations. Prolonging hole spin stability relies on a better understanding of the hole to nuclear spin hyperfine coupling which we address both in experiment and theory in the symmetric (111) GaAs/AlGaAs droplet dots. In magnetic fields applied along the growth axis, we create a strong nuclear spin polarization detected through the positively charged trion X+ Zeeman and Overhauser splittings. The observation of four clearly resolved photoluminescence lines—a unique property of the (111) nanosystems—allows us to measure separately the electron and hole contribution to the Overhauser shift. The hyperfine interaction for holes is found to be about five times weaker than that for electrons. Our theory shows that this ratio depends not only on intrinsic material properties but also on the dot shape and carrier confinement through the heavy-hole mixing, an opportunity for engineering the hole-nuclear spin interaction by tuning dot size and shape.

  11. Ion-number-density-dependent effects on hyperfine transition of trapped 199Hg+ ions in quadrupole linear ion traps

    NASA Astrophysics Data System (ADS)

    Yang, Zhihui; Chen, Yihe; Yan, Bibo; Wang, Man; Wan, Yongquan; Liu, Hao; She, Lei; Li, Jiaomei

    2017-04-01

    The ion-number-density-dependent frequency offsets and broadening of the ground state hyperfine transition spectra of trapped 199Hg+ ions were measured as a function of the end-cap voltage of the quadrupole linear ion trap. The number density of trapped 199Hg+ ions in the quadrupole linear trap was controlled by the end-cap voltage. The fractional frequency stability of 199Hg+ hyperfine transition to the 1 mV end-cap voltage variation was preliminary estimated to be less than 1 ×10-16. The causes of the ion-number-density-dependent frequency shift and spectrum broadening were analyzed theoretically and explained.

  12. Single-Crystal Equations of State and Hyperfine Fields of Magnesiowüstite at High Pressures

    NASA Astrophysics Data System (ADS)

    Finkelstein, G. J.; Zhang, D.; Jackson, J. M.

    2015-12-01

    In recent years, seismic observations have provided increasing evidence for significant heterogeneity in Earth's lower mantle at both large (i.e. large low shear velocity provinces, or LLSVPs) and comparatively small (ultra-low velocity zones, or ULVZs) scales. One possible source of heterogeneity is variation in the Fe-content of the (Mg,Fe)O component of the lower mantle due to melting events and/or reactions with Earth's outer core. Most previous studies have focused on compositions containing ~10-20 mol% Fe, but small amounts of compositions with an enhanced Fe concentration may strongly impact the elastic properties of the bulk phase assemblage. Here, we present results from two high-precision single-crystal x-ray diffraction studies on (Fe0.78Mg0.22)O magnesiowüstite to pressures of about 55 GPa at 300 K, one using neon and the other using helium as pressure-transmitting media. We observe a noticeably different compression behavior in the two pressure media at pressures greater than about 20 GPa, and compare to previous work on similar compositions. We also conducted a complementary single-crystal time domain synchrotron Mössbauer spectroscopy (SMS) study on the same composition in a helium medium to about 70 GPa to gain insight into the atom-scale properties of the Fe sublattice. We discuss the resulting hyperfine fields as a function of pressure, including the isomer shift, quadrupole splitting, magnetic, and texturing parameters. The advantages of using single crystals for such investigations will also be discussed. Finally, implications for the elastic properties of magnesiowüstite in the deep mantle will be considered.

  13. 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

    SciTech Connect

    Bhattacharjee, Kaustav; Das, G. C.; Pati, Satya P.; Das, D.

    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.

  14. Nitric Oxide Line Parameters: Review of 1996 HITRAN Update and New Results

    NASA Technical Reports Server (NTRS)

    Goldmant, A.; Giver, L. P.; Brown, L. R.; Risland, C. P.; Spencer, M. N.; Coudert, L. H.; Chackerian, C.; Dana, V.; Mandin, J. Y.

    1997-01-01

    The 1996 HITRAN database incorporated an extensive update of NO line parameters in the 5.3 mue region. Hyperfine lines associated with the 0-1 band up to J=46.5 were included and accuracies were greatly imporved.

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

    NASA Astrophysics Data System (ADS)

    Riis, E.; Sinclair, A. G.; Poulsen, O.; Drake, G. W. F.; Rowley, W. R. C.; Levick, A. P.

    1994-01-01

    High-precision laser-resonance measurements accurate to +/-0.5 MHz or better are reported for transitions among the 1s2s 3S1-1s2p 3PJ hyperfine manifolds for each of J=0, 1, and 2 in both 6Li+ and 7Li+. A detailed analysis of hyperfine structure is performed for both the S and P states, using newly calculated values for the magnetic dipole and electric quadrupole coupling constants, and the hyperfine shifts subtracted from the measurements. The resulting transition frequencies are then analyzed on three different levels. First, the isotope shifts in the fine-structure splittings are calculated from the relativistic reduced mass and recoil terms in the Breit interaction, and compared with experiment at the +/-0.5-MHz level of accuracy. This comparison is particularly significant because J-independent theoretical uncertainties reduce through cancellation to the +/-0.01-MHz level. Second, the isotope shifts in the full transition frequencies are used to deduce the difference in rms nuclear radii. The result is Rrms(6Li)-Rrms(7Li)=0.15+/-0.01 fm, in agreement with nuclear scattering data, but with substantially improved accuracy. Third, high-precision calculations of the low-order non-QED contributions to the transition frequencies are subtracted from the measurements to obtain the residual QED shifts. The isotope-averaged and spin-averaged effective shift for 7Li+ is 37 429.40+/-0.39 MHz, with an additional uncertainty of +/-1.5 MHz due to finite nuclear size corrections. The accuracy of 11 parts per million is the best two-electron Lamb shift measurement in the literature, and is comparable to the accuracies achieved in hydrogen. Theoretical contributions to the two-electron Lamb shift are discussed, including terms of order (αZ)4 recently obtained by Chen, Cheng, and Johnson [Phys. Rev. A 47, 3692 (1993)], and the results used to extract a QED shift for the 2 3S1 state. The result of 30 254+/-12 MHz is shown to be in good accord with theory (30 250+/-30 MHz) when

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

    NASA Astrophysics Data System (ADS)

    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.

  17. Radiative decays of double heavy baryons in a relativistic constituent three-quark model including hyperfine mixing effects

    SciTech Connect

    Branz, Tanja; Faessler, Amand; Gutsche, Thomas; Lyubovitskij, Valery E.; Oexl, Bettina; Ivanov, Mikhail A.; Koerner, Juergen G.

    2010-06-01

    We study flavor-conserving radiative decays of double-heavy baryons using a manifestly Lorentz covariant constituent three-quark model. Decay rates are calculated and compared to each other in the full theory, keeping masses finite, and also in the heavy quark limit. We discuss in some detail hyperfine mixing effects.

  18. Observation of nuclear quadrupole hyperfine structure in the infrared spectrum of hydrogen iodide using a tunable-diode laser

    NASA Technical Reports Server (NTRS)

    Strow, L. L.

    1980-01-01

    Nuclear quadrupole hyperfine structure has been observed in the 1-0 vibration-rotation band of hydrogen iodide with a tunable-diode laser. The measured splittings agree well with microwave measurements of the HI molecule. Evidence for a slight change in the iodine nuclear quadrupole coupling constant from the ground to first excited vibrational state in hydrogen iodide was found.

  19. Hyperfine fields of Fe in Nd2Fe14BandSm2Fe17N3

    NASA Astrophysics Data System (ADS)

    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.

  20. Hyperfine interactions and electric dipole moments in the [16.0]1.5(v = 6), [16.0]3.5(v = 7), and X2Δ(5/2) states of iridium monosilicide, IrSi.

    PubMed

    Le, Anh; Steimle, Timothy C; Morse, Michael D; Garcia, Maria A; Cheng, Lan; Stanton, John F

    2013-12-19

    The (6,0)[16.0]1.5-X(2)Δ(5/2) and (7,0)[16.0]3.5-X(2)Δ(5/2) bands of IrSi have been recorded using high-resolution laser-induced fluorescence spectroscopy. The field-free spectra of the (191)IrSi and (193)IrSi isotopologues were modeled to generate a set of fine, magnetic hyperfine, and nuclear quadrupole hyperfine parameters for the X(2)Δ(5/2)(v = 0), [16.0]1.5(v = 6), and [16.0]3.5 (v = 7) states. The observed optical Stark shifts for the (193)IrSi and (191)IrSi isotopologues were analyzed to produce the permanent electric dipole moments, μ(el), of -0.414(6) D and 0.782(6) D for the X(2)Δ(5/2) and [16.0]1.5 (v = 6) states, respectively. Properties of the X(2)Δ(5/2) state computed using relativistic coupled-cluster methods clearly indicate that electron correlation plays an essential role. Specifically, inclusion of correlation changes the sign of the dipole moment and is essential for achieving good accuracy for the nuclear quadrupole coupling parameter eQq0.

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

    SciTech Connect

    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.

  2. Quadrupole Hyperfine Structure in the Rotational Spectra of 1,2- and 1,3-Dichlorobenzene

    NASA Astrophysics Data System (ADS)

    Keussen, Ch.; Dreizler, H.; Merke, I.

    1990-12-01

    The high resolution of microwave Fourier transform spectroscopy was used to investigate the 35chlorine hyperfine structure of 1,2- and 1,3-dichlorobenzene, C6H435Cl2 , very accurately in the rotational spectrum of their ground vibrational state. The careful analysis with a new evaluation program also yielded the off-diagonal element of the coupling tensor. The tensor elements are χaa= -41.1153(35) MHz,χbb = 8.3415(96) MHz, χcc = 32.7738(61) MHz, and χab = ±52.41 (58) MHz for 1,2-dichlorobenzene and χaa= -44.174(12) MHz, χbb= 10.876(12) MHz, χcc = 33.298(12) MHz, and χab= ±48.181(39) MHz for 1,3-dichlorobenzene.

  3. Hyperfine dipole-dipole broadening of selective reflection spectroscopy at the gas-solid interface

    NASA Astrophysics Data System (ADS)

    Meng, Tengfei; Ji, Zhonghua; Zhao, Yanting; Xiao, Liantuan; Jia, Suotang

    2016-09-01

    We theoretically and experimentally investigate hyperfine dipole-dipole broadening in the selective reflection (SR) spectroscopy at the gas-solid interface with the atomic density of 1014-1015 cm-3. The two-level SR theory considering pump beam and dipole-dipole interaction between excited-state atom and ground-state atom is presented. The numerical simulation of the SR spectrum is in agreement with experimental results. The reduction of spectral width is observed by introducing a pump beam which is an effective technique to improve the resolution of spectroscopy. We analyze the dependence of dipole-dipole broadening on atomic density and pump beam power. This study is helpful for the description of the SR spectroscopy at the gas-solid interface where the Doppler broadening is comparable with dipole-dipole broadening.

  4. Relativistic extended-coupled-cluster method for the magnetic hyperfine structure constant

    NASA Astrophysics Data System (ADS)

    Sasmal, Sudip; Pathak, Himadri; Nayak, Malaya K.; Vaval, Nayana; Pal, Sourav

    2015-02-01

    The article deals with the general implementation of the four-component spinor relativistic extended-coupled-cluster (ECC) method to calculate first-order property of atoms and molecules in their open-shell ground-state configuration. The implemented relativistic ECC is employed to calculate hyperfine structure constants of alkali metals (Li, Na, K, Rb, and Cs), singly charged alkaline-earth-metal atoms (Be+ ,Mg+,Ca+, and Sr+), and molecules (BeH, MgF, and CaH). We have compared our ECC results with the calculations based on the restricted active space configuration interaction (RAS-CI) method. Our results are in better agreement with the available experimental values than those of the RAS-CI values.

  5. Metal ion oxidation state assignment based on coordinating ligand hyperfine interaction.

    PubMed

    Oyala, Paul H; Stich, Troy A; Britt, R David

    2015-04-01

    In exchange-coupled mixed-valence spin systems, the magnitude and sign of the effective ligand hyperfine interaction (HFI) can be useful in determining the formal oxidation state of the coordinating metal ion, as well as provide information about the coordination geometry. This is due to the fact that the observed ligand HFI is a function of the projection factor (Clebsch-Gordon coefficient) that maps the site spin value S i of the local paramagnetic center onto the total spin of the exchange-coupled system, S T. Recently, this relationship has been successfully exploited in identifying the oxidation state of the Mn ion coordinated by the sole nitrogenous ligand to the oxygen-evolving complex in certain states of photosystem II. The origin and evolution of these efforts is described.

  6. (29)Si hyperfine structure of the E(')(alpha) center in amorphous silicon dioxide.

    PubMed

    Buscarino, G; Agnello, S; Gelardi, F M

    2006-09-29

    We report a study by electron paramagnetic resonance on the E'(alpha) point defect in amorphous silicon dioxide (a-SiO(2)). Our experiments were performed on gamma-ray irradiated oxygen-deficient materials and pointed out that the (29)Si hyperfine structure of the E'(alpha) consists of a pair of lines split by approximately 49 mT. On the basis of the experimental results, a microscopic model is proposed for the E'(alpha) center, consisting of a hole trapped in an oxygen vacancy with the unpaired electron sp(3) orbital pointing away from the vacancy in a back-projected configuration and interacting with an extra oxygen atom of the a-SiO(2) matrix.

  7. A Classical Description of the Hyperfine Structure of the Hydrogen Atom

    NASA Astrophysics Data System (ADS)

    Chaney, Andrea; Espinosa, James; Woodyard, James

    2010-10-01

    As stronger dispersion gratings are utilized, the Hydrogen spectrum is broken into small groupings. At first, the fine structure was successfully described by Sommerfeld by utilizing the special theory of relativity. The fine structure groupings are three orders of magnitude smaller than the series separations as described by Balmer and others. With even further powerful instruments, Michelson was the first to split these lines into further groupings which are a further two orders of magnitude smaller. It was almost fifty years before Breit used quantum mechanics to describe this hyperfine structure. It is almost universally believed that classical theory utterly fails to describe this phenomenon. We will show how our classical Hydrogen atom based on Ritz's magnetic model can account for the splitting of the 1s state, which is famous for its use by radio astronomers to map out the distribution of hydrogen in the universe.

  8. Hyperfine frequencies of {sup 87}Rb and {sup 133}Cs atoms in Xe gas

    SciTech Connect

    McGuyer, B. H.; Xia, T.; Jau, Y.-Y.; Happer, W.

    2011-09-15

    The microwave resonant frequencies of ground-state {sup 87}Rb and {sup 133}Cs atoms in Xe buffer gas are shown to have a relatively large nonlinear dependence on the Xe pressure, presumably because of RbXe or CsXe van der Waals molecules. The nonlinear shifts for Xe are opposite in sign to the previously measured shifts for Ar and Kr, even though all three gases have negative linear shifts. The Xe data show striking discrepancies with the previous theory for nonlinear shifts. Most of this discrepancy is eliminated by accounting for the spin-rotation interaction, {gamma}N{center_dot}S, in addition to the hyperfine-shift interaction, {delta} A I{center_dot}S, in the molecules. To the limit of our experimental accuracy, the shifts of {sup 87}Rb and {sup 133}Cs in He, Ne, and N{sub 2} were linear with pressure.

  9. Precise measurements of hyperfine components in the spectrum of molecular iodine

    SciTech Connect

    Sansonetti, C.J.

    1996-05-01

    Absolute wave numbers with a typical uncertainty of 1 MHz (95% confidence) were measured for 102 hyperfine-structure components of {sup 127}I{sub 2}. The data cover the range 560-656 nm, with no gaps over 50 cm{sup -1}. The spectra were observed using Doppler-free frequency modulation spectroscopy with tunable cw laser. The laser was locked to selected iodine components and its wave number measured with a high precision Fabry-Perot wavemeter. Accuracy is confirmed by good agreement of 9 of the lines with previous results from other laboratories. These measurements provide a well-distributed set of precise reference lines for this spectral region.

  10. Hyperfine splitting of B mesons and Bs production at the Υ(5S)

    NASA Astrophysics Data System (ADS)

    Lee-Franzini, J.; Heintz, U.; Lovelock, D. M. J.; Narain, M.; Schamberger, R. D.; Willins, J.; Yanagisawa, C.; Franzini, P.; Tuts, P. M.

    1990-12-01

    Using the Columbia University-Stony Brook (CUSB-II) detector we have studied the inclusive photon spectrum from 2.9×104 Υ(5S) decays. We observe a strong signal due to B*-->Bγ decays. From this we obtain (i) the average B*-B mass difference, 46.7+/-0.4 MeV, (ii) the photon yield per Υ(5S) decay, <γ/Υ(5S)>=1.09+/-0.06, and (iii) the average velocity of the B*'s, <β>=0.156+/-0.010, for a mix of nonstrange (B) and strange (Bs) B* mesons from Υ(5S) decays. From the shape of the photon line, we find that both B and Bs mesons are produced with nearly equal values for the hyperfine splitting of the B and Bs meson systems.

  11. A triple resonance hyperfine sublevel correlation experiment for assignment of electron-nuclear double resonance lines

    NASA Astrophysics Data System (ADS)

    Potapov, Alexey; Epel, Boris; Goldfarb, Daniella

    2008-02-01

    A new, triple resonance, pulse electron paramagnetic resonance (EPR) sequence is described. It provides spin links between forbidden electron spin transitions (ΔMS=±1, ΔMI≠0) and allowed nuclear spin transitions (ΔMI=±1), thus, facilitating the assignment of nuclear frequencies to their respective electron spin manifolds and paramagnetic centers. It also yields the relative signs of the hyperfine couplings of the different nuclei. The technique is based on the combination of electron-nuclear double resonance (ENDOR) and electron-electron double resonance (ELDOR)-detected NMR experiments in a way similar to the TRIPLE experiment. The feasibility and the information content of the method are demonstrated first on a single crystal of Cu-doped L-histidine and then on a frozen solution of a Cu-histidine complex.

  12. Measurement of Nitrogen Hyperfine Structure on the 53 CM (562 MHz) Butyronitrile Line

    NASA Astrophysics Data System (ADS)

    Dewberry, Christopher T.; Grubbs, Garry S. Grubbs, II; Raphelt, Andrew; Cooke, Stephen A.

    2009-06-01

    Recent improvements to our cavity-based Fourier transform radiofrequency spectrometer will be presented. Amongst other improvements use of Miteq amp, model AMF-6F-00100400-10-10P (0.1 GHz to 4 GHz, 65 dB gain minimum, 1 dB noise figure maximum) together with shielding from an improved Faraday cage have significantly helped us in this regard. Electromagnetic fields within our near-spherical cavity have been modeled and results will be presented. We have been able to easily resolve the nitrogen hyperfine structure on the ^aQ_{0,-1} transition 1_{1,0} ← 1_{1,1} located at 562 MHz. This result will be discussed.

  13. Hyperfine splitting and the Zeeman effect in holographic heavy-light mesons

    SciTech Connect

    Herzog, Christopher P.; Stricker, Stefan A.; Vuorinen, Aleksi

    2010-08-15

    We inspect the mass spectrum of heavy-light mesons in deformed N=2 super Yang-Mills theory using the AdS/CFT correspondence. We demonstrate how some of the degeneracies of the supersymmetric meson spectrum can be removed upon breaking the supersymmetry, thus leading to the emergence of a hyperfine structure. The explicit SUSY breaking scenarios we consider involve on the one hand, tilting one of the two fundamental D7-branes inside the internal R{sup 6} space, and on the other hand, applying an external magnetic field on the (untilted) branes. The latter scenario leads to the well-known Zeeman effect, which we inspect for both weak and strong magnetic fields.

  14. Toward the measurement of the hyperfine splitting in the ground state of muonic hydrogen

    NASA Astrophysics Data System (ADS)

    Bakalov, Dimitar; Adamczak, Andrzej; Stoilov, Mihail; Vacchi, Andrea

    2015-08-01

    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.

  15. Fine and hyperfine structure of P-wave levels in muonic hydrogen

    SciTech Connect

    Martynenko, A. P.

    2008-01-15

    Corrections of order {alpha}{sup 5} and {alpha}{sup 6} are calculated for muonic hydrogen in the fine-structure interval {delta}E{sup fs} = E(2P{sub 3/2}) - E(2P{sub 1/2}) and in the hyperfine structure of the 2P{sub 1/2}-and 2P{sub 3/2}-wave energy levels. The resulting values of {delta}E{sup fs} = 8352.08 {mu}eV, {delta}E-tilde {sup hfs}(2P{sub 1/2}) = 7819.80 {mu}eV, and {delta}E-tilde {sup hfs}(2P{sub 3/2}) = 3248.03 {mu}eV provide reliable guidelines in performing a comparison with relevant experimental data and in more precisely extracting the experimental value of the (2P-2S) Lamb shift in the muonic-hydrogen atom.

  16. Self-energy correction to the hyperfine splitting and the electron g factor in hydrogenlike ions

    SciTech Connect

    Yerokhin, Vladimir A.; Jentschura, Ulrich D.

    2010-01-15

    The hyperfine structure (hfs) and the g factor of a bound electron are caused by external magnetic fields. For the hfs, the magnetic field is due to the nuclear spin. A uniform-in-space and constant-in-time magnetic field is used to probe the bound-electron g factor. The self-energy corrections to these effects are more difficult to evaluate than those to the Lamb shift. Here, we describe a numerical approach for both effects in the notoriously problematic regime of hydrogenlike bound systems with low nuclear charge numbers. The calculation is nonperturbative in the binding Coulomb field. Accurate numerical values for the remainder functions are provided for 2P states and for nS states with n=1,2,3.

  17. Hyperfine structure measurement of 87Rb atoms injected into superfluid helium as highly energetic ion beam

    NASA Astrophysics Data System (ADS)

    Imamura, Kei; Furukawa, Takeshi; Yang, Xiaofei; Fujita, Tomomi; Wakui, Takashi; Mitsuya, Yousuke; Hayasaka, Miki; Ichikawa, Yuichi; Hatakeyama, Atsushi; Kobayashi, Tohru; Odashima, Hitoshi; Ueno, Hideki; Matsuo, Yukari; Orochi Collaboration

    2014-09-01

    We have developed a new nuclear laser spectroscopy technique that is called OROCHI (Optical RI-atoms Observation in Condensed Helium as Ioncatcher). In OROCHI, highly energetic ion beam is injected into superfluid helium (He II) and is trapped as atoms. Hyperfine structure (HFS) and Zeeman splitting of trapped atoms is measured using laser-microwave (MW)/radiofrequency (RF) double resonance method. We deduce nuclear moments and spin values from the measured splittings, respectively So far, we measured Zeeman splitting of 84-87Rb atoms To evaluate the validity of the OROCHI method, it is necessary to investigate the following two points not only for Zeeman but also for HFS splitings. (i) What is the accuracy in frequency in our measurement? (ii) How high beam intensity is necessary to observe resonance spectra? For this purpose we conducted online experiment using 87Rb beam and measured the HFS splitting of injected 87Rb atoms in He II.

  18. Relativistic many-body investigation of hyperfine interactions in excited S states of alkali metals: Francium and potassium

    SciTech Connect

    Owusu, A.; Dougherty, R.W.; Gowri, G.; Das, T.P.; Andriessen, J.

    1997-07-01

    To enhance the current understanding of mechanisms contributing to magnetic hyperfine interactions in excited states of atomic systems, in particular, alkali-metal atom systems, the hyperfine fields in the excited 5{sup 2}S{sub 1/2}{endash}8{sup 2}S{sub 1/2} states of potassium and 8{sup 2}S{sub 1/2}{endash}12{sup 2}S{sub 1/2} states of francium atoms have been studied using the relativistic linked-cluster many-body perturbation procedure. The net theoretical values of the hyperfine fields for the excited states studied are in excellent agreement with available experimental data for both atoms. There is a significant decrease in importance of the correlation contribution in going from the ground state to the excited states, the correlation contributions as ratios of the direct contribution decreasing rapidly as one moves to the higher excited states. However, the contribution from the exchange core polarization (ECP) effect is nearly a constant fraction of the direct effect for all the excited states considered. Physical explanations are offered for the observed trends in the contributions from the different mechanisms. A comparison is made of the different contributing effects to the hyperfine fields in potassium and francium to those in the related system, rubidium, studied earlier. Extrapolating from our results to the highly excited states of alkali-metal atoms, referred to as the Rydberg states, it is concluded that in addition to the direct contribution from the excited valence electron to the hyperfine fields, a significant contribution is expected from the ECP effect arising from the influence of exchange interactions between electrons in the valence and core states. {copyright} {ital 1997} {ital The American Physical Society}

  19. Hyperfine structure and Zeeman tuning of the A {sup 2}PI-X {sup 2}SIGMA{sup +}(0,0) band system of the odd isotopologue of strontium monofluoride {sup 87}SrF

    SciTech Connect

    Le, Anh T.; Wang Hailing; Steimle, Timothy C.

    2009-12-15

    The low-rotational lines of the A {sup 2}PI-X {sup 2}SIGMA{sup +}(0,0) band system of the odd isotopologue of strontium monofluoride, {sup 87}SrF, were recorded and analyzed. The {sup 87}Sr(I=9/2) magnetic hyperfine interaction is significant only in the |OMEGA|=1/2 spin-orbit component of the A {sup 2}PI state. Optical transitions appropriate for monitoring ultracold samples of {sup 87}SrF are identified. The determined fine-structure parameters were used to predict the anisotropic magnetic g factor, g{sub l}, for the X {sup 2}SIGMA{sup +}(v=0) state. The g factors were used to predict the magnetic tuning of the N=0 (+parity) and N=1 (-parity) levels of the X {sup 2}SIGMA{sup +}(v=0) state. A comparison to spectroscopic parameters for the {sup 88}SrF isotopologue is given.

  20. Spin dependent recombination; A sup 29 Si hyperfine study of radiation-induced P sub b centers at the Si/SiO sub 2 interface

    SciTech Connect

    Jupina, M.A.; Lenahan, P.M. )

    1990-12-01

    The spin dependent recombination (SDR) technique is used to observe the {sup 29}Si hyperfine spectra of radiation-induced P{sub b} centers at the Si/SiO{sub 2} interface in a MOSFET. The P{sub b} center is a paramagnetic, trivalent silicon defect that is the dominant radiation-induced interface state. The {sup 29}Si hyperfine spectra give detailed atomic scale information about the P{sub b} center. The authors' SDR results show that the {sup 29}Si hyperfine spectra vary with surface potential. This result indicates that differences in the defect's local geometry lead to substantial differences in the defect's energy level. However, the {sup 29}Si hyperfine spectra are found to be relatively independent of the ionizing radiation dosage.

  1. Polarized {sup 3}He{sup −} ion source with hyperfine state selection

    SciTech Connect

    Dudnikov, V.; Morozov, V.; Dudnikov, A.

    2015-04-08

    High beam polarization is essential to the scientific productivity of a collider. Polarized {sup 3}He ions are an essential part of the nuclear physics programs at existing and future ion-ion and electron-ion colliders such as BNL's RHIC and eRHIC and JLab's ELIC. Ion sources with performance exceeding that achieved today are a key requirement for the development of these next generation high-luminosity high-polarization colliders. The development of high-intensity high-brightness arc-discharge ion sources at the Budker Institute of Nuclear Physics (BINP) has opened up an opportunity for realization of a new type of a polarized {sup 3}He{sup −} ion source. This report discusses a polarized {sup 3}He{sup −} ion source based on the large difference of extra-electron auto-detachment lifetimes of the different {sup 3}He{sup −} ion hyperfine states. The highest momentum state of 5/2 has the largest lifetime of τ ∼ 350 µs while the lower momentum states have lifetimes of τ ~ 10 µs. By producing {sup 3}He{sup −} ion beam composed of only the |5/2, ±5/2> hyperfine states and then quenching one of the states by an RF resonant field, {sup 3}He{sup −} beam polarization of 90% can be achieved. Such a method of polarized {sup 3}He{sup −} production has been considered before; however, due to low intensities of the He{sup +} ion sources existing at that time, it was not possible to produce any interesting intensity of polarized {sup 3}He{sup −} ions. The high-brightness arc-discharge ion source developed at BINP can produce a high-brightness {sup 3}He{sup +} beam with an intensity of up to 2 A allowing for selection of up to ∼1-4 mA of {sup 3}He{sup −} ions with ∼90% polarization. The high gas efficiency of an arc-discharge source is important due to the high cost of {sup 3}He gas. Some features of such a PIS as well as prototype designs are considered. An integrated {sup 3}He{sup −} ion source design providing high beam polarization could be

  2. Searching for an Oscillating Massive Scalar Field as a Dark Matter Candidate Using Atomic Hyperfine Frequency Comparisons.

    PubMed

    Hees, A; Guéna, J; Abgrall, M; Bize, S; Wolf, P

    2016-08-05

    We use 6 yrs of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions, and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but provide improved constraints on the coupling of the putative scalar field to standard matter. Our limits are complementary to previous results that were only sensitive to the fine structure constant and improve them by more than an order of magnitude when only a coupling to electromagnetism is assumed.

  3. Quantum gates in hyperfine levels of ultracold alkali dimers by revisiting constrained-phase optimal control design

    NASA Astrophysics Data System (ADS)

    Jaouadi, A.; Barrez, E.; Justum, Y.; Desouter-Lecomte, M.

    2013-07-01

    We simulate the implementation of a 3-qubit quantum Fourier transform gate in the hyperfine levels of ultracold polar alkali dimers in their first two lowest rotational levels. The chosen dimer is 41K87Rb supposed to be trapped in an optical lattice. The hyperfine levels are split by a static magnetic field. The pulses operating in the microwave domain are obtained by optimal control theory. We revisit the problem of phase control in information processing. We compare the efficiency of two optimal fields. The first one is obtained from a functional based on the average of the transition probabilities for each computational basis state but constrained by a supplementary transformation to enforce phase alignment. The second is obtained from a functional constructed on the phase sensitive fidelity involving the sum of the transition amplitudes without any supplementary constrain.

  4. The β-phosphorus hyperfine coupling constant in nitroxides: 6. Solvent effects in non-cyclic nitroxides.

    PubMed

    Audran, Gérard; Bosco, Lionel; Nkolo, Paulin; Bikanga, Raphael; Brémond, Paul; Butscher, Teddy; Marque, Sylvain R A

    2016-04-12

    In two recent articles (Org. Biomol. Chem., 2015 and 2016), we showed that changes in the phosphorus hyperfine coupling constant aP at position β in β-phosphorylated nitroxides can be dramatic. Such changes were applied to the titration of water in organic solvents and conversely of organic solvents in water. One of the molecules tested was a non-cyclic nitroxide meaning that a thorough investigation of the solvent effect on the EPR hyperfine coupling constant is timely due. In this article, we show that the aP of persistent non-cyclic β-phosphorylated nitroxides decrease with the normalized polarity Reichardt's constant E(N)T. The Koppel-Palm and Kalmet-Abboud-Taft relationships were applied to gain deeper insight into the effects influencing aN and aP: polarity/polarizability, hydrogen bond donor properties, and the structuredness of the cybotactic region.

  5. Rapid-scan coherence signals in X-band EPR spectra of semiquinones with small hyperfine splittings.

    PubMed

    Elajaili, Hanan; Rinard, George A; Yu, Zhelin; Mitchell, Deborah G; Quine, Richard W; Eaton, Sandra S; Eaton, Gareth R

    2015-10-01

    Rapid-scan EPR signals for semiquinones with very-small well-resolved hyperfine splittings exhibit coherence signals at a time after passing through the EPR line that is proportional to the reciprocal of the hyperfine splitting. Such coherences are a general phenomenon due to constructive interference of the responses to transient excitation of spins by rapid scan of the magnetic field across equally spaced spin packets. Examples are shown for 2,3,5,6-tetramethoxy-1,4-benzosemiquinone with aH=46 mG for 12 protons and for 2,5-di-t-butyl-1,4-benzosemiquinone with aH=59 mG for 18 protons.

  6. Rapid-scan coherence signals in X-band EPR spectra of semiquinones with small hyperfine splittings

    PubMed Central

    Elajaili, Hanan; Rinard, George A.; Yu, Zhelin; Mitchell, Deborah G.; Quine, Richard W.; Eaton, Sandra S.; Eaton, Gareth R.

    2015-01-01

    Rapid-scan EPR signals for semiquinones with very-small well-resolved hyperfine splittings exhibit coherence signals at a time after passing through the EPR line that is proportional to the reciprocal of the hyperfine splitting. Such coherences are a general phenomenon due to constructive interference of the responses to transient excitation of spins by rapid scan of the magnetic field across equally spaced spin packets. Examples are shown for 2,3,5,6-tetramethoxy-1,4-benzosemiquinone with aH = 46 mG for 12 protons and for 2,5-di-t-butyl-1,4-benzosemiquinone with aH = 59 mG for 18 protons. PMID:26277376

  7. Spectrally resolved hyperfine interactions between polaron and nuclear spins in organic light emitting diodes: Magneto-electroluminescence studies

    SciTech Connect

    Crooker, S. A.; Kelley, M. R.; Martinez, N. J. D.; Nie, W.; Mohite, A.; Nayyar, I. H.; Tretiak, S.; Smith, D. L.; Liu, F.; Ruden, P. P.

    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.

  8. High-accuracy measurement of the 87Rb ground-state hyperfine splitting in an atomic fountain

    NASA Astrophysics Data System (ADS)

    Bize, S.; Sortais, Y.; Santos, M. S.; Mandache, C.; Clairon, A.; Salomon, C.

    1999-03-01

    We describe the operation of a laser-cooled rubidium 87Rb frequency standard. We present a new measurement of the 87Rb hyperfine frequency with a 1.3 × 10-14 relative accuracy, by comparison with a Cs fountain primary standard. The measured 87Rb ground-state hyperfine splitting is ν87 = 6 834 682 610.90429(9) Hz. This value differs from previously published values (see Essen L., Hope E. G. and Sutcliffe D., Nature 189 1961 298; Penselin S., Moran T., Cohen W. and Wscinkler G., Phys. Rev. 127 1962 524; Arditi M. and Cerez P. IEEE Trans. Instrum. Meas. IM-21 1972 391) by about 2 - 3 Hz and is 104 times more accurate. Because of the low collisional shift in 87Rb, future improvements may lead to a stability of 1 × 10-14τ-1/2 and a relative accuracy in the 10-17 range.

  9. Searching for an Oscillating Massive Scalar Field as a Dark Matter Candidate Using Atomic Hyperfine Frequency Comparisons

    NASA Astrophysics Data System (ADS)

    Hees, A.; Guéna, J.; Abgrall, M.; Bize, S.; Wolf, P.

    2016-08-01

    We use 6 yrs of accurate hyperfine frequency comparison data of the dual rubidium and caesium cold atom fountain FO2 at LNE-SYRTE to search for a massive scalar dark matter candidate. Such a scalar field can induce harmonic variations of the fine structure constant, of the mass of fermions, and of the quantum chromodynamic mass scale, which will directly impact the rubidium/caesium hyperfine transition frequency ratio. We find no signal consistent with a scalar dark matter candidate but provide improved constraints on the coupling of the putative scalar field to standard matter. Our limits are complementary to previous results that were only sensitive to the fine structure constant and improve them by more than an order of magnitude when only a coupling to electromagnetism is assumed.

  10. Hyperfine-Interaction-Driven Suppression of Quantum Tunneling at Zero Field in a Holmium(III) Single-Ion Magnet.

    PubMed

    Chen, Yan-Cong; Liu, Jun-Liang; Wernsdorfer, Wolfgang; Liu, Dan; Chibotaru, Liviu F; Chen, Xiao-Ming; Tong, Ming-Liang

    2017-03-15

    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(-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 (165) Ho (I=7/2) with a natural abundance of 100 %.

  11. Rotational Spectroscopy of CF_2ClCCl_3 and Analysis of Hyperfine Structure from Four Quadrupolar Nuclei

    NASA Astrophysics Data System (ADS)

    Kisiel, Zbigniew; Bialkowska-Jaworska, Ewa; Uriarte, Iciar; Basterretxea, Francisco J.; Cocinero, Emilio J.

    2016-06-01

    CF_2ClCCl_3 has recently been identified among several new ozone- depleting substances in the atmosphere. There are no literature reports concerning rotational spectroscopy of this molecule, although we were recently able to report its first chirped pulse, supersonic expansion spectrum. CF_2ClCCl_3 has a rather small dipole moment so that the spectrum is weak and each transition displays very complex nuclear quadrupole hyperfine structure resulting from the presence of four chlorine nuclei. We have presently been able to carry out a complete analysis of the hyperfine structure by combining the information from chirped pulse spectra with dedicated higher resolution measurements made with a cavity supersonic expansion instrument. The hyperfine analysis was carried out with Pickett's SPFIT/SPCAT package and the sizes of Hamiltonian matrices are sufficiently large to require the use of 64-bit compilation of these programs (made available for both Windows and Linux systems on the PROSPE website). The resulting fit is to within experimental accuracy and is supported by ab initio calculations. The precise values of off-diagonal hyperfine constants for all nuclei lead to useful angular information that is complementary to direct structural information from moments of inertia. J.C.Laube, M.J.Newland, C.Hogan, et al., Nature Geoscience 7, 266 (2014). Z.Kisiel, E.Białkowska-Jaworska, L.Pszczółkowski, I.Uriarte, P.Ejica, F.J.Basterretxea, E.J.Cocinero, 70th ISMS, Champaign-Urbana, Illinois, RF-11 (2015). Z.Kisiel, E.Białkowska-Jaworska, L.Pszczółkowski, J.Chem.Phys. 109, 10263 (1998).

  12. Long-range interactions of hydrogen atoms in excited states. II. Hyperfine-resolved (2 S -2 S ) systems

    NASA Astrophysics Data System (ADS)

    Jentschura, U. D.; Debierre, V.; Adhikari, C. M.; Matveev, A.; Kolachevsky, N.

    2017-02-01

    The interaction of two excited hydrogen atoms in metastable states constitutes a theoretically interesting problem because of the quasidegenerate 2 P1 /2 levels that are removed from the 2 S states only by the Lamb shift. The total Hamiltonian of the system is composed of the van der Waals Hamiltonian, the Lamb shift, and the hyperfine effects. The van der Waals shift becomes commensurate with the 2 S -2 P3 /2 fine-structure splitting only for close approach (R <100 a0 , where a0 is the Bohr radius) and one may thus restrict the discussion to the levels with n =2 and J =1 /2 to a good approximation. Because each S or P state splits into an F =1 triplet and an F =0 hyperfine singlet (eight states for each atom), the Hamiltonian matrix a priori is of dimension 64. A careful analysis of the symmetries of the the problem allows one to reduce the dimensionality of the most involved irreducible submatrix to 12. We determine the Hamiltonian matrices and the leading-order van der Waals shifts for states that are degenerate under the action of the unperturbed Hamiltonian (Lamb shift plus hyperfine structure). The leading first- and second-order van der Waals shifts lead to interaction energies proportional to 1 /R3 and 1 /R6 and are evaluated within the hyperfine manifolds. When both atoms are metastable 2 S states, we find an interaction energy of order Ehχ (a0/R ) 6 , where Eh and L are the Hartree and Lamb shift energies, respectively, and χ =Eh/L ≈6.22 ×106 is their ratio.

  13. Ultra-soft magnetic properties and correlated phase analysis by {sup 57}Fe Mössbauer spectroscopy of Fe{sub 74}Cu{sub 0.8}Nb{sub 2.7}Si{sub 15.5}B{sub 7} alloy

    SciTech Connect

    Manjura Hoque, S.; Liba, S. I.; Akhter, Shireen; Anirban, A.; Choudhury, Shamima

    2016-02-15

    A detailed study of magnetic softness has been performed on FINEMENT type of ribbons by investigating the BH loop with maximum applied field of 960 A/m. The ribbon with the composition of Fe{sub 74}Cu{sub 0.8}Nb{sub 2.7}Si{sub 15.5}B{sub 7} was synthesized by rapid solidification technique and the compositions volume fraction was controlled by changing the annealing condition. Detail phase analysis was performed through X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Vibrating sample magnetometer (VSM) and Mössbauer spectroscopy in order to correlate the ultrasoft magnetic properties with the volume fraction of amorphous and α-Fe(Si) soft nano composites. Bright (BF) and dark field (DF) image with selective area diffraction (SAD) patterns by the transmission electron microscopy (TEM) of the sample annealed for the optimized annealed condition at 853 K for 3 min reveals nanocrystals with an average size between 10-15 nm possessing the bcc structure which matches with the grain size revealed by the X-ray diffraction. Kinetics of crystallization of α-Fe(Si) phases has been determined by DSC curves. Extremely small coercivity of 30.9 A/m and core loss of 2.5 W/Kg for the sample annealed at 853 K for 3 min was found. Similar values for other crystalline conditions were determined by using BH loop tracer with a maximum applied field of around 960 A/m. Mössbauer spectroscopy was used to determine chemical shift, hyperfine field distribution (HFD), and peak width of different phases. The volume fractions of the relative amount of amorphous and crystalline phases are also determined by Mössbauer spectroscopy. High saturation magnetization along with ultrasoft magnetic properties exhibits very high potentials technological applications.

  14. Combined effect of coherent Z exchange and the hyperfine interaction in the atomic parity-nonconserving interaction

    SciTech Connect

    Johnson, W.R.; Safronova, M.S.; Safronova, U.I.

    2003-06-01

    The nuclear spin-dependent parity-nonconserving (PNC) interaction arising from a combination of the hyperfine interaction and the coherent, spin-independent, PNC interaction from Z exchange is evaluated using many-body perturbation theory. For the 6s{sub 1/2}-7s{sub 1/2} transition in {sup 133}Cs, we obtain a result that is about 40% smaller than that found previously by Bouchiat and Piketty [Phys. Lett. B 269, 195 (1991)]. Applying this result to {sup 133}Cs leads to an increase in the experimental value of nuclear anapole moment and exacerbates differences between constraints on PNC meson coupling constants obtained from the Cs anapole moment and those obtained from other nuclear parity violating experiments. Nuclear spin-dependent PNC dipole matrix elements, including contributions from the combined weak-hyperfine interaction, are also given for the 7s{sub 1/2}-8s{sub 1/2} transition in {sup 211}Fr and for transitions between ground-state hyperfine levels in K, Rb, Cs, Ba{sup +}, Au, Tl, Fr, and Ra{sup +}.

  15. Hyperfine fields in the BaFe2As2 family and their relation to the magnetic moment

    NASA Astrophysics Data System (ADS)

    Derondeau, Gerald; Minár, Ján; Ebert, Hubert

    2016-12-01

    The hyperfine field Bhf and the magnetic properties of the BaFe2As2 family are studied using the fully relativistic Dirac formalism for different types of substitution. The study covers electron doped Ba (Fe1-xCox) 2As2 and Ba (Fe1-xNix) 2As2 , hole doped (Ba1 -xKx) Fe2As2 , and also isovalently doped Ba (Fe1-xRux) 2As2 and BaFe2(As1-xPx) 2 for a wide range of the concentration x . For the substituted compounds the hyperfine fields show a very strong dependence on the dopant type and its concentration x . Relativistic contributions were found to have a significantly stronger impact for the iron pnictides when compared to bulk Fe. As an important finding, we demonstrate that it is not sensible to relate the hyperfine field Bhf to the average magnetic moment μ of the compound, as it was done in earlier literature.

  16. Mixing of {0}^{+} and {0}^{-} observed in the hyperfine and Zeeman structure of ultracold {{Rb}}_{2} molecules

    NASA Astrophysics Data System (ADS)

    Deiß, Markus; Drews, Björn; Hecker Denschlag, Johannes; Tiemann, Eberhard

    2015-08-01

    We study the combination of the hyperfine and Zeeman structure in the spin-orbit coupled {A}1{Σ }u+-{b}3{\\Pi }u complex of {}87{{Rb}}2. For this purpose, absorption spectroscopy at a magnetic field around B=1000 G is carried out. We drive optical dipole transitions from the lowest rotational state of an ultracold Feshbach molecule to various vibrational levels with {0}+ symmetry of the A-b complex. In contrast to previous measurements with rotationally excited alkali-dimers, we do not observe equal spacings of the hyperfine levels. In addition, the spectra vary substantially for different vibrational quantum numbers, and exhibit large splittings of up to 160 MHz, unexpected for {0}+ states. The level structure is explained to be a result of the repulsion between the states {0}+ and {0}- of {b}3{\\Pi }u, coupled via hyperfine and Zeeman interactions. In general, {0}- and {0}+ have a spin-orbit induced energy spacing Δ, that is different for the individual vibrational states. From each measured spectrum we are able to extract Δ, which otherwise is not easily accessible in conventional spectroscopy schemes. We obtain values of Δ in the range of +/- 100 GHz which can be described by coupled channel calculations if a spin-orbit coupling is introduced that is different for {0}- and {0}+ of {b}3{\\Pi }u.

  17. Hyperfine interaction in InAs/GaAs self-assembled quantum dots: dynamical nuclear polarization versus spin relaxation

    NASA Astrophysics Data System (ADS)

    Krebs, Olivier; Eble, Benoît; Lemaître, Aristide; Voisin, Paul; Urbaszek, Bernhard; Amand, Thierry; Marie, Xavier

    2008-10-01

    We report on the influence of the hyperfine interaction on the optical orientation of singly charged excitons X in self-assembled InAs/GaAs quantum dots. All measurements were carried out on individual quantum dots studied by micro-photoluminescence at low temperature. We show that the hyperfine interaction leads to an effective partial spin relaxation, under 50 kHz modulated excitation polarization, which becomes, however, strongly inhibited under steady optical pumping conditions because of dynamical nuclear polarization. This optically created magnetic-like nuclear field can become very strong (up to ˜4 T) when it is generated in the direction opposite to a longitudinally applied field, and exhibits then a bistability regime. This effect is very well described by a theoretical model derived in a perturbative approach, which reveals the key role played by the energy cost of an electron spin flip in the total magnetic field. Finally, we emphasize the similarities and differences between X and X trions with respect to the hyperfine interaction, which turn out to be in perfect agreement with the theoretical description. To cite this article: O. Krebs et al., C. R. Physique 9 (2008).

  18. Schonland ambiguity in the electron nuclear double resonance analysis of hyperfine interactions: principles and practice.

    PubMed

    Vrielinck, H; De Cooman, H; Tarpan, M A; Sagstuen, E; Waroquier, M; Callens, F

    2008-12-01

    For the analysis of the angular dependence of electron paramagnetic resonance (EPR) spectra of low-symmetry centres with S=1/2 in three independent planes, it is well-established-but often overlooked-that an ambiguity may arise in the best-fit g<--> tensor result. We investigate here whether a corresponding ambiguity also arises when determining the hyperfine coupling (HFC) A<--> tensor for nuclei with I=1/2 from angular dependent electron nuclear double resonance (ENDOR) measurements. It is shown via a perturbation treatment that for each set of M(S) ENDOR branches two best-fit A<--> tensors can be derived, but in general only one unique solution simultaneously fits both. The ambiguity thus only arises when experimental data of only one M(S) multiplet are used in analysis or in certain limiting cases. It is important to realise that the ambiguity occurs in the ENDOR frequencies and therefore the other best-fit result for an ENDOR determined A<--> tensor depends on various details of the ENDOR experiment: the M(S) state of the fitted transitions, the microwave frequency (or static magnetic field) in the ENDOR measurements and the rotation planes in which data have been collected. The results are of particular importance in the identification of radicals based on comparison of theoretical predictions of HFCs with published literature data. A procedure for obtaining the other best-fit result for an ENDOR determined A<--> tensor is outlined.

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

    NASA Technical Reports Server (NTRS)

    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(+).

  20. Hyperfine coupling tensors of the benzosemiquinone radical anion from Car-Parrinello molecular dynamics.

    PubMed

    Asher, James R; Kaupp, Martin

    2007-01-08

    Based on Car-Parrinello ab initio molecular dynamics simulations of the benzosemiquinone radical anion in both aqueous solution and the gas phase, density functional calculations provide the currently most refined EPR hyperfine coupling (HFC) tensors of semiquinone nuclei and solvent protons. For snapshots taken at regular intervals from the molecular dynamics trajectories, cluster models with different criteria for inclusion of water molecules and an additional continuum solvent model are used to analyse the HFCs. These models provide a detailed picture of the effects of dynamics and of different intermolecular interactions on the spin-density distribution and HFC tensors. Comparison with static calculations allows an assessment of the importance of dynamical effects, and of error compensation in static DFT calculations. Solvent proton HFCs depend characteristically on the position relative to the semiquinone radical anion. A point-dipolar model works well for in-plane hydrogen-bonded protons but deviates from the quantum chemical values for out-of-plane hydrogen bonding.

  1. A SETI Search of Nearby Solar-Type Stars at the 203-GHz Positronium Hyperfine Resonance

    NASA Technical Reports Server (NTRS)

    Steffes, Paul G.; DeBoer, David R.

    1994-01-01

    The development of advanced millimeter-wave technology has made it possible to construct low-noise receivers and high-power transmitters comparable to those available at much lower frequencies. This technology, plus certain physical characteristics of the millimeter-wave spectrum, suggests possible advantages for use of this wavelength range for interstellar communications. As a result, a Search for ExtraTerrestrial Intelligence(SETI) type search has been conducted for narrow-bandwidth signals at frequencies near the positronium hyperfine spectral line (203.385 GHz), a potential natural reference frequency. A total of 40 solar-type stars within 23 parsecs were observed, in addition to three locations near the galactic center. No detections were made at the detection threshold of 2.3 x 10(exp -19) W/sq m in each of two orthogonal linear polarizations Future observations will be made with a higher resolution Fast Fourier Transform Spectrum Analyzer (FFTSA), which should improve sensitivity by an order of magnitude and reduce required observing time.

  2. Critically evaluated theoretical energies, lifetimes, hyperfine constants, and multipole polarizabilities in {sup 87}Rb

    SciTech Connect

    Safronova, M. S.; Safronova, U. I.

    2011-05-15

    Systematic study of Rb atomic properties is carried out using a high-precision relativistic all-order method. Excitation energies of the ns, np, nd, and nf (n{<=}10) states in neutral rubidium are evaluated. Reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for the levels up to n=8. Recommended values and estimates of their uncertainties are provided for a large number of electric-dipole transitions. Electric-dipole (5s-np, n=5-26), electric-quadrupole (5s-nd{sub j}, n=4-26), and electric-octupole (5s-nf{sub j}, n=4-26) matrix elements are calculated to obtain the ground state E1, E2, and E3 static polarizabilities. Scalar polarizabilities of the ns, np, and nd states, and tensor polarizabilities of the np{sub 3/2} and nd excited states of Rb are evaluated. The hyperfine A and B values in {sup 87}Rb are determined for the first low-lying levels up to n=9. These calculations provide recommended values critically evaluated for their accuracy for a number of Rb atomic properties useful for a variety of applications.

  3. Properties of Gd2O3 nanoparticles studied by hyperfine interactions and magnetization measurements

    NASA Astrophysics Data System (ADS)

    Correa, E. L.; Bosch-Santos, B.; Cavalcante, F. H. M.; Correa, B. S.; Freitas, R. S.; Carbonari, A. W.; Potiens, M. P. A.

    2016-05-01

    The magnetic behavior of Gd2O3 nanoparticles, produced by thermal decomposition method and subsequently annealed at different temperatures, was investigated by magnetization measurements and, at an atomic level, by perturbed γ - γ angular correlation (PAC) spectroscopy measuring hyperfine interactions at 111In(111Cd) probe nuclei. Nanoparticle structure, size and shape were characterized by X-ray diffraction (XRD) and Transmission Electron Microscopy (TEM). Magnetization measurements were carried out to characterize the paramagnetic behavior of the samples. XRD results show that all samples crystallize in the cubic-C form of the bixbyite structure with space group Ia3. TEM images showed that particles annealed at 873 K present particles with highly homogeneous sizes in the range from 5 nm to 10 nm and those annealed at 1273 K show particles with quite different sizes from 5 nm to 100 nm, with a wide size distribution. PAC and magnetization results show that samples annealed at 873 and 1273 K are paramagnetic. Magnetization measurements show no indication of blocking temperatures for all samples down to 2 K and the presence of antiferromagnetic correlations.

  4. Structural, optical, hyperfine and magnetization studies of ZnO encapsulated α-Fe nanoparticles

    SciTech Connect

    Rathore, A.K.; Pati, S.P.; Roychowdhury, A.; Das, D.

    2014-12-15

    We report the successful preparation and characterization of magnetic-fluorescent nanoparticles (NPs) by overcoming the difficulty of handling α-Fe nanoparticles that are less stable and have high affinity to get oxidized in air even at room temperature. Nanocrystalline α-Fe particles embedded by ZnO have been synthesized by a two step chemical route. Concentration of α-Fe has been varied as 15, 30 and 50 wt% of the sample. Detailed investigations on structural, hyperfine, optical and magnetic characteristics have been carried out. X-ray diffraction, transmission electron microscopy and fourier transform infrared spectroscopy studies have been used to confirm the coexistence of Fe and ZnO phases in the nanocomposites (NCs). The presence of α-Fe is also confirmed by Mössbauer spectroscopy. However, other forms of iron are also detected in the sample. UV–vis spectrum of nanocomposites shows a red shift with respect to the pristine ZnO which is attributed to the electron transfer between Fe and ZnO that provides support to the formation of the Fe- ZnO NC. The photoluminescence (PL) spectra of Fe-ZnO nanocomposites exhibit blue shift of the UV and weaker visible emission lines compared to the pristine ZnO. Nanocomposites are found to be magnetically soft having high saturation magnetization with very low remanence. Low temperature coercivity enhancement due to freezing of uncompensated surface spins is also found in all samples.

  5. Measurement of the hyperfine splitting of 133Cs atoms in superfluid helium

    NASA Astrophysics Data System (ADS)

    Imamura, K.; Furukawa, T.; Yang, X. F.; Mitsuya, Y.; Fujita, T.; Hayasaka, M.; Kobayashi, T.; Hatakeyama, A.; Ueno, H.; Odashima, H.; Matsuo, Y.

    2015-04-01

    We have been developing a new nuclear laser spectroscopy method named "OROCHI" (Optical RI-atom Observation in Condensed Helium as Ion-catcher). OROCHI utilizes superfluid helium (He II) not only as an efficient stopping medium of highly energetic ions but also as a host matrix of in-situ atomic laser spectroscopy. Using these characteristic of He II, we produce atomic spin polarization and measure Zeeman and hyperfine structure (HFS) splitting using laser-RF (radio frequency) / MW (microwave) double resonance method. From the measured energy splittings, we can deduce nuclear spins and moments. So far, we have conducted a series of experiments using both stable (85,87Rb, 133Cs, 197Au, 107,109Ag) and unstable isotopes (84,86Rb) to confirm the feasibility of OROCHI method, especially observing Zeeman resonance and determining nuclear spins. The measurement of HFS splitting of atoms introduced into He II is indispensable to clarify the nuclear properties by deducing nuclear moments as well as the study of nuclear spins. For this purpose, we perform a precision measurement of HFS of 133Cs atoms immersed in He II using laser ablation technique. In this paper, we describe the result of the experiment.

  6. Composite Sequences for Triple-dot Qubits that Compensate for Miscalibration and Hyperfine Gradients

    NASA Astrophysics Data System (ADS)

    Ladd, Thaddeus

    2014-03-01

    Exchange-only qubits defined in triple quantum dots form a promising means for all-electrical semiconductor quantum control, but they suffer from both charge noise and random magnetic field gradients. Low-frequency noise sources can be compensated using composite sequences, but the development of such sequences is constrained by the fact that exchange energies are always positive and the control axes are non-orthogonal. Here, we present the results of both analytical approaches and computational searches for composite pulse sequences, which compensate for simultaneous low-frequency miscalibration (due to fixed random electric fields) and hyperfine effects (due to nuclear magnetic fields) in a single triple-dot qubit. We also present compensation sequences for multi-qubit gates. These results can substantially improve the working fidelity of quantum operations in semiconductor quantum dot devices. Sponsored by United States Department of Defense. The views and conclusions contained in this document are those of the authors and should not be interpreted as representing the official policies, either expressly or implied, of the United States Department of Defense or the U.S. Government.

  7. LETTER TO THE EDITOR: ? hyperfine structure of the ? interface defect in thermal ?

    NASA Astrophysics Data System (ADS)

    Stesmans, A.; Nouwen, B.; Afanas'ev, V. V.

    1998-07-01

    The observation of the electron spin resonance hyperfine (hf) spectra associated with the unpaired electron of the 0953-8984/10/27/004/img4 interface defect in thermal 0953-8984/10/27/004/img5 shows that the dominant interaction arises from a single 0953-8984/10/27/004/img6 isotope. The hf tensor displays weakly monoclinic I (nearly axial) symmetry, with the principal axes of the g and hf tensors coinciding. A molecular orbital analysis indicates that the unpaired electron resides for 0953-8984/10/27/004/img7 in a single unpaired Si hybrid orbital, found to be 14% s-like and 86% p-like, with the p-orbital markedly pointing closely along a 0953-8984/10/27/004/img8 direction at 0953-8984/10/27/004/img9 with the [100] interface normal. With oxygen not constituting an immediate part of the defect, the results firmly establish the key part of the 0953-8984/10/27/004/img4 defect as a tilted (0953-8984/10/27/004/img11 about 0953-8984/10/27/004/img12) 0953-8984/10/27/004/img13 unit.

  8. Fine and hyperfine structure of P-wave levels in muonic hydrogen

    SciTech Connect

    Martynenko, A. P.

    2008-01-15

    Corrections of order {alpha}{sup 5} and {alpha}{sup 6} are calculated for muonic hydrogen in the fine-structure interval {Delta}E{sup fs} = E(2P{sub 3/2}) - E(2P{sub 1/2}) and in the hyperfine structure of the 2P{sub 1/2}-and 2P{sub 3/2}-wave energy levels. The resulting values of {Delta}E{sup fs} = 8352.08 Micro-Sign eV, {Delta}E-tilde {sup hfs}(2P{sub 1/2}) = 7819.80 Micro-Sign eV, and {Delta}E-tilde {sup hfs}(2P{sub 3/2}) = 3248.03 Micro-Sign eV provide reliable guidelines in performing a comparison with relevant experimental data and in more precisely extracting the experimental value of the (2P-2S) Lamb shift in the muonic-hydrogen atom.

  9. Hyperfine and Nuclear Quadrupole Tensors of Nitrogen Donors in the QA Site of Bacterial Reaction Centers: Correlation of the Histidine Nδ Tensors with Hydrogen Bond Strength

    PubMed Central

    2015-01-01

    X- and Q-band pulsed EPR spectroscopy was applied to study the interaction of the QA site semiquinone (SQA) with nitrogens from the local protein environment in natural abundance 14N and in 15N uniformly labeled photosynthetic reaction centers of Rhodobacter sphaeroides. The hyperfine and nuclear quadrupole tensors for His-M219 Nδ and Ala-M260 peptide nitrogen (Np) were estimated through simultaneous simulation of the Q-band 15N Davies ENDOR, X- and Q-band 14,15N HYSCORE, and X-band 14N three-pulse ESEEM spectra, with support from DFT calculations. The hyperfine coupling constants were found to be a(14N) = 2.3 MHz, T = 0.3 MHz for His-M219 Nδ and a(14N) = 2.6 MHz, T = 0.3 MHz for Ala-M260 Np. Despite that His-M219 Nδ is established as the stronger of the two H-bond donors, Ala-M260 Np is found to have the larger value of a(14N). The nuclear quadrupole coupling constants were estimated as e2Qq/4h = 0.38 MHz, η = 0.97 and e2Qq/4h = 0.74 MHz, η = 0.59 for His-M219 Nδ and Ala-M260 Np, respectively. An analysis of the available data on nuclear quadrupole tensors for imidazole nitrogens found in semiquinone-binding proteins and copper complexes reveals these systems share similar electron occupancies of the protonated nitrogen orbitals. By applying the Townes–Dailey model, developed previously for copper complexes, to the semiquinones, we find the asymmetry parameter η to be a sensitive probe of the histidine Nδ–semiquinone hydrogen bond strength. This is supported by a strong correlation observed between η and the isotropic coupling constant a(14N) and is consistent with previous computational works and our own semiquinone-histidine model calculations. The empirical relationship presented here for a(14N) and η will provide an important structural characterization tool in future studies of semiquinone-binding proteins. PMID:25026433

  10. {sup 33}S hyperfine interactions in H{sub 2}S and SO{sub 2} and revision of the sulfur nuclear magnetic shielding scale

    SciTech Connect

    Helgaker, Trygve; Gauss, Jürgen; Cazzoli, Gabriele Puzzarini, Cristina

    2013-12-28

    Using the Lamb-dip technique, the hyperfine structure in the rotational spectra of H{sub 2}{sup 33}S and {sup 33}SO{sub 2} has been resolved and the corresponding parameters—that is, the sulfur quadrupole-coupling and spin–rotation tensors—were determined. The experimental parameters are in good agreement with results from high-level coupled-cluster calculations, provided that up to quadruple excitations are considered in the cluster operator, sufficiently large basis sets are used, and vibrational corrections are accounted for. The {sup 33}S spin-rotation tensor for H{sub 2}S has been used to establish a new sulfur nuclear magnetic shielding scale, combining the paramagnetic part of the shielding as obtained from the spin–rotation tensor with a calculated value for the diamagnetic part as well as computed vibrational and temperature corrections. The value of 716(5) ppm obtained in this way for the sulfur shielding of H{sub 2}S is in good agreement with results from high-accuracy quantum-chemical calculations but leads to a shielding scale that is about 28 ppm lower than the one suggested previously in the literature, based on the {sup 33}S spin-rotation constant of OCS.

  11. Hyperfine interaction and its effects on spin dynamics in organic solids

    NASA Astrophysics Data System (ADS)

    Yu, Z. G.; Ding, Feizhi; Wang, Haobin

    2013-05-01

    Hyperfine interaction (HFI) and spin-orbit coupling are two major sources that affect electron spin dynamics. Here we present a systematic study of the HFI and its role in organic spintronic applications. For electron spin dynamics in disordered π-conjugated organics, the HFI can be characterized by an effective magnetic field whose modular square is a weighted sum of contact and dipolar contributions. We determine the effective HFI fields of some common π-conjugated organics studied in the literature via first-principles calculations. Most of them are found to be less than 2 mT. While the H atoms are the major source of the HFI in organics containing only the C and H atoms, many organics contain other nuclear spins, such as Al and N in tris-(8-hydroxyquinoline) aluminum, that contribute to the total HFI. Consequently, the deuteration effect on the HFI in the latter may be much weaker than in the former. The HFI gives rise to multiple resonance peaks in electron spin resonance. In disordered organic solids, these individual resonances are unresolved, leading to a broad peak whose width is proportional to the effective HFI field. As electrons hop among adjacent organic molecules, they experience a randomly varying local HFI field, inducing electron spin relaxation and diffusion. This is analyzed rigorously based on master equations. Electron spin relaxation undergoes a crossover along the ratio between the electron hopping rate η¯ and the Larmor frequency Ω of the HFI field. The spin relaxation rate increases (decreases) with η¯ when η¯≪Ω (η¯≫Ω). A coherent beating of electron spin at Ω is possible when the external field is small compared to the HFI. In this regime, the magnetic field is found to enhance the spin relaxation.

  12. Ortho-para mixing hyperfine interaction in the H2O+ ion and nuclear spin equilibration.

    PubMed

    Tanaka, Keiichi; Harada, Kensuke; Oka, Takeshi

    2013-10-03

    The ortho to para conversion of water ion, H2O(+), due to the interaction between the magnetic moments of the unpaired electron and protons has been theoretically studied to calculate the spontaneous emission lifetime between the ortho- and para-levels. The electron spin-nuclear spin interaction term, Tab(SaΔIb + SbΔIa) mixes ortho (I = 1) and para (I = 0) levels to cause the "forbidden" ortho to para |ΔI| = 1 transition. The mixing term with Tab = 72.0 MHz is 4 orders of magnitude higher for H2O(+) than for its neutral counterpart H2O where the magnetic field interacting with proton spins is by molecular rotation rather than the free electron. The resultant 10(8) increase of ortho to para conversion rate possibly makes the effect of conversion in H2O(+) measurable in laboratories and possibly explains the anomalous ortho to para ratio recently reported by Herschel heterodyne instrument for the far-infrared (HIFI) observation. Results of our calculations show that the ortho ↔ para mixings involving near-degenerate ortho and para levels are high (∼10(-3)), but they tend to occur at high energy levels, ∼300 K. Because of the rapid spontaneous emission, such high levels are not populated in diffuse clouds unless the radiative temperature of the environment is very high. The low-lying 101 (para) and 111 (ortho) levels of H2O(+) are mixed by ∼10(-4) making the spontaneous emission lifetime for the para 101 → ortho 000 transition 520 years and 5200 years depending on the F value of the hyperfine structure. Thus the ortho ↔ para conversion due to the unpaired electron is not likely to seriously affect thermalization of interstellar H2O(+) unless either the radiative temperature is very high or number density of the cloud is very low.

  13. Hyperfine structure constants of singly ionized manganese obtained from analysis of Fourier Transform spectra

    NASA Astrophysics Data System (ADS)

    Townley-Smith, Keeley; Nave, Gillian; Imperial College London

    2016-01-01

    There is an on-going project in the Atomic Spectroscopy Group at NIST to obtain comprehensive spectral data for all of the singly ionized iron group elements and acquire more accurate energy levels, wavelengths and hyperfine structure (HFS) constants. The heavy abundance of the iron group elements and their contributions to a wide range of stellar spectra makes them of interest for astrophysical observations.Existing spectroscopic data for Mn are insufficient to model spectra obtained from HgMn stars such as HD 175640. Since manganese has an odd number of nucleons, its spectral lines generally exhibit HFS, a relativistic effect due to interaction between the magnetic moment of the nucleus and the orbiting electrons. If proper treatment of line broadening effects such as HFS is not taken, there is a poor fit of the lines in stellar spectra, leading to an overestimate of the abundance of Mn. The abnormally high abundance of manganese in HgMn stars means both weak and strong transitions are important. Weak lines may not be observed in the laboratory, but HFS constants for them can be derived from stronger transitions that combine with the two levels involved in the weak transition.Holt et al. (1999) measured HFS constants for 56 energy levels using laser spectroscopy. We have analyzed Fourier Transform spectra of a high current Mn/Ni hollow cathode lamp to obtain magnetic dipole A constants levels of Mn II. The A constants of Holt et al. (1999, MNRAS 306, 1007) for the z5P, z7P2, a5P and z5F levels were the starting point for our analysis, from which we derived A constants for 71 energy levels, including 51 previously unstudied levels. Our A constant for the a7S3 ground level differs by 5x10-4 cm-1 from that of Blackwell-Whitehead et al. (2005, ApJS 157, 402) and has a factor of 6 lower uncertainty.

  14. Quantum tomography of the full hyperfine manifold of atomic spins via continuous measurement on an ensemble

    NASA Astrophysics Data System (ADS)

    Riofrío, Carlos A.; Jessen, Poul S.; Deutsch, Ivan H.

    2011-08-01

    Quantum state reconstruction based on weak continuous measurement has the advantage of being fast, accurate and almost non-perturbative. In this work we present a pedagogical review of the protocol proposed by Silberfarb et al (2005 Phys. Rev. Lett. 95 030402), whereby an ensemble of identically prepared systems is collectively probed and controlled in a time-dependent manner so as to create an informationally complete continuous measurement record. The measurement history is then inverted to determine the state at the initial time through a maximum-likelihood estimate. The general formalism is applied to the case of reconstruction of the quantum state encoded in the magnetic sublevels of a large-spin alkali atom, 133Cs. We detail two different protocols for control. Using magnetic interactions and a quadratic ac Stark shift, we can reconstruct a chosen hyperfine manifold F, e.g. the seven-dimensional F = 3 manifold in the electronic ground state of Cs. We review the procedure as implemented in experiments (Smith et al 2006 Phys. Rev. Lett. 97 180403). We extend the protocol to the more ambitious case of reconstruction of states in the full 16-dimensional electronic ground subspace (F = 3⊕F = 4), controlled by microwaves and radio-frequency (RF) magnetic fields. We give detailed derivations of all physical interactions, approximations, numerical methods and fitting procedures, tailored to the realistic experimental setting. For the case of light-shift and magnetic control, reconstruction fidelities of ~0.95 have been achieved, limited primarily by inhomogeneities in the light-shift. For the case of microwave/RF-control we simulate fidelity >0.97, limited primarily by signal-to-noise.

  15. Magnetic and hyperfine properties of Fe2P nanoparticles dispersed in a porous carbon matrix

    NASA Astrophysics Data System (ADS)

    Viali, G. L.; Gonçalves, G. R.; Passamani, E. C.; Freitas, J. C. C.; Schettino, M. A.; Takeuchi, A. Y.; Larica, C.

    2016-03-01

    Structural and magnetic properties of nanocomposite, consisting of Fe2P particles dispersed in a porous carbon matrix, have fully been investigated using X-ray diffraction, Mössbauer and ac and dc magnetization measurements. Besides production of the nanocomposite, using an activated carbon (prepared by chemical activation of a char with H3PO4), impregnation with a Fe3+ salt in aqueous medium and subsequent heat treatments under N2 flow, we found a formation of hexagonal Fe2-xP and orthorhombic FeP in a mass ratio of 4:1, respectively. Low temperature Mössbauer spectra revealed that a large fraction (ca. 28%) of the material is in the paramagnetic state, suggesting that part of the Fe2-xP phase appears in the form of very small particles. A metamagnetic phase transition was also observed for non-stoichiometric Fe2-xP nanoparticles. It is observed at about 150 K, well below the ordering temperature of the Fe2P phase (230 K), and is dependent on the dc-probe fields. Also, the Fe2-xP nanoparticles were found to have a hard-like magnetic character at low temperatures, with coercive field HC of 1.3 KOe. Considering these interesting magnetic and hyperfine properties and also the large specific surface area of the porous carbon matrix, which is not severely reduced after impregnation with the Fe-containing compounds, one may point to promising technological applications of the produced nanocomposite.

  16. A comparison of the cesium and hydrogen hyperfine frequencies by means of Loran-C and portable clocks

    NASA Technical Reports Server (NTRS)

    Reinhardt, V. S.; Lavanceau, J.

    1974-01-01

    A comparison of the hydrogen and cesium hyperfine frequencies is made using a hydrogen maser calibrated directly against the Flexible Bulb Large Storage Box Hydrogen Maser and a Hewlett-Packard portable high performance cesium clock calibrated indirectly against the USNO Master Clock via a Loran-C link. The portable cesium clock is transported from the USNO to Harvard University in operating condition. This allows the evaluation of the portable clock's performance under transport. Data are presented on the epoch and frequency stability of the portable clock under transport as well as the usefulness of a closure measurement in determining clock drift.

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

    SciTech Connect

    Leary, A.; Wicha, A.; Harack, B.; Coish, W. A.; Hilke, M.; Yu, G.; Gupta, J. A.; Payette, C.; Austing, D. G.

    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.

  18. Doppler-Free Spectroscopy Measurements of Isotope Shifts and Hyperfine Components of Near-IR Xenon Lines

    SciTech Connect

    Mazouffre, S.; Pawelec, E.; Tran Bich, N.; Sadeghi, N.

    2006-01-15

    Xenon is currently used as propellant gas in electric thrusters, in which ejection of corresponding ions produces the desired thrust. As such a gas contains 9 stable isotopes, a non-intrusive determination of the velocity distribution function of atoms and ions in the thruster plasma plume, by means of absorption or fluorescence techniques, requires a precise knowledge of the line structure. We used Doppler-free Lamb-dip spectroscopy to determine isotopic shifts and hyperfine components of odd isotopes of several spectral lines of Xe atom and Xe+ ion in the 825 - 835 nm range.

  19. Rotation of hyperfine fields at the V site in the multiband metal K2V8O6

    NASA Astrophysics Data System (ADS)

    Shimizu, Yasuhiro; Okai, Katsunori; Itoh, Masayuki; Isobe, Masahiro; Yamaura, Jun-ichi; Ueda, Yutaka

    2010-01-01

    51V nuclear magnetic resonance measurements are conducted on a single crystal of the mixed valence compound K2V8016 with 1.25 3d electrons per one V site. We determine the 51V Knight shift tensor, 51K, in the metallic state. 51K has the small anisotropy despite the conduction electrons in the anisotropic 3d orbitals. The principal axis of 51K rotates continuously on cooling temperature in the metallic state without breaking the lattice symmetry, I4/m. Taking into account the isotropic spin susceptibility, the thermal variation is attributed to a change in the hyperfine field tensor reflecting the 3d orbital shape.

  20. Hydrogen maser wall shift experiments and determination of the unperturbed hyperfine frequency of the ground state of the hydrogen atom

    SciTech Connect

    Cheng, Y.M.; Hua, Y.L.; Chen, C.B.; Gao, J.H.; Shen, W.

    1980-12-01

    Experiments on hydrogen maser wall shift are described in detail. Values of K(40 C) -293 + or - 17 mHz.cm and a(40 C) (-17 + or 2) x 10 to the -3rd per deg C were obtained. The unperturbed hyperfine frequency of the ground state of the hydrogen atom was obtained by comparing five hydrogen masers to Loran C signals for one month. The average value with respect to TAI is 1,420,405,751.768 + or - 0.002 Hz.

  1. The World Beyond Iron

    NASA Astrophysics Data System (ADS)

    Kalvius, G. Michael

    The mere fact that the Mössbauer effect was discovered with the 129.4 keV transition in 191Ir demonstrates immediately the availability of Mössbauer isotopes other than 57Fe. Nevertheless, the 57Fe resonance remains the soul of Mössbauer spectroscopy. It combines a number of favorable properties: a source with convenient half-life (270 days), a large recoil-free fraction which allows measurements well above room temperature, and an energy resolution of ˜ 10 - 8 eV which is one to two orders of magnitude smaller than the typical hyperfine interaction energies. Yet, the energy resolution is not high enough to lead to substantial line broadenings by the unavoidable small distortions in the crystalline lattice of a real solid. The low natural abundance (2,2%) of the 57Fe is compensated by the large resonance cross-section and isotopic enrichment is only needed for materials containing iron in very low concentration or for extremely small samples. 57Fe was in fact not the second Mössbauer transition to be used after 191Ir. In establishing the correctness of the, not immediately believed, result of Mössbauer, the group at Argonne National Laboratory [1] measured not only the recoil-free resonance absorption in 191Ir, but also that of the 100 keV transition in 182W. This historically number two resonance has later mainly be used for the establishment of nuclear parameters.

  2. The effect of spin polarization on zero field splitting parameters in paramagnetic pi-electron molecules.

    PubMed

    van Gastel, Maurice

    2009-09-28

    Spin polarization effects play an important role in the theory of isotropic hyperfine interactions for aromatic protons. The spin polarization gives rise to significant isotropic proton hyperfine interactions--spin-dependent one-electron properties--smaller than 0 MHz and the effect has been theoretically described [H. M. McConnell and D. B. J. Chesnut, Chem. Phys. 28, 107 (1958)]. The influence of spin polarization on the zero field splitting parameters, which are spin-dependent two-electron properties, has not been clearly identified yet. A phenomenological equation is proposed here for the contribution of spin polarization to the zero field splitting parameter D in analogy to McConnell's equation for hyperfine interactions. The presence of the effect is demonstrated in a series of calculations on polyacenes in the triplet state and turns out to be responsible for up to 50% of the D parameter in the case of naphthalene! It is found that spin-unrestricted single-determinant methods, including the widely used density functional theory methods, do not accurately reproduce the two-electron reduced electron density required for the evaluation of two-electron spin-dependent properties. For the accurate calculation of zero field splitting parameters by quantum chemical methods, it thus seems necessary to resort to correlated ab initio methods which do not give rise to spin contamination and which do provide an accurate description of the two-electron reduced electron density.

  3. Investigation of Coupled Surface and Bulk Reaction Phenomena Using Combined-Backscatter-Conversion Electron and Backscatter-Photon Mossbauer Spectroscopy (CEAPS)

    DTIC Science & Technology

    1988-08-30

    Lee, T.D. Placek and J.A. Dumesic. "Generation of Low Energy Resonant Electrons During Relaxation of 57Fe," Hyperfine Interactions 41, 737, 1988, with...B18, 182, (1987), T.S. Lee, T.D. Placek , J.A. Dumesic and B.J. Tatarchuk. 3. "Generation of Low Energy Resonant Electrons During Relaxation of 57Fe

  4. Hyperfine-induced spin relaxation of a diffusively moving carrier in low dimensions: Implications for spin transport in organic semiconductors

    DOE PAGES

    Mkhitaryan, V. V.; Dobrovitski, V. V.

    2015-08-24

    The hyperfine coupling between the spin of a charge carrier and the nuclear spin bath is a predominant channel for the carrier spin relaxation in many organic semiconductors. We theoretically investigate the hyperfine-induced spin relaxation of a carrier performing a random walk on a d-dimensional regular lattice, in a transport regime typical for organic semiconductors. We show that in d=1 and 2, the time dependence of the space-integrated spin polarization P(t) is dominated by a superexponential decay, crossing over to a stretched-exponential tail at long times. The faster decay is attributed to multiple self-intersections (returns) of the random-walk trajectories, whichmore » occur more often in lower dimensions. We also show, analytically and numerically, that the returns lead to sensitivity of P(t) to external electric and magnetic fields, and this sensitivity strongly depends on dimensionality of the system (d=1 versus d=3). We investigate in detail the coordinate dependence of the time-integrated spin polarization σ(r), which can be probed in the spin-transport experiments with spin-polarized electrodes. We also demonstrate that, while σ(r) is essentially exponential, the effect of multiple self-intersections can be identified in transport measurements from the strong dependence of the spin-decay length on the external magnetic and electric fields.« less

  5. Hyperfine-induced spin relaxation of a diffusively moving carrier in low dimensions: Implications for spin transport in organic semiconductors

    SciTech Connect

    Mkhitaryan, V. V.; Dobrovitski, V. V.

    2015-08-24

    The hyperfine coupling between the spin of a charge carrier and the nuclear spin bath is a predominant channel for the carrier spin relaxation in many organic semiconductors. We theoretically investigate the hyperfine-induced spin relaxation of a carrier performing a random walk on a d-dimensional regular lattice, in a transport regime typical for organic semiconductors. We show that in d=1 and 2, the time dependence of the space-integrated spin polarization P(t) is dominated by a superexponential decay, crossing over to a stretched-exponential tail at long times. The faster decay is attributed to multiple self-intersections (returns) of the random-walk trajectories, which occur more often in lower dimensions. We also show, analytically and numerically, that the returns lead to sensitivity of P(t) to external electric and magnetic fields, and this sensitivity strongly depends on dimensionality of the system (d=1 versus d=3). We investigate in detail the coordinate dependence of the time-integrated spin polarization σ(r), which can be probed in the spin-transport experiments with spin-polarized electrodes. We also demonstrate that, while σ(r) is essentially exponential, the effect of multiple self-intersections can be identified in transport measurements from the strong dependence of the spin-decay length on the external magnetic and electric fields.

  6. Relativistic many-body calculation of energies, lifetimes, polarizabilities, blackbody radiative shift, and hyperfine constants in Lu2 +

    NASA Astrophysics Data System (ADS)

    Safronova, U. I.; Safronova, M. S.; Johnson, W. R.

    2016-09-01

    Energy levels of 30 low-lying states of Lu2 + and allowed electric-dipole matrix elements between these states are evaluated using a relativistic all-order method in which all single, double, and partial triple excitations of Dirac-Fock wave functions are included to all orders of perturbation theory. Matrix elements are critically evaluated for their accuracy and recommended values of the matrix elements are given together with uncertainty estimates. Line strengths, transition rates, and lifetimes of the metastable 5 d3 /2 and 5 d5 /2 states are calculated. Recommended values are given for static polarizabilities of the 6 s , 5 d , and 6 p states and tensor polarizabilities of the 5 d and 6 p3 /2 states. Uncertainties of the polarizability values are estimated in all cases. The blackbody radiation shift of the 6 s1 /2-5 d5 /2 transition frequency of the Lu2 + ion is calculated with the aid of the recommended scalar polarizabilities of the 6 s1 /2 and 5 d5 /2 states. Finally, A and B hyperfine constants are determined for states of 2+175Lu with n ≤9 . This work provides recommended values of transition matrix elements, polarizabilities, and hyperfine constants of Lu2 +, critically evaluated for accuracy, for benchmark tests of high-precision theoretical methodology and planning of future experiments.

  7. The magnetic behavior of the intermetallic compound NdMn2Ge2 studied by magnetization and hyperfine interactions measurements

    NASA Astrophysics Data System (ADS)

    Bosch-Santos, B.; Carbonari, A. W.; Cabrera-Pasca, G. A.; Saxena, R. N.; Freitas, R. S.

    2015-05-01

    The magnetic behavior of the intermetallic compound NdMn2Ge2 was investigated by bulk magnetization measurements and measurements of hyperfine interactions using perturbed γ-γ angular correlation (PAC) spectroscopy. Magnetization measurements indicate the presence of four magnetic transitions associated with the Mn and Nd magnetic sublattices. At high temperatures, magnetic measurements show a change in the slope of the magnetization due to an antiferromagnetic transition around TN ˜ 425 K and a well defined ferromagnetic transition at TC ˜ 320 K. Moreover, at ˜210 K a peak is observed in the magnetization curve, which is assigned to the reorientation of the Mn spin, and at ˜25 K an increase in the magnetic moment is also observed, which is ascribed to the ordering of Nd ions. PAC measurements using 140La(140Ce) and 111In(111Cd) probe nuclei allowed the determination of the temperature dependence of the magnetic hyperfine field (Bhf) at Nd and Mn sites, respectively. PAC results with 111Cd probe nuclei at Mn sites show that the dependence of Bhf with temperature follows the expected behavior for the host magnetization associated with the magnetic ordering of Mn ions. From these results, the antiferromagnetic transition followed by a ferromagnetic ordering is clearly observed. PAC results with 140Ce probe nuclei at Nd sites, however, showed a strong deviation from the Brillouin function, which is attributed to the Ce 4f-electron contribution to Bhf.

  8. The effect of oxygen vacancies on the hyperfine properties of metal-doped SnO2

    NASA Astrophysics Data System (ADS)

    Aragón, F. H.; Villegas-Lelovsky, L.; Martins, J. B. L.; Coaquira, J. A. H.; Cohen, R.; Nagamine, L. C. C. M.; Morais, P. C.

    2017-03-01

    We have performed a Mössbauer investigation of oxygen-vacancy formation on a doped substitutional solution of Sn1‑y M y O2 (M  =  Al, Fe, Ce and Er) nanoparticles. Experimental results were assessed from Mössbauer spectroscopy data, which suggest the rise of the oxygen-vacancy population while increasing the content of dopant ions (M). Likewise, we have analyzed the dependence of the structural, electronic and hyperfine properties on the oxygen-vacancy concentration through first-principles calculations of the SnO2‑x (where x varies from 0 to 0.25) system. The results obtained from the isomer shift and quadrupole splitting indicate a significant dependence of the hyperfine properties on the number of oxygen vacancies. Moreover, after structural optimization of the Sn16O32-Vo supercell (where Vo is the number of oxygen vacancies) we found an increase of the unit-cell volume with the increase of Vo, while the bulk modulus showed a linear decrease with Vo. Indeed, our results corroborate the experimental findings for pure and transition-metal-doped SnO2 systems for which the presence of the oxygen vacancy plays a key role.

  9. Observation of hyperfine mixing in measurements of a magnetic octupole decay in isotopically pure nickel-like 129Xe and 132Xe ions

    SciTech Connect

    Trabert, E; Beiersdorfer, P; Brown, G V

    2006-12-21

    We present measurements of high statistical significance of the rate of the magnetic octupole (M3) decay in nickel-like ions of isotopically pure {sup 129}Xe and {sup 132}Xe. On {sup 132}Xe, an isotope with zero nuclear spin and therefore without hyperfine structure, the lifetime of the metastable level was established as (15.06 {+-} 0.24) ms. On {sup 129}Xe, an additional fast (2.7 {+-} 0.1 ms) decay component was established that represents hyperfine mixing with a level that decays by electric quadrupole (E2) radiation.

  10. Investigation of the nitrogen hyperfine coupling of the second stable radical in γ-irradiated L-alanine crystals by 2D-HYSCORE spectroscopy

    NASA Astrophysics Data System (ADS)

    Maltar-Strmečki, Nadica; Rakvin, Boris

    2012-09-01

    The second stable radical, NH3+C(CH3)COO, R2, in the γ-irradiated single crystal of L-alanine and its fully 15N-enriched analogue were studied by an advanced pulsed EPR technique, 2D-HYSCORE (two-dimensional hyperfine sublevel correlation) spectroscopy at 200 K. The nitrogen hyperfine coupling tensor of the R2 radical was determined from the HYSCORE data and provides new experimental data for improved characterization of the R2 radical in the crystal lattice. The results obtained complement the experimental proton data available for the R2 radical and could lead to increased accuracy and reliability of EPR spectrum simulations.

  11. Aminoxyl Radicals of B/P Frustrated Lewis Pairs: Refinement of the Spin-Hamiltonian Parameters by Field- and Temperature-Dependent Pulsed EPR Spectroscopy.

    PubMed

    de Oliveira, Marcos; Knitsch, Robert; Sajid, Muhammad; Stute, Annika; Elmer, Lisa-Maria; Kehr, Gerald; Erker, Gerhard; Magon, Claudio J; Jeschke, Gunnar; Eckert, Hellmut

    2016-01-01

    Q-band and X-band pulsed electron paramagnetic resonance spectroscopic methods (EPR) in the solid state were employed to refine the parameters characterizing the anisotropic interactions present in six nitroxide radicals prepared by N,N addition of NO to various borane-phosphane frustrated Lewis pairs (FLPs). The EPR spectra are characterized by the g-anisotropy as well as by nuclear hyperfine coupling between the unpaired electron and the 11B/10B, 14N and 31P nuclear magnetic moments. It was previously shown that continuous-wave spectra measured at X-band frequency (9.5 GHz) are dominated by the magnetic hyperfine coupling to 14N and 31P, whereas the g-tensor values and the 11B hyperfine coupling parameters cannot be refined with high precision from lineshape fitting. On the other hand, the X-band electron spin echo envelope modulation (ESEEM) and hyperfine sublevel correlation (HYSCORE) spectra are completely dominated by the nuclear hyperfine coupling to the 11B nuclei, allowing a selective determination of their interaction parameters. In the present work this analysis has been further validated by temperature dependent ESEEM measurements. In addition, pulsed EPR data measured in the Q-band (34 GHz) are reported, which present an entirely different situation: the g-tensor components can be measured with much higher precision, and the ESEEM and HYSCORE spectra contain information about all of the 10B, 11B, 14N and 31P hyperfine interaction parameters. Based on these new results, we report here high-accuracy and precision data of the EPR spin Hamiltonian parameters measured on six FLP-NO radical species embedded in their corresponding hydroxylamine host structures. While the ESEEM spectra at Q-band frequency turn out to be very complex (due to the multinuclear contribution to the overall signal) in the HYSCORE experiment the extension over two dimensions renders a better discrimination between the different nuclear species, and the signals arising from hyperfine

  12. Aminoxyl Radicals of B/P Frustrated Lewis Pairs: Refinement of the Spin-Hamiltonian Parameters by Field- and Temperature-Dependent Pulsed EPR Spectroscopy

    PubMed Central

    de Oliveira, Marcos; Knitsch, Robert; Sajid, Muhammad; Stute, Annika; Elmer, Lisa-Maria; Kehr, Gerald; Erker, Gerhard; Magon, Claudio J.; Jeschke, Gunnar; Eckert, Hellmut

    2016-01-01

    Q-band and X-band pulsed electron paramagnetic resonance spectroscopic methods (EPR) in the solid state were employed to refine the parameters characterizing the anisotropic interactions present in six nitroxide radicals prepared by N,N addition of NO to various borane-phosphane frustrated Lewis pairs (FLPs). The EPR spectra are characterized by the g-anisotropy as well as by nuclear hyperfine coupling between the unpaired electron and the 11B/10B, 14N and 31P nuclear magnetic moments. It was previously shown that continuous-wave spectra measured at X-band frequency (9.5 GHz) are dominated by the magnetic hyperfine coupling to 14N and 31P, whereas the g-tensor values and the 11B hyperfine coupling parameters cannot be refined with high precision from lineshape fitting. On the other hand, the X-band electron spin echo envelope modulation (ESEEM) and hyperfine sublevel correlation (HYSCORE) spectra are completely dominated by the nuclear hyperfine coupling to the 11B nuclei, allowing a selective determination of their interaction parameters. In the present work this analysis has been further validated by temperature dependent ESEEM measurements. In addition, pulsed EPR data measured in the Q-band (34 GHz) are reported, which present an entirely different situation: the g-tensor components can be measured with much higher precision, and the ESEEM and HYSCORE spectra contain information about all of the 10B, 11B, 14N and 31P hyperfine interaction parameters. Based on these new results, we report here high-accuracy and precision data of the EPR spin Hamiltonian parameters measured on six FLP-NO radical species embedded in their corresponding hydroxylamine host structures. While the ESEEM spectra at Q-band frequency turn out to be very complex (due to the multinuclear contribution to the overall signal) in the HYSCORE experiment the extension over two dimensions renders a better discrimination between the different nuclear species, and the signals arising from hyperfine

  13. Where Millimeter Wave Spectra are Sensitive to Small Electric Fields: High Rydberg States of Xenon and Their Hyperfine Structures

    NASA Astrophysics Data System (ADS)

    Schäfer, Martin; Raunhardt, Matthias; Merkt, Frédéric

    2009-06-01

    In the range 0-45 cm^{-1} below the ionization limit, the separation between adjacent electronic states (Rydberg states with principal quantum number n>50) of atoms and molecules is smaller than 2 cm^{-1}. In order to resolve the fine or hyperfine structure of these states, it is necessary to combine high-resolution vacuum ultraviolet (VUV) laser radiation, which is required to access the Rydberg states from the ground state, with millimeter wave radiation. Such double-resonance experiments have been used to study the hyperfine structure of high Rydberg states of ^{83}Kr, H_2 or D_2. Millimeter wave transitions (240-350 GHz) between nℓ (52≤ n≤64, ℓ≤3) Rydberg states of different xenon isotopes were detected by pulsed field ionization followed by mass-selective detection of the cations. Because of the high polarizability of high-n Rydberg states (∝ n^7, ˜10^4 MHz cm^{2} V^{-2} for n≈ 50), it is necessary to reduce the electric stray fields to values of the order of mV/cm (or less) in order to minimize the (quadratic) Stark shift of the millimeter wave transitions. Some p and d Rydberg states of Xe are nearly degenerate and efficiently mixed by small stray fields, making it possible to observe transitions forbidden by the Δℓ=±1 selection rule or transitions exhibiting a linear Stark effect, which is typical for the degenerate high-ℓ Rydberg states. Multichannel quantum defect theory (MQDT) was used to analyze the millimeter wave data and to determine the hyperfine structures of the ^2P_{3/2} ground electronic states of ^{129}Xe^+ and ^{131}Xe^+. C. Fabre, P. Goy, S. Haroche, J. Phys. B: Atom. Mol. Phys. 10, L183-189 (1977). F. Merkt, A. Osterwalder, Int. Rev. Phys. Chem. 21, 385-403 (2002). M. Schäfer, M. Andrist, H. Schmutz, F. Lewen, G. Winnewisser, F. Merkt, J. Phys. B: At. Mol. Opt. Phys. 39, 831-845 (2006) M. Schäfer, F. Merkt, Phys. Rev. A, 74, 062506 (2006). A. Osterwalder, A. Wüest, F. Merkt, Ch. Jungen, J. Chem. Phys., 121, 11810

  14. Spectroscopy of {sup 127}I{sub 2} hyperfine structure near 532 mm using frequency - doubled diode - laser - pumped Nd:YAG lasers

    SciTech Connect

    Guellati, S.; Elandaloussi, H.; Fretel, E.

    1994-12-31

    Frequency - doubled diode - laser - pumped Nd : Yag laser can constitute an interesting optical standard around 532 nm. More than ten of {sup 127}I{sub 2} lines can be observed inside the laser spectral range. Two independent systems, stabilized on one {sup 127}I{sub 2} hyperfine component, are used to check the frequency long term stability for metrological purpose.

  15. Hyperfine excitation of linear molecules by para- and ortho-H{sub 2}: Application to the HCl–H{sub 2} system

    SciTech Connect

    Lanza, Mathieu; Lique, François

    2014-10-28

    The determination of hyperfine structure resolved excitation cross sections and rate coefficients due to H{sub 2} collisions is required to interpret astronomical spectra. In this paper, we present several theoretical approaches to compute these data. An almost exact recoupling approach and approximate sudden methods are presented. We apply these different approaches to the HCl–H{sub 2} collisional system in order to evaluate their respective accuracy. HCl–H{sub 2} hyperfine structure resolved cross sections and rate coefficients are then computed using recoupling and approximate sudden methods. As expected, the approximate sudden approaches are more accurate when the collision energy increases and the results suggest that these approaches work better for para-H{sub 2} than for ortho-H{sub 2} colliding partner. For the first time, we present HCl–H{sub 2} hyperfine structure resolved rate coefficients, computed here for temperatures ranging from 5 to 300 K. The usual Δj{sub 1} = ΔF{sub 1} propensity rules are observed for the hyperfine transitions. The new rate coefficients will significantly help the interpretation of interstellar HCl emission lines observed with current and future telescopes. We expect that these new data will allow a better determination of the HCl abundance in the interstellar medium, that is crucial to understand the interstellar chlorine chemistry.

  16. Nuclear Hyperfine Structure in the Donor – Acceptor Complexes (CH3)3N-BF3 and (CH)33N-B(CH3)3

    EPA Science Inventory

    The donor-acceptor complexes (CH3)3N-BF3 and (CH3)3N-B(CH3)3 have been reinvestigated at high resolution by rotational spectroscopy in a supersonic jet. Nuclear hyperfine structure resulting from both nitrogen and boron has been resolved and quadrupole coupling constants have bee...

  17. Measurement of the blackbody radiation shift of the {sup 133}Cs hyperfine transition in an atomic fountain

    SciTech Connect

    Levi, Filippo; Calonico, Davide; Lorini, Luca; Micalizio, Salvatore; Godone, Aldo

    2004-09-01

    We used a Cs fountain to measure the Stark shift of the ground-state hyperfine transition frequency in cesium (9.2 GHz) due to the electric field of the blackbody radiation. The relative shift at 300 K deduced from our measurements, including the leading and the second-order term in temperature, is (-1.45{+-}0.09)x10{sup -14} and agrees with our recent theoretical evaluation (-1.51{+-}0.07)x10{sup -14} [Micalizio et al. Phys. Rev. A 69, 053401 (2004)]. These values differ from that currently used (-1.735{+-}0.003)x10{sup -14}, with significant implications on frequency standards accuracy, on clocks comparison and on a variety of high-precision physics tests, such as the time stability of fundamental constants.

  18. Trace analysis of rubidium hyperfine structure in a flame atomizer using sub-Doppler laser wave-mixing spectroscopy.

    PubMed

    Weed, Kenneth M; Tong, William G

    2003-12-01

    Nonlinear laser wave mixing is a versatile spectroscopic method for trace elemental analysis at high spectral resolution. Sub-Doppler spectral resolution allows isotope and hyperfine structure measurements of some of the elements even when using a room-pressure analytical flame (i.e., sub-Doppler but Lorentzian broadened spectra). A non-planar wave-mixing optical setup offers some advantages as compared to the conventional planar wave-mixing setup including better signal collection efficiency and easier optical alignment. Using our absorption-based wave mixing, a detection limit of 0.05 ng/mL (i.e., 50 parts-per-trillion) is reported for Rb in an air/acetylene flame, while still maintaining sub-Doppler spectral resolution for the infrared 780.0-nm Rb transition line.

  19. Quantum beats in the recombination fluorescence of radical ion pairs caused by the hyperfine coupling in radical anions

    NASA Astrophysics Data System (ADS)

    Bagryansky, V. A.; Borovkov, V. I.; Molin, Yu. N.; Egorov, M. P.; Nefedov, O. M.

    1998-10-01

    The ratios of the radiofluorescence decay curves for n-decane solutions of 1,2,3,4-tetraphenylcyclopenta-1,3-diene and its silicon and germanium analogs (siloles and germoles) in high and zero magnetic fields have an oscillating component caused by singlet-triplet evolution of the pair S +/A -, where S + is the solvent hole and A - is the radical anion of the acceptor (a compound added). It is shown that the beats are due to the hyperfine couplings (hfc) with either the protons of CH 2, SiH 2 and GeH 2 moieties or chlorine atoms in the GeCl 2 and GeClMe moieties of radical anions. The hfc constants in the anions and spin relaxation times of radical ion pairs were obtained by fitting the experimental curves.

  20. High-Accuracy Measurement of the Blackbody Radiation Frequency Shift of the Ground-State Hyperfine Transition in Cs133

    NASA Astrophysics Data System (ADS)

    Jefferts, S. R.; Heavner, T. P.; Parker, T. E.; Shirley, J. H.; Donley, E. A.; Ashby, N.; Levi, F.; Calonico, D.; Costanzo, G. A.

    2014-02-01

    We report a high-accuracy direct measurement of the blackbody radiation shift of the Cs133 ground-state hyperfine transition. This frequency shift is one of the largest systematic frequency biases encountered in realizing the current definition of the International System of Units (SI) second. Uncertainty in the blackbody radiation frequency shift correction has led to its being the focus of intense theoretical effort by a variety of research groups. Our experimental measurement of the shift used three primary frequency standards operating at different temperatures. We achieved an uncertainty a factor of five smaller than the previous best direct measurement. These results tend to validate the claimed accuracy of the recently calculated values.

  1. Liquid helium-free cryostat and hermetically sealed cryogenic microwave cavity for hyperfine spectroscopy of antiprotonic helium.

    PubMed

    Massiczek, O; Friedreich, S; Juhász, B; Widmann, E; Zmeskal, J

    2011-12-11

    The design and properties of a new cryogenic set-up for laser-microwave-laser hyperfine structure spectroscopy of antiprotonic helium - an experiment performed at the CERN-Antiproton Decelerator (AD), Geneva, Switzerland - are described. Similar experiments for (4)He have been performed at the AD for several years. Due to the usage of a liquid helium operated cryostat and therefore necessary refilling of coolants, a loss of up to 10% beamtime occurred. The decision was made to change the cooling system to a closed-circuit cryocooler. New hermetically sealed target cells with minimised (3)He gas volume and different dimensions of the microwave resonator for measuring the (3)He transitions were needed. A new set-up has been designed and tested at Stefan Meyer Institute in Vienna before being used for the 2009 and 2010 beamtimes at the AD.

  2. Separating hyperfine from spin-orbit interactions in organic semiconductors by multi-octave magnetic resonance using coplanar waveguide microresonators

    NASA Astrophysics Data System (ADS)

    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.

  3. Determination of the hyperfine magnetic field in magnetic carbon-based materials: DFT calculations and NMR experiments

    PubMed Central

    Freitas, Jair C. C.; Scopel, Wanderlã L.; Paz, Wendel S.; Bernardes, Leandro V.; Cunha-Filho, Francisco E.; Speglich, Carlos; Araújo-Moreira, Fernando M.; Pelc, Damjan; Cvitanić, Tonči; Požek, Miroslav

    2015-01-01

    The prospect of carbon-based magnetic materials is of immense fundamental and practical importance, and information on atomic-scale features is required for a better understanding of the mechanisms leading to carbon magnetism. Here we report the first direct detection of the microscopic magnetic field produced at 13C nuclei in a ferromagnetic carbon material by zero-field nuclear magnetic resonance (NMR). Electronic structure calculations carried out in nanosized model systems with different classes of structural defects show a similar range of magnetic field values (18–21 T) for all investigated systems, in agreement with the NMR experiments. Our results are strong evidence of the intrinsic nature of defect-induced magnetism in magnetic carbons and establish the magnitude of the hyperfine magnetic field created in the neighbourhood of the defects that lead to magnetic order in these materials. PMID:26434597

  4. Direct measurement of excited-state dipole matrix elements using electromagnetically induced transparency in the hyperfine Paschen-Back regime

    NASA Astrophysics Data System (ADS)

    Whiting, Daniel J.; Keaveney, James; Adams, Charles S.; Hughes, Ifan G.

    2016-04-01

    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 |<5 P ||e r ||5 D >| matrix element in 87Rb. 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 |<5 P3 /2||e r ||5 D5 /2>| =(2.290 ±0 .002stat±0 .04syst) e a0 , which is in excellent agreement with the theoretical calculations of Safronova, Williams, and Clark [Phys. Rev. A 69, 022509 (2004), 10.1103/PhysRevA.69.022509].

  5. Relativistically corrected hyperfine structure constants calculated with the regular approximation applied to correlation corrected ab initio theory

    NASA Astrophysics Data System (ADS)

    Filatov, Michael; Cremer, Dieter

    2004-09-01

    The infinite-order regular approximation (IORA) and IORA with modified metric (IORAmm) is used to develop an algorithm for calculating relativistically corrected isotropic hyperfine structure (HFS) constants. The new method is applied to the calculation of alkali atoms Li-Fr, coinage metal atoms Cu, Ag, and Au, the Hg+ radical ion, and the mercury containing radicals HgH, HgCH3, HgCN, and HgF. By stepwise improvement of the level of theory from Hartree-Fock to second-order Møller-Plesset theory and to quadratic configuration interaction theory with single and double excitations, isotropic HFS constants of high accuracy were obtained for atoms and for molecular radicals. The importance of relativistic corrections is demonstrated.

  6. Pulsed electron spin nutation spectroscopy for weakly exchange-coupled multi-spin molecular systems with nuclear hyperfine couplings: a general approach to bi- and triradicals and determination of their spin dipolar and exchange interactions

    NASA Astrophysics Data System (ADS)

    Ayabe, Kazuki; Sato, Kazunobu; Nakazawa, Shigeaki; Nishida, Shinsuke; Sugisaki, Kenji; Ise, Tomoaki; Morita, Yasushi; Toyota, Kazuo; Shiomi, Daisuke; Kitagawa, Masahiro; Suzuki, Shuichi; Okada, Keiji; Takui, Takeji

    2013-10-01

    Weakly exchange-coupled biradicals have attracted much attention in terms of their dynamic nuclear polarisation application in NMR spectroscopy for biological systems or the use of synthetic electron-spin qubits in quantum information processing/quantum-computing technology. Analogues multi-partite molecular systems are important in entering a new phase of the relevant fields. Many stable organic biradicals known so far have nitrogen nuclei at their electron spin sites, where singly occupied molecular orbitals are dominating and large hyperfine couplings occur. A salient feature of such weakly exchange-coupled molecular systems in terms of electronic spin structures is underlain by small zero-field splitting (ZFS) parameters comparable with nuclear hyperfine and/or exchange interactions. Pulse-based electron spin nutation (ESN) spectroscopy of weakly exchange-coupled biradicals, applicable to oriented or non-oriented media, has proven to be a useful and facile approach to the determination of ZFS parameters, which reflect relatively short distances between unpaired electron spins. In the present study, we first treat two-dimensional single-crystal ESN spectroscopy (Q-band) of a 15N-labelled weakly exchange-coupled biradical, showing the nuclear hyperfine effects on the ESN phenomena from both the experimental and theoretical side. ESN spectroscopy is transition moment spectroscopy, in which the nutation frequency as a function of the microwave irradiation strength ω1 (angular frequency) for any cases of weakly exchange-coupled systems can be treated. The results provide a testing ground for the simplified but general approach to the ESN analysis. In this study, we have invoked single-crystal electron-electron double resonance measurements on a typical biradical well incorporated in a diamagnetic host lattice and checked the accuracy of our ESN analysis for the spin dipolar tensor and exchange interaction. Next, we extend the general approach to analogues multi

  7. High-resolution millimeter wave spectroscopy and multichannel quantum defect theory of the hyperfine structure in high Rydberg states of molecular hydrogen H2

    NASA Astrophysics Data System (ADS)

    Osterwalder, A.; Wüest, A.; Merkt, F.; Jungen, Ch.

    2004-12-01

    Experimental and theoretical methodologies have been developed to determine the hyperfine structure of molecular ions from detailed studies of the Rydberg spectrum and have been tested on molecular hydrogen. The hyperfine structure in l=0-3 Rydberg states of H2 located below the X2Σg+(v+=0,N+=1) ground state of ortho H2+ has been measured in the range of principal quantum number n=50-65 at sub-MHz resolution by millimeter wave spectroscopy following laser excitation to np and nd Rydberg states using a variety of single-photon and multiphoton excitation sequences. The np11, nd11, and the nf10-3 Rydberg states were found to be metastable and to have lifetimes of more than 5 μs beyond n=50. Members of other series, such as the nd12, nd13, and the np10 series, were found to have lifetimes of more than 1 μs. Local perturbations induced by low-n Rydberg states belonging to series converging on rovibrationally excited levels of H2+ reduce the lifetimes in narrow ranges of n values. The hyperfine structure is strongly dependent on the value of the orbital angular momentum l. In the penetrating s and p states at n≈50 the exchange interaction dominates over the hyperfine interaction and the levels can be labeled by the total electron spin angular momentum quantum number S (S=0 or 1). In the less penetrating d and f Rydberg states, the hyperfine interaction between the core nuclear and electron spins is larger than the exchange interaction and the Rydberg states are of mixed singlet and triplet character. A procedure based on the Stark effect and on the systematic analysis of selection rules and combination differences was developed to determine the orbital and the total angular momentum quantum numbers l and F and to construct an energy map of p and f Rydberg levels between n=54 and 64 with relative positions of an accuracy of better than 1 MHz. Multichannel quantum defect theory (MQDT) was extended to treat the hyperfine structure in molecular Rydberg states and was

  8. Articulatory Parameters.

    ERIC Educational Resources Information Center

    Ladefoged, Peter

    1980-01-01

    Summarizes the 16 parameters hypothesized to be necessary and sufficient for linguistic phonetic specifications. Suggests seven parameters affecting tongue shapes, three determining the positions of the lips, one controlling the position of the velum, four varying laryngeal actions, and one controlling respiratory activity. (RL)

  9. Etudes structurales de composés de type cémentite: Effet de l'hydroge`ne sur Fe 3C suivi par diffraction neutronique. Spectrométrie Mössbauer sur FeCo 2B et Co 3B dopés au 57Fe

    NASA Astrophysics Data System (ADS)

    Fruchart, D.; Chaudouet, P.; Fruchart, R.; Rouault, A.; Senateur, J. P.

    1984-02-01

    Accurate neutron diffractograms obtained using Fe 3C powdered samples have been recorded using position sensitive detectors. The structure parameters have been determined in the 20-650°C range both in vacuo and in hydrogen atmosphere. No significant location of hydrogen atoms in the cell could be detected before the complete decomposition of Fe 3C, which is considerably enhanced by H 2 gas and is accompanied by an initial loss of carbon (<5%). The magnetic diffraction peaks correspond to ferromagnetic moments directed along the yaxis: M(4 c) ⋍ M(8f) = 1.8 ± 0.1 μ B(extrapolated). Such a value agrees reasonably well with those obtained from Mössbauer data. Comparison with the isomorphous borides or Fe-substitutedCo 3X compounds indicates that a rigid band model is inadequate to describe the electronic scheme of Fe in cementite and related compounds. Analysis of the stability of M3Xcementite-type structured materials reveals the major role of M(d)-X(p) hybridization.

  10. Spectrum, radial wave functions, and hyperfine splittings of the Rydberg states in heavy alkali-metal atoms

    NASA Astrophysics Data System (ADS)

    Sanayei, Ali; Schopohl, Nils

    2016-07-01

    for the hyperfine splitting constant An,j ,0 (HFS ). As an application we consider recent spectroscopic data for the hyperfine splittings of the isotopes 85Rb and 87Rb and find a remarkable agreement with the predicted scaling relation An,j ,0 (HFS )=const .

  11. Unrestricted Hartree-Fock Investigation of the Electron Distribution on the Heme System in Azidohemoglobin-^57mFe and ^14N Hyperfine Interactions.

    NASA Astrophysics Data System (ADS)

    Dubey, Archana; Saha, H. P.; Chow, Lee; Scheicher, R. H.; Sahoo, N.; Pink, R. H.; Mahato, Dip N.; Huang, M. B.; Das, T. P.

    2006-03-01

    We have a program of investigations in progress on the electronic structure of azidohemoglobin by the first-principles Unrestricted Hartree-Fock procedure to understand the substantial amount of magnetic (g-tensor), magnetic hyperfine, and nuclear quadrupole interaction, data available [1] from electron paramagnetic resonance, Mosbauer and electron-nuclear double resonance measurements. Earlier semi-empirical Self-Consistent Charge Extended Huckel investigations have provided semiquantitative results [2] with different degrees of agreement for the available properties and suggested the need for more accurate and quantitative investigations. Results of our investigations will be presented for the ^57mFe and ^14N nuclear quadrupole and magnetic hyperfine interaction properties and compared with experimental data. *Also UCF Orlando [1] See Refs. 2-4 listed in Ref.[2]. [2] Santosh K. Mishra, J.N. Roy, K.C. Mishra and T.P. Das, Theo. Chim. Acta 75, 195(1989).

  12. Proton, muon and ¹³C hyperfine coupling constants of C₆₀X and C₇₀X (X = H, Mu).

    PubMed

    Brodovitch, Jean-Claude; Addison-Jones, Brenda; Ghandi, Khashayar; McKenzie, Iain; Percival, Paul W

    2015-01-21

    The reaction of H atoms with fullerene C70 has been investigated by identifying the radical products formed by addition of the atom muonium (Mu) to the fullerene in solution. Four of the five possible radical isomers of C70Mu were detected by avoided level-crossing resonance (μLCR) spectroscopy, using a dilute solution of enriched (13)C70 in decalin. DFT calculations were used to predict muon and (13)C isotropic hyperfine constants as an aid to assigning the observed μLCR signals. Computational methods were benchmarked against previously published experimental data for (13)C60Mu in solution. Analysis of the μLCR spectrum resulted in the first experimental determination of (13)C hyperfine constants in either C70Mu or C70H. The large number of values confirms predictions that the four radical isomers have extended distributions of unpaired electron spin.

  13. Hyperfine polarization and its normal gradient coefficient of (87)Rb atoms in the vicinity (approximately 10(-5) cm) of coated and uncoated Pyrex glass surfaces.

    PubMed

    Zhao, K; Wu, Z

    2003-09-12

    We have made regionally specific measurement of the hyperfine polarization of 87Rb atoms in the vicinity ( approximately 10(-5) cm) of coated and uncoated Pyrex glass surfaces. We find that the polarization near an uncoated surface decreases rapidly with decreasing distance from the surface whereas for a silicone-coated surface the polarization is independent of the distance from the surface. We have also determined the normal gradient coefficient micro (S.I) of the hyperfine polarization in uncoated cells. In a representative uncoated cell, at a Rb density 7.35 x 10(13) cm(-3) and a pump beam intensity 1.3 W/cm(2), we find micro(S.I)=24+/-7 microm(-1).

  14. Hyperfine structures and Landé g{sub J}-factors for n=2 states in beryllium-, boron-, carbon-, and nitrogen-like ions from relativistic configuration interaction calculations

    SciTech Connect

    Verdebout, S.; Nazé, C.; Rynkun, P.; Godefroid, M.

    2014-09-15

    Energy levels, hyperfine interaction constants, and Landé g{sub J}-factors are reported for n=2 states in beryllium-, boron-, carbon-, and nitrogen-like ions from relativistic configuration interaction calculations. Valence, core–valence, and core–core correlation effects are taken into account through single and double-excitations from multireference expansions to increasing sets of active orbitals. A systematic comparison of the calculated hyperfine interaction constants is made with values from the available literature.

  15. Resolving ligand hyperfine couplings of type 1 and 2 Cu(II) in ascorbate oxidase by high field pulse EPR correlation spectroscopy.

    PubMed

    Potapov, Alexey; Pecht, Israel; Goldfarb, Daniella

    2010-01-07

    Ascorbate oxidase contains two paramagnetic Cu(ii) binding sites, type 1 (T1) and type 2 (T2) and in both sites the Cu(ii) is coordinated to histidine residues. We use several pulse EPR techniques at high field (95 GHz) to determine ligand (1)H and (14)N hyperfine couplings in the two sites and identify the T1 signals by a new triple resonance correlation technique named THYCOS.

  16. Hyperfine splitting of the 2s1/2 and 2p1/2 levels in lithium-like Pr56+

    DOE PAGES

    Trabert, E.; Beiersdorfer, P.; Brown, G. V.; ...

    2015-01-29

    Measurements of hyperfine splittings in highly charged ions are sensitive to details of the nuclear structure and the nuclear magnetic field distribution, but the proper interpretation of the measurements requires that the atomic structure is understood in sufficient detail. Lastly, we discuss the reasoning behind various recent experiments and what advantage is offered by the study of the Li-like ion of a mid-Z element such as praseodymium.

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

    NASA Astrophysics Data System (ADS)

    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.

  18. Sub-Doppler Spectra of Infrared Hyperfine Transitions of Nitric Oxide Using a Pulse Modulated Quantum Cascade Laser: Rapid Passage, Free Induction Decay and the AC Stark Effect

    SciTech Connect

    Duxbury, Geoffrey; Kelly, James F.; Blake, Thomas A.; Langford, Nigel

    2012-05-07

    Using a low power, rapid (nsec) pulse-modulated quantum cascade (QC) laser, collective coherent effects in the 5 {micro}m spectrum of nitric oxide have been demonstrated by the observation of sub-Doppler hyperfine splitting and also Autler-Townes splitting of Doppler broadened lines. For nitrous oxide, experiments and model calculations have demonstrated that two main effects occur with ulsemodulated (chirped) quantum cascade lasers: free induction decay signals, and signals induced by rapid passage during the laser chirp. In the open shell molecule, NO, in which both {Lambda}-doubling splitting and hyperfine structure occur, laser field-induced coupling between the hyperfine levels of the two {Lambda}-doublet components can induce a large AC Stark effect. This may be observed as sub-Doppler structure, field-induced splittings, or Autler-Townes splitting of a Doppler broadened line. These represent an extension of the types of behaviour observed in the closed shell molecule nitrous oxide, using the same apparatus, when probed with an 8 {micro}m QC laser.

  19. Sub-Doppler spectra of infrared hyperfine transitions of nitric oxide using a pulse modulated quantum cascade laser: rapid passage, free induction decay, and the ac Stark effect.

    PubMed

    Duxbury, Geoffrey; Kelly, James F; Blake, Thomas A; Langford, Nigel

    2012-05-07

    Using a low power, rapid (nsec) pulse-modulated quantum cascade (QC) laser, collective coherent effects in the 5 μm spectrum of nitric oxide have been demonstrated by the observation of sub-Doppler hyperfine splitting and also Autler-Townes splitting of Doppler broadened lines. For nitrous oxide, experiments and model calculations have demonstrated that two main effects occur with pulse-modulated (chirped) quantum cascade lasers: free induction decay signals, and signals induced by rapid passage during the laser chirp. In the open shell molecule, NO, in which both Λ-doubling splitting and hyperfine structure occur, laser field-induced coupling between the hyperfine levels of the two Λ-doublet components can induce a large ac Stark effect. This may be observed as sub-Doppler structure, field-induced splittings, or Autler-Townes splitting of a Doppler broadened line. These represent an extension of the types of behaviour observed in the closed shell molecule nitrous oxide, using the same apparatus, when probed with an 8 μm QC laser.

  20. Laser-Induced Optical Pumping Measurements of Cross Section for Fine- and Hyperfine-Structure Transitions in Sodium Induced by Collisions with Helium and Argon Atoms

    NASA Technical Reports Server (NTRS)

    Dobson, Chris C.; Sung, C. C.

    1999-01-01

    Optical pumping of the ground states of sodium can radically alter the shape of the laser-induced fluorescence excitation spectrum, complicating measurements of temperature, pressure, etc., which are based on these spectra. Modeling of the fluorescence using rate equations for the eight hyperfine states of the sodium D manifolds can be used to quantify the contribution to the ground state pumping of transitions among the hyperfine excited states induced by collisions with buffer gas atoms. This model is used here to determine, from the shape of experimental spectra, cross sections lor DELTA.F transitions of the P(sub 3/2) state induced by collisions with helium and argon atoms, for a range of values assumed for the P(sub 1/2), DELTA.F cross sections. The hyperfine cross sections measured using this method, which to our knowledge is novel, are compared with cross sections for transitions involving polarized magnetic substates m(sub F) measured previously using polarization sensitive absorption. Also, fine-structure transition cross sections were measured in the pumped vapor, giving agreement with previous measurements made in the absence of pumping.

  1. Laser Induced Optical Pumping Measurements of Cross Sections for Fine and Hyperfine Structure Transitions in Sodium Induced by Collisions with Helium Argon Atoms

    NASA Technical Reports Server (NTRS)

    Dobson, Chris C.; Sung, C. C.

    1998-01-01

    Optical pumping of the ground states of sodium can radically alter the shape of the laser induced fluorescence excitation spectrum, complicating measurements of temperature, pressure, etc., which are based on these spectra. Modeling of the fluorescence using rate equations for the eight hyperfine states of the sodium D manifolds can be used to quantify the contribution to the ground state pumping of transitions among the hyperfine excited states induced by collisions with buffer gas atoms. This model is used here to determine, from the shape of experimental spectra, cross sections for (Delta)F transitions of the P(sub 3/2) state induced by collisions with helium and argon atoms, for a range of values assumed for the P(sub 1/2), (Delta)F cross sections. The hyperfine cross sections measured using this method, which is thought to be novel, are compared with cross sections for transitions involving polarized magnetic substates, m(sub F), measured previously using polarization sensitive absorption. Also, fine structure transition ((Delta)J) cross sections were measured in the pumped vapor, giving agreement with previous measurements made in the absence of pumping.

  2. Polarization quantum beat spectroscopy of HCF(A1A"). I. 19F and 1H hyperfine structure and Zeeman effect.

    PubMed

    Fan, Haiyan; Ionescu, Ionela; Xin, Ju; Reid, Scott A

    2004-11-08

    To further investigate the (19)F and (1)H nuclear hyperfine structure and Zeeman effect in the simplest singlet carbene, HCF, we recorded polarization quantum beat spectra (QBS) of the pure bending levels 2(0) (n) with n = 0-7 and combination bands 1(0) (1)2(0) (n) with n = 1-6 and 2(0) (n)3(0) (1) with n = 0-3 in the HCF A(1)A(")<--X(1)A(') system. The spectra were measured under jet-cooled conditions using a pulsed discharge source, both at zero field and under application of a weak magnetic field (<30 G). Analysis yielded the nuclear spin-rotation constants C(aa) and weak field Lande g(aa) factors. Consistent with a two-state model, the majority of observed vibrational levels exhibit a linear correlation of C(aa) and g(aa), and our analysis yielded effective (a) hyperfine constants for the (19)F and (1)H nuclei (in MHz) of 728(23) and 55(2), respectively. The latter was determined here owing to the high resolving power of QBS. The vibrational state selectivity of the (19)F hyperfine constants is discussed, and we suggest that the underlying Renner-Teller interaction may play an important role.

  3. Imaging the Stereodynamics of Cl + CH4(ν3 = 1): Polarization Dependence on the Rotational Branch and the Hyperfine Depolarization.

    PubMed

    Pan, Huilin; Yang, Jiayue; Wang, Fengyan; Liu, Kopin

    2014-11-06

    The transition state in the Cl + CH4 reaction is of Cl-H-C collinear geometry, which serves as the bottleneck to reaction. When the reactant CH4 is antisymmetrically stretch-excited to ν3 = 1 by absorbing a linearly polarized photon, all four C-H bonds are collectively excited, and any one of the H atoms could be attacked by the Cl atom. At first sight, it is not obvious how an excited spherical-top molecule like CH4 is aligned and what consequences will be on chemical reactivity by polarizing the CH4 reagents. As shown here, an enormous steric effect on reactivity is observed, which depends sensitively on the selected rotational states. By exploiting various rotational branches in optical excitation, we quantify the degree of stereospecificity for a few lowest rovibrational states of the aligned CH4(ν3 = 1) reagents, as well as account for the hyperfine depolarization factor. This information lays the foundation for a full stereorequirement study of the Cl + CH4(ν3 = 1) reaction.

  4. Hyperfine interaction, spin polarization, and spin delocalization as probes of donor-bridge-acceptor interactions in exchange-coupled biradicals.

    PubMed

    Kirk, Martin L; Shultz, David A; Habel-Rodriguez, Diana; Schmidt, Robert D; Sullivan, Ubie

    2010-11-18

    Computations and EPR spectroscopy are used to probe the spin distribution of donor-bridge-acceptor (D-B-A) biradical complexes: Tp(Cum,Me)Zn(SQ-NN) (1), Tp(Cum,Me)Zn(SQ-1,4-Ph-NN) (2), Tp(Cum,Me)Zn(SQ-2,5-TP-NN) (3), and Tp(Cum,Me)Zn(SQ-2,5-Xyl-NN) (4) (SQ = orthosemiquinone and NN = nitronylnitroxide). These complexes are ground-state analogs of the charge-separated excited states formed in photoinduced electron transfer reactions. The intraligand magnetic exchange interaction (J) in these complexes is mediated by the bridges and has been found to stabilize the triplet ground states of 1 and 2. Detailed spectroscopic and bonding calculations have been used to elucidate the role of the bridge fragment (B) and its conformation relative to donor (SQ) and acceptor (NN) on spin density distributions. The computed results correlate well with experimental nitrogen hyperfine coupling constants.

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

    NASA Astrophysics Data System (ADS)

    Sauerzopf, Clemens; Capon, Aaron A.; Diermaier, Martin; Fleck, Markus; Kolbinger, Bernadette; Malbrunot, Chloé; Massiczek, Oswald; Simon, Martin C.; Vamosi, Stefan; Zmeskal, Johann; Widmann, Eberhard

    2017-02-01

    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.

  6. The Zeeman effect and hyperfine interactions in J = 1-0 transitions of CH+ and its isotopologues.

    PubMed

    Amano, T

    2010-12-28

    The J = 1-0 transitions of (12)CH(+), (13)CH(+), and (12)CD(+) in the ground X(1)Σ(+) state have been unambiguously identified by using an extended negative glow discharge as an ion source. Unexpectedly large Zeeman splittings have been observed, and the (13)CH(+) line exhibits nuclear spin-rotation hyperfine splitting in addition to the Zeeman effect. The nuclear spin-rotation coupling constant was determined to be 1.087(50) MHz for the (13)C species. The rotational g-factor is found to be -7.65(29), in terms of the nuclear magneton for the J = 1 and v = 0 state, more than an order of magnitude larger than values for typical diamagnetic closed shell molecules. These larger than usual magnetic interactions for a (1)Σ molecule are caused by the large rotational energy and relatively small excitation energy of the excited A(1)Π state. The effective g-factor and the spin-rotation coupling constant obtained by ab initio calculations agree very well with the experimentally determined values.

  7. Covalency in La2CuO4: A study of 17O hyperfine couplings in the paramagnetic phase

    NASA Astrophysics Data System (ADS)

    Walstedt, R. E.; Cheong, S.-W.

    2001-07-01

    17O nuclear magnetic resonance spectra from single crystals of La2CuO4 are reported for temperatures ranging from 285 to 800 K. Hyperfine tensor data for the planar sites are analyzed using a spin Hamiltonian model that includes spin-orbit coupling effects. The results show a 7.7% hybridization effect of the oxygen 2pσ orbital from a single copper neighbor, in good agreement with recent density-functional (DF) calculations by Hüsser et al. (HSSM). A large, positive isotropic shift component is also reported, presumably originating from the contact interaction with a hybridized 2s orbital component. First-order quadrupolar-splitting data lead to complete characterization of the electric-field gradient (EFG) tensor, which varies only slightly with temperature up to 800 K. EFG tensors for both doped and undoped La2CuO4 are fitted with a two-component model, which incorporates a substantial anisotropy in for the 2pσ wave functions, an effect that originated in the DF calculations of HSSM. This analysis reveals an increased charge density on the planar oxygens for the superconducting phase, in accord with the original Zhang-Rice model. However, the increase is found to correspond to only ~80% of the nominal doped-hole density, corroborating a similar conclusion reached recently by Hammel et al. Regarding the anomalous spin HF interaction reported in a previous paper for the weakly ferromagnetic state, the present results show that its effects extend all the way to and slightly beyond the orthorhombic-tetragonal phase boundary (TO-T~=550 K). Further, the predominant 2s contact HF interaction reported here supports the notion, suggested earlier, that a 2s admixture underlies the anomaly. However, the basic mechanism of the anomaly remains obscure.

  8. Optical Spectroscopic Measurements of Isotope Shift and Hyperfine Structure in BISMUTH-207, BISMUTH-208 and LEAD-205.

    NASA Astrophysics Data System (ADS)

    Barboza Flores, Marcelino

    The isotope shift and hyperfine structure (hfs) of 38-yr ^{207}Bi and 3.7 times 10^5 -yr ^{208}Bi were measured, in the 6p^3 ^4S_ {1/2} - 6p^2 7s ^4P_{1/2} 306.7-nm resonance line, as well as the isotope shift of 1.4 times 10^7-yr ^ {205}Pb in the 6p^2 ^3P_0 - 6p7s ^3P_1 283.3-nm transition. A 9.1-m focal-length Czerny-Turner grating monochromator with a 25-cm wide diffraction grating (resolving power ~10^6) was used to obtain high resolution absorption spectra of an atomic vapor of lead and bismuth. The spectra were recorded photoelectrically using a signal-averaging spectrum scanning technique. The measured isotope shifts are IS(^ {207}Bi-^{209} Bi) = 0.0999(20) cm^{-1} , IS(^{208}Bi- ^{209}Bi) = 0.072(6) cm ^{-1} and IS(^ {205}Pb-^{208} Pb) = -123.9(2.0) times 10^{-3} cm ^{-1}. The derived magnetic dipole (A) and electric quadrupole (B) hfs interaction constants are A(^4P_{1/2})= 0.1630(3) cm^{-1}, B( ^4S_{3/2}) = -0.016(3) cm^{-1} for ^{207}Bi and A( ^4P_{1/2}) = 0.1639(20) cm^{-1} for ^ {208}Bi. The nuclear magnetic dipole (mu) and electric quadrupole moment (Q) were found to be mu(^{207 }Bi) = 4.051(7)mu_{N }, Q(^{207}Bi) = -0.60(11)b and mu(^ {208}Bi) = 4.52(6)mu_ {N}. The magnetic dipole moments agree with theoretical predictions based on the nuclear shell model including configuration mixing and meson exchange contributions.

  9. Solving the Tautomeric Equilibrium of Purine Through the Analysis of the Complex Hyperfine Structure of the Four 14N Nuclei

    NASA Astrophysics Data System (ADS)

    Cocinero, Emilio J.; Uriarte, Iciar; Ecija, Patricia; Favero, Laura B.; Spada, Lorenzo; Calabrese, Camilla; Caminati, Walther

    2016-06-01

    Microwave spectroscopy has been restricted to the investigation of small molecules in the last years. However, with the advent of FTMW and CP-FTMW spectroscopies coupled with laser vaporization techniques it has turned into a very competitive methodology in the studies of moderate-size biomolecules. Here, we present the study of purine, characterized by two aromatic rings, one six- and one five-membered, fused together to give a planar aromatic bicycle. Biologically, it is the mainframe of two of the five nucleobases of DNA and RNA. Two tautomers were observed by FTMW spectroscopy coupled to UV ultrafast laser vaporization system. The population ratio of the two main tautomers [N(7)H]/[N(9)H] is about 1/40 in the gas phase. It contrasts with the solid state where only the N(7)H species is present, or in solution where a mixture of both tautomers is observed. For both species, a full quadrupolar hyperfine analysis has been performed. This has led to the determination of the full sets of diagonal quadrupole coupling constants of the four 14N atoms, which have provided crucial information for the unambiguous identification of both species. T. J. Balle and W. H. Flygare Rev. Sci. Instrum. 52, 33-45, 1981 J.-U. Grabow, W. Stahl and H. Dreizler Rev. Sci. Instrum. 67, 4072-4084, 1996 G. G. Brown, B. D. Dian, K. O. Douglass, S. M. Geyer, S. T. Shipman and B. H. Pate Rev. Sci. Instrum. 79, 0531031/1-053103/13, 2008 E. J. Cocinero, A. Lesarri, P. écija, F. J. Basterretxea, J. U. Grabow, J. A. Fernández and F. Castaño Angew. Chem. Int. Ed. 51, 3119-3124, 2012

  10. Investigation of magnetic, thermal and hyperfine properties of Tb 3+ in the single crystal of terbium trifluoromethanesulfonate nonahydrate

    NASA Astrophysics Data System (ADS)

    Neogy, D.; Paul, P.; Chattopadhyay, K. N.

    2004-12-01

    The single crystals of terbium trifluoromethanesulfonate nonahydrates Tb(CF3SO3)3·9H2O (TbTFMS) were grown and the principal magnetic susceptibilities measured from 300 K down to 13 K, for external field orientations both parallel and perpendicular to the c-axis which is the symmetry axis of this hexagonal crystal. The non-Kramers ion Tb3+ occupies a site of C3h symmetry in this uniaxial crystal. The principal magnetic susceptibilities, observed by us and the Friedberg group, over the range of temperature, 300 down to ∼1.0 K, are explained very well by the theoretical expressions of susceptibility obtained from the crystal field perturbed J-mixed eigenvectors with due consideration of the intermediate coupling effects. No noticeable ordering effects were observed down to ∼13 K; this indicates the interionic interactions to be weak, being predominantly of the dipolar type, which is consistent with the detection of a ferromagnetic transition at T ∼ 0.24 K by the Friedberg group. The g-values derived from other sources are also reasonably accounted for. The crystal field energy level structure predicts a Schottky anomaly in the heat capacity at around 0.23 K, which agrees well with that observed by Friedberg et al.; another Schottky peak appears at around 48 K. One interesting aspect of the present analysis is that almost all the principal features of the magnetic, thermal and optical properties of TbTFMS at high temperatures as well as liquid helium temperatures could be explained quite satisfactorily with a single CF alone. Present analysis also suggests that two singlets lie lowest whose separation is 0.37 cm-1; this profoundly influences the magnetic and thermal properties. The interaction of the nuclear spin with the electric field gradient and the hyperfine magnetic field has also been discussed.

  11. Energy-Level Related Nuclear-Spin Effects and Super-Hyperfine Spectral Patterns: how Molecules do Self-Nmr

    NASA Astrophysics Data System (ADS)

    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)

  12. A path integral molecular dynamics study of the hyperfine coupling constants of the muoniated and hydrogenated acetone radicals

    NASA Astrophysics Data System (ADS)

    Oba, Yuki; Kawatsu, Tsutomu; Tachikawa, Masanori

    2016-08-01

    The on-the-fly ab initio density functional path integral molecular dynamics (PIMD) simulations, which can account for both the nuclear quantum effect and thermal effect, were carried out to evaluate the structures and "reduced" isotropic hyperfine coupling constants (HFCCs) for muoniated and hydrogenated acetone radicals (2-muoxy-2-propyl and 2-hydoxy-2-propyl) in vacuo. The reduced HFCC value from a simple geometry optimization calculation without both the nuclear quantum effect and thermal effect is -8.18 MHz, and that by standard ab initio molecular dynamics simulation with only the thermal effect and without the nuclear quantum effect is 0.33 MHz at 300 K, where these two methods cannot distinguish the difference between muoniated and hydrogenated acetone radicals. In contrast, the reduced HFCC value of the muoniated acetone radical by our PIMD simulation is 32.1 MHz, which is about 8 times larger than that for the hydrogenated radical of 3.97 MHz with the same level of calculation. We have found that the HFCC values are highly correlated with the local molecular structures; especially, the Mu—O bond length in the muoniated acetone radical is elongated due to the large nuclear quantum effect of the muon, which makes the expectation value of the HFCC larger. Although our PIMD result calculated in vacuo is about 4 times larger than the measured experimental value in aqueous solvent, the ratio of these HFCC values between muoniated and hydrogenated acetone radicals in vacuo is in reasonable agreement with the ratio of the experimental values in aqueous solvent (8.56 MHz and 0.9 MHz); the explicit presence of solvent molecules has a major effect on decreasing the reduced muon HFCC of in vacuo calculations for the quantitative reproduction.

  13. 57Fe Mössbauer Studies in Mo Fe Supported Catalysts

    NASA Astrophysics Data System (ADS)

    Castelão-Dias, M.; Costa, B. F. O.; Quinta-Ferreira, R. M.

    2001-09-01

    Industrially, the Mo Fe catalysts used in the selective oxidation of methanol to formaldehyde can rapidly deactivate. The use of support materials may reduce the high temperatures in the catalytic bed and/or increase thermal and mechanical resistance. However, during the preparation of these catalysts, or even during reaction conditions, the active species may react with the support material losing their catalytic activity. In this work silica, silicium carbide and titania were studied as supported catalysts by Mössbauer spectroscopy which proved to be a useful technique in the choice of supported materials.

  14. Investigations of Iron Minerals Formed by Dissimilatory Alkaliphilic Bacterium with {sup 57}Fe Moessbauer Spectroscopy

    SciTech Connect

    Chistyakova, N. I.; Rusakov, V. S.; Shapkin, A. A.; Zhilina, T. N.; Zavarzina, D. G.; Kohout, J.

    2010-07-13

    Anaerobic alkaliphilic bacterium of Geoalkalibacter ferrihydriticus type (strain Z-0531), isolated from a bottom sediment sample from the weakly mineralized soda Lake Khadyn, have been analyzed. The strain uses the amorphous Fe(III)-hydroxide (AFH) as an electron acceptor and acetate CH{sub 3}COO{sup -} as an electron donor. Moessbauer investigations of solid phase samples obtained during the process of the bacterium growth were carried out at room temperature, 77.8 K, 4.2 K without and with the presence of an external magnetic field (6 T) applied perpendicular to the {gamma}-bebam.

  15. Corrosion studies of iron and its alloys by means of57Fe Mössbauer spectroscopy

    NASA Astrophysics Data System (ADS)

    Marco, J. F.; Dávalos, J.; Gracia, M.; Gancedo, J. R.

    1994-12-01

    Some of the advantages and limitations of Mössbauer spectroscopy when used in corrosion research are shown by using three examples taken from the work of the authors on (i) the passive layer of iron, (ii) the corrosion of weathering steels by SO2-polluted atmospheres and (iii) the performance of rust converters.

  16. Theoretical 57Fe Mössbauer spectroscopy: isomer shifts of [Fe]-hydrogenase intermediates.

    PubMed

    Hedegård, Erik Donovan; Knecht, Stefan; Ryde, Ulf; Kongsted, Jacob; Saue, Trond

    2014-03-14

    Mössbauer spectroscopy is an indispensable spectroscopic technique and analytical tool in iron coordination chemistry. The linear correlation between the electron density at the nucleus ("contact density") and experimental isomer shifts has been used to link calculated contact densities to experimental isomer shifts. Here we have investigated relativistic methods of systematically increasing sophistication, including the eXact 2-Component (X2C) Hamiltonian and a finite-nucleus model, for the calculation of isomer shifts of iron compounds. While being of similar accuracy as the full four-component treatment, X2C calculations are far more efficient. We find that effects of spin-orbit coupling can safely be neglected, leading to further speedup. Linear correlation plots using effective densities rather than contact densities versus experimental isomer shift lead to a correlation constant a = -0.294 a0(-3) mm s(-1) (PBE functional) which is close to an experimentally derived value. Isomer shifts of similar quality can thus be obtained both with and without fitting, which is not the case if one pursues a priori a non-relativistic model approach. As an application for a biologically relevant system, we have studied three recently proposed [Fe]-hydrogenase intermediates. The structures of these intermediates were extracted from QM/MM calculations using large QM regions surrounded by the full enzyme and a solvation shell of water molecules. We show that a comparison between calculated and experimentally observed isomer shifts can be used to discriminate between different intermediates, whereas calculated atomic charges do not necessarily correlate with Mössbauer isomer shifts. Detailed analysis reveals that the difference in isomer shifts between two intermediates is due to an overlap effect.

  17. 5 7 Fe Mössbauer spectroscopic studies of single-crystalline K x Fe2- y S 2 and K x Fe2- y Se 2

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Yuu; Ikeda, Shugo; Kobayashi, Hisao

    2016-12-01

    We have investigated the physical properties of single-crystalline K x Fe2- y S 2 and K x Fe2- y Se2 samples using 57Fe Mössbauer spectroscopy. The observed 57Fe Mössbauer spectra were reconstructed using a major antiferromagnetic ordered K2Fe4Se5 phase and a minor paramagnetic phase down to 5 K, despite being superconducting below 32.2 K in K x Fe2- y Se2. The analysis of 57Fe Mössbauer spectrum for K x Fe2- y S 2 at 290 K confirms the presence of a major antiferromagnetic ordered K2Fe4 S 5 phase and a minor paramagnetic phase in the K x Fe2- y S 2 single crystal. The derived hyperfine interaction parameters of the paramagnetic phase in K x Fe2- y S 2 suggest that the microstructure of this phase in K x Fe2- y S 2 is similar to that of the superconducting phase in K x Fe2- y Se2 although the K x Fe2- y S 2 single crystals exhibit no superconductivity down to 5 K.

  18. Extracting order parameters from powder EPR lineshapes for spin-labelled lipids in membranes

    NASA Astrophysics Data System (ADS)

    Schorn, Karl; Marsh, Derek

    1997-10-01

    The corrections that must be made to the spectral separations of the hyperfine extrema in the pseudo-powder EPR lineshapes from lipid spin labels in randomly oriented membranes have been investigated by spectral simulations that include slow motional components. Using simulation parameters that are able to describe the corresponding experimental spectra rather well, it is found that any correction required to the outer hyperfine splitting, 2 Amax, is small, but that the correction to the inner splitting, 2 Amin, differs from that obtained previously from motional narrowing theory. Both Amax and Amin deduced from the simulated spectra are found to vary almost linearly with the molecular-frame order parameter, Szz. The corrections to Amin are used to obtain order parameters from the experimental line splittings. These are found to be in reasonable agreement with the order parameters derived from direct spectral simulation. The inclusion of slow motional components in the simulations represents an improvement over the correction to Amin that is routinely used for membrane systems and which is based on motional narrowing theory.

  19. Supergranular Parameters

    NASA Astrophysics Data System (ADS)

    Udayashankar, Paniveni

    2016-07-01

    I study the complexity of supergranular cells using intensity patterns from Kodaikanal solar observatory. The chaotic and turbulent aspect of the solar supergranulation can be studied by examining the interrelationships amongst the parameters characterizing supergranular cells namely size, horizontal flow field, lifetime and physical dimensions of the cells and the fractal dimension deduced from the size data. The findings are supportive of Kolmogorov's theory of turbulence. The Data consists of visually identified supergranular cells, from which a fractal dimension 'D' for supergranulation is obtained according to the relation P α AD/2 where 'A' is the area and 'P' is the perimeter of the supergranular cells. I find a fractal dimension close to about 1.3 which is consistent with that for isobars and suggests a possible turbulent origin. The cell circularity shows a dependence on the perimeter with a peak around (1.1-1.2) x 105 m. The findings are supportive of Kolmogorov's theory of turbulence.

  20. Hyperfine and X-ray investigations of amorphous Fe2Er and Fe2Ce alloys and the effect of hydrogenation on short-range order

    NASA Astrophysics Data System (ADS)

    Ghafari, M.; Keune, W.; Matsuura, M.; Schletz, K. P.

    1990-07-01

    The effect of hydrogenation on the short-range order of amorphous Fe2Er and Fe2Ce alloys has been investigated by Mössbauer, X-ray and magnetization measurements. The hydrogenation leads to drastic changes in the short-range order. The results of Mössbauer measurements show two different distributions of magnetic hyperfine fields for amorphous Fe2CeH4 alloys (a-Fe2CeH4). For a-Fe2ErH3 alloys we found drastic changes in magnetic structure, which is different from the well-known magnetic structures.

  1. Lower bound for the variation of the hyperfine populations in the ground state of spin-1 condensates against a magnetic field

    NASA Astrophysics Data System (ADS)

    Xie, W. F.; He, Y. Z.; Bao, C. G.

    2015-10-01

    A simple and analytical expression for the variation of the lower bound and upper bound of the population density ρ0 of hyperfine component μ = 0 particles in the ground state of spin-1 condensates against a magnetic field B has been derived. The lower bound has a distinguished feature, namely, it will tend to the actual ρ0 when B tends to zero and infinite. This feature assures that, in the whole range of B, the lower bound can provide an effective constraint. Numerical examples are given to demonstrate the applicability of the bound.

  2. First corrections to hyperfine splitting and the Lamb shift induced by diagrams with two external photons and second-order radiative insertions in the electron line

    SciTech Connect

    Eides, M.I.; Karshenboim, S.G.; Shelyuto, V.A.

    1994-07-01

    Contributions to hyperfine splitting (HFS) and to the Lamb shift on the order of {alpha}{sup 2}(Z{alpha}){sup 5} induced by graphs with two radiative photons inserted into the electron line are considered. It is shown that this gauge-invariant set of diagrams, which give corrections of the considered order, consists of nineteen topologically different diagrams. Contributions to both HFS and the Lamb shift induced by graphs containing the one-loop electron self-energy as a subgraph and by the graph containing two one-loop vertices are obtained. 15 refs., 3 figs.

  3. Corrections to hyperfine splitting and the Lamb shift due to the insertion of the two-loop electron self-energy with overlapping divergences in the electron line

    SciTech Connect

    Eides, M.I.; Karshenboim, S.G.; Shelyuto, V.A.

    1994-12-01

    Contributions on the order of {alpha}{sup 2}(Z{alpha}){sup 5} to hyperfine splitting (HFS) and the Lamb shift due to the insertion of the two-loop electron self-energy diagram with overlapping divergences in the electron line are considered. An explicit expression for the two-loop self-energy diagram with overlapping divergences is obtained in the Fried-Yennie gauge. Contributions to HFS and the Lamb shift due to the diagram containing this subgraph are calculated. 5 refs., 1 fig.

  4. Radiative nonrecoil nuclear finite size corrections of order α(Zα)5 to the hyperfine splitting of S-states in muonic hydrogen

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    On the basis of quasipotential method in quantum electrodynamics we calculate nuclear finite size radiative corrections of order α(Zα)5 to the hyperfine structure of S-wave energy levels in muonic hydrogen and muonic deuterium. For the construction of the particle interaction operator we employ the projection operators on the particle bound states with definite spins. The calculation is performed in the infrared safe Fried-Yennie gauge. Modern experimental data on the electromagnetic form factors of the proton and deuteron are used.

  5. Observation of a very large internal hyperfine field (62.4 T) in the ferromagnetically ordered state of the S = 1 alpha-iron(II) octaethyltetraazaporphyrin.

    PubMed

    Reiff, W M; Frommen, C M; Yee, G T; Sellers, S P

    2000-05-15

    The origins of the extraordinarily large internal hyperfine field (62.4 T) for the three-dimensional (weak) ferromagnetically ordered ground state of alpha-Fe(OETAP) are discussed semiquantitatively in terms of existing physical theory. In particular, the classical Fermi-contact contribution to the internal field is found to be highly enhanced by a very large orbital contribution and a significant dipolar term of the same sign. A rationale for the unexpected ordering of this S = 1 non-Kramers system is also presented.

  6. Detection of Anisotropic Hyperfine Components of Chemically Prepared Carotenoid Radical Cations:1D and 2D ESEEM and Pulsed ENDOR Study

    SciTech Connect

    Konovalova, Tatyana A.; Dikanov, Sergei A.; Bowman, Michael K.; Kispert, Lowell D.

    2001-09-06

    Canthaxanthin and 8'-apo-B-caroten-8'-al radical cations chemically prepared on activated silica-alumina and in CH2CI2 solution containing A1C13 were studied by pulsed EPR and ENDOR spectroscopies. Both the 1D three-pulse ESEEM and the 2D HYSCORE spectra of the carotenoid-A1C13 mixtures exhibited the 27 A1 nuclei peak at 3.75 MHz. This indicates electron-transfer interactions between carotenoids and A1III ions resulting in the formation and stabilization of carotenoid radical cations. Davies ENDOR measurements of the canthaxanthin radical cation on silica-alumina determined the hyperfine couplings of B protons belonging to three different methyl groups with ahI=2.6 MHz, aH2=8.6MHz, and ah3 ca. 13 MHz. The principal components of the proton hyperfine tensors were obtained from HYSCORE spectra in A1C13 solutions and on the solid support. Identification of the protons was made on the basis of isotropic hyperfine couplings determined by RHF-INDO/SP molecular orbital calculations. In frozen A1C13 solution, the C(7, 7')Ha and C(14, 14')-Ha a protons were observed for Canthaxanthin and the C(8 or 14')-Ha, C(15')-Ha were observed for 8'-apo-B-caroten-8'-al. On the silica-alumina support, the C(10, 10')-Ha, C(11, 11')-Ha, and C(15,15')-Ha a protons were measured for Canthaxanthin and the C(12)-Ha and C(15')-Ha were measured for 8' apo-B-caroten-8'-al. Some protons with large isotropic couplings (>10 MHz) determined from HYSCORE analysis could be assigned to B protons, but the principal components of their hyperfine tensors are much more anisotropic than those reported previously for B protons. We suggest that cis/trans isomerization of carotenoids on silica-alumina results in stabilization of di-cis isomers with large isotropic couplings for some a protons which are comparable to those of B protons.

  7. Power spectra and auto correlation analysis of hyperfine-induced long period oscillations in the tunneling current of coupled quantum dots

    SciTech Connect

    Harack, B.; Leary, A.; Coish, W. A.; Hilke, M.; Yu, G.; Gupta, J. A.; Payette, C.; Austing, D. G.

    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.

  8. Electronic structure calculations of ESR parameters of melanin units.

    PubMed

    Batagin-Neto, Augusto; Bronze-Uhle, Erika Soares; Graeff, Carlos Frederico de Oliveira

    2015-03-21

    Melanins represent an important class of natural pigments present in plants and animals that are currently considered to be promising materials for applications in optic and electronic devices. Despite their interesting properties, some of the basic features of melanins are not satisfactorily understood, including the origin of their intrinsic paramagnetism. A number of experiments have been performed to investigate the electron spin resonance (ESR) response of melanin derivatives, but until now, there has been no consensus regarding the real structure of the paramagnetic centers involved. In this work, we have employed electronic structure calculations to evaluate the ESR parameters of distinct melanin monomers and dimers in order to identify the possible structures associated with unpaired spins in this biopolymer. The g-factors and hyperfine constants of the cationic, anionic and radicalar structures were investigated. The results confirm the existence of at least two distinct paramagnetic centers in melanin structure, identifying the chemical species associated with them and their roles in electrical conductivity.

  9. Epitaxial MgO/Fe(001) and Fe/MgO(001): Structures of the interfaces

    NASA Astrophysics Data System (ADS)

    Młyńczak, E.; Freindl, K.; Spiridis, N.; Korecki, J.

    2013-01-01

    The chemical, electronic and magnetic structures of the interfaces between Fe(001) and MgO(001) thin films were studied using conversion electron Mössbauer spectroscopy (CEMS). A 1 ML thick 57Fe probe located at either of the interfaces in the MgO/56Fe/MgO epitaxial structure enabled precise measurements of the interfacial hyperfine interactions. Analysis of the CEMS spectra showed that both the "MgO/Fe" and "Fe/MgO" interfaces are partially oxidized (63% and 86%, respectively), although, despite good crystallinity, no well-defined iron oxide phases were detected. At the "MgO/Fe" interface, 14% of the oxidized Fe sites were found to be defective (located at steps, corners or kinks). The "Fe/MgO" interface, from which the formation of 57Fe islands of at least 3 ML in height was inferred, was found to be almost defect-free. No modification of the hyperfine parameters of Fe atoms located away from the interface was detected for "Fe/MgO," in contrast with the "MgO/Fe" interface. Approximately 6% of the probe layer diffused into the MgO films at both interfaces.

  10. Lower bound for the hyperfine populations of spin-2 condensates against a magnetic field under the single-spatial-mode approximation

    NASA Astrophysics Data System (ADS)

    Liu, Y. M.; He, Y. Z.; Bao, C. G.

    2015-12-01

    The variation of the hyperfine populations N ρμ of the ground state (g.s.) of spin-2 condensates against a magnetic field B is studied. A N -body theory which is rigorous in dealing with the spin degrees of freedom has been adopted. The conservation of the total magnetization M is assumed. A combined hyperfine population N ρcomb=N (ρ0-3 ρ2-3 ρ-2) , which is an observable, is defined. The lower bound for this population has been derived analytically. It turns out that the lower bound is identical to the actual population when B =0 and ∞ , and the population is monotonically uprising in between. Thus, via the analytical form of the lower bound, the variation of the population against B can be roughly known in advance. Numerical examples are given to demonstrate the applicability of the bound. When M =0 , the g.s. in the polar phase was found to be highly unstable against B because the neighboring level density is extremely high. When M =N , the g.s. in the cyclic phase was also found to be highly unstable. This is because the appearance of B , even if it is very weak, will break the high degeneracy of the g.s. and result in having numerous levels emerging in the neighborhood of the g.s.

  11. High-precision, systematic study of hyperfine structure in the 4f/sup N/6s/sup 2/ configuration of the neutral rare earths

    SciTech Connect

    Childs, W.J.; Goodman, L.S.; Pfeufer, V.

    1983-01-01

    Although the hyperfine structure (hfs) of many-electron atoms has been studied intensively in recent years, it is still difficult to distinguish between the competing effects of relativity and configuration interaction. The 4f/sup N/6s/sup 2/ configuration of the neutral rare earths is of particular interest because (a) the low-lying terms are relatively free of configuration interaction, and (b) trends can be examined systematically as one proceeds through the long 4f-shell. The procedure is to deduce, from the measured hfs constants of low levels, the underlying hyperfine radial integrals for comparison with ab initio predictions. Since some of these integrals are extremely sensitive to any configuration interaction and others are not, it is possible to determine both the extent and type of configuration interaction present in some cases. Prior to the start of the present research no precise hfs information existed for the entire second half of the 4f shell of the rare earths. The present measurements were designed both to provide such data and to make possible a systematic study of the hfs throughout the 4f shell. The atomic-beam, laser-rf, double-resonance method was used for the measurements. With this technique, the occurrence of a radiofrequency transition between atomic hfs levels is detected by noting an increase in the laser-induced fluorescence.

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

    SciTech Connect

    Sowmya, K.; Nagendra, K. N.; Sampoorna, M.; Stenflo, J. O. E-mail: knn@iiap.res.in E-mail: stenflo@astro.phys.ethz.ch

    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.

  13. Assignment of selected hyperfine proton NMR resonances in the met forms of Glycera dibranchiata monomer hemoglobins and comparisons with sperm whale metmyoglobin

    SciTech Connect

    Constantinidis, I.; Satterlee, J.D.; Pandey, R.K.; Leung, H.K.; Smith, K.M.

    1988-04-19

    This work indicates a high degree of purity for our preparations of all three of the primary Glycera dibranchiata monomer hemoglobins and details assignments of the heme methyl and vinyl protons in the hyperfine shift region of the ferric (aquo.) protein forms. The assignments were carried out by reconstituting the apoproteins of each component with selectively deuteriated hemes. The results indicate that even though the individual component preparations consist of essentially a single protein, the proton NMR spectra indicate spectroscopic heterogeneity. Evidence is presented for identification and classification of major and minor protein forms that are present in solutions of each component. Finally, in contrast to previous results, a detailed analysis of the proton hyperfine shift patterns of the major and minor forms of each component, in comparison to the major and minor forms of metmyoglobin, leads to the conclusions that the corresponding forms of the proteins from each species have strikingly similar heme-globin contacts and display nearly identical heme electronic structures and coordination numbers.

  14. Hyperfine excitation of N2H+ by H2: towards a revision of N2H+ abundance in cold molecular clouds

    NASA Astrophysics Data System (ADS)

    Lique, François; Daniel, Fabien; Pagani, Laurent; Feautrier, Nicole

    2015-01-01

    The modelling of emission spectra of molecules seen in interstellar clouds requires the knowledge of collisional rate coefficients. Among the commonly observed species, N2H+ is of particular interest since it was shown to be a good probe of the physical conditions of cold molecular clouds. Thus, we have calculated hyperfine-structure-resolved excitation rate coefficients of N2H+(X1Σ+) by H2(j = 0), the most abundant collisional partner in the cold interstellar medium. The calculations are based on a new potential energy surface, obtained from highly correlated ab initio calculations. State-to-state rate coefficients between the first hyperfine levels were calculated, for temperatures ranging from 5 to 70 K. By comparison with previously published N2H+-He rate coefficients, we found significant differences which cannot be reproduced by a simple scaling relationship. As a first application, we also performed radiative transfer calculations, for physical conditions typical of cold molecular clouds. We found that the simulated line intensities significantly increase when using the new H2 rate coefficients, by comparison with the predictions based on the He rate coefficients. In particular, we revisited the modelling of the N2H+ emission in the LDN 183 core, using the new collisional data, and found that all three of the density, gas kinetic temperature and N2H+ abundance had to be revised.

  15. Sub-Doppler millimetre-wave spectroscopy of DBS and HBS: accurate values of nuclear electric and magnetic hyperfine structure constants.

    PubMed

    Bizzocchi, Luca; Esposti, Claudio Degli; Dore, Luca

    2008-02-07

    The unstable thioborine molecule and its deuterated variant have been produced by a high-temperature reaction between hydrogen sulfide and crystalline boron at 1100 degrees C in a flow system. Five rotational transitions from J = 2 <-- 1, to J = 6 <-- 5 have been recorded with sub-Doppler resolution for the vibrational ground state of H10/11BS and D10/11BS using the Lamb-dip technique. The hyperfine structure due to the electric quadrupole interaction of deuterium nucleus has been resolved yielding the first experimental determination of the deuterium quadrupole coupling constant in thioborine, which is 0.1403(75) MHz in D11 BS and 0.1360(38) MHz in D10BS. Fairly accurate values of 10/11B spin-rotation coupling constants and of the hydrogen-boron spin-spin coupling constants have also been determined. Additionally, the hyperfine structure of the rotational lines for the nu2 = 1 excited state has been investigated, thus obtaining information on the asymmetry of the electric field gradient at the B nucleus in the bending state.

  16. Measurement of hyperfine fields and the Δg-effect in π-conjugated polymer-based OLEDs using multi-frequency electrically detected magnetic resonance

    NASA Astrophysics Data System (ADS)

    Joshi, Gajadhar; Malissa, Hans; Miller, Richard; Ogden, Lillie; Baird, Douglas; Jamali, Shirin; Kavand, Marzieh; Ambal, Kapil; van Tol, Johan; Lupton, John; Boehme, Christoph

    Magneto-opto-electronic properties of organic semiconductors, such as organic magnetoresistance or magneto-electroluminescence, are strongly influenced by the interplay of proton induced hyperfine fields to which charge carrier spins are coupled [Nguyen et al., Nat. Mater. 9, 345-352 (2010), McCamey et al. Phys. Rev. Lett. 104, 017601 (2010)]. In addition, the weak but non-negligible and highly inhomogeneously distributed spin-orbit effects caused by the material's structural disorder can affect spin-dependent processes. In order to quantitatively access and discriminate between these mechanisms, we investigate the inhomogeneous broadening of polaron spin-resonances using electrically detected magnetic resonance (EDMR) spectroscopy at various magnetic fields between 3mT and 12T. While random local hyperfine fields cause an external magnetic field-independent line broadening, spin-orbit contributions give rise to a distribution of the charge carrier g-factors. This Δg effect leads to a resonance line-width contribution that is proportional to the external magnetic field. We observe an EDMR line that is largely field-independent in the low-magnetic field, but shows substantial broadening of line shape at higher fields.

  17. Hyperfine field at Mn in the intermetallic compound LaMnSi2 measured by PAC using 111Cd nuclear probe

    NASA Astrophysics Data System (ADS)

    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.

  18. 29Si-NMR study of magnetic anisotropy and hyperfine interactions in the uranium-bsed ferromagnet UNiSi2

    SciTech Connect

    Sakai, Hironori; Baek, Seung H; Bauer, Eric D; Ronning, Filip; Thompson, J D

    2009-01-01

    UNiSi{sub 2} orders ferromagnetically below T{sub Curie} = 95 K. This material crystallizes in the orthorhombic CeNiSi{sub 2}-type structure. The uranium atoms form double-layers, which are stacked along the crystallographic b axis (the longest axis). From magnetization measurement the easy (hard) magnetization axis is found to be the c axis (b axis). {sup 29}Si-NMR measurements have been performed in the paramagnetic state. In UNiSi{sub 2}, two crystallographic Si sites exist with orthorhombic local symmetry. The Knight shifts on each Si site have been estimated from the spectra of random and oriented powders. The transferred hyperfine couplings have been also derived. It is found that the transferred hyperfine coupling constants on each Si site are nearly isotropic, and that their Knight shift anisotropy comes from that of the bulk susceptibility. The nuclear-spin lattice relaxation rate 1/T{sub 1} shows temperature-independent behavior, which indicates the existence of localized 5f electron.

  19. Electron-paramagnetic-resonance parameters of molybdenum(V) in sulphite oxidase from chicken liver.

    PubMed Central

    Lamy, M T; Gutteridge, S; Bary, R C

    1980-01-01

    A study has been made of e.p.r. signals due to Mo(V) in reduced sulphite oxidase (EC 1.8.3.1) from chicken liver. Reduction by SO3(2-), or photochemically in the presence of a deazaflavin derivative, produces spectra indistinguishable from one another. Three types of spectra from the enzyme were distingusihed and shown to correspond to single chemical species, since they could be simulated at both 9 and 35 GHz by using the same parameters. These were the low-pH form of the enzyme, with gav. 1.9805, the high-pH form, with gav. 1.9681 and a phosphate complex, with gav. 1.9741. The low-H form shows interaction with a single exchangeable proton, with A(1H)av. (hyperfine coupling constant) = 0.98 mT, probably in the form of an MoOH group. Parameters of the signals are compared with those for signals from xanthine oxidase and nitrate reductase. The signal from the phosphate complex of sulphite oxidase in unique among anion complexes of Mo-containing enzymes in showing no hyperfine coupling to protons. There is no evidence for additional weakly coupled protons or nitrogen nuclei in the sulphite oxidase signals. The possibility is considered that the enzymic mechanism involves abstraction of a proton and two electrons from HSO3- by a Mo = O group in the enzyme. PMID:6249254

  20. Massively parallel implementations of coupled-cluster methods for electron spin resonance spectra. I. Isotropic hyperfine coupling tensors in large radicals

    SciTech Connect

    Verma, Prakash; Morales, Jorge A.; Perera, Ajith

    2013-11-07

    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 {sup 11}B, {sup 17}O, {sup 9}Be, {sup 19}F, {sup 1}H, {sup 13}C, {sup 35}Cl, {sup 33}S,{sup 14}N, {sup 31}P, and {sup 67}Zn 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 N{sup 7}-scaling in CCSD(T). The importance of these accurate computations of isotropic hyperfine coupling constants to elucidate

  1. Massively parallel implementations of coupled-cluster methods for electron spin resonance spectra. I. Isotropic hyperfine coupling tensors in large radicals

    NASA Astrophysics Data System (ADS)

    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

  2. I. Effects of Perturbations on Ion Motion in Fourier Transform Ion Cyclotron Resonance Mass Spectrometry. I. First Principles Investigation of Hyperfine Properties in Zinc Chalcogenides and Spinels.

    NASA Astrophysics Data System (ADS)

    Mitchell, Dale Wesley

    I. Many FT-ICR systems are approximately described by the so-called quadrupole approximation; the dynamics of a single ion in a constant magnetic field and a quadratic electrostatic potential. The quadrupole approximation is considered the unperturbed problem while all other forces are treated as perturbations to this motion. Averaging methods are employed to study the effects of electrostatic and excitation field inhomogeneities on ion motion in a cubic ICR cell. A theory of ion motion based on averaging methods in a cubic ICR cell is presented for differential sinusoidal excitation that explains the observed stability, orders of magnitude and resonance positions for excitation frequencies away from the cyclotron frequency. FT-ICR double resonance experiments are used to test the theoretical predictions. For excitation frequencies near the cyclotron frequency, a previously unknown and simple expression is derived for the phase synchronization process in ICR which relates how the cyclotron radius and phase depend on the initial conditions. Finally, Lie transform perturbation theory and averaging methods are used to derive frequency shifts and mode amplitudes to all three fundamental ICR modes for the true electrostatic cubic cell potential. These analytical results give good agreement with numerical results. II. All electron Hartree-Fock cluster calculations are carried out to derive electron densities, electric field gradients and electronic structures in zinc chalcogenides, zinc fluoride and oxide spinels in order to theoretically interpret the available hyperfine interactions data. The theoretical densities at the zinc nucleus are combined with experimental isomer shifts to estimate a value for the mean square nuclear charge radius for the Mossbauer transition in ^{67}Zn of Delta< r^2 > = {+(13.9} +/- 1.4)times10 ^{-3} fm^2. For ZnO (wurtzite) and ZnF_2, the electric field gradient tensors are calculated at all nuclei and compared with the available data

  3. Theoretical studies of the local structure and EPR parameters for Cu2+ centers in disodium malonate trihydrate single crystal

    NASA Astrophysics Data System (ADS)

    Chao-Ying, Li; Ying, Huang; Xue-Mei, Zheng

    2015-01-01

    The electron paramagnetic resonance (EPR) parameters (g factors gxx, gyy, gzz and hyperfine structure constants Axx, Ayy, Azz) of the two Cu2+ centers in disodium malonate trihydrate (DSMT) single crystal are theoretically interpreted using the high order perturbation formulas of these parameters for a 3d9 ions in rhombically elongated octahedra. In the calculation, the rhombic crystal-field parameters are determined from the superposition model and the admixture of d-orbitals in the ground state wave function are taking account, the results show that although the admixture of the | d z 2 > state to the ground state wave function is small, it should not be neglected in calculations of the EPR parameters. The theoretical EPR parameters show good agreement with the observed values. The results are discussed.

  4. Hyperfine suppression of 2 {sup 3}S{sub 1} - 3 {sup 3}P{sub J} transitions in {sup 3}He.

    SciTech Connect

    Sulai, A.; Wu, Q.; Bishof, M.; Drake, G. W. F.; Lu, Z.-T.; Mueller, P.; Santra, R.; Univ. of Chicago; Univ. of Winsdor

    2008-01-01

    Two anomalously weak transitions within the 2{sup 3}S{sub 1}-3{sup 3}P{sub J} manifolds in {sup 3}He have been identified. Their transition strengths are measured to be 1000 times weaker than that of the strongest transition in the same group. This dramatic suppression of transition strengths is due to the dominance of the hyperfine interaction over the fine-structure interaction. An alternative selection rule based on IS coupling (where the nuclear spin is first coupled to the total electron spin) is proposed. This provides qualitative understanding of the transition strengths. It is shown that the small deviations from the IS coupling model are fully accounted for by an exact diagonalization of the strongly interacting states.

  5. Effect of hyperfine-induced spin mixing on the defect-enabled spin blockade and spin filtering in GaNAs

    NASA Astrophysics Data System (ADS)

    Puttisong, Y.; Wang, X. J.; Buyanova, I. A.; Chen, W. M.

    2013-03-01

    The effect of hyperfine interaction (HFI) on the recently discovered room-temperature defect-enabled spin-filtering effect in GaNAs alloys is investigated both experimentally and theoretically based on a spin Hamiltonian analysis. We provide direct experimental evidence that the HFI between the electron and nuclear spin of the central Ga atom of the spin-filtering defect, namely, the Gai interstitials, causes strong mixing of the electron spin states of the defect, thereby degrading the efficiency of the spin-filtering effect. We also show that the HFI-induced spin mixing can be suppressed by an application of a longitudinal magnetic field such that the electronic Zeeman interaction overcomes the HFI, leading to well-defined electron spin states beneficial to the spin-filtering effect. The results provide a guideline for further optimization of the defect-engineered spin-filtering effect.

  6. Energy, fine structure, hyperfine structure, and radiative transition rates of the high-lying multi-excited states for B-like neon

    NASA Astrophysics Data System (ADS)

    Zhang, Chun Mei; Chen, Chao; Sun, Yan; Gou, Bing Cong; Shao, Bin

    2015-04-01

    The Rayleigh-Ritz variational method with multiconfiguration interaction wave functions is used to obtain the energies of high-lying multi-excited quartet states 1 s 22 s2 pnl and 1 s 22 p 2 nl 4Pe,o ( n ≥ 2) in B-like neon, including the mass polarization and relativistic corrections. The fine structure and hyperfine structure of the excited quartet states for this system are investigated. Configuration structures of the high-lying multi-excited series are further identified by relativistic corrections and fine structure splittings. The transition rates and wavelengths are also calculated. Calculated wavelengths include the quantum electrodynamic effects. The results are compared with other theoretical and experimental data in the literature.

  7. The magnetic behavior of the intermetallic compound NdMn{sub 2}Ge{sub 2} studied by magnetization and hyperfine interactions measurements

    SciTech Connect

    Bosch-Santos, B. Carbonari, A. W.; Cabrera-Pasca, G. A.; Saxena, R. N.; Freitas, R. S.

    2015-05-07

    The magnetic behavior of the intermetallic compound NdMn{sub 2}Ge{sub 2} was investigated by bulk magnetization measurements and measurements of hyperfine interactions using perturbed γ–γ angular correlation (PAC) spectroscopy. Magnetization measurements indicate the presence of four magnetic transitions associated with the Mn and Nd magnetic sublattices. At high temperatures, magnetic measurements show a change in the slope of the magnetization due to an antiferromagnetic transition around T{sub N} ∼ 425 K and a well defined ferromagnetic transition at T{sub C} ∼ 320 K. Moreover, at ∼210 K a peak is observed in the magnetization curve, which is assigned to the reorientation of the Mn spin, and at ∼25 K an increase in the magnetic moment is also observed, which is ascribed to the ordering of Nd ions. PAC measurements using {sup 140}La({sup 140}Ce) and {sup 111}In({sup 111}Cd) probe nuclei allowed the determination of the temperature dependence of the magnetic hyperfine field (B{sub hf}) at Nd and Mn sites, respectively. PAC results with {sup 111}Cd probe nuclei at Mn sites show that the dependence of B{sub hf} with temperature follows the expected behavior for the host magnetization associated with the magnetic ordering of Mn ions. From these results, the antiferromagnetic transition followed by a ferromagnetic ordering is clearly observed. PAC results with {sup 140}Ce probe nuclei at Nd sites, however, showed a strong deviation from the Brillouin function, which is attributed to the Ce 4f-electron contribution to B{sub hf}.

  8. Relativistic unitary coupled-cluster study of the electric quadrupole moment and magnetic dipole hyperfine constants of {sup 199}Hg{sup +}

    SciTech Connect

    Sur, Chiranjib; Chaudhuri, Rajat K.

    2007-09-15

    Searching for an accurate optical clock which can serve as a better time standard than the present-day atomic clock is highly demanding from several areas of science and technology. Several attempts have been made to build more accurate clocks with different ion species. In this paper, we discuss the electric quadrupole and hyperfine shifts in the 5d{sup 9}6s{sup 2} {sup 2}D{sub 5/2}(F=0,m{sub F}=0){r_reversible}5d{sup 10}6s {sup 2}S{sub 1/2}(F=2,m{sub F}=0) clock transition in {sup 199}Hg{sup +}, one of the most promising candidates for next-generation optical clocks. We have applied Fock-space unitary coupled-cluster theory to study the electric quadrupole moment of the 5d{sup 9}6s{sup 2} {sup 2}D{sub 5/2} state and magnetic dipole hyperfine constants of 5d{sup 9}6s{sup 2} {sup 2}D{sub 3/2,5/2} and 5d{sup 10}6s{sup 1} {sup 2}S{sub 1/2} states, respectively, of {sup 199}Hg{sup +}. We have also compared our results with available data. To the best of our knowledge, this is the first time a variant of coupled-cluster theories has been applied to study these kinds of properties of Hg{sup +} and is the most accurate estimate of these quantities to date.

  9. Mössbauer spectroscopy of H, L and LL ordinary chondrites

    NASA Astrophysics Data System (ADS)

    Maksimova, A. A.; Oshtrakh, M. I.; Petrova, E. V.; Grokhovsky, V. I.; Semionkin, V. A.

    2016-12-01

    Fifteen fragments of H, L and LL ordinary chondrites were studied using Mössbauer spectroscopy with a high velocity resolution at 295 K. A new approach to fit troilite magnetic sextet using simulation of the full static Hamiltonian was applied that decreased spectra misfits. This approach permitted to obtain more correct and reliable parameters for the minor spectral components. Small variations in the 57Fe hyperfine parameters were revealed for the M1 and M2 sites in both olivine and orthopyroxene as well as for α-Fe(Ni, Co), α 2-Fe(Ni, Co) and γ-Fe(Ni, Co) phases in different ordinary chondrites. Some Mössbauer parameters showed the possibility to distinguish ordinary chondrites from H, L and LL groups that may be useful for their systematics.

  10. Hyperfine splitting of the 2s1/2 and 2p1/2 levels in lithium-like Pr56+

    SciTech Connect

    Trabert, E.; Beiersdorfer, P.; Brown, G. V.; Clementson, J.; Thorn, D. B.; Chen, M. H.; Cheng, K. T.; Sapirstein, J.

    2015-01-29

    Measurements of hyperfine splittings in highly charged ions are sensitive to details of the nuclear structure and the nuclear magnetic field distribution, but the proper interpretation of the measurements requires that the atomic structure is understood in sufficient detail. Lastly, we discuss the reasoning behind various recent experiments and what advantage is offered by the study of the Li-like ion of a mid-Z element such as praseodymium.

  11. Investigations of the EPR Parameters and Local Lattice Structure for the Rhombic Cu2+ Centre in TZSH Crystal

    NASA Astrophysics Data System (ADS)

    Li, Chao-Ying; Liu, Shi-Fei; Fu, Jin-Xian

    2016-03-01

    The electron paramagnetic resonance (EPR) parameters [i.e. g factors gi (i=x, y, z) and hyperfine structure constants Ai] and the local lattice structure for the Cu2+ centre in Tl2Zn(SO4)2·6H2O (TZSH) crystal were theoretically investigated by utilising the perturbation formulae of these parameters for a 3d9 ion under rhombically elongated octahedra. In the calculations, the admixture of d orbitals in the ground state and the ligand orbital and spin-orbit coupling interactions are taken into account based on the cluster approach. The theoretical EPR parameters show good agreement with the observed values, and the Cu2+-H2O bond lengths are obtained as follows: Rx≈1.98 Å, Ry≈2.09 Å, Rz≈2.32 Å. The results are discussed.

  12. Rotational and Hyperfine Structure in the [17.6]2.5 - X2.5 and [23.3]2.5 - X2.5 Transitions of Iridium Monoxide

    NASA Astrophysics Data System (ADS)

    Linton, C.; Tokaryk, D. W.; Adam, A. G.; Daigle, J. A.; Esson, L. M.; Granger, A. D.; Smith, A. M.; Steimle, T. C.

    2013-06-01

    Laser induced fluorescence spectra of two electronic transitions, [17.6]2.5 - X2.5 and [23.3]2.5 - X2.5, of IrO have been obtained at high resolution by using a single mode ring dye laser to excite IrO molecules in a laser-ablation molecular beam source. From spectra taken at the University of New Brunswick at a linewidth of 180 MHz, the ^{193}IrO - ^{191}IrO isotope shifts in the rotational lines established the vibrational assignment of the [23.3]2.5 - X2.5 band as 1 - 0 and confirmed previous 0 - 0 assignments of the [17.6]2.5 - X2.5 band. The higher J rotational lines of both transitions are observed to split into closely spaced doublets resulting from quadrupole hyperfine structure caused by the I = 3/2 nuclear spin on both Ir isotopes. Higher resolution [17.6]2.5 - X2.5 spectra with an approximate linewidth of 30 MHz, were taken at Arizona State University and showed clearly resolved hyperfine structure in the low J lines. The results of the hyperfine structure analysis will be discussed as well as (hopefully) Stark and Zeeman effect experiments to determine the permanent electric and the magnetic dipole moments of IrO.

  13. Cd hyperfine interactions in DNA bases and DNA of mouse strains infected with Trypanosoma cruzi investigated by perturbed angular correlation spectroscopy and ab initio calculations.

    PubMed

    Petersen, Philippe A D; Silva, Andreia S; Gonçalves, Marcos B; Lapolli, André L; Ferreira, Ana Maria C; Carbonari, Artur W; Petrilli, Helena M

    2014-06-03

    In this work, perturbed angular correlation (PAC) spectroscopy is used to study differences in the nuclear quadrupole interactions of Cd probes in DNA molecules of mice infected with the Y-strain of Trypanosoma cruzi. The possibility of investigating the local genetic alterations in DNA, which occur along generations of mice infected with T. cruzi, using hyperfine interactions obtained from PAC measurements and density functional theory (DFT) calculations in DNA bases is discussed. A comparison of DFT calculations with PAC measurements could determine the type of Cd coordination in the studied molecules. To the best of our knowledge, this is the first attempt to use DFT calculations and PAC measurements to investigate the local environment of Cd ions bound to DNA bases in mice infected with Chagas disease. The obtained results also allowed the detection of local changes occurring in the DNA molecules of different generations of mice infected with T. cruzi, opening the possibility of using this technique as a complementary tool in the characterization of complicated biological systems.

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

    SciTech Connect

    Lim, Jung Tae; Kim, Chul Sung

    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.

  15. Calculations with spectroscopic accuracy for energies, transition rates, hyperfine interaction constants, and Landé gJ-factors in nitrogen-like Kr XXX

    NASA Astrophysics Data System (ADS)

    Wang, K.; Li, S.; Jönsson, P.; Fu, N.; Dang, W.; Guo, X. L.; Chen, C. Y.; Yan, J.; Chen, Z. B.; Si, R.

    2017-01-01

    Extensive self-consistent multi-configuration Dirac-Fock (MCDF) calculations and second-order many-body perturbation theory (MBPT) calculations are performed for the lowest 272 states belonging to the 2s22p3, 2s2p4, 2p5, 2s22p23l, and 2s2p33l (l=s, p, d) configurations of N-like Kr XXX. Complete and consistent data sets of level energies, wavelengths, line strengths, oscillator strengths, lifetimes, AJ, BJ hyperfine interaction constants, Landé gJ-factors, and electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), magnetic quadrupole (M2) transition rates among all these levels are given. The present MCDF and MBPT results are compared with each other and with other available experimental and theoretical results. The mean relative difference between our two sets of level energies is only about 0.003% for these 272 levels. The accuracy of the present calculations are high enough to facilitate identification of many observed spectral lines. These accurate data can be served as benchmark for other calculations and can be useful for fusion plasma research and astrophysical applications.

  16. Structure and function of quinones in biological solar energy transduction: a differential pulse voltammetry, EPR, and hyperfine sublevel correlation (HYSCORE) spectroscopy study of model benzoquinones.

    PubMed

    Weyers, Amanda M; Chatterjee, Ruchira; Milikisiyants, Sergey; Lakshmi, K V

    2009-11-19

    Quinones are widely used electron transport cofactors in photosynthetic reaction centers. Previous studies have suggested that the structure of the quinone cofactors and the protein interactions or "smart" matrix effects from the surrounding environment govern the redox potential and hence the function of quinones in photosynthesis. In the present study, a series of 1,4-benzoquinone models are examined via differential pulse voltammetry to provide relative redox potentials. In parallel, CW and pulsed EPR methods are used to directly determine the electronic properties of each benzoquinone in aprotic and protic environments. The shifts in the redox potential of the quinones are found to be dependent on the nature of the substituent group and the number of substituent groups on the quinone molecule. Further, we establish a direct correlation between the nature of the substituent group and the change in electronic properties of the benzosemiquinone by analysis of the isotropic and anisotropic components of the electron-nuclear hyperfine interactions observed by CW and pulsed EPR studies, respectively. Examination of an extensive library of model quinones in both aprotic and protic solvents indicates that hydrogen-bonding interactions consistently accentuate the effects of the substituent groups of the benzoquinones. This study provides direct support for the tuning and control of quinone cofactors in biological solar energy transduction through interactions with the surrounding protein matrix.

  17. Hyperfine and magnetic properties of a Y{sub x}La{sub 1−x}FeO{sub 3} series (0 ≤ x ≤ 1)

    SciTech Connect

    Cristóbal, A.A.; Botta, P.M.; Bercoff, P.G.

    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.

  18. Nuclear magnetization distribution radii determined by hyperfine transitions in the 1s level of H-like ions 185Re74+ and 187Re74+

    NASA Astrophysics Data System (ADS)

    Crespo López-Urrutia, J. R.; Beiersdorfer, P.; Widmann, K.; Birkett, B. B.; Mårtensson-Pendrill, A.-M.; Gustavsson, M. G. H.

    1998-02-01

    The F=3 to F=2 hyperfine transitions in the 1s ground state of the two isotopes 185Re74+ and 187Re74+ were measured to be (4560.5+/-3) Å and (4516.9+/-3) Å, respectively, using emission spectroscopy in an electron beam ion trap. After applying appropriate corrections for the nuclear charge distribution and QED effects, a Bohr-Weisskopf effect of ɛ=2.23(9)% and 2.30(9)% are found for 185Re and 187Re, respectively. This value is almost twice that of a previous theoretical estimate, and indicates a distribution of the nuclear magnetization far more extended than that of the nuclear charge. A radius of the magnetization distribution of 1/2=7.57(32) fm and 1/2=7.69(32) fm for 185Re and 187Re, respectively, is inferred from the data. These radii are larger than the nuclear charge distribution radius [1/2=5.39(1) fm] for both isotopes by factors 1.40(6) and 1.43(6), respectively. We find that the Bohr-Weisskopf effect in H-like ions is a sensitive probe of nuclear magnetization distribution, especially for cases where the charge distribution and magnetic moments are accurately known.

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

    SciTech Connect

    Rowe, Mary Anderson

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

    SciTech Connect

    Wood, M. P.; Lawler, J. E.; Den Hartog, E. A.; Sneden, C.; Cowan, J. J. E-mail: jelawler@wisc.edu E-mail: chris@verdi.as.utexas.edu

    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.

  1. Detection and classification of hyperfine-shifted 1H, 2H, and 15N resonances of the Rieske ferredoxin component of toluene 4-monooxygenase.

    PubMed

    Xia, B; Pikus, J D; Xia, W; McClay, K; Steffan, R J; Chae, Y K; Westler, W M; Markley, J L; Fox, B G

    1999-01-12

    T4MOC is a 12.3 kDa soluble Rieske ferredoxin that is obligately required for electron transfer between the oxidoreductase and diiron hydroxylase components of toluene 4-monooxygenase from Pseudomonas mendocina KR1. Our preliminary 1H NMR studies of oxidized and reduced T4MOC [Markley, J. L., Xia, B., Chae, Y. K., Cheng, H., Westler, W. M., Pikus, J. D., and Fox, B. G. (1996) in Protein Structure Function Relationships (Zaidi, Z., and Smith, D., Eds.) pp 135-146, Plenum Press, London] revealed the presence of hyperfine-shifted 1H resonances whose short relaxation times made it impractical to use nuclear Overhauser effect (NOE) measurements for assignment purposes. We report here the use of selective isotopic labeling to analyze the hyperfine-shifted 1H, 2H, and 15N signals from T4MOC. Selective deuteration led to identification of signals from the four Hbeta atoms of cluster ligands C45 and C64 in the oxidized and reduced forms of T4MOC. In the reduced state, the Curie temperature dependence of the Hbeta protons corresponded to that predicted from the simple vector spin-coupling model for nuclei associated with the localized ferric site. The signal at 25.5 ppm in the 1H spectrum of reduced T4MOC was assigned on the basis of selective 2H labeling to the His Hepsilon1 atom of one of the cluster ligands (H47 or H67). This assignment was corroborated by a one bond 1H-13C correlation (at 25.39 ppm 1H and 136.11 ppm 13C) observed in spectra of [U-13C]T4MOC with a 1H-13C coupling constant of approximately 192 Hz. The carbon chemical shift and one bond coupling constant are those expected for 1Hepsilon1-13Cepsilon1 in the imidazolium ring of histidine and are inconsistent with values expected for cysteine 1Halpha-13Calpha. The His Hepsilon1 proton exhibited weak Curie temperature dependence from 283 to 303 K, contrary to the anti-Curie temperature dependence predicted from the spin coupling model for nuclei associated with the localized ferrous site. A 1H peak at -12.3 ppm

  2. The Electronic Structure of Metallic and Bimetallic Clusters of IRON-57 with Chromium, TIN-119 and Platinum.

    NASA Astrophysics Data System (ADS)

    Nagarathna, H. M.

    Rare gas matrix isolation techniques have been used in conjunction with Mossbauer spectroscopy to study the bimetallic clusters of ('57)Fe with Cr, ('119)Sn and Pt. Various molecules have been identified by concentration and temperature dependence studies and also with the aid of Monte Carlo calculations. The iron-tin system is studied using both ('57)Fe and ('119)Sn Mossbauer isotopes. The Mossbauer parameters of FeCr, FeSn and FePt heteronuclear diatomic molecules and Sn(,2) homonuclear diatomic molecules isolated in argon at 4.2 K are obtained very accurately and used to determine their electronic ground states. In addition to diatomic molecules, the larger clusters have also been characterized using Mossbauer spectroscopy and their relevance to bulk alloys is discussed. SCF-X(alpha)-SW molecular orbital calculations are performed on Fe(,2), FeCr, Sn(,2), FeSn and FePt diatomic molecules to determine their electronic ground states by looking at the calculations which agreed with the measured Mossbauer hyperfine parameters. The most probable electronic ground state for Fe(,2) is determined to be a ('7)(SIGMA)(,g) and for FeCr a ('7)(SIGMA) or ('7)(DELTA) indicating a ferromagnetic coupling between the atoms. The calculations indicated a need for a smaller value of the quadrupole moment of the ('57)Fe nucleus. For Sn(,2) a ('3)(SIGMA)(,g) is the most probable ground state and for FeSn a ('7)(DELTA). The calculations showed a ('5)(SIGMA) state as the most probable electronic ground state for FePt. The X(alpha)-SW calculations are found to be very useful in understanding the nature of chemical bonding between the atoms in the above molecules. Antimony metal clusters are also studied using ('121)Sb Mossbauer spectroscopy and extended Huckel molecular orbital calculations. A good correlation is observed between the experimental and calculated data.

  3. Density functional calculations of (55)Mn, (14)N and (13)C electron paramagnetic resonance parameters support an energetically feasible model system for the S(2) state of the oxygen-evolving complex of photosystem II.

    PubMed

    Schinzel, Sandra; Schraut, Johannes; Arbuznikov, Alexei V; Siegbahn, Per E M; Kaupp, Martin

    2010-09-10

    Metal and ligand hyperfine couplings of a previously suggested, energetically feasible Mn(4)Ca model cluster (SG2009(-1)) for the S(2) state of the oxygen-evolving complex (OEC) of photosystem II (PSII) have been studied by broken-symmetry density functional methods and compared with other suggested structural and spectroscopic models. This was carried out explicitly for different spin-coupling patterns of the S=1/2 ground state of the Mn(III)(Mn(IV))(3) cluster. By applying spin-projection techniques and a scaling of the manganese hyperfine couplings, computation of the hyperfine and nuclear quadrupole coupling parameters allows a direct evaluation of the proposed models in comparison with data obtained from the simulation of EPR, ENDOR, and ESEEM spectra. The computation of (55)Mn hyperfine couplings (HFCs) for SG2009(-1) gives excellent agreement with experiment. However, at the current level of spin projection, the (55)Mn HFCs do not appear sufficiently accurate to distinguish between different structural models. Yet, of all the models studied, SG2009(-1) is the only one with the Mn(III) site at the Mn(C) center, which is coordinated by histidine (D1-His332). The computed histidine (14)N HFC anisotropy for SG2009(-1) gives much better agreement with ESEEM data than the other models, in which Mn(C) is an Mn(IV) site, thus supporting the validity of the model. The (13)C HFCs of various carboxylates have been compared with (13)C ENDOR data for PSII preparations with (13)C-labelled alanine.

  4. Determination of μd chemistry kinetic parameters for the MuSun Experiment

    NASA Astrophysics Data System (ADS)

    Raha, Nandita

    2014-09-01

    The MuSun experiment at PSI will measure the muon doublet capture rate Λd in ultra pure deuterium gas to 1.5% precision from the measured decay-electron time distribution. This reaction cleanly determines the strength of the two-nucleon weak axial current interaction. The kinetic parameters of the μd chemistry are essential for extracting Λd, which in turn are determined from the process of muon catalyzed fusion in deuterium. This process yields 3 He recoils and 2.45 MeV monoenergetic neutrons from the reaction ddμ -->3 He + n + μ . Encoded in the time dependence of the fusion products are the ddμ molecular formation rates from the F = 1 / 2 , 3 / 2 hyperfine states (λd and λq) and the hyperfine transition rate (λqd) from the higher-energy F = 3 / 2 state to the lower-energy F = 1 / 2 state. This work concentrates on the analysis of the fusion neutrons, which are detected by an array of eight neutron detectors. Pulse shape discrimination was used to distinguish neutrons from background gamma rays. A least squared fit to the time spectrum of the fusion neutrons determines the μd chemistry kinetic parameters λqd and the ratio λq / λd. The MuSun experiment at PSI will measure the muon doublet capture rate Λd in ultra pure deuterium gas to 1.5% precision from the measured decay-electron time distribution. This reaction cleanly determines the strength of the two-nucleon weak axial current interaction. The kinetic parameters of the μd chemistry are essential for extracting Λd, which in turn are determined from the process of muon catalyzed fusion in deuterium. This process yields 3 He recoils and 2.45 MeV monoenergetic neutrons from the reaction ddμ -->3 He + n + μ . Encoded in the time dependence of the fusion products are the ddμ molecular formation rates from the F = 1 / 2 , 3 / 2 hyperfine states (λd and λq) and the hyperfine transition rate (λqd) from the higher-energy F = 3 / 2 state to the lower-energy F = 1 / 2 state. This work concentrates

  5. Redefining solubility parameters: the partial solvation parameters.

    PubMed

    Panayiotou, Costas

    2012-03-21

    The present work reconsiders a classical and universally accepted concept of physical chemistry, the solubility parameter. Based on the insight derived from modern quantum chemical calculations, a new definition of solubility parameter is proposed, which overcomes some of the inherent restrictions of the original definition and expands its range of applications. The original single solubility parameter is replaced by four partial solvation parameters reflecting the dispersion, the polar, the acidic and the basic character of the chemical compounds as expressed either in their pure state or in mixtures. Simple rules are adopted for the definition and calculation of these four parameters and their values are tabulated for a variety of common substances. In contrast, however, to the well known Hansen solubility parameters, their design and evaluation does not rely exclusively on the basic rule of "similarity matching" for solubility but it makes also use of the other basic rule of compatibility, namely, the rule of "complementarity matching". This complementarity matching becomes particularly operational with the sound definition of the acidic and basic components of the solvation parameter based on the third σ-moments of the screening charge distributions of the quantum mechanics-based COSMO-RS theory. The new definitions are made in a simple and straightforward manner, thus, preserving the strength and appeal of solubility parameter stemming from its simplicity. The new predictive method has been applied to a variety of solubility data for systems of pharmaceuticals and polymers. The results from quantum mechanics calculations are critically compared with the results from Abraham's acid/base descriptors.

  6. The Magnetic Properties of Mn0.3Mg0.2Zn0.5Fe2O4 and Mn0.3Mg0.2Co0.5Fe2O4: The Effect of Milling

    NASA Astrophysics Data System (ADS)

    Dlamini, W. B.; Msomi, J. Z.; Moyo, T.

    Mn0.3Mg0.2Zn0.5Fe2O4 and Mn0.3Mg0.2Co0.5Fe2O4 nanoparticles with particle diameters of about 13 nm were synthesized by glycol-thermal method. The as-prepared specimens were then milled at different times up to 50 h and the single phase spinel structure confirmed by X-ray diffraction. The properties for the as-prepared and milled samples for the two systems were deduced and contrasted. Significant changes induced by milling in particle size, magnetization, coercive field and hyperfine parameters are reported. 57Fe Mössbauer spectra at room temperature show ordered magnetic spin states in both Mn0.3Mg0.2Zn0.5Fe2O4 and Mn0.3Mg0.2Co0.5Fe2O4 by magnetization measurements.

  7. Anomalies in magnetoelastic properties of DyFe{sub 11.2}Nb{sub 0.8} compound

    SciTech Connect

    Wang, J. L.; Md Din, M. F.; Cheng, Z. X.; Dou, S. X.; Kennedy, S. J.; Campbell, S. J.; Kimpton, J. A.

    2015-05-07

    The structural and magnetic properties of DyFe{sub 11.2}Nb{sub 0.8} compound have been investigated by high intensity, high resolution synchrotron x-ray diffraction, ac magnetic susceptibility, and dc magnetization measurements as well as Mössbauer spectroscopy (5–300 K). The easy magnetization direction at room temperature is along the c-axis. With decreasing temperature, the magnetocrystalline anisotropy changes from easy-axis to easy-cone at T{sub sr2} (∼202 K), then to easy plane at T{sub sr1} (∼94 K). The thermal expansion coefficient obtained from the synchrotron x-ray study exhibits clear anomalies around both of the spin reorientation transition temperatures. The {sup 57}Fe hyperfine interaction parameters and magnetic moments values have been determined for the 8i, 8j, and 8f sites from the Mössbauer spectra.

  8. Comparative study of the iron cores in human liver ferritin, its pharmaceutical models and ferritin in chicken liver and spleen tissues using Mössbauer spectroscopy with a high velocity resolution.

    PubMed

    Alenkina, I V; Oshtrakh, M I; Klepova, Yu V; Dubiel, S M; Sadovnikov, N V; Semionkin, V A

    2013-01-01

    Application of Mössbauer spectroscopy with a high velocity resolution (4096 channels) for comparative analysis of iron cores in a human liver ferritin and its pharmaceutically important models Imferon, Maltofer(®) and Ferrum Lek as well as in iron storage proteins in chicken liver and spleen tissues allowed to reveal small variations in the (57)Fe hyperfine parameters related to differences in the iron core structure. Moreover, it was shown that the best fit of Mössbauer spectra of these samples required different number of components. The latter may indicate that the real iron core structure is more complex than that following from a simple core-shell model. The effect of different living conditions and age on the iron core in chicken liver was also considered.

  9. Effect of Cu and Zn Substitutions on MnSb Properties

    SciTech Connect

    Mitsiuk, V. I.; Ryzhkovskii, V. M.; Tkachenka, T. M.

    2008-10-28

    The NiAs-type solid solutions based on manganese antimonide Mn{sub 1.1}Sb with Zn or Cu (up to 10 at % of substituting component) have been studied by {sup 57}Fe Moessbauer spectroscopy. It has been shown that the replacement of the manganese antimonide by Cu or Zn does not appreciably affect the main Moessbauer parameters in comparison to those of the parent compound. Two different values of hyperfine magnetic field at Fe are present in all the samples and can be attributed to the metal atoms located in MeI and MeII positions. The substitution of Cu or Zn for manganese antimonide leads to the redistribution of the metal atoms between two cation sublattices.

  10. The optical depth of the 158 micrometer (C-12 II) line: Detection of the F=1 yields 0 (C-13 III) hyperfine-structure component

    NASA Technical Reports Server (NTRS)

    Stacey, G. J.; Townes, C. H.; Poglitsch, A.; Madden, S. C.; Jackson, J. M.; Herrmann, F.; Genzel, R.; Geis, N.

    1991-01-01

    The first detection of the F = 1 yields 0 hyperfine component of the 158 micrometer (C-13 II) fine structure line in the interstellar medium is reported. A twelve point intensity map was obtained of the (C-13 II) distribution over the inner 190 inch (right ascension) by 190 inch (declination) regions of the Orion nebula using an imaging Fabry-Perot interferometer. The (C-12 II)/(C-13 II) line intensity ratio varied significantly over the region mapped. It is highest (86 plus or minus 9) in the core of the Orion H II region and significantly lower (62 plus or minus 7) in the outer regions of the map, reflecting higher optical depth in the (C-12 II) line here. It is suggested that this enhanced optical depth is the result of limb brightening of the optically thin (C-13 II) line at the edges of the bowl-shaped H II region blister. If the C-12/C-13 abundance ratio is 43, the (C-12 II) line in the inner regions of the Orion nebula, has a low optical depth: tau sub 12 approximately = 0.75 plus or minus 0.25. The optical depth together with the large brightness temperature of the (C-12 II) line (approximately 160 K) requires that the excitation temperature of the P-2 sub 3/2 level be approximately 310 K, in very good agreement with the previous analysis of the physical conditions of the Orion interface region based on fine structure line intensity ratios and photodissociation region models. If the C-12/C-13 abundance ratio is 67, the line optical depth is somewhat larger (tau sub 12 approximately = 1.85), and the transition excitation temperature is somewhat smaller (approximately 190 K) than that predicted by these models. The present results therefore support values approximately = 43 for the C-12/C-13 abundance ratio in the Orion nebula.

  11. Nonlinear magneto-optical resonances at D{sub 1} excitation of {sup 85}Rb and {sup 87}Rb for partially resolved hyperfine F levels

    SciTech Connect

    Auzinsh, M.; Ferber, R.; Gahbauer, F.; Jarmola, A.; Kalvans, L.

    2009-05-15

    Experimental signals of nonlinear magneto-optical resonances at D{sub 1} excitation of natural rubidium in a vapor cell have been obtained and described with experimental accuracy by a detailed theoretical model based on the optical Bloch equations. The D{sub 1} transition of rubidium is a challenging system to analyze theoretically because it contains transitions that are only partially resolved under Doppler broadening. The theoretical model took into account all nearby transitions, the coherence properties of the exciting laser radiation, and the mixing of magnetic sublevels in an external magnetic field and also included averaging over the Doppler profile. The experimental signals were reproduced very well at each hyperfine transition and over a wide range of laser power densities, beam diameters, and laser detunings from the exact transition frequency. The bright resonance expected at the F{sub g}=1{yields}F{sub e}=2 transition of {sup 87}Rb has been observed. A bright resonance was observed at the F{sub g}=2{yields}F{sub e}=3 transition of {sup 85}Rb, but displaced from the exact position of the transition due to the influence of the nearby F{sub g}=2{yields}F{sub e}=2 transition, which is a dark resonance whose contrast is almost 2 orders of magnitude larger than the contrast of the bright resonance at the F{sub g}=2{yields}F{sub e}=3 transition. Even in this very delicate situation, the theoretical model described in detail the experimental signals at different laser detunings.

  12. THEORETICAL RESEARCH OF THE OPTICAL SPECTRA AND EPR PARAMETERS FOR Cs2NaYCl6:Dy3+ CRYSTAL

    NASA Astrophysics Data System (ADS)

    Dong, Hui-Ning; Dong, Meng-Ran; Li, Jin-Jin; Li, Deng-Feng; Zhang, Yi

    2013-09-01

    The calculated EPR parameters are in reasonable agreement with the observed values. The important material Cs2NaYCl6 doped with rare earth ions have received much attention because of its excellent optical and magnetic properties. Based on the superposition model, in this paper the crystal field energy levels, the electron paramagnetic resonance parameters g factors of Dy3+ and hyperfine structure constants of 161Dy3+ and 163Dy3+ isotopes in Cs2NaYCl6 crystal are studied by diagonalizing the 42 × 42 energy matrix. In the calculations, the contributions of various admixtures and interactions such as the J-mixing, the mixtures among the states with the same J-value, and the covalence are all considered. The calculated results are in reasonable agreement with the observed values. The results are discussed.

  13. Synthesis of α-Fe{sub 2}O{sub 3}-functionalised graphene oxide nanocomposite by a facile low temperature method and study of its magnetic and hyperfine properties

    SciTech Connect

    Nag, Sanchayita; Roychowdhury, Anirban; Das, Dipankar

    2016-02-15

    Highlights: • Synthesis of reduced graphene oxide (rGO)/α-Fe{sub 2}O{sub 3} nanocomposites (NCs) by sol–gel method. • Samples exhibited ferromagnetism originated due to surface canted spins. • rGO enhanced the value of saturation magnetization and coercivity of the bare nanoparticle. • RKKY coupling between the isolated rGO spins and the magnetic nanoparticles. - Abstract: Reduced graphene oxide/α-Fe{sub 2}O{sub 3} nanocomposites were synthesized by a simple sol–gel method. Initially, the samples were investigated by X-ray diffraction, high resolution transmission electron microscopy and Raman spectroscopy. High resolution transmission electron micrographs indicate that the magnetic nanoparticles are well dispersed in the reduced graphene oxide sheet-like structure. Fourier transform infrared spectroscopy studies corroborate the results obtained by X-ray diffraction. Temperature as well as field dependent magnetic measurements revealed ferromagnetism in the pristine α-Fe{sub 2}O{sub 3} as well as in the nanocomposite sample that is attributed to surface canted spins and defects present in the samples. The enhanced value of coercivity in case of the nanocomposite sample could be ascribed to the Ruderman–Kittel–Kasuya–Yosida type of interaction between the isolated reduced graphene oxide spin and the magnetic ions. Presence of super paramagnetic doublet as well as sextet patterns related to hematite phase is confirmed by the {sup 57}Fe-Mössbauer spectroscopy.

  14. Resonant nuclear scattering of synchrotron radiation: Detector development and specular scattering from a thin layer of {sup 57}Fe

    SciTech Connect

    Baron, A.Q.R.

    1995-04-01

    This thesis explores resonant nudear scattering of synchrotron radiation. An introductory chapter describes some useful concepts, such as speedup and coherent enhancement, in the context of some basic physical principles. Methods of producing highly monochromatic synchrotron beams usmg either electronic or nuclear scattering are also discussed. The body of the thesis concentrates on detector development and specular scattering from iynthetic layered materials. A detector employing n-dcrochannel plate electron multipliers is shown to have good ({approximately}50%) effidency for detecting 14.4 key x-rays incident at small ({approximately}0.5 degree) grazing angles onto Au or CsI photocathodes. However, being complicated to use, it was replaced with a large area (>=lan2) avalanche photodiode (APD) detector. The APD`s are simpler to use and have comparable (30--70%) efficiencies at 14.4 key, subnanosecond time resolution, large dynan-dc range (usable at rates up to {approximately}10{sup 8} photons/second) and low (<{approximately}0.01 cts/sec) background rates. Maxwell`s equations are used to derive the specular x-ray reflectivity of layered materials with resonant transitions and complex polarization dependencies. The effects of interfadal roughness are treated with some care, and the distorted wave Born approximation (DWBA) used to describe electronic scattering is generalized to the nuclear case. The implications of the theory are discussed in the context of grazing incidence measurements with emphasis on the kinematic and dynamical aspects of the scattering.

  15. 57Fe Mössbauer, SEM/EDX, p-XRF and μ-XRF studies on a Dutch painting

    NASA Astrophysics Data System (ADS)

    Lehmann, R.; Schmidt, H.-J.; Costa, B. F. O.; Blumers, M.; Sansano, A.; Rull, F.; Wengerowsky, D.; Nürnberger, F.; Maier, H. J.; Klingelhöfer, G.; Renz, F.

    2016-12-01

    The painting of a rich Jewish merchant "Bildnis eines jüdischen Kaufmanns" from the Netherlands is dated presumably to the 16th century. After a vivid historical background, i.e. robbed by the Nazis by order of Hermann Göring, it was recently discovered on an Austrian flea market. Different analysis methods were combined to identify the time of the production of this historically interesting looted art. Non-destructive MIMOS II Fe-57 Mössbauer spectroscopy was utilised for mesurements in selected spots. This mainly revealed haematite ( α-Fe2O3) in the red curtain. In spots of the brown jacket Mössbauer spectra indicated the presence of mainly Iron(III) in super-paramagnetic oxide or oxide-hydroxide. Consecutively SEM measurements revealed a restoration by partly over-painting. The elementary composition of the pigments was examined by a portable-X-ray fluorescence. μ-XRF analysis for element distribution at different areas was performed. The look into a crack showed Zinc-white at the bottom of the crack. Traces of Titanium-white could be found within some locations on the surface of the painting. In terms of provenance of the artwork, the presence of Zink-white suggests that the painting was painted around the 19th century. Titanium-white indicates a reconstruction during the 20th century, approximately between 1917 and 1958.

  16. The ν 2 and 2ν 2 - ν 2 bands of 14N 16O 2: Electron Spin-Rotation and Hyperfine Contact Resonances in the (010) Vibrational State

    NASA Astrophysics Data System (ADS)

    Perrin, A.; Flaud, J. M.; Camypeyret, C.; Goldman, A.; Murcray, F. J.; Blatherwick, R. D.; Rinsland, C. P.

    1993-08-01

    High-resolution Fourier transform spectra covering the 720-920 cm -1 spectral region have been used to perform a reanalysis of the ν 2 band ((010)-(000) vibrational transition) together with the first analysis of the 2ν 2 - ν 2 hot band of nitrogen dioxide ((020)-(010) vibrational transition). The high-quality spectra show that, for numerous ν 2 lines, the hyperfine structure is easily observable in the case of resonances due to the hyperfine Fermi-type operator. By performing a full treatment of the spin-rotation and of the hyperfine operators, a new line list of the ν 2 band (positions and intensities) has been generated, and it is in excellent agreement with the experimental spectrum. Also, a thorough analysis of the 2ν 2 - ν 2 hot band has been performed leading to an extended set of new (020) spin-rotation levels. These levels, together with the {(100), (020), (001)} spin-rotation levels deduced previously from the analysis of the ν 1, 2ν 2, and ν 3 cold bands performed in the 6.3- to 7.5-μm spectral range [A. Perrin, J.-M. Flaud, C. Camy-Peyret. A.-M. Vasserot, G. Guelachvili, A. Goldman, F. J. Murcray, and R. D. Blatherwick, J. Mol. Spectrosc.154, 391-406 (1992)] were least-squares fitted, allowing one to derive a new set of vibrational band centers and rotational, spin-rotation, and interaction constants for the {(l00)(020)(001)} interacting states of 14N 16O 2.

  17. Weak- and hyperfine-interaction-induced 1s2s 1S0 → 1s2 1S0 E1 transition rates of He-like ions

    NASA Astrophysics Data System (ADS)

    Laima, Radžiūtė; Erikas, Gaidamauskas; Gediminas, Gaigalas; Li, Ji-Guang; Dong, Chen-Zhong; Jönsson, Per

    2015-04-01

    Weak- and hyperfine-interaction-induced 1s2s 1S0 → 1s2 1S0 E1 transition rates for the isoelectronic sequence of He-like ions have been calculated using the multi-configuration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction methods. The results should be helpful for the future experimental investigations of parity non-conservation effects. Project supported by the National Natural Science Foundation of China (Grant Nos. 11274254, 11147108, 10979007, U1331122, and U1332206) and in part by the National Basic Research Program of China (Grant No. 2013CB922200).

  18. Theoretical research on the spin-Hamiltonian parameters of the rhombic W5+ centers in CaWO4:Y3+ crystal

    NASA Astrophysics Data System (ADS)

    Mei, Yang; Wei, Cheng-Fu; Zheng, Wen-Chen

    2016-02-01

    Detailed theoretical calculations for the spin-Hamiltonian parameters (g factors gi and hyperfine structure constants Ai, where i=x, y, z) of the rhombic W5+ center in CaWO4:Y3+ crystal are performed by using the high-order perturbation formulas for d1 ions in rhombic tetrahedral clusters with the ground state |dz2>. These formulas consist of the contributions from two mechanisms, the crystal-field (CF) mechanism connected with CF excited states in the vastly-used CF theory and the frequently-neglected charge-transfer (CT) mechanism related to CT excited states. The calculated results agree well with the experimental values. The calculations indicate that for W5+ ion (or other high valence state dn ions) in crystals, the model calculations of spin-Hamiltonian parameters should take both the CF and CT mechanisms into account. The signs of hyperfine structure constants Ai are suggested and the forming (or defect model) of rhombic W5+ center in CaWO4:Y3+ crystal is confirmed from the calculations.

  19. Parameter Plane Design Method

    DTIC Science & Technology

    1989-03-01

    Th usr a toente aninteer a thca sms b esta 1 Fp-ocsing 2. Enter P1 values, lwgt, ldig - > 9 Table I give us proper values. Table 1. PARAMETER TABLE...necessary and identify by block number) In this thesis a control systems analysis package is developed using parameter plane methods. It is an interactive...designer is able to choose values of the parameters which provide a good compromise between cost and dynamic behavior. 20 Distribution Availability of

  20. HYDROGEN ATOM THERMAL PARAMETERS.

    PubMed

    JENSEN, L H; SUNDARALINGAM, M

    1964-09-11

    Isotropic hydrogen atom thermal parameters for N,N'- hexamethylenebispropionamide have been determined. They show a definite trend and vary from approximately the same as the mean thermal parameters for atoms other than hydrogen near the center of the molecule to appreciably greater for atoms near the end. The indicated trend for this compound, along with other results, provides the basis for a possible explanation of the anomolous values that have been obtained for hydrogen atom thermal parameters.