EFFECTIVE HYPERFINE-STRUCTURE FUNCTIONS OF AMMONIA

DOE Office of Scientific and Technical Information (OSTI.GOV)

Augustovičová, L.; Soldán, P.; Špirko, V., E-mail: spirko@marge.uochb.cas.cz

The hyperfine structure of the rotation-inversion ( v {sub 2} = 0{sup +}, 0{sup −}, 1{sup +}, 1{sup −}) states of the {sup 14}NH{sub 3} and {sup 15}NH{sub 3} 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.more » 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.« less

Ground-state hyperfine splitting for Rb, Cs, Fr, Ba+, and Ra+

NASA Astrophysics Data System (ADS)

Ginges, J. S. M.; Volotka, A. V.; Fritzsche, S.

2017-12-01

We have systematically investigated the ground-state hyperfine structure for alkali-metal atoms 87Rb,133Cs, and 211Fr and alkali-metal-like ions +135Ba and +225Ra, which are of particular interest for parity violation studies. The quantum electrodynamic one-loop radiative corrections have been rigorously evaluated within an extended Furry picture employing core-Hartree and Kohn-Sham atomic potentials. Moreover, the effect of the nuclear magnetization distribution on the hyperfine structure intervals has been studied in detail and its uncertainty has been estimated. Finally, the theoretical description of the hyperfine structure has been completed with full many-body calculations performed in the all-orders correlation potential method.

Hyperfine structure of excited states and quadrupole moment of Ne-21 using laser-induced line-narrowing techniques.

NASA Technical Reports Server (NTRS)

Ducas, T. W.; Feld, M. S.; Ryan, L. W., Jr.; Skribanowitz, N.; Javan, A.

1972-01-01

Observation results are presented on the optical hyperfine structure in Ne-21 obtained with the aid of laser-induced line-narrowing techniques. The output from a long stabilized single-mode 1.15-micron He-Ne laser focused into an external sample cell containing Ne-21 was used in implementing these techniques. Their applicability is demonstrated for optical hyperfine structure observation in systems whose features are ordinarily masked by Doppler broadening.

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.

Fine- and hyperfine-structure effects in molecular photoionization. I. General theory and direct photoionization.

PubMed

Germann, Matthias; Willitsch, Stefan

2016-07-28

We develop a model for predicting fine- and hyperfine intensities in the direct photoionization of molecules based on the separability of electron and nuclear spin states from vibrational-electronic states. Using spherical tensor algebra, we derive highly symmetrized forms of the squared photoionization dipole matrix elements from which we derive the salient selection and propensity rules for fine- and hyperfine resolved photoionizing transitions. Our theoretical results are validated by the analysis of the fine-structure resolved photoelectron spectrum of O2 reported by Palm and Merkt [Phys. Rev. Lett. 81, 1385 (1998)] and are used for predicting hyperfine populations of molecular ions produced by photoionization.

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

NASA Astrophysics Data System (ADS)

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

2013-05-01

Hyperfine magnetic fields induced on the nuclei of nonmagnetic ions 139La and 89Y in LaTiO3 and YTiO3, 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.

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)

Fine- and hyperfine-structure effects in molecular photoionization. I. General theory and direct photoionization

DOE Office of Scientific and Technical Information (OSTI.GOV)

Germann, Matthias; Willitsch, Stefan, E-mail: stefan.willitsch@unibas.ch

2016-07-28

We develop a model for predicting fine- and hyperfine intensities in the direct photoionization of molecules based on the separability of electron and nuclear spin states from vibrational-electronic states. Using spherical tensor algebra, we derive highly symmetrized forms of the squared photoionization dipole matrix elements from which we derive the salient selection and propensity rules for fine- and hyperfine resolved photoionizing transitions. Our theoretical results are validated by the analysis of the fine-structure resolved photoelectron spectrum of O{sub 2} reported by Palm and Merkt [Phys. Rev. Lett. 81, 1385 (1998)] and are used for predicting hyperfine populations of molecular ionsmore » produced by photoionization.« less

Matrix elements of hyperfine structure operators in the SL and jj representations for the s, p{sup N}, and d{sup N} configurations and the SL-jj transformation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Childs, W.J.

1997-09-01

Matrix elements of the hyperfine operators corresponding to the magnetic-dipole (A) and electric-quadrupole (B) hyperfine structures constants are given as linear combinations of the appropriate radial integrals for all states of the s, p{sup N}, and d{sub N} configurations in both the SL and pure jj representations. The associated SL-jj transformations are also given. 13 refs., 10 tabs.

Real-Time Noise Reduction for Mossbauer Spectroscopy through Online Implementation of a Modified Kalman Filter

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abrecht, David G.; Schwantes, Jon M.; Kukkadapu, Ravi K.

2015-02-01

Spectrum-processing software that incorporates a gaussian smoothing kernel within the statistics of first-order Kalman filtration has been developed to provide cross-channel spectral noise reduction for increased real-time signal-to-noise ratios for Mossbauer spectroscopy. The filter was optimized for the breadth of the gaussian using the Mossbauer spectrum of natural iron foil, and comparisons between the peak broadening, signal-to-noise ratios, and shifts in the calculated hyperfine parameters are presented. The results of optimization give a maximum improvement in the signal-to-noise ratio of 51.1% over the unfiltered spectrum at a gaussian breadth of 27 channels, or 2.5% of the total spectrum width. Themore » full-width half-maximum of the spectrum peaks showed an increase of 19.6% at this optimum point, indicating a relatively weak increase in the peak broadening relative to the signal enhancement, leading to an overall increase in the observable signal. Calculations of the hyperfine parameters showed no statistically significant deviations were introduced from the application of the filter, confirming the utility of this filter for spectroscopy applications.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 approachmore » is applied to the estimation of the spin Hamiltonian parameters of the oxovanadium-EDTA complex.« less

Hyperfine Structure Constants of Energetically High-lying Levels of Odd Parity of Atomic Vanadium

NASA Astrophysics Data System (ADS)

Güzelçimen, F.; Yapıcı, B.; Demir, G.; Er, A.; Öztürk, I. K.; Başar, Gö.; Kröger, S.; Tamanis, M.; Ferber, R.; Docenko, D.; Başar, Gü.

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-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 34s4p and 55 to the configuration 3d 44p. Of these 90 constants, 67 have been determined for the first time, with 23 corresponding to the configuration 3d 34s4p and 44 to 3d 44p.

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

NASA Astrophysics Data System (ADS)

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

2017-11-01

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

Hyperfine structure investigations for the odd-parity configuration system in atomic holmium

NASA Astrophysics Data System (ADS)

Stefanska, D.; Furmann, B.

2018-02-01

In this work new experimental results of the hyperfine structure (hfs) in the holmium atom are reported, concerning the odd-parity level system. Investigations were performed by the method of laser induced fluorescence in a hollow cathode discharge lamp on 97 spectral lines in the visible part of the spectrum. Hyperfine structure constants: magnetic dipole - A and electric quadrupole - B for 40 levels were determined for the first time; for another 21 levels the hfs constants available in the literature were remeasured. Results for the A constants can be viewed as fully reliable; for B constants further possibilities of improving the accuracy are considered.

A field programmable gate array-based time-resolved scaler for collinear laser spectroscopy with bunched radioactive potassium beams

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rossi, D. M., E-mail: rossi@nscl.msu.edu; Davis, M.; Ringle, R.

A new data acquisition system including a Field Programmable Gate Array (FPGA) based time-resolved scaler was developed for laser-induced fluorescence and beam bunch coincidence measurements. The FPGA scaler was tested in a collinear laser-spectroscopy experiment on radioactive {sup 37}K at the BEam COoler and LAser spectroscopy (BECOLA) facility at the National Superconducting Cyclotron Laboratory at Michigan State University. A 1.29 μs bunch width from the buncher and a bunch repetition rate of 2.5 Hz led to a background suppression factor of 3.1 × 10{sup 5} in resonant photon detection measurements. The hyperfine structure of {sup 37}K and its isotope shiftmore » relative to the stable {sup 39}K were determined using 5 × 10{sup 4} s{sup −1} {sup 37}K ions injected into the BECOLA beam line. The obtained hyperfine coupling constants A({sup 2}S{sub 1/2}) = 120.3(1.4) MHz, A({sup 2}P{sub 1/2}) = 15.2(1.1) MHz, and A({sup 2}P{sub 3/2}) = 1.4(8) MHz, and the isotope shift δν{sup 39,} {sup 37} = −264(3) MHz are consistent with the previously determined values, where available.« less

Ghost features in Doppler-broadened spectra of rovibrational transitions in trapped HD+ ions

NASA Astrophysics Data System (ADS)

Patra, Sayan; Koelemeij, J. C. J.

2017-02-01

Doppler broadening plays an important role in laser rovibrational spectroscopy of trapped deuterated molecular hydrogen ions (HD+), even at the millikelvin temperatures achieved through sympathetic cooling by laser-cooled beryllium ions. Recently, Biesheuvel et al. (2016) presented a theoretical lineshape model for such transitions which not only considers linestrengths and Doppler broadening, but also the finite sample size and population redistribution by blackbody radiation, which are important in view of the long storage and probe times achievable in ion traps. Here, we employ the rate equation model developed by Biesheuvel et al. to theoretically study the Doppler-broadened hyperfine structure of the (v, L) : (0, 3) → (4, 2) rovibrational transition in HD+ at 1442 nm. We observe prominent yet hitherto unrecognized ghost features in the simulated spectrum, whose positions depend on the Doppler width, transition rates, and saturation levels of the hyperfine components addressed by the laser. We explain the origin and behavior of such features, and we provide a simple quantitative guideline to assess whether ghost features may appear. As such ghost features may be common to saturated Doppler-broadened spectra of rotational and vibrational transitions in trapped ions composed of partly overlapping lines, our work illustrates the necessity to use lineshape models that take into account all the relevant physics.

A High Resolution Spectroscopic Study of the Nu2 Band of Hydrogen Sulfide and the 1-0 Band of Hydrogen Iodide. Ph.D. Thesis - Maryland Univ.

NASA Technical Reports Server (NTRS)

Strow, L. L.

1981-01-01

A tunable diode laser spectrometer was constructed and used to study: (1) the effects of centrifugal distortion on the transition frequencies and strengths of the nu sub 2 band of H2S, and (2) nuclear quadrupole hyperfine structure in the 1-0 band of HI. A total of 126 line frequencies and 94 line strengths in the nu sub 2 band of H2S were measured. The average accuracy of the line frequency measurements was + or - 0.0016 cm. The line strengths were measured to an average accuracy of about 3 percent. The effect of the finite spectral width of the diode laser on the measurement of line strengths is discussed. The observed H2S line frequencies were fit to Watson's AS and NS reduced Hamiltonian in both the Ir and IIIr coordinate representations in order to determine the best set of rotation distortion constants for the upper state of the nu sub 2 band. Comparisons of the observed line strengths in this band to rigid rotor line strengths are also presented. Nuclear quadrupole hyperfine structure in the low J lines of the 1-0 band of HI was observed. The upper vibrational state nuclear quadrupole coupling constant, determined from the observed splittings, was -1850 MHz + or - 12 MHz or 1.2 percent + or - 0.7 percent larger than the ground state coupling constant.

Hyperfine structure of 2Σ molecules containing alkaline-earth-metal atoms

NASA Astrophysics Data System (ADS)

Aldegunde, Jesus; Hutson, Jeremy M.

2018-04-01

Ultracold molecules with both electron spin and an electric dipole moment offer new possibilities in quantum science. We use density-functional theory to calculate hyperfine coupling constants for a selection of molecules important in this area, including RbSr, LiYb, RbYb, CaF, and SrF. We find substantial hyperfine coupling constants for the fermionic isotopes of the alkaline-earth-metal and Yb atoms. We discuss the hyperfine level patterns and Zeeman splittings expected for these molecules. The results will be important both to experiments aimed at forming ultracold open-shell molecules and to their applications.

Structural phase transition of as-synthesized Sr-Mn nanoferrites by annealing temperature

NASA Astrophysics Data System (ADS)

Amer, M. A.; Meaz, T. M.; Attalah, S. S.; Ghoneim, A. I.

2015-11-01

The Sr0.2Mn0.8Fe2O4 nanoparticle ferrites were synthesized by the co-precipitation method and annealed at different temperatures T. XRD, TEM, FT-IR, VSM and Mössbauer techniques were used to characterize the samples. This study proved that the structural phase of nanoferrites was transformed from cubic spinel for T≤500 °C to Z-type hexagonal for T≥700 °C. The structural transformation was attributed to Jahn-Teller effect of the Mn3+ ions and/or atomic disorder existed in the crystal lattice. The obtained spectra and parameters for the samples were affected by the transformation process. The lattice constant a showed a splitting to a and c for T>500 °C. The lattice constant c, grain and crystallite size R, strain, octahedral B-site band position and force constant, Debye temperature, coercivity Hc, remnant magnetization, squareness and magnetic moment, spontaneous magnetization and hyperfine magnetic fields showed increase against T. The lattice constant a, distortion and dislocation parameters, specific surface area, tetrahedral A-site band position and force constant, threshold frequency, Young's and bulk moduli, saturation magnetization Ms, area ratio of B-/A-sites, A-site line width were decreased with T. Experimental and theoretical densities, porosity, Poison ratio, stiffness constants, rigidity modulus, B-site line width and spontaneous magnetization showed dependence on T, whereas Ms and Hc proved dependence on R.

Revised energy levels of singly ionized lanthanum

NASA Astrophysics Data System (ADS)

Güzelçimen, Feyza; Tonka, Mehdi; Uddin, Zaheer; Bhatti, Naveed Anjum; Windholz, Laurentius; Kröger, Sophie; Başar, Gönül

2018-05-01

Based on the experimental wavenumbers of 344 spectral lines from calibrated Fourier transform (FT) spectra as well as wavenumbers of 81 lines from the wavelength tables from literature, the energy of 115 fine structure levels of singly ionized lanthanum has been revised by weighted global fits. The classifications of the lines are provided by numerous previous investigations of lanthanum by different spectroscopic methods and authors. For the high accurate determination of the center of gravity wavenumbers from the experimental spectrum, the hyperfine constants of the involved levels have been taken into account, if possible. For the 94 levels with known hyperfine constants the accuracy of energy values is better than 0.01 cm-1. For 34 levels the magnetic dipole hyperfine constants A have been determined from FT spectra as part of this work. For four of these 34 levels even electric quadrupole hyperfine constants B could be estimated. For levels, which have experimentally unknown hyperfine constants and which are connected only by lines not found in the FT spectra but taken from literature, the uncertainties of energy values are about a factor of 10 higher. A list of all revised level energies together with a compilation of hyperfine structure data is given as well as a list of all lines used.

Hyperfine field and electronic structure of magnetite below the Verwey transition

NASA Astrophysics Data System (ADS)

Řezníček, R.; Chlan, V.; Štěpánková, H.; Novák, P.

2015-03-01

Magnetite represents a prototype compound with a mixed valence of iron cations. Its structure and electron ordering below the Verwey transition have been studied for decades. A recently published precise crystallographic structure [Senn et al., Nature (London) 481, 173 (2012), 10.1038/nature10704] accompanied by a suggestion of a "trimeron" model has given a new impulse to magnetite research. Here we investigate hyperfine field anisotropy in the C c phase of magnetite by quantitative reanalysis of published measurements of the dependences of the 57Fe nuclear magnetic resonance frequencies on the external magnetic field direction. Further, ab initio density-functional-theory-based calculations of hyperfine field depending on the magnetization direction using the recently reported crystal structure are carried out, and analogous hyperfine anisotropy data linked to particular crystallographic sites are determined. These two sets of data are compared, and mutually matching groups of the iron B sites in the 8:5:3 ratio are found. Moreover, information on electronic structure is obtained from the ab initio calculations. Our results are compared with the trimeron model and with an alternative analysis [Patterson, Phys. Rev. B 90, 075134 (2014), 10.1103/PhysRevB.90.075134] as well.

Materials for optical memory: Resolved hyperfine structure in KY3F10:Ho3+

NASA Astrophysics Data System (ADS)

Popova, M. N.

2013-08-01

Basic principles of creating a quantum optical memory (QOM) and requirements for relevant materials, in particular, for crystals doped with rare-earth ions, are briefly reviewed. A combined approach to studying the hyperfine structure, which is essential for QOM applications, is presented on the example of KY3F10:Ho3+.

HYPERFINE-DEPENDENT gf-VALUES OF Mn I LINES IN THE 1.49-1.80 μm H BAND

DOE Office of Scientific and Technical Information (OSTI.GOV)

Andersson, M.; Hutton, R.; Zou, Y.

2015-01-01

The three Mn I lines at 17325, 17339, and 17349 Å are among the 25 strongest lines (log (gf) > 0.5) in the H band. They are all heavily broadened due to hyperfine structure, and the profiles of these lines have so far not been understood. Earlier studies of these lines even suggested that they were blended. In this work, the profiles of these three infrared (IR) lines have been studied theoretically and compared to experimental spectra to assist in the complete understanding of the solar spectrum in the IR. It is shown that the structure of these lines cannot be describedmore » in the conventional way using the diagonal A and B hyperfine interaction constants. The off-diagonal hyperfine interaction not only has a large impact on the energies of the hyperfine levels, but also introduces a large intensity redistribution among the hyperfine lines, changing the line profiles dramatically. By performing large-scale calculations of the diagonal and off-diagonal hyperfine interaction and the gf-values between the upper and lower hyperfine levels and using a semi-empirical fitting procedure, we achieved agreement between our synthetic and experimental spectra. Furthermore, we compare our results with observations of stellar spectra. The spectra of the Sun and the K1.5 III red giant star Arcturus were modeled in the relevant region, 1.73-1.74 μm, using our theoretically predicted gf-values and energies for each individual hyperfine line. Satisfactory fits were obtained and clear improvements were found using our new data compared with the old available Mn I data. A complete list of energies and gf-values for all the 3d {sup 5}4s({sup 7} S)4d e{sup 6}D - 3d {sup 5}4s({sup 7} S)4f w{sup 6}F hyperfine lines are available as supporting material, whereas only the stronger lines are presented and discussed in detail in this paper.« less

The fine-structure intervals of (N-14)+ by far-infrared laser magnetic resonance

NASA Technical Reports Server (NTRS)

Brown, John M.; Varberg, Thomas D.; Evenson, Kenneth M.; Cooksy, Andrew L.

1994-01-01

The far-infrared laser magnetic resonance spectra associated with both fine-structure transitions in (N-14)+ in its ground P-3 state have been recorded. This is the first laboratory observation of the J = 1 left arrow 0 transition and its frequency has been determined two orders of magnitude more accurately than previously. The remeasurement of the J = 2 left arrow 1 spectrum revealed a small error in the previous laboratory measurements. The fine-structure splittings (free of hyperfine interactions) determined in this work are (delta)E(sub 10) = 1461.13190 (61) GHz, (delta)E(sub 21) = 2459.38006 (37) GHz. Zero-field transition frequencies which include the effects of hyperfine structure have also been calculated. Refined values for the hyperfine constants and the g(sub J) factors have been obtained.

Two-photon exchange correction to the hyperfine splitting in muonic hydrogen

NASA Astrophysics Data System (ADS)

Tomalak, Oleksandr

2017-12-01

We reevaluate the Zemach, recoil and polarizability corrections to the hyperfine splitting in muonic hydrogen expressing them through the low-energy proton structure constants and obtain the precise values of the Zemach radius and two-photon exchange (TPE) contribution. The uncertainty of TPE correction to S energy levels in muonic hydrogen of 105 ppm exceeds the ppm accuracy level of the forthcoming 1S hyperfine splitting measurements at PSI, J-PARC and RIKEN-RAL.

Two tyrosyl radicals stabilize high oxidation states in cytochrome c oxidase for efficient energy conservation and proton translocation

NASA Astrophysics Data System (ADS)

Rousseau, Denis

2012-02-01

The reaction of hydrogen peroxide (H2O2) with oxidized bovine cytochrome c oxidase (bCcO) was studied by electron paramagnetic resonance (EPR) to determine the properties of radical intermediates. Two distinct radicals with widths of 12 and 46 G are directly observed by X-band CW-EPR in the reaction of bCcO with H2O2 at pH 6 and pH 8. High-frequency EPR (D-band) provides assignments to tyrosine for both radicals based on well-resolved g-tensors. The 46 G wide radical has extensive hyperfine structure and can be fit with parameters consistent with Y129. However, the 12 G wide radical has minimal hyperfine structure and can be fit using parameters unique to the post-translationally modified Y244 in CcO. The results are supported by mixed quantum mechanics and molecular mechanics calculations. This study reports spectroscopic evidence of a radical formed on the modified tyrosine in CcO and resolves the much debated controversy of whether the wide radical seen at low pH in the bovine system is a tyrosine or tryptophan. A model is presented showing how radical formation and migration may play an essential role in proton translocation. This work was done in collaboration with Michelle A. Yu, Tsuyoshi Egawa, Syun-Ru Yeh and Gary J. Gerfen from Albert Einstein College of Medicine; Kyoko Shinzawa-Itoh and Shinya Yoshikawa from the University of Hyogo; and Victor Guallar from the Barcelona Supercomputing Center.

Sensitive sub-Doppler nonlinear spectroscopy for hyperfine-structure analysis using simple atomizers

NASA Astrophysics Data System (ADS)

Mickadeit, Fritz K.; Kemp, Helen; Schafer, Julia; Tong, William M.

1998-05-01

Laser wave-mixing spectroscopy is presented as a sub-Doppler method that offers not only high spectral resolution, but also excellent detection sensitivity. It offers spectral resolution suitable for hyperfine structure analysis and isotope ratio measurements. In a non-planar backward- scattering four-wave mixing optical configuration, two of the three input beams counter propagate and the Doppler broadening is minimized, and hence, spectral resolution is enhanced. Since the signal is a coherent beam, optical collection is efficient and signal detection is convenient. This simple multi-photon nonlinear laser method offers un usually sensitive detection limits that are suitable for trace-concentration isotope analysis using a few different types of simple analytical atomizers. Reliable measurement of hyperfine structures allows effective determination of isotope ratios for chemical analysis.

Hyperfine excitation of linear molecules by para- and ortho-H{sub 2}: Application to the HCl–H{sub 2} system

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lanza, Mathieu; Lique, François, E-mail: francois.lique@univ-lehavre.fr

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 resultsmore » 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.« less

Hyperfine structure of electronic levels and the first measurement of the nuclear magnetic moment of 63Ni

NASA Astrophysics Data System (ADS)

D'yachkov, A. B.; Firsov, V. A.; Gorkunov, A. A.; Labozin, A. V.; Mironov, S. M.; Saperstein, E. E.; Tolokonnikov, S. V.; Tsvetkov, G. O.; Panchenko, V. Y.

2017-01-01

Laser resonant photoionization spectroscopy was used to study the hyperfine structure of the optical 3d84s2 {}3F4→ 3d84s4p {}3G^o3 and 3d94s {}3D3→ 3d84s4p {}3G^o3 transitions of 63Ni and 61Ni isotopes. Experimental spectra allowed us to derive hyperfine interaction constants and determine the magnetic dipole moment of the nuclear ground state of 63Ni for the first time: μ=+0.496(5)μ_N. The value obtained agrees well with the prediction of the self-consistent theory of finite Fermi systems.

Fine- and hyperfine structure investigations of the even-parity configuration system of the atomic holmium

NASA Astrophysics Data System (ADS)

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

2018-04-01

In this work new experimental results concerning the hyperfine structure (hfs) for the even-parity level system of the holmium atom (Ho I) were obtained; additionally, hfs data obtained recently as a by-product in investigations of the odd-parity level system were summarized. In the present work the values of the magnetic dipole and the electric quadrupole hfs constants A and B were determined for 24 even-parity levels, for 14 of them for the first time. On the basis of these results, as well as on available literature data, a parametric study of the fine structure and the hyperfine structure for the even-parity configurations of atomic holmium was performed. A multi-configuration fit of 7 configurations was carried out, taking into account second-order of the perturbation theory. For unknown electronic levels predicted values of the level energies and hfs constants are given, which can facilitate further experimental investigations.

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...

Experimental observation and determination of the laser-induced frequency shift of hyperfine levels of ultracold polar molecules

NASA Astrophysics Data System (ADS)

Liu, Wenliang; Wang, Xiaofeng; Wu, Jizhou; Su, Xingliang; Wang, Shen; Sovkov, Vladimir B.; Ma, Jie; Xiao, Liantuan; Jia, Suotang

2017-08-01

We report on the experimental observation and quantitative determination of the laser-induced frequency shift (LIFS) of the ultracold polar molecules formed by photoassociation (PA). The experiments are performed by detecting a series of double PA spectra with a molecular hyperfine structure, which are induced by two PA lasers with a precise and adjustable frequency reference. We find that the LIFS of the molecular hyperfine levels shows a linear dependence on PA laser intensity.

Hyperfine-resolved 3.4-{mu}m spectroscopy of CH{sub 3}I with a widely tunable difference frequency generation source and a cavity-enhanced cell: A case study of a local Coriolis interaction between the v{sub 1}=1 and (v{sub 2},v{sub 6}{sup l})=(1,2{sup 2}) states

DOE Office of Scientific and Technical Information (OSTI.GOV)

Okubo, Sho; Nakayama, Hirotaka; Sasada, Hiroyuki

Saturated absorption spectra of the {nu}{sub 1} fundamental band of CH{sub 3}I are recorded with a cavity-enhanced cell and a tunable difference frequency generation source having an 86-cm{sup -1} range. The recorded spectral lines are 250 kHz wide, and most of them are resolved into the individual hyperfine components. The Coriolis interaction between the v{sub 1}=1 and (v{sub 2},v{sub 6}{sup l})=(1,2{sup 2}) states locally perturbing the hyperfine structures is analyzed to yield the Coriolis and hyperfine coupling constants with uncertainties similar to those in typical microwave spectroscopy. The spectrometer has demonstrated the potential for precisely determining the energy structure inmore » the vibrational excited states.« less

EPR hyperfine structure of the Mo-related defect in CdWO4

NASA Astrophysics Data System (ADS)

Elsts, E.; Rogulis, U.

2005-01-01

The hyperfine structure (hf) of the electron paramagnetic resonance (EPR) spectrum of Mo-related impurity defects in CdWO4 crystals observed previously (U. Rogulis, Radiat. Meas. 29, 287 (1998) [1]) is reconsidered taking into account interactions with two different groups of neighbouring Cd nuclei. The best fit calculated EPR spectrum to the experimental is obtained considering 2 groups of 3 and 2 equivalent Cd nuclei, respectively.

Electron paramagnetic resonance studies on conformation states and metal ion exchange properties of vanadium bromoperoxidase

DOE Office of Scientific and Technical Information (OSTI.GOV)

de Boer, E.; Boon, K.; Wever, R.

An electron paramagnetic resonance (EPR) study was carried out to examine structural aspects of vanadium-containing bromoperoxidase from the brown seaweed Ascophyllum nodosum. At high pH, the reduced form of bromoperoxidase showed an apparently axially symmetric EPR signal with 16 hyperfine lines. When the pH was lowered, a new EPR spectrum was formed. When EPR spectra of the reduced enzyme were recorded in the pH range from 4.2 to 8.4, it appeared that these changes were linked to a functional group with an apparent pK/sub a/ of about 5.4. In D/sub 2/O this value for the pK/sub a/ was 5.3. Itmore » is suggested that these effects arise from protonation of histidine or aspartate/glutamate residues near the metal ion. The values for the isotropic hyperfine coupling constant of the reduced enzyme at both high and low pH are also consistent with a ligand field containing nitrogen and/or oxygen donor atoms. When reduced bromoperoxidase was dissolved in D/sub 2/O or H/sub 2//sup 17/O instead of H/sub 2//sup 16/O, vanadium (IV) hyperfine line widths were markedly affected, demonstrating that water is a ligand of the metal ion. Together with previous work these findings suggest that vanadium (IV) is not involved in catalytic turnover and confirm the model in which the vanadium (V) ion of the native enzyme only serves to bind both hydrogen peroxide and bromide. After excess vanadate was added to a homogeneous preparation of purified bromoperoxidase, the extent of vanadium bound to the protein increased from 0.5 to 1.1, with a concomitant enhancement of enzymic activity. Finally, it is demonstrated that both vanadate (VO/sub 4//sup 3 -/) and molybdate (MoO/sub 4//sup 2 -/) compete for the same site on apobromoperoxidase.« less

Optogalvanic spectroscopy of lanthanum hyperfine structure

NASA Astrophysics Data System (ADS)

Nelson, Amanda; Hankes, Jessie; Banner, Patrick; Olmschenk, Steven

2017-04-01

Optogalvanic spectroscopy is a sensitive technique to measure optical transitions of atoms and ions produced in a high voltage discharge. Advantages of this technique include a comparatively simple optical setup and the ability to interrogate excited state transitions. Here, we use optogalavanic spectroscopy in a hollow cathode lamp to measure the hyperfine spectrum of several transitions in lanthanum. Hyperfine coefficients are determined for the corresponding energy levels and compared to available previous measurements. This research is supported by the Army Research Office, Research Corporation for Science Advancement, and Denison University.

Higher order Stark effect and transition probabilities on hyperfine structure components of hydrogen like atoms

NASA Astrophysics Data System (ADS)

Pal'Chikov, V. G.

2000-08-01

A quantum-electrodynamical (QED) perturbation theory is developed for hydrogen and hydrogen-like atomic systems with interaction between bound electrons and radiative field being treated as the perturbation. The dependence of the perturbed energy of levels on hyperfine structure (hfs) effects and on the higher-order Stark effect is investigated. Numerical results have been obtained for the transition probability between the hfs components of hydrogen-like bismuth.

Laser pumping Cs atom magnetometer of theory research based on gradient tensor measuring

NASA Astrophysics Data System (ADS)

Yang, Zhang; Chong, Kang; Wang, Qingtao; Lei, Cheng; Zheng, Caiping

2011-02-01

At present, due to space exploration, military technology, geological exploration, magnetic navigation, medical diagnosis and biological magnetic fields study of the needs of research and development, the magnetometer is given strong driving force. In this paper, it will discuss the theoretical analysis and system design of laser pumping cesium magnetometer, cesium atomic energy level formed hyperfine structure with the I-J coupling, the hyperfine structure has been further split into Zeeman sublevels for the effects of magnetic field. To use laser pump and RF magnetic field make electrons transition in the hyperfine structure to produce the results of magneto-optical double resonance, and ultimately through the resonant frequency will be able to achieve accurate value of the external magnetic field. On this basis, we further have a discussion about magnetic gradient tensor measuring method. To a large extent, it increases the magnetic field measurement of information.

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).

Mass spectra and decay properties of the c\\bar{c} meson

NASA Astrophysics Data System (ADS)

Chaturvedi, Raghav; Kumar Rai, Ajay

2018-06-01

In this article we present the result of c\\bar{c} meson mass calculation by solving the Schrödinger equation numerically considering the Coulomb plus linear potential. The spin-hyperfine, spin-orbit and tensor components of one-gluon-exchange interactions are employed to obtain the mass spectra of c\\bar{c} meson. The calculated mass spectra are compared with the latest results of PDG and are found to be in good accordance. The Regge trajectories of the calculated mass spectra have also been constructed. The values of the wave function are extracted and employed to calculate the leptonic decay constant, γγ, gg, e+e-, light hadron (LH) and γγγ decay widths of S-wave 0^{-+} and 1^{- -} states of c\\bar{c} meson, the widths have been calculated by Van Royen-Weisskopf formula and by NRQCD mechanism incorporating relativistic corrections of order ν2. The γγ and gg decay widths of χ0 and χ2 states of c\\bar{c} meson have also been calculated. The calculated decay constants and widths have been compared with the experimental results.

Hyperfine coupling of the iodine {\\boldsymbol{D}}{0}_{{\\boldsymbol{u}}}^{+} and β1 g ion-pair states

NASA Astrophysics Data System (ADS)

Baturo, V. V.; Cherepanov, I. N.; Lukashov, S. S.; Petrov, A. N.; Poretsky, S. A.; Pravilov, A. M.

2018-05-01

Detailed studies of I2(β1 g , v β = 13, J β ∼ D{0}u+, v D = 12, J D and D, 48, J D ∼ β, 47, J β ) rovibronic state coupling have been carried out using two-step two-color, hν 1 + hν 2 and hν 1 + 2hν 2, optical–optical double resonance excitation schemes, respectively. The hyperfine interaction satisfying the | {{Δ }}J| = 0, 1 selection rules (magnetic-dipole interaction) has been observed. No electric-quadrupole hyperfine coupling (| {{Δ }}J| = 2) has been found. The dependences of ratios of luminescence intensities from the rovibronic states populated due to the hyperfine coupling to those from optically populated ones on energy gaps between these states have been experimentally determined. The matrix elements as well as the hyperfine structure constant have been obtained using these dependences. It is shown that they increase slightly with the vibrational quantum number of the states.

Magnetoelectroluminescence of organic heterostructures: Analytical theory and spectrally resolved measurements

NASA Astrophysics Data System (ADS)

Liu, Feilong; Kelley, Megan R.; Crooker, Scott A.; Nie, Wanyi; Mohite, Aditya D.; Ruden, P. Paul; Smith, Darryl L.

2014-12-01

The effect of a magnetic field on the electroluminescence of organic light emitting devices originates from the hyperfine interaction between the electron/hole polarons and the hydrogen nuclei of the host molecules. In this paper, we present an analytical theory of magnetoelectroluminescence for organic semiconductors. To be specific, we focus on bilayer heterostructure devices. In the case we are considering, light generation at the interface of the donor and acceptor layers results from the formation and recombination of exciplexes. The spin physics is described by a stochastic Liouville equation for the electron/hole spin density matrix. By finding the steady-state analytical solution using Bloch-Wangsness-Redfield theory, we explore how the singlet/triplet exciplex ratio is affected by the hyperfine interaction strength and by the external magnetic field. To validate the theory, spectrally resolved electroluminescence experiments on BPhen/m-MTDATA devices are analyzed. With increasing emission wavelength, the width of the magnetic field modulation curve of the electroluminescence increases while its depth decreases. These observations are consistent with the model.

Hyperfine interaction in K 2Ba[Fe(NO 2) 6

NASA Astrophysics Data System (ADS)

Padmakumar, K.; Manoharan, P. T.

2000-04-01

Magnetic hyperfine splitting observed in the low temperature Mössbauer spectrum of potassium barium hexanitro ferrate(II), in the absence of any external field, is attributed to the 5T 2g state of the central metal atom further split into a ground 5E g state and a first excited 5B 2g state under a distorted octahedral symmetry in contrast to the earlier prediction of 1A 1g ground state on the basis of room temperature Mössbauer spectral and other properties. The central iron atom is co-ordianted to six nitrito groups (NO 2-), having an oxidation state of +2. The temperature dependence of Mössbauer spectra is explained on the basis of electronic relaxation among the spin-orbit coupled levels of the 5E g ground state. Various kinds of electronic relaxation mechanisms have been compared to explain the proposed mechanism. The observed temperature dependent spectra with varying internal magnetic field and line width can be explained by simple spin lattice relaxation.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Puzzarini, Cristina, E-mail: cristina.puzzarini@unibo.it; Cazzoli, Gabriele; Harding, Michael E.

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 andmore » 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)].« less

Solid-state EPR strategies for the structural characterization of paramagnetic NO adducts of frustrated Lewis pairs (FLPs)

NASA Astrophysics Data System (ADS)

de Oliveira, Marcos; Wiegand, Thomas; Elmer, Lisa-Maria; Sajid, Muhammad; Kehr, Gerald; Erker, Gerhard; Magon, Claudio José; Eckert, Hellmut

2015-03-01

Anisotropic interactions present in three new nitroxide radicals prepared by N,N addition of NO to various borane-phosphane frustrated Lewis pairs (FLPs) have been characterized by continuous-wave (cw) and pulsed X-band EPR spectroscopies in solid FLP-hydroxylamine matrices at 100 K. Anisotropic g-tensor values and 11B, 14N, and 31P hyperfine coupling tensor components have been extracted from continuous-wave lineshape analyses, electron spin echo envelope modulation (ESEEM), and hyperfine sublevel correlation spectroscopy (HYSCORE) experiments with the help of computer simulation techniques. Suitable fitting constraints are developed on the basis of density functional theory (DFT) calculations. These calculations reveal that different from the situation in standard nitroxide radicals (TEMPO), the g-tensors are non-coincident with any of the nuclear hyperfine interaction tensors. The determination of these interaction parameters turns out to be successful, as the cw- and pulse EPR experiments are highly complementary in informational content. While the continuous-wave lineshape is largely influenced by the anisotropic hyperfine coupling to 14N and 31P, the ESEEM and HYSCORE spectra contain important information about the 11B hyperfine coupling and nuclear electric quadrupolar interaction. The set of cw- and pulsed EPR experiments, with fitting constraints developed by DFT calculations, defines an efficient strategy for the structural analysis of paramagnetic FLP adducts.

Solid-state EPR strategies for the structural characterization of paramagnetic NO adducts of frustrated Lewis pairs (FLPs)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Oliveira, Marcos de; Magon, Claudio José; Wiegand, Thomas

2015-03-28

Anisotropic interactions present in three new nitroxide radicals prepared by N,N addition of NO to various borane-phosphane frustrated Lewis pairs (FLPs) have been characterized by continuous-wave (cw) and pulsed X-band EPR spectroscopies in solid FLP-hydroxylamine matrices at 100 K. Anisotropic g-tensor values and {sup 11}B, {sup 14}N, and {sup 31}P hyperfine coupling tensor components have been extracted from continuous-wave lineshape analyses, electron spin echo envelope modulation (ESEEM), and hyperfine sublevel correlation spectroscopy (HYSCORE) experiments with the help of computer simulation techniques. Suitable fitting constraints are developed on the basis of density functional theory (DFT) calculations. These calculations reveal that differentmore » from the situation in standard nitroxide radicals (TEMPO), the g-tensors are non-coincident with any of the nuclear hyperfine interaction tensors. The determination of these interaction parameters turns out to be successful, as the cw- and pulse EPR experiments are highly complementary in informational content. While the continuous-wave lineshape is largely influenced by the anisotropic hyperfine coupling to {sup 14}N and {sup 31}P, the ESEEM and HYSCORE spectra contain important information about the {sup 11}B hyperfine coupling and nuclear electric quadrupolar interaction. The set of cw- and pulsed EPR experiments, with fitting constraints developed by DFT calculations, defines an efficient strategy for the structural analysis of paramagnetic FLP adducts.« less

The NaK 1 1,3delta states: theoretical and experimental studies of fine and hyperfine structure of rovibrational levels near the dissociation limit.

PubMed

Wilkins, A D; Morgus, L; Hernandez-Guzman, J; Huennekens, J; Hickman, A P

2005-09-22

Earlier high-resolution spectroscopic studies of the fine and hyperfine structure of rovibrational levels of the 1 3delta state of NaK have been extended to include high lying rovibrational levels with v < or = 59, of which the highest levels lie within approximately 4 cm(-1) of the dissociation limit. A potential curve is determined using the inverted perturbation approximation method that reproduces these levels to an accuracy of approximately 0.026 cm(-1). For the largest values of v, the outer turning points occur near R approximately 12.7 angstroms, which is sufficiently large to permit the estimation of the C6 coefficient for this state. The fine and hyperfine structure of the 1 3delta rovibrational levels has been fit using the matrix diagonalization method that has been applied to other states of NaK, leading to values of the spin-orbit coupling constant A(v) and the Fermi contact constant b(F). New values determined for v < or = 33 are consistent with values determined by a simpler method and reported earlier. The measured fine and hyperfine structure for v in the range 44 < or = v < or = 49 exhibits anomalous behavior whose origin is believed to be the mixing between the 1 3delta and 1 1delta states. The matrix diagonalization method has been extended to treat this interaction, and the results provide an accurate representation of the complicated patterns that arise. The analysis leads to accurate values for A(v) and b(F) for all values of v < or = 49. For higher v (50 < or = v < or = 59), several rovibrational levels have been assigned, but the pattern of fine and hyperfine structure is difficult to interpret. Some of the observed features may arise from effects not included in the current model.

Nuclear spin noise in the central spin model

NASA Astrophysics Data System (ADS)

Fröhling, Nina; Anders, Frithjof B.; Glazov, Mikhail

2018-05-01

We study theoretically the fluctuations of the nuclear spins in quantum dots employing the central spin model which accounts for the hyperfine interaction of the nuclei with the electron spin. These fluctuations are calculated both with an analytical approach using homogeneous hyperfine couplings (box model) and with a numerical simulation using a distribution of hyperfine coupling constants. The approaches are in good agreement. The box model serves as a benchmark with low computational cost that explains the basic features of the nuclear spin noise well. We also demonstrate that the nuclear spin noise spectra comprise a two-peak structure centered at the nuclear Zeeman frequency in high magnetic fields with the shape of the spectrum controlled by the distribution of the hyperfine constants. This allows for direct access to this distribution function through nuclear spin noise spectroscopy.

Isotopic determination of uranium in soil by laser induced breakdown spectroscopy

DOE PAGES

Chan, George C. -Y.; Choi, Inhee; Mao, Xianglei; ...

2016-03-26

Laser-induced breakdown spectroscopy (LIBS) operated under ambient pressure has been evaluated for isotopic analysis of uranium in real-world samples such as soil, with U concentrations in the single digit percentage levels. The study addresses the requirements for spectral decomposition of 235U and 238U atomic emission peaks that are only partially resolved. Although non-linear least-square fitting algorithms are typically able to locate the optimal combination of fitting parameters that best describes the experimental spectrum even when all fitting parameters are treated as free independent variables, the analytical results of such an unconstrained free-parameter approach are ambiguous. In this work, five spectralmore » decomposition algorithms were examined, with different known physical properties (e.g., isotopic splitting, hyperfine structure) of the spectral lines sequentially incorporated into the candidate algorithms as constraints. It was found that incorporation of such spectral-line constraints into the decomposition algorithm is essential for the best isotopic analysis. The isotopic abundance of 235U was determined from a simple two-component Lorentzian fit on the U II 424.437 nm spectral profile. For six replicate measurements, each with only fifteen laser shots, on a soil sample with U concentration at 1.1% w/w, the determined 235U isotopic abundance was (64.6 ± 4.8)%, and agreed well with the certified value of 64.4%. Another studied U line - U I 682.691 nm possesses hyperfine structure that is comparatively broad and at a significant fraction as the isotopic shift. Thus, 235U isotopic analysis with this U I line was performed with spectral decomposition involving individual hyperfine components. For the soil sample with 1.1% w/w U, the determined 235U isotopic abundance was (60.9 ± 2.0)%, which exhibited a relative bias about 6% from the certified value. The bias was attributed to the spectral resolution of our measurement system - the measured line width for this U I line was larger than its isotopic splitting. In conclusion, although not the best emission line for isotopic analysis, this U I emission line is sensitive for element analysis with a detection limit of 500 ppm U in the soil matrix; the detection limit for the U II 424.437 nm line was 2000 ppm.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sowmya, K.; Nagendra, K. N.; Sampoorna, M.

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 scatteringmore » 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.« less

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.

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.

Collisional relaxation of MnH (X7Σ+) in a magnetic field: effect of the nuclear spin of Mn.

PubMed

Stoecklin, T; Halvick, Ph

2011-11-14

In the present study we investigate the role played by the hyperfine structure of manganese in the cooling and magnetic trapping of MnH((7)Σ(+)). The effect of the hyperfine structure of Mn on the relaxation of the magnetically trappable maximally stretched low-field seeking state of MnH((7)Σ(+)) in collisions with (3)He is deduced from comparison between the results of the present approach and our previous nuclear spin free calculations. We show that our previous results are unchanged at the temperature of the buffer gas cooling experiment but find a new resonance at very low collision energy. The role played by the different contributions to the hyperfine diatomic Hamiltonian considered in this work as well as the effect of an applied magnetic field on this resonance are also analyzed.

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: All computers with a license of the computer algebra package MAPLE Installations: University of Kassel (Germany) Operating systems under which the program has been tested: Linux 9.0 Program language used:MAPLE, Release 7, 8 and 9 Memory required to execute with typical data: 5 MB No. of lines in distributed program, including test data, etc.: 34 300 No. of bytes in distributed program, including test data, etc.: 954 196 Distribution format: tar.gz Nature of the physical problem: Atomic state functions of an many configuration many electron atom with several open shells are defined by a number of quantum numbers, by their coupling and selection rules such as the Pauli exclusion principal or parity conservation. The matrix elements of any one-particle operator acting on these wavefunctions can be analytically integrated up to the radial part [G. Gaigalas, O. Scharf, S. Fritzsche, Central European J. Phys. 2 (2004) 720]. The decoupling of the interacting electrons is general, the obtained submatrix element holds all the peculiarities of the operator in question. These so-called submatrix elements are the key to do hyperfine structure calculations. The interaction between the electrons and the atomic nucleus leads to an additional splitting of the fine structure lines, the hyperfine structure. The leading components are the magnetic dipole interaction defining the so-called A factor and the electric quadrupole interaction, defining the so-called B factor. They express the energetic splitting of the spectral lines. Moreover, they are obtained directly by experiments and can be calculated theoretically in an ab initio approach. A semiempirical approach allows the fitting of the radial parts of the wavefunction to the experimentally obtained A and B factors. Method of solution: Extending the existing csf_LS() and asf_LS() to several open shells and implementing a data structure level_LS() for the fine structure level, the atomic environment is defined in MAPLE. It is used in a general approach to decouple the interacting shells for any one-particle operator. Further submatrix elements for the magnetic dipole and electric quadrupole interaction are implemented, allowing to calculate the A and B factors up to the radial part. Several procedures for standard quantities of the hyperfine structure are defined, too. The calculations are accelerated by using a hyper-geometric approach for three, six and nine symbols. Restrictions onto the complexity of the problem: Only atomic state functions in nonrelativistic LS-coupling with states having l⩽3 are supported. Typical running time: The program replies promptly on most requests. The least square fit depends heavily on the number of levels and can take a few minutes.

Chiral effective-field theory of the nucleon spin structure

NASA Astrophysics Data System (ADS)

Pascalutsa, Vladimir

2017-01-01

I will review the recent chiral EFT calculations of the nucleon (spin) structure functions at low Q2, confronted with the Jefferson Lab measurements. The moments of the structure functions correspond with various polarizabilities, and I will explain why one of them - δLT - is especially interesting. I will also discuss how the spin structure functions at low Q enter in the atomic calculations of the hyperfine splittings and how they are impacting the ongoing experimental program at PSI (Switzerland) to measure the ground-state hyperfine splitting of muonic hydrogen. Partially supported by the Deutsche Forschungsgemeinschaft (DFG) through the Collaborative Research Center SFB 1044 [The Low-Energy Frontier of the Standard Model].

Structure and nature of manganese(II) imidazole complexes in frozen aqueous solutions.

PubMed

Un, Sun

2013-04-01

A common feature of a large majority of the manganese metalloenzymes, as well as many synthetic biomimetic complexes, is the bonding between the manganese ion and imidazoles. This interaction was studied by examining the nature and structure of manganese(II) imidazole complexes in frozen aqueous solutions using 285 GHz high magnet-field continuous-wave electron paramagnetic resonance (cw-HFEPR) and 95 GHz pulsed electron-nuclear double resonance (ENDOR) and pulsed electron-double resonance detected nuclear magnetic resonance (PELDOR-NMR). The (55)Mn hyperfine coupling and isotropic g values of Mn(II) in frozen imidazole solutions continuously decreased with increasing imidazole concentration. ENDOR and PELDOR-NMR measurements demonstrated that the structural basis for this behavior arose from the imidazole concentration-dependent distribution of three six-coordinate and two four-coordinate species: [Mn(H2O)6](2+), [Mn(imidazole)(H2O)5](2+), [Mn(imidazole)2(H2O)4](2+), [Mn(imidazole)3(H2O)](2+), and [Mn(imidazole)4](2+). The hyperfine and g values of manganese proteins were also fully consistent with this imidazole effect. Density functional theory methods were used to calculate the structures, spin and charge densities, and hyperfine couplings of a number of different manganese imidazole complexes. The use of density functional theory with large exact-exchange admixture calculations gave isotropic (55)Mn hyperfine couplings that were semiquantitative and of predictive value. The results show that the covalency of the Mn-N bonds play an important role in determining not only magnetic spin parameters but also the structure of the metal binding site. The relationship between the isotropic (55)Mn hyperfine value and the number of imidazole ligands provides a quick and easy test for determining whether a protein binds an Mn(II) ion using histidine residues and, if so, how many are involved. Application of this method shows that as much as 40% of the Mn(II) ions in Deinococcus radiodurans are ligated to two histidines (Tabares, L. C.; Un, S. J. Biol. Chem 2013, in press).

Gold atoms and clusters on MgO(100) films; an EPR and IRAS study

NASA Astrophysics Data System (ADS)

Yulikov, M.; Sterrer, M.; Risse, T.; Freund, H.-J.

2009-06-01

Single gold atoms deposited on single crystalline MgO(1 0 0) films grown on Mo(1 0 0) are characterized by electron paramagnetic resonance spectroscopy as well as IR spectroscopy using CO as probe molecules. In this article we describe the first angular dependent measurements to determine the principal hyperfine components of a secondary hyperfine interaction, namely, with 17O of the MgO. The values determined here are in perfect agreement with theoretical expectations and corroborate the previously reported binding mechanism of Au atoms on the oxygen anions of the MgO terrace. The temperature dependent EPR data reveal an onset of Au atom mobility at about 80 K while the formation of Au particles occurs only above 125 K. By an analysis of the EPR line width in combination with STM measurements it is possible to deduce an increase of the interatomic distance above 80 K. The Au/CO complexes show a somewhat smaller temperature stability as compared to the Au atoms. The observed thermal stability is in perfect agreement with theoretical predictions for CO desorption.

Magnetoelectroluminescence of organic heterostructures: Analytical theory and spectrally resolved measurements

DOE PAGES

Liu, Feilong; Kelley, Megan R.; Crooker, Scott A.; ...

2014-12-22

The effect of a magnetic field on the electroluminescence of organic light emitting devices originates from the hyperfine interaction between the electron/hole polarons and the hydrogen nuclei of the host molecules. In this paper, we present an analytical theory of magnetoelectroluminescence for organic semiconductors. To be specific, we focus on bilayer heterostructure devices. In the case we are considering, light generation at the interface of the donor and acceptor layers results from the formation and recombination of exciplexes. The spin physics is described by a stochastic Liouville equation for the electron/hole spin density matrix. By finding the steady-state analytical solutionmore » using Bloch-Wangsness-Redfield theory, we explore how the singlet/triplet exciplex ratio is affected by the hyperfine interaction strength and by the external magnetic field. In order to validate the theory, spectrally resolved electroluminescence experiments on BPhen/m-MTDATA devices are analyzed. With increasing emission wavelength, the width of the magnetic field modulation curve of the electroluminescence increases while its depth decreases. Furthermore, these observations are consistent with the model.« less

Molecular beam electric resonance study of KCN, K 13CN and KC 15N

NASA Astrophysics Data System (ADS)

van Vaals, J. J.; Leo Meerts, W.; Dymanus, A.

1984-08-01

The microwave spectra of the isotopic species K 13CN and KC 15N have been investigated by molecular beam electric resonance spectroscopy, using the seeded beam technique. For both isotopic species about 20 rotational transitions originating in the ground vibrational state were observed in the frequency range 9-38 GHz. The observed transitions were fitted to an asymmetric rotor model to determine the three rotational, as well as the five quartic and three sextic centrifugal distortion constants. The hyperfine spectrum of KCN has been unravelled with the help of microwave-microwave double-resonance techniques. One hundred and forty hyperfine transitions in 11 rotational transitions have been assigned. The hyperfine structures of K 13CN and KC 15N were also studied. For all three isotopic species the quadrupole coupling constants and some spin-rotation coupling constants could be deduced. The rotational constants of the 13C and 15N isotopically substituted species of potassium cyanide, combined with those of the normal isotopic species (determined more accurately in this work), allowed an accurate and unambiguous evaluation of the structure, which was confirmed to be T shaped. Both the effective structure of the ground vibrational state and the substitution structure were evaluated. The results for the effective structural parameters are r CN = 1.169(3) Å, r KC = 2.716(9) Å, and r KN = 2.549(9) Å. The values obtained for the principal hyperfine coupling constant eQqz(N), the angle between the CN axis and zN, and the bond length rCN indicate that in gaseous potassium cyanide the CN group can be considered as an almost unperturbed CN - ion.

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.

Angular Distribution of Hyperfine Magnetic Field in Fe3O4 and Fe66Ni34 from Mössbauer Polarimetry

NASA Astrophysics Data System (ADS)

Szymański, K.; Satuła, D.; Dobrzyński, L.

2004-12-01

Experimental determination of some angular averages of hyperfine field is demonstrated. The averages relates to magnetic structure. Exemplary results of the measurements for Fe3O4 and Fe66Ni34 show that it is possible to obtain valuable information about the field magnitudes and orientations even when distributions of fields are present in the system under study.

[Hyperfine structure analysis in magnetic resonance spectroscopy: from astrophysical measurements towards endogenous biosensors in human tissue].

PubMed

Schröder, Leif

2007-01-01

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

Hyperfine Structure and Abundances of Heavy Elements in 68 Tauri (HD 27962)

NASA Astrophysics Data System (ADS)

Martinet, S.; Monier, R.

2017-12-01

HD 27962, also known as 68 Tauri, is a Chemically Peculiar Am star member of the Hyades Open Cluster in the local arm of the Galaxy. We have modeled the high resolution SOPHIE (R=75000) spectrum of 68 Tauri using updated model atmosphere and spectrum synthesis to derive chemical abundances in its atmosphere. In particular, we have studied the effect of the inclusion of Hyperfine Structure of various Baryum isotopes on the determination of the Baryum abundance in 68 Tauri. We have also derived new abundances using updated accurate atomic parameters retrieved from the NIST database.

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 interactions fluctuate at rates comparable to the time scale of a hyperfine method, there is a loss in signal coherence, and spectra are damped. The degree of damping can be used to determine fluctuation rates, provided that theoretical expressions for spectra can be derived for relevant physical models of the fluctuations. SHIML provides routines to help researchers quickly develop code to incorporate stochastic models of fluctuating hyperfine interactions in calculations of hyperfine spectra. Solution method: Calculations are based on the method for modeling stochastic hyperfine interactions for PAC by Winkler and Gerdau [5]. The method is extended to include other hyperfine methods following the work of Dattagupta [6]. The code provides routines for reading model information from text files, allowing researchers to develop new models quickly without the need to modify computer code for each new model to be considered. Restrictions: In the present version of the code, only methods that measure the hyperfine interaction on one probe spin state, such as PAC, μSR, and NMR, are supported. Running time: Varies

Atomic dark matter with hyperfine interactions

NASA Astrophysics Data System (ADS)

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

2017-11-01

We consider dark matter as an analog of hydrogen in a secluded sector and study its astrophysical implications. The self interactions between dark matter particles include elastic scatterings as well as inelastic processes from hyperfine transitions. We show that for a dark hydrogen mass in the 10-100 GeV range and a dark fine-structure constant larger than 0.01, the self-interaction cross section has the right magnitude and velocity dependence to explain the low dark matter density cores seen in small galaxies while being consistent with all constraints from observations of galaxy clusters. Excitations to the hyperfine state and subsequent decays, however, may cause significant cooling losses and affect the evolution of low-mass halos. We also find minimum halo masses in the range of 103.5-107 M⊙, which are significantly larger than the typical predictions for weakly interacting dark matter models. This pattern of observables in structure formation is unique to this model, making it possible to determine the viability of hidden-sector hydrogen as a dark matter candidate.

Spin polarization of {sup 87}Rb atoms with ultranarrow linewidth diode laser: Numerical simulation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, Z. G.; Interdisciplinary Center of Quantum Information, National University of Defense Technology, Changsha, 410073; College of Science, National University of Defense Technology, Changsha, 410073

2016-08-15

In order to polarize {sup 87}Rb vapor effectively with ultranarrow linewidth diode laser, we studied the polarization as a function of some parameters including buffer gas pressure and laser power. Moreover, we also discussed the methods which split or modulate the diode laser frequency so as to pump the two ground hyperfine levels efficiently. We obtained some useful results through numerical simulation. If the buffer gas pressure is so high that the hyperfine structure is unresolved, the polarization is insensitive to laser frequency at peak absorption point so frequency splitting and frequency modulation methods do not show improvement. At lowmore » pressure and laser power large enough, where the hyperfine structure is clearly resolved, frequency splitting and frequency modulation methods can increase polarization effectively. For laser diodes, frequency modulation is easily realized with current modulation, so this method is attractive since it does not add any other components in the pumping laser system.« less

Subpicosecond X rotations of atomic clock states

NASA Astrophysics Data System (ADS)

Song, Yunheung; Lee, Han-gyeol; Kim, Hyosub; Jo, Hanlae; Ahn, Jaewook

2018-05-01

We demonstrate subpicosecond-timescale population transfer between the pair of hyperfine ground states of atomic rubidium using a single laser-pulse. Our scheme utilizes the geometric and dynamic phases induced during Rabi oscillation through the fine-structure excited state to construct an X rotation gate for the hyperfine-state qubit system. The experiment performed with a femtosecond laser and cold rubidium atoms, in a magnetooptical trap, shows over 98% maximal population transfer between the clock states.

Modulated magnetic structure of F e3P O7 as seen by 57Fe Mössbauer spectroscopy

NASA Astrophysics Data System (ADS)

Sobolev, A. V.; Akulenko, A. A.; Glazkova, I. S.; Pankratov, D. A.; Presniakov, I. A.

2018-03-01

The paper reports results of the 57Fe Mössbauer measurements on an F e3P O4O3 powder sample recorded at various temperatures, including the point of magnetic phase transition TN≈163 K . The spectra measured above TN consist of a quadrupole doublet with high quadrupole splitting of Δ300 K≈1.10 mm /s , emphasizing that F e3 + ions are located in crystal positions with a strong electric-field gradient (EFG). To predict the sign and orientation of the main components of the EFG tensor, we calculated the EFG using the density-functional-theory approach. In the temperature range T

Discriminating the structure of exo-2-aminonorbornane using nuclear quadrupole coupling interactions.

PubMed

Écija, Patricia; Cocinero, Emilio J; Lesarri, Alberto; Millán, Judith; Basterretxea, Francisco; Fernández, José A; Castaño, Fernando

2011-04-28

The intrinsic conformational and structural properties of the bicycle exo-2-aminonorbornane have been probed in a supersonic jet expansion using Fourier-transform microwave (FT-MW) spectroscopy and quantum chemical calculations. The rotational spectrum revealed two different conformers arising from the internal rotation of the amino group, exhibiting small (MHz) hyperfine patterns originated by the (14)N nuclear quadrupole coupling interaction. Complementary ab initio (MP2) and DFT (B3LYP and M05-2X) calculations provided comparative predictions for the structural properties, rotational and centrifugal distortion data, hyperfine parameters, and isomerization barriers. Due to the similarity of the rotational constants, the structural assignment of the observed rotamers and the calculation of the torsion angles of the amino group were based on the conformational dependence of the (14)N nuclear quadrupole coupling hyperfine tensor. In the most stable conformation (ss), the two amino N-H bonds are staggered with respect to the adjacent C-H bond. In the second conformer (st), only one of the N-H bonds is staggered and the other is trans. A third predicted conformer (ts) was not detected, consistent with a predicted conformational relaxation to conformer ss through a low barrier of 5.2 kJ mol(-1).

HYPERFINE STRUCTURES AND NUCLEAR MOMENTS OF Lu$sup 176$m, Br$sup 80$, Br$sup 80$m, AND I$sup 132$ (thesis)

DOE Office of Scientific and Technical Information (OSTI.GOV)

White, M.B.

1962-09-01

The method of atomic-beam radiofrequency spectroscopy was used to determine some nuclear and atomic properties of Lu/sup 176m/, Br/sup 80/, Br/sup 80m/, and I/sup 132/. Hyperfine structure me asurements were raade to determine the magnetic dipole interaction constants and the electric quadrupole interaction constants of all these isotopes. Also the nuclear spin and the electronic g/sub J/ factor were measured for Lu/sup 176m/, and the nuclear magnetic dipole moments and the electric quadrupole moments for the isotopes were calculated. All results are listed. 62 references. (auth)

The gj factor of a bound electron and the hyperfine structure splitting in hydrogenlike ions

NASA Astrophysics Data System (ADS)

Beier, Thomas

2000-12-01

The comparison between theory and experiment of the hyperfine structure splitting and the electronic gj factor in heavy highly charged ions provides a unique testing ground for quantum electrodynamics in the presence of strong electric and magnetic fields. A theoretical evaluation is presented of all quantum electrodynamical contributions to the ground-state hfs splitting in hydrogenlike and lithiumlike atoms as well as to the gj factor. Binding and nuclear effects are discussed as well. A comparison with the available experimental data is performed, and a detailed discussion of theoretical sources of uncertainty is included which is mainly due to insufficiently known nuclear properties.

Time-resolved ESR spectra of the α-hydroxybenzyl-amine complex

NASA Astrophysics Data System (ADS)

Kawai, Akio; Kobori, Yasuhiro; Obi, Kinichi

1993-11-01

Time-resolved ESR spectra of the α-hydroxybenzyl radical were measured in benzene and 2-propanol solutions by the photo-dissociation of benzoin. The hyperfine structure (hfs) of α-hydroxybenzyl depends on the solvents. In a benzene solution containing triethylamine, two species with different hyperfine structure appeared simultaneously. As the ratio of intensity for the two species depends on the concentration of triethylamine, one of them is assigned to the bare α-hydroxybenzyl and the other to the 1:1 complex of α-hydroxybenzyl and triethylamine. The equilibrium constant of complex formation was estimated to be about 450 M -1 from the analysis of CIDEP intensities.

Theory of the n = 2 levels in muonic helium-3 ions

NASA Astrophysics Data System (ADS)

Franke, Beatrice; Krauth, Julian J.; Antognini, Aldo; Diepold, Marc; Kottmann, Franz; Pohl, Randolf

2017-12-01

The present knowledge of Lamb shift, fine-, and hyperfine structure of the 2S and 2P states in muonic helium-3 ions is reviewed in anticipation of the results of a first measurement of several 2S → 2P transition frequencies in the muonic helium-3 ion, μ3He+. This ion is the bound state of a single negative muon μ- and a bare helium-3 nucleus (helion), 3He++. A term-by-term comparison of all available sources, including new, updated, and so far unpublished calculations, reveals reliable values and uncertainties of the QED and nuclear structure-dependent contributions to the Lamb shift and the hyperfine splitting. These values are essential for the determination of the helion rms charge radius and the nuclear structure effects to the hyperfine splitting in μ3He+. With this review we continue our series of theory summaries in light muonic atoms [see A. Antognini et al., Ann. Phys. 331, 127 (2013); J.J. Krauth et al., Ann. Phys. 366, 168 (2016); and M. Diepold et al. arXiv:1606.05231 (2016)].

Hyperfine Structure in the Pure Rotational Spectrum of 208Pb35Cl

NASA Astrophysics Data System (ADS)

Dewberry, Christopher T.; Grubbs, Garry S., II; Etchison, Kerry C.; Cooke, Stephen A.

2010-06-01

Initially in our laboratory the pure rotational spectrum of the title molecule was studied using a Balle-Flygare Fourier transform microwave spectrometer. Analysis was troublesome and so the spectrum was remeasured using a chirped pulse Fourier transform microwave (CP-FTMW) spectrometer. The correct intensity aspect of the CP-FTMW experiment allowed successful quantum number assignments for the hyperfine structure for the correct isotopologue. Spectroscopic constants have been obtained from a fit to a data set consisting of our measurements combined with those of a prior study on the X_2^2Π3/2 → X_1^2Π_{1/2 fine structure transitions. K. Ziebarth, K. D. Setzer, O. Shestakov and E. H. Fink J. Mol. Spectrosc., 191 108, 1998.

Structural investigation of new vanadium-bismuth-phosphate glasses by IR and ESR spectroscopy

NASA Astrophysics Data System (ADS)

Vedeanu, N.; Cozar, O.; Stanescu, R.; Cozar, I. B.; Ardelean, I.

2013-07-01

IR spectra changes of the xV2O5(1 - x)[0.8P2O5ṡ0.2Bi2O3] glass system with 0 ⩽ x ⩽ 50 mol% show that vanadium oxide acts as a network modifier at low concentration (x ⩽ 5 mol%), affecting especially the Bi2O3 network. In the same time the phosphate groups (structures) impose their presence by themselves, fact which is illustrated by the increasing of the intensity of characteristic 910, 1040, 1230 cm-1 bands. The IR bands belonging to the phosphate groups are strongly reduced for x ⩾ 10 mol% due to the phosphate network depolymerization and to the appearance of new vibrations characteristic for POV and VOV linkages, showing the network former role of V2O5. In the same time the changes observed in the ESR spectra of these glasses are explained supposing the superposition of two signals, one with a well-resolved hyperfine structure typical for isolated V4+ ions and a broad line characteristic for clustered ions. The line width dependence versus V2O5 content shows that dipole-dipole interactions exist between vanadium ions until x = 5 mol% and the superexchange interactions prevail at high content (x ⩾ 10 mol%).

Theoretical hyperfine structures of 19F i and 17O i

NASA Astrophysics Data System (ADS)

Aourir, Nouria; Nemouchi, Messaoud; Godefroid, Michel; Jönsson, Per

2018-03-01

Multiconfiguration Hartree-Fock (MCHF) and multiconfiguration Dirac-Hartree-Fock (MCDHF) calculations are performed for the 2 p5P2o , 2 p4(3P ) 3 s 4P , 2 p4(3P ) 3 s 2P , and 2 p4(3P ) 3 p 4So states of 19F i to determine their hyperfine constants. Several computing strategies are considered to investigate electron correlation and relativistic effects. High-order correlation contributions are included in MCHF calculations based on single and double multireference expansions. The largest components of the single reference MCHF wave functions are selected to define the multireference (MR) sets. In this scheme, relativistic corrections are evaluated in the Breit-Pauli approximation. A similar strategy is used for the calculation of MCDHF relativistic wave functions and hyperfine parameters. While correlation and relativistic corrections are found to be rather small for the ground state, we highlight large relativistic effects on the hyperfine constant A3 /2 of 2 p4(3P ) 3 p 4So and, to a lesser extent, on A1 /2 of 2 p4(3P ) 3 s 4P . As expected for such a light system, electron correlation effects dominate over relativity in the calculation of the hyperfine interaction of all other levels considered. We also revisit the hyperfine constants of 2 p3(4S ) 3 s S5o and 2 p3(4S ) 3 p 5P in 17O using similar strategies. The results are found to be in excellent agreement with experiment.

Hyperfine excitation of OH+ by H

NASA Astrophysics Data System (ADS)

Lique, François; Bulut, Niyazi; Roncero, Octavio

2016-10-01

The OH+ ions are widespread in the interstellar medium and play an important role in the interstellar chemistry as they act as precursors to the H2O molecule. Accurate determination of their abundance rely on their collisional rate coefficients with atomic hydrogen and electrons. In this paper, we derive OH+-H fine and hyperfine-resolved rate coefficients by extrapolating recent quantum wave packet calculations for the OH+ + H collisions, including inelastic and exchange processes. The extrapolation method used is based on the infinite order sudden approach. State-to-state rate coefficients between the first 22 fine levels and 43 hyperfine levels of OH+ were obtained for temperatures ranging from 10 to 1000 K. Fine structure-resolved rate coefficients present a strong propensity rule in favour of Δj = ΔN transitions. The Δj = ΔF propensity rule is observed for the hyperfine transitions. The new rate coefficients will help significantly in the interpretation of OH+ spectra from photon-dominated region (PDR), and enable the OH+ molecule to become a powerful astrophysical tool for studying the oxygen chemistry.

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

NASA Astrophysics Data System (ADS)

Nardali, Ş.; Ucun, F.; Karakaya, M.

2017-11-01

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

Ultrafast time scale X-rotation of cold atom storage qubit using Rubidium clock states

NASA Astrophysics Data System (ADS)

Song, Yunheung; Lee, Han-Gyeol; Kim, Hyosub; Jo, Hanlae; Ahn, Jaewook

2017-04-01

Ultrafast-time-scale optical interaction is a local operation on the electronic subspace of an atom, thus leaving its nuclear state intact. However, because atomic clock states are maximally entangled states of the electronic and nuclear degrees of freedom, their entire Hilbert space should be accessible only with local operations and classical communications (LOCC). Therefore, it may be possible to achieve hyperfine qubit gates only with electronic transitions. Here we show an experimental implementation of ultrafast X-rotation of atomic hyperfine qubits, in which an optical Rabi oscillation induces a geometric phase between the constituent fine-structure states, thus bringing about the X-rotation between the two ground hyperfine levels. In experiments, cold atoms in a magneto-optical trap were controlled with a femtosecond laser pulse from a Ti:sapphire laser amplifier. Absorption imaging of the as-controlled atoms initially in the ground hyperfine state manifested polarization dependence, strongly agreeing with the theory. The result indicates that single laser pulse implementations of THz clock speed qubit controls are feasible for atomic storage qubits. Samsung Science and Technology Foundation [SSTF-BA1301-12].

The Hyperfine Structure of the Ground State in the Muonic Helium Atoms

NASA Astrophysics Data System (ADS)

Aznabayev, D. T.; Bekbaev, A. K.; Korobov, V. I.

2018-05-01

Non-relativistic ionization energies 3He2+μ-e- and 4He2+μ-e- of helium-muonic atoms are calculated for ground states. The calculations are based on the variational method of the exponential expansion. Convergence of the variational energies is studied by an increasing of a number of the basis functions N. This allows to claim that the obtained energy values have 26 significant digits for ground states. With the obtained results we calculate hyperfine splitting of the muonic helium atoms.

Hyperfine field and magnetic structure in the B phase of CeCoIn5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graf, Matthias J; Curro, Nicholas J; Young, Ben - Li

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 themore » [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.« less

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.

Hyperfine interaction constants of 14NO2 in 14 500-16 800 cm-1 energy region

NASA Astrophysics Data System (ADS)

Tada, Kohei; Hirata, Michihiro; Kasahara, Shunji

2017-10-01

We observed hyperfine-resolved high-resolution fluorescence excitation spectra of k = 0, N = 1 ← 0 transitions in 82 vibronic bands of the à 2B2 ← X ˜ 2A1 system of 14NO2 in the 14 500-16 800 cm-1 region by crossing a jet-cooled molecular beam and a single-mode dye laser beam at right angles. We determined hyperfine interaction constants of the lower and upper states for all the observed vibronic bands based on the analysis of the hyperfine structures of k = 0, N = 1 ← 0 transitions. Most of the determined Fermi contact interaction constants were found to be distributed in 0.0013-0.0038 cm-1, which are intermediate in magnitude between those in lower and higher energy region reported by other groups. A sharp decreasing of the Fermi contact interaction constant was found in 16 200-16 600 cm-1, and it may be caused by the interaction with the dark C ˜ 2A2 state. The hyperfine interaction constants are powerful clues to obtain reliable vibronic assignment. We tentatively assigned vibronic bands located at 14 836 cm-1, 15 586 cm-1, and 16 322 cm-1 as the transitions to the intrinsic (0,7,0), (0,8,0), and (0,9,0) vibrational levels of the à 2B2 state, respectively.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

Hyperfine fibers based on biodegradable poly (3-hydroxybutyrate) with encapsulated drug substance (dipyridamol) were obtained by using electrospinning method. Addition of dipyridamol has a significant effect on geometrical shape and structure of microfibers as well as total porosity of fibrous material. Observation of fibers using scanning electron microscopy (SEM) method showed that without or at lower dipyridamol content (<3%) fibers consisted of interleaved ellipsoid and cylindrical fragments. At higher dipyridamol content (3-5%) anomalous ellipsoid structures did not practically form, and fiber’s shape became cylindrical. The totality of morphological and structural characteristics determined the rate of dipyridamol diffusive transports. The simplified model of drug desorption from fibrous matrix was presented. In current work it was showed that the rate-limiting stage of transport was the diffusion of dipyridamol in the bulk of cylindrical fibers.

Hyperfine structure and isotope shift of /sup 208/Bi in the 3067-A resonance line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lamontagne, J.J.

1982-01-01

The hyperfine structure of /sup 208/Bi (I = 5) was measured using the 3067 A spectral line from the 6p/sup 2/7s (/sup 4/P/sub 1/2/) - 6p/sup 3/ (/sup 4/S/sub 3/2/) transition. After production of the isotope at the Princeton University Cyclotron, chemical separation, and mass separation, some 10/sup 12/ atoms were used to produce an absorption spectrum. The monochromator, Czerny-Turner design), had a 9.1 m focal length with a 25 cm diffraction grating used in autocollimation near 63/sup 0/. The spectrum was recorded on photographic plates. Measurements were made of the position of the components. From these the value /supmore » 208/A (/sup 4/P/sub 1/2) = 166 (1.5) mK was obtained. Neglecting hyperfine anomalies this gives /sup 208/A (/sup 4/S/sub 3/2/) = 15.07 (.1). The isotope shift /sup 208/Bi-/sup 208/Bi was measured to be 50.58 (7.5) mK.« less

Orbitally excited spectra and decay of cc¯ meson

NASA Astrophysics Data System (ADS)

Chaturvedi, Raghav; Rai, A. K.

2018-05-01

We use the hydrogen like trial wave function for computation of the mass spectra and decay properties of charmonia within the framework of phenomenological quark anti-quark Coulomb plus power potential with varying potential index from 0.5 to 2.0. The spin-spin hyperfine interaction is considered to incorporate splitting of the ground and radially excited states energy levels, further spin-orbit and tensor interactions are employed to calculate the masses of orbitally excited states. We construct the Regge trajectories from the mass spectra in (J, M2) and (nr, M2) planes. We also compute γγ decay width of P wave states of cc¯.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herojit Singh, L.; Govindaraj, R., E-mail: govind@igcar.gov.in; Rajagopalan, S.

Mössbauer spectroscopic studies have been carried out at different temperatures across ferromagnetic to paramagnetic transition in Ni{sub 50}Fe{sub 35}Co{sub 15} and the evolution of hyperfine parameters such as centre shift and magnetic hyperfine fields with temperature has been studied. Mössbauer spectrum obtained at 300 K in Ni{sub 50}Fe{sub 35}Co{sub 15} exhibiting fcc crystal structure is a six line pattern with the mean value of the hyperfine field close to 33 Tesla. Ferromagnetic to paramagnetic transition has been observed to occur in this system around 895 K matching with that of magnetization results. Debye temperature of this nickel rich alloy ismore » deduced to be around 470 K matching with that of Ni. Effect of prolonged annealing at 750 K on the magnetic property is also investigated with respect to the thermal stability of the alloy.« less

Reanalysis and extension of the MnH A7Π- X7Σ + (0, 0) band: Fine structure and hyperfine-induced rotational branches

NASA Astrophysics Data System (ADS)

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

1992-12-01

The A7Π- X7Σ + (0, 0) band of MnH at 568 nm has been recorded by laser fluorescence excitation spectroscopy. The original rotational analysis of Nevin [ Proc. R. Irish Acad.48A, 1-45 (1942); 50A, 123-137 (1945)] has been extended with some corrections at low J. Systematic internal hyperfine perturbations in the X7Σ + state, caused by the Δ N = 0, Δ J = ±1 matrix elements of the 55Mn hyperfine term in the Hamiltonian, have been observed in all seven electron spin components over the entire range of N″ studied. These perturbations destroy the "goodness" of J″ as a quantum number, giving rise to hyperfine-induced Δ J = ±2 rotational branches and to observable energy shifts of the most severely affected levels. The A7Π state, with A = 40.5 cm -1 and B = 6.35 cm -1, evolves rapidly from Hund's case ( a) to case ( b) coupling, which produces anomalous branch patterns at low J. A total of 156 rotational branches have been identified and fitted by least squares to an effective Hamiltonian, providing precise values for the rotational and fine structure constants. Values of the principal constants determined in the fit are (1σ errors in units of the last digit are listed in parentheses): The fine structures of the A7Π and X7Σ + states confirm the assignment of the A ← X transition as Mn 4 pπ ← 4 sσ in the presence of a spectator, nonbonding Mn 3 d5 ( 6S) open core.

Characterising molecules for fundamental physics: an accurate spectroscopic model of methyltrioxorhenium derived from new infrared and millimetre-wave measurements.

PubMed

Asselin, Pierre; Berger, Yann; Huet, Thérèse R; Margulès, Laurent; Motiyenko, Roman; Hendricks, Richard J; Tarbutt, Michael R; Tokunaga, Sean K; Darquié, Benoît

2017-02-08

Precise spectroscopic analysis of polyatomic molecules enables many striking advances in physical chemistry and fundamental physics. We use several new high-resolution spectroscopic devices to improve our understanding of the rotational and rovibrational structure of methyltrioxorhenium (MTO), the achiral parent of a family of large oxorhenium compounds that are ideal candidate species for a planned measurement of parity violation in chiral molecules. Using millimetre-wave and infrared spectroscopy in a pulsed supersonic jet, a cryogenic buffer gas cell, and room temperature absorption cells, we probe the ground state and the Re[double bond, length as m-dash]O antisymmetric and symmetric stretching excited states of both CH 3 187 ReO 3 and CH 3 185 ReO 3 isotopologues in the gas phase with unprecedented precision. By extending the rotational spectra to the 150-300 GHz range, we characterize the ground state rotational and hyperfine structure up to J = 43 and K = 41, resulting in refinements to the rotational, quartic and hyperfine parameters, and the determination of sextic parameters and a centrifugal distortion correction to the quadrupolar hyperfine constant. We obtain rovibrational data for temperatures between 6 and 300 K in the 970-1015 cm -1 range, at resolutions down to 8 MHz and accuracies of 30 MHz. We use these data to determine more precise excited-state rotational, Coriolis and quartic parameters, as well as the ground-state centrifugal distortion parameter D K of the 187 Re isotopologue. We also account for hyperfine structure in the rovibrational transitions and hence determine the upper state rhenium atom quadrupole coupling constant eQq'.

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.

The Submillimeter Spectrum of MnH and MnD (X7Σ+)

NASA Astrophysics Data System (ADS)

Halfen, D. T.; Ziurys, L. M.

2008-01-01

The submillimeter-wave spectrum of the MnH and MnD radicals in their 7Σ+ ground states has been measured in the laboratory using direct absorption techniques. These species were created in the gas phase by the reaction of manganese vapor, produced in a Broida-type oven, with either H2 or D2 gas in the presence of a DC discharge. The N = 0 → 1 transition of MnH near 339 GHz was recorded, which consisted of multiple hyperfine components arising from both the manganese and hydrogen nuclear spins. The N = 2 → 3 transition of MnD near 517 GHz was measured as well, but in this case only the manganese hyperfine interactions were resolved. Both data sets were analyzed with a Hund's case b Hamiltonian, and rotational, fine structure, magnetic hyperfine, and electric quadrupole constants have been determined for the two manganese species. An examination of the magnetic hyperfine constants shows that MnH is primarily an ionic species, but has more covalent character than MnF. MnH is a good candidate species for astronomical searches with Herschel, particularly toward material associated with luminous blue variable stars.

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.

Radiative transfer of HCN: interpreting observations of hyperfine anomalies

NASA Astrophysics Data System (ADS)

Mullins, A. M.; Loughnane, R. M.; Redman, M. P.; Wiles, B.; Guegan, N.; Barrett, J.; Keto, E. R.

2016-07-01

Molecules with hyperfine splitting of their rotational line spectra are useful probes of optical depth, via the relative line strengths of their hyperfine components. The hyperfine splitting is particularly advantageous in interpreting the physical conditions of the emitting gas because with a second rotational transition, both gas density and temperature can be derived. For HCN however, the relative strengths of the hyperfine lines are anomalous. They appear in ratios which can vary significantly from source to source, and are inconsistent with local thermodynamic equilibrium (LTE). This is the HCN hyperfine anomaly, and it prevents the use of simple LTE models of HCN emission to derive reliable optical depths. In this paper, we demonstrate how to model HCN hyperfine line emission, and derive accurate line ratios, spectral line shapes and optical depths. We show that by carrying out radiative transfer calculations over each hyperfine level individually, as opposed to summing them over each rotational level, the anomalous hyperfine emission emerges naturally. To do this requires not only accurate radiative rates between hyperfine states, but also accurate collisional rates. We investigate the effects of different sets of hyperfine collisional rates, derived via the proportional method and through direct recoupling calculations. Through an extensive parameter sweep over typical low-mass star-forming conditions, we show the HCN line ratios to be highly variable to optical depth. We also reproduce an observed effect whereby the red-blue asymmetry of the hyperfine lines (an infall signature) switches sense within a single rotational transition.

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.

Laboratory rotational spectroscopy of cyano substituted polycyclic aromatic hydrocarbons

NASA Astrophysics Data System (ADS)

McNaughton, Don; Jahn, Michaela K.; Travers, Michael J.; Wachsmuth, Dennis; Godfrey, Peter D.; Grabow, Jens-Uwe

2018-06-01

The rotational spectra of the four cyano substituted polycyclic aromatic hydrocarbon (PAH) molecules 1-cyanonaphthalene, 2-cyanonaphthalene, 9-cyanoanthracene, and 9-cyanophenanthrene have been recorded in molecular expansions using a Stark-modulated millimetre-wave spectrometer and a Fourier transform microwave spectrometer in the centimetre-wave region. The spectra have been assigned and fitted to provide molecular constants and quadrupole hyperfine constants of sufficient accuracy to enable complete hyperfine structure line predictions for interstellar searches. The data may provide a route into detection of small PAHs in the interstellar medium.

Electrical detection of nuclear spins in organic light-emitting diodes

NASA Astrophysics Data System (ADS)

Malissa, H.; Kavand, M.; Waters, D. P.; Lupton, J. M.; Vardeny, Z. V.; Saam, B.; Boehme, C.

2014-03-01

We present pulsed combined electrically detected electron paramagnetic and nuclear magnetic resonance experiments on MEH-PPV OLEDs. Spin dynamics in these structures are governed by hyperfine interactions between charge carriers and the surrounding hydrogen nuclei, which are abundant in these materials. Hyperfine coupling has been observed by monitoring the device current during coherent spin excitation. Electron spin echoes (ESEs) are detected by applying one additional readout pulse at the time of echo formation. This allows for the application of high-resolution spectroscopy based on ESE detection, such as electron spin echo envelope modulation (ESEEM) and electron nuclear double resonance (ENDOR) available for electrical detection schemes. We conduct electrically detected ESEEM and ENDOR experiments and show how hyperfine interactions in MEH-PPV with and without deuterated polymer side groups can be observed by device current measurements. We acknowledge support by the Department of Energy, Office of Basic Energy Sciences under Award #DE-SC0000909.

Structural and magnetic properties of FeCoC system obtained by mechanical alloying

NASA Astrophysics Data System (ADS)

Rincón Soler, A. I.; Rodríguez Jacobo, R. R.; Medina Barreto, M. H.; Cruz-Muñoz, B.

2017-11-01

Fe96-XCoXC4 (x = 0, 10, 20, 30, 40 at. %) alloys were obtained by mechanical alloying of Fe, C and Co powders using high-energy milling. The structural and magnetic properties of the alloy system were analyzed by X-ray diffraction, Scanning Electron Microscopy (SEM), Vibrating Sample Magnetometer (VSM) and Mössbauer Spectrometry at room temperature. The X-ray diffraction patterns showed a BCC-FeCoC structure phase for all samples, as well as a lattice parameter that slightly decreases with Co content. The saturation magnetization and coercive field were analyzed as a function of Co content. The Mössbauer spectra were fitted with a hyperfine magnetic field distribution showing the ferromagnetic behavior and the disordered character of the samples. The mean hyperfine magnetic field remained nearly constant (358 T) with Co content.

Where's water? The many binding sites of hydantoin.

PubMed

Gruet, Sébastien; Pérez, Cristóbal; Steber, Amanda L; Schnell, Melanie

2018-02-21

Prebiotic hydantoin and its complexes with one and two water molecules are investigated using high-resolution broadband rotational spectroscopy in the 2-8 GHz frequency range. The hyperfine structure due to the nuclear quadrupole coupling of the two 14 N atoms is analysed for the monomer and the complexes. This characteristic hyperfine structure will support a definitive assignment from low frequency radioastronomy data. Experiments with H 2 18 O provide accurate experimental information on the preferred binding sites of water, which are compared with quantum-chemically calculated coordinates. In the 2-water complexes, the water molecules bind to hydantoin as a dimer instead of individually, indicating the strong water-water interactions. This information provides first insight on how hydantoin interacts with water on the molecular level.

Research investigation directed toward extending the useful range of the electromagnetic spectrum

NASA Technical Reports Server (NTRS)

Hartmann, S. R.

1971-01-01

The lifetimes and fine structure of He(-) were studied using time-of-flight techniques and quenching by a static axial magnetic field. Using level-crossing spectroscopy the hyperfine constants A and B and the lifetime of the 3 2P3/2 state of Li-7 were measured. Polarization of the Ru 7S level was created as a first step in determining the hyperfine structure of the alkali excited S state. The parametric interaction between light and microwaves in optically pumped Rb-87 vapor were investigated. Measurements and analyses of transitions in formaldehyde and its isotopic species and in the lowest two excited vibrational states of H2CO were also made, as well as of transitions in furan, pyrrole, formic acid, and cyanoacetylene. The Hanle effect was studied in the NO molecule, and RF oscillators were developed with flat, wideband output to observe excited state hyperfine transitions at zero field. Data was generated on the time-dependent behavior of photon echoes in ruby. Stimulated Raman scattering was studied in atomic Tl vapor. A Q switched, temperature-tuned ruby laser was developed which operates between 6934 and 6938 A. The frequency shift due to resonant interaction between identical radiating atoms was calculated.

Ground-State Hyperfine Structure of Heavy Hydrogen-Like Ions

NASA Astrophysics Data System (ADS)

Kühl, T.; Borneis, S.; Dax, A.; Engel, T.; Faber, S.; Gerlach, M.; Holbrow, C.; Huber, G.; Marx, D.; Merz, P.; Quint, W.; Schmitt, F.; Seelig, P.; Tomaselli, M.; Winter, H.; Wuertz, M.; Beckert, K.; Franzke, B.; Nolden, F.; Reich, H.; Steck, M.

Contributions of quantum electrodynamics (QED) to the combined electric and magnetic interaction between the electron and the nucleus can be studied by optical spectroscopy in high-Z hydrogen-like heavy ions. The transition studied is the ground-state hyperfine structure transition, well known from the 21 cm line in atomic hydrogen. The hyperfine splitting of the is ground state of hydrogen-like systems constitutes the simplest and most basic magnetic interaction in atomic physics. The Z3-increase leads to a transition energy in the UV-region of the optical spectrum for the case of Bi82+. At the same time, the QED correction rises to nearly 1 fraction of higher order contributions. This situation is particularly useful for a comparison with non-perturbative QED calculations. The combination of exceptionally intense electric and magnetic fields electric and magnetic fields is unique. This transition has become accessible to precision laser spectroscopy at the high-energy heavy-ion storage ring at GSI-Darmstadt in the hydrogen-like 209Bi82+ and 207Pb81+. In the meantime, 165Ho66+ and 185,187Re74+ were also studied with reduced resolution by conventional optical spectroscopy at the SuperEBIT ion trap at Lawrence Livermore National Laboratory.

Hyperfine rather than spin splittings dominate the fine structure of the B (4)Σ(-)-X (4)Σ(-) bands of AlC.

PubMed

Clouthier, Dennis J; Kalume, Aimable

2016-01-21

Laser-induced fluorescence and wavelength resolved emission spectra of the B (4)Σ(-)-X (4)Σ(-) band system of the gas phase cold aluminum carbide free radical have been obtained using the pulsed discharge jet technique. The radical was produced by electron bombardment of a precursor mixture of trimethylaluminum in high pressure argon. High resolution spectra show that each rotational line of the 0-0 and 1-1 bands of AlC is split into at least three components, with very similar splittings and intensities in both the P- and R-branches. The observed structure was reproduced by assuming bβS magnetic hyperfine coupling in the excited state, due to a substantial Fermi contact interaction of the unpaired electron in the aluminum 3s orbital. Rotational analysis has yielded ground and excited state equilibrium bond lengths in good agreement with the literature and our own ab initio values. Small discrepancies in the calculated intensities of the hyperfine lines suggest that the upper state spin-spin constant λ' is of the order of ≈ 0.025-0.030 cm(-1).

Theoretical Studies of the Electron Paramagnetic Resonance Parameters and Local Structure for VO2+ in Oxyfluoroborate Glasses

NASA Astrophysics Data System (ADS)

Zhang, Huaming; Yu, Xiaopeng; Xiao, Wenbo

2017-12-01

The electron paramagnetic resonance parameters (g factors g ‖, g ⊥ and hyperfine structure constants A ‖, A ⊥) of a tetragonal V4+ center in oxyfluoroborate glasses (20Li2O-10Li2F2-70B2O3) are theoretically investigated by using the perturbation formulas for a 3d1 ion in tetragonally compressed octahedra. The calculated results are in good agreement with the experimental data. Local structure parameters of [VO6]8- clusters are obtained from the calculation (i.e., R‖ ≈ 1.74 Å and R⊥ ≈ 1.985 Å for the metal-ligand distances parallel and perpendicular to the C4 axis, respectively). It is shown that the local structure around the V4+ ion possesses a compressed tetragonal distortion along C 4 axis. The signs of the hyperfine structure constants A‖ and A ⊥ for V4+ centers in oxyfluoroborate glasses were also suggested in the discussion.

Molecules in high spin states: The millimeter and submillimeter spectrum of the MnS radical (X 6Sigma+)

NASA Astrophysics Data System (ADS)

Thompsen, J. M.; Brewster, M. A.; Ziurys, L. M.

2002-06-01

The pure rotational spectrum of MnS (v=0) in its X 6Sigma+ ground state has been recorded using millimeter and submillimeter direct absorption techniques in the range 160-502 GHz. MnS was synthesized in the gas phase by the reaction of manganese vapor and CS2 in a high-temperature Broida-type oven. Fourteen rotational transitions for this radical were measured, each consisting of six fine-structure components. In the lower rotational lines, hyperfine structure, arising from the 55Mn nuclear spin of 5/2, was also resolved in each spin component. These data were analyzed using a case (b) Hamiltonian, and rotational, fine structure, and hyperfine parameters determined for MnS. In the analysis, the third-order correction to the spin-rotation interaction, gammaS, and the fourth-order spin-spin coupling term, theta, were found necessary for an acceptable fit. The hyperfine constants determined suggest that MnS is more covalent than MnO, but more ionic than MnH. There additionally appears to be considerable sdsigma hybridization in molecular orbital formation for this molecule. Bond lengths of the 3d transition-metal sulfides were compared as well, and those of MnS, CuS, and TiS do not follow the trend of their oxide analogs. This result indicates that there are significant bonding differences between transition-metal sulfides and transition-metal oxides.

Rotational spectroscopic study of carbonyl sulfide solvated with hydrogen molecules.

PubMed

Michaud, Julie M; Jäger, Wolfgang

2008-10-14

Rotational spectra of small-sized (H(2))(N)-OCS clusters with N = 2-7 were measured using a pulsed-jet Fourier transform microwave spectrometer. These include spectra of pure (para-H(2))(N)-OCS clusters, pure (ortho-H(2))(N)-OCS clusters, and mixed ortho-H(2) and para-H(2) containing clusters. The rotational lines of ortho-H(2) molecules containing clusters show proton spin-proton spin hyperfine structure, and the pattern evolves as the number of ortho-H(2) molecules in the cluster increases. Various isotopologues of the clusters were investigated, including those with O(13)CS, OC(33)S, OC(34)S, and O(13)C(34)S. Nuclear quadrupole hyperfine structures of rotational transitions were observed for (33)S (nuclear spin quantum number I = 3/2) containing isotopologues. The (33)S nuclear quadrupole coupling constants are compared to the corresponding constant of the OCS monomer and those of the He(N)-OCS clusters. The assignment of the number of solvating hydrogen molecules N is supported by the analyses of the proton spin-proton spin hyperfine structures of the mixed clusters, the dependence of line intensities on sample conditions (pressure and concentrations), and the agreement of the (para-H(2))(N)-OCS and (ortho-H(2))(N)-OCS rotational constants with those from a previous infrared study [J. Tang and A. R. W. McKellar, J. Chem. Phys. 121, 3087 (2004)].

Structure and magnetic behaviors of melt-spun SmFeSiB ribbons and their nitrides

NASA Astrophysics Data System (ADS)

Luo, Y.; Zhang, K.; Li, K. S.; Yu, D. B.; Ling, J. J.; Men, K.; Dou, Q. Y.; Yan, W. L.; Xie, J. J.; Yang, Y. F.

2016-05-01

SmFe9.3+xSi0.2B0.1 (x=0, 0.5, 1.0) ribbons and their nitrides were prepared by melt-spinning, followed by annealing and subsequent nitriding. The structure and magnetic properties have been investigated by means of powder X-ray diffraction, vibrating sample magnetometer and Mossbauer spectroscopy. Rietveld analysis shows that the augment of Fe content gives rise to an increase of the c/a ratio and cell volume. The increasing amount of Fe atoms occupying the 2e sites results in the change of initial structure. It is indicated that the isomer shift of 3g and 6l atom remains quasi-constant while the 2e atom shows a noticeable increase with the increase of iron content, which further conforms the preferential occupation of excessive Fe atoms at this site. Consistent with Tc, the mean hyperfine field 〈Bhf〉 has the highest value of 25.7 T when x=0.5. The hyperfine fields at different Fe sites follow the order H2e>H3g>H6l. The highest curie temperature of 477.68 K and the hyperfine field of 25.7 T in the as-quenched ribbons were obtained when x=0.5. Meanwhile, the highest magnetic properties of Hcj=4.31 kOe, (BH)m=3.5 MGOe in the nitride powders were found.

Studies of molecular physics in sodium-potassium: An analysis of the 4(3)Sigma+ state and interactions between the 2(A)(1)Sigma+ and 1(b)(3)Pi states

NASA Astrophysics Data System (ADS)

Burns, Patrick

2004-12-01

In this dissertation we report the results of three experiments designed to provide new information on the structure and interactions of the NaK molecule. Specifically these experiments investigate 2(A)1Sigma +(upsilonA, J) + M → 1(b)3 pi0(upsilonb, J) + M collisional excitation transfers (where M is a collision partner), hyperfine structure of the NaK 1(b)3pi and 1(b)3pi0 ˜ 2(A)1Sigma+ spin-orbit interactions, and the structure and spectra of the NaK 43Sigma+ state, respectively. In this first experiment, populations of collisionally populated levels were recorded near the NaK 1(b)3pi0(upsilon =18, J = 44) ˜ 2(A)1Sigma+ (upsilon = 20, J = 44) center of spin-orbit perturbation. Our data indicate that population is transferred from the pumped level, 2(A) 1Sigma+(upsilon = 20, J = 49), directly to the surrounding "daughter" levels [1(b)3Sigma 0(upsilon =18, J = 45--48) and 2(A)1Sigma +(upsilon = 20, J = 45--48)]. The relative populations of the daughter levels appear anomalous, as their populations do not monotonically decrease for levels further away in energy from the pumped level. We have measured the hyperfine structure of mutually perturbing ro-vibrational levels of the 1(b)3pi0 and 2(A)1Sigma + states of the NaK molecule, using the PFOODR method with co-propagating lasers. Unperturbed 1(b)3pi0 levels are split into four hyperfine components by the Fermi contact interaction b FI·S. Mixing between the 1(b)3pi0 and 2(A)1Sigma + levels imparts hyperfine structure to the nominally singlet component, and reduces the hyperfine splitting of the nominally triplet component, of the perturbed levels. We determined a value for the Fermi constant, bF= (0.00989 +/- 0.00027) cm-1, and the magnitude of the electronic part of the 1(b)3pi 0 ˜ 2(A)1Sigma+ spin-orbit coupling, |Hel| = (15.65 +/- 0.14) cm-1 , from an analysis of the measured hyperfine splittings of the mixed singlet-triplet levels. High-resolution spectra have been observed for numerous vibrational-rotational levels (upsilon, N) of the 43Sigma + state of NaK. A potential curve was obtained from the data using the inverse perturbation approximation method. Measured bound-free emission, 43Sigma+ → 1(a)3Sigma +, was used to determine both the absolute vibrational numbering and the transition dipole moment function M(R). Each (upsilon, N) level is typically split into three sets of sublevels by the Fermi contact interaction bFI·S. Further splitting (of order 0.004 cm-1) has been attributed to the spin-rotation interaction gammaN·S. The values of bF that fit the data best are ˜(0.99 +/- 0.04) x 10-2 cm-1, with weak dependence on upsilon. The best fit values of gamma are in the range 1--6 x 10-4 cm-1 and depend strongly on upsilon.

Spectroscopy of the 1/2 2S → 3/2 2P transition in Yb ii: Isotope shifts, hyperfine splitting, and branching ratios

NASA Astrophysics Data System (ADS)

Feldker, T.; Fürst, H.; Ewald, N. V.; Joger, J.; Gerritsma, R.

2018-03-01

We report on spectroscopic results on the 1/2 2S → 3/2 2P transition in single trapped Yb+ ions. We measure the isotope shifts for all stable Yb+ isotopes except +173Yb, as well as the hyperfine splitting of the 3/2 2P state in +171Yb. Our results are in agreement with previous measurements but are a factor of 5-9 more precise. For the hyperfine constant A (3/2 2P)=875.4 (10 )MHz our results also agree with previous measurements but deviate significantly from theoretical predictions. We present experimental results on the branching ratios for the decay of the 3/2 2P state. We find branching fractions for the decay to the 3/2 2D state and 5/2 2D state of 0.17(1)% and 1.08(5)%, respectively, in rough agreement with theoretical predictions. Furthermore, we measured the isotope shifts of the 7/2 2F →1D[5/2 ] 5 /2 transition and determine the hyperfine structure constant for the 1D[5/2 ] 5 /2 state in +171Yb to be A (1D[5/2 ] 5 /2)=-107 (6 ) MHz .

Mössbauer spectra of iron (III) sulfide particles

NASA Astrophysics Data System (ADS)

Kubono, I.; Nishida, N.; Kobayashi, Y.; Yamada, Y.

2017-11-01

Trivalent iron sulfide (Fe2 S 3) particles were synthesized using a modified polyol method. These particles exhibited a needle-like shape (diameter = 10-50 nm, length = 350-1000 nm) and generated a clear XRD pattern. Mössbauer spectra of the product showed a paramagnetic doublet at room temperature and distributed hyperfine magnetic splitting at low temperature. The Curie temperature of this material was determined to be approximately 60 K. The data suggest that the Fe2 S 3 had a structure similar to that of maghemite ( γ-Fe2 O 3) with a lattice constant of a = 10.6 Å. The XRD pattern calculated from this structure was in agreement with the experimental pattern and the calculated hyperfine magnetic field was also equivalent to that observed in the experimental Mössbauer spectrum.

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.

Hyperfine structure of the MnH X 7Sigma + state: A large gas-to-matrix shift in the Fermi contact interaction

NASA Astrophysics Data System (ADS)

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

1990-06-01

Sub-Doppler spectra of the A 7Π-X 7Σ+ (0,0) band of gas phase MnH near 5680 Å were recorded by intermodulated fluorescence spectroscopy. The spectra reveal hyperfine splittings arising from both the 55Mn and 1H nuclear spins. Internal hyperfine perturbations have been observed between the different spin components of the ground state at low N`. From a preliminary analysis of several rotational lines originating from the isolated and unperturbed F1(J`=3) spin component of the X 7Σ+(N`=0) level, the 55Mn Fermi contact interaction in the ground state has been measured as bF=Aiso =276(1) MHz. This value is 11% smaller than the value obtained by Weltner et al. from an electron-nuclear double resonance (ENDOR) study of MnH in an argon matrix at 4 K. This unprecedented gas-to-matrix shift in the Fermi contact parameter is discussed.

An ESR study of the stable radical in a γ-irradiated single crystal of 17α-dydroxy-progesterone

NASA Astrophysics Data System (ADS)

Krzyminiewski, R.; Pietrzak, J.; Konopka, R.

1990-11-01

Electron spin resonance spectroscopy was used to investigate γ-radiation damage of 17α-hydroxy-progesterone molecules in a single crystal. Two types of radicals with different rates of recombination were observed and a definite structure was assigned to the specimen by analyzing the orientational variation of the spectra. The unpaired electron of the radical is delocalized in the 2 pz orbitals of the C(6), C(4) and C(3) atoms, giving rise to a hyperfine spectrum by interaction with two equivalent α-protons in positions 4 and 6 and with two non-equivalent β-protons attached to C(7). The hyperfine coupling tensors are reported, together with the g tensor of the radical. The presence of additional intermolecular interactions caused by hydrogen bonding between O(3) and HO(17) of two molecules does not change the type of radical (which is the same as the stable radical in a γ-irradiated single crystal of progesterone) but does increase the hyperfine coupling anisotropy.

57Fe Mössbauer study of unusual magnetic structure of multiferroic 3R-AgFeO2

NASA Astrophysics Data System (ADS)

Sobolev, A.; Rusakov, V.; Moskvin, A.; Gapochka, A.; Belik, A.; Glazkova, I.; Akulenko, A.; Demazeau, G.; Presniakov, I.

2017-07-01

We report new results of a 57Fe Mössbauer study of hyperfine magnetic interactions in the layered multiferroic 3R-AgFeO2 demonstrating two magnetic phase transitions at T N1 and T N2. The asymptotic value β *  ≈  0.34 for the critical exponent obtained from the temperature dependence of the hyperfine field H hf(T) at 57Fe the nuclei below T N1  ≈  14 K indicates that 3R-AgFeO2 shows quasi-3D critical behavior. The spectra just above T N1 (T N1  <  T  <  T  *  ≈  41 K) demonstrate a relaxation behavior due to critical spin fluctuations which indicates the occurrence of short-range correlations. At the intermediate temperature range, T N2  <  T  <  T N1, the 57Fe Mössbauer spectra are described in terms of collinear spin-density-waves (SDW) with the inclusion of many high-order harmonics, indicating that the real magnetic structure of the ferrite appears to be more complicated than a pure sinusoidally modulated SDW. Below T  <  T N2  ≈  9 K, the hyperfine field H hf reveals a large spatial anisotropy (ΔH anis  ≈  30 kOe) which is related with a local intra-cluster (FeO6) spin-dipole term that implies a conventional contribution of the polarized oxygen ions. We proposed a simple two-parametric formula to describe the dependence of H anis on the distortions of the (FeO6) clusters. Analysis of different mechanisms of spin and hyperfine interactions in 3R-AgFeO2 and its structural analogue CuFeO2 points to a specific role played by the topology of the exchange coupling and the oxygen polarization in the delafossite-like structures.

Reduction process of nitroxyl spin probes used in Overhauser-enhanced magnetic resonance imaging: An ESR study

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meenakumari, V.; Premkumar, S.; Benial, A. Milton Franklin, E-mail: miltonfranklin@yahoo.com

The Electron spin resonance studies on the reduction process of nitroxyl spin probes were carried out for 1mM {sup 14}N- labeled nitroxyl radicals in pure water and 1 mM concentration of ascorbic acid as a function of time. The electron spin resonance parameters, such as line width, hyperfine coupling constant, g-factor, signal intensity ratio and rotational correlation time were estimated. The 3-carbamoyl-PROXYL radical has narrowest line width and fast tumbling motion compared with 3-carboxy-PROXYL, 4-methoxy-TEMPO, and 4-acetamido-TEMPO radicals. The half life time and decay rate were estimated for 1mM concentration of {sup 14}N- labeled nitroxyl radicals in 1 mM concentration ofmore » ascorbic acid. From the results, the 3-carbamoyl-PROXYL has long half life time and high stability compared with 3-carboxy-PROXYL, 4-methoxy-TEMPO and 4-acetamido-TEMPO radicals. Therefore, this study reveals that the 3-carbamoyl-PROXYL radical can act as a good redox sensitive spin probe for Overhauser-enhanced Magnetic Resonance Imaging.« less

Reduction process of nitroxyl spin probes used in Overhauser-enhanced magnetic resonance imaging: An ESR study

NASA Astrophysics Data System (ADS)

Meenakumari, V.; Jawahar, A.; Premkumar, S.; Benial, A. Milton Franklin

2016-05-01

The Electron spin resonance studies on the reduction process of nitroxyl spin probes were carried out for 1mM 14N- labeled nitroxyl radicals in pure water and 1 mM concentration of ascorbic acid as a function of time. The electron spin resonance parameters, such as line width, hyperfine coupling constant, g-factor, signal intensity ratio and rotational correlation time were estimated. The 3-carbamoyl-PROXYL radical has narrowest line width and fast tumbling motion compared with 3-carboxy-PROXYL, 4-methoxy-TEMPO, and 4-acetamido-TEMPO radicals. The half life time and decay rate were estimated for 1mM concentration of 14N- labeled nitroxyl radicals in 1 mM concentration of ascorbic acid. From the results, the 3-carbamoyl-PROXYL has long half life time and high stability compared with 3-carboxy-PROXYL, 4-methoxy-TEMPO and 4-acetamido-TEMPO radicals. Therefore, this study reveals that the 3-carbamoyl-PROXYL radical can act as a good redox sensitive spin probe for Overhauser-enhanced Magnetic Resonance Imaging.

Paramagnetic species on catalytic surfaces--DFT investigations into structure sensitivity of the hyperfine coupling constants.

PubMed

Sojka, Zbigniew; Pietrzyk, Piotr

2004-05-01

Structure sensitivity of the hyperfine coupling constants was investigated by means of DFT calculations for selected surface paramagnetic species. A *CH2OH radical trapped on silica and intrazeolite copper nitrosyl adducts encaged in ZSM-5 were taken as the examples. The surface of amorphous silica was modeled with a [Si5O8H10] cluster, whereas the zeolite hosting sites were epitomized by [Si4AlO5(OH)10]- cluster. Three different coordination modes of the *CH2OH radical were considered and the isotropic 13C and 1H hyperfine constants of the resultant van der Waals complexes, calculated with B3LYP/6-311G(d), were discussed in terms of the angular deformations caused by hydrogen bonds with the cluster. The magnetic parameters of the eta1-N[CuNO]11 and eta1-O[CuNO]11 linkage isomers were calculated at the BPW91/LanL2DZ and 6-311G(df) level. For the most stable eta1-N adduct a clear dependence of the spin density distribution within the Cu-NO moiety on changes in the Cu-N-O angle and the Cu-N bond distance was observed and accounted for by varying spin polarization and delocalization contributions.

Gd(III) complexes as paramagnetic tags: Evaluation of the spin delocalization over the nuclei of the ligand

NASA Astrophysics Data System (ADS)

Collauto, A.; Feintuch, A.; Qi, M.; Godt, A.; Meade, T.; Goldfarb, D.

2016-02-01

Complexes of the Gd(III) ion are currently being established as spin labels for distance determination in biomolecules by pulse dipolar spectroscopy. Because Gd(III) is an f ion, one expects electron spin density to be localized on the Gd(III) ion - an important feature for the mentioned application. Most of the complex ligands have nitrogens as Gd(III) coordinating atoms. Therefore, measurement of the 14N hyperfine coupling gives access to information on the localization of the electron spin on the Gd(III) ion. We carried out W-band, 1D and 2D 14N and 1H ENDOR measurements on the Gd(III) complexes Gd-DOTA, Gd-538, Gd-595, and Gd-PyMTA that serve as spin labels for Gd-Gd distance measurements. The obtained 14N spectra are particularly well resolved, revealing both the hyperfine and nuclear quadrupole splittings, which were assigned using 2D Mims ENDOR experiments. Additionally, the spectral contributions of the two different types of nitrogen atoms of Gd-PyMTA, the aliphatic N atom and the pyridine N atom, were distinguishable. The 14N hyperfine interaction was found to have a very small isotropic hyperfine component of -0.25 to -0.37 MHz. Furthermore, the anisotropic hyperfine interactions with the 14N nuclei and with the non-exchangeable protons of the ligands are well described by the point-dipole approximation using distances derived from the crystal structures. We therefore conclude that the spin density is fully localized on the Gd(III) ion and that the spin density distribution over the nuclei of the ligands is rightfully ignored when analyzing distance measurements.

Anomalous behavior of the magnetic hyperfine field at 140Ce impurities at La sites in LaMnSi2

NASA Astrophysics Data System (ADS)

Domienikan, C.; Bosch-Santos, B.; Cabrera-Pasca, G. A.; Saxena, R. N.; Carbonari, A. W.

2018-05-01

Magnetic hyperfine field has been measured in the orthorhombic intermetallic compound LaMnSi2 with perturbed angular correlation (PAC) spectroscopy using radioactive 140La(140Ce) nuclear probes. Magnetization measurements were also carried out in this compound with MPSM-SQUID magnetometer. Samples of LaMnSi2 compound were prepared by arc melting the component metals with high purity under argon atmosphere followed by annealing at 1000°C for 60 h under helium atmosphere and quenching in water. X-ray analysis confirmed the samples to be in a single phase with correct crystal structure expected for LaMnSi2 compound. The radioactive 140La (T1/2 = 40 h) nuclei were produced by direct irradiation of the sample with neutrons in the IEA-R1 nuclear research reactor at IPEN with a flux of ˜ 1013 n cm-2s-1 for about 3 - 4 min. The PAC measurements were carried out with a six BaF2 detector spectrometer at several temperatures between 10 K and 400 K. Temperature dependence of the hyperfine field, Bhf was found to be anomalous. A modified two-state model explained this anomalous behavior where the effective magnetic hyperfine field at 140Ce is believed to have two contributions, one from the unstable localized spins at Ce impurities and another from the magnetic Mn atoms of the host. The competition of these two contributions explains the anomalous behavior observed for the temperature dependence of the magnetic hyperfine field at 140Ce. The ferromagnetic transition temperature (TC) of LaMnSi2 was determined to be 400(1) K confirming the magnetic measurements.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Modi, K. B., E-mail: kunalbmodi2003@yahoo.com; Raval, P. Y.; Dulera, S. V.

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cazzoli, Gabriele; Lattanzi, Valerio; Puzzarini, Cristina

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 hfmore » splittings in astronomical spectra has been discussed.« less

Electron paramagnetic resonance study of radiation-induced paramagnetic centers in succinic anhydride single crystal

NASA Astrophysics Data System (ADS)

Caliskan, Betul; Caliskan, Ali Cengiz; Er, Emine

2017-09-01

Succinic anhydride single crystals were exposed to 60Co-gamma irradiation at room temperature. The irradiated single crystals were investigated at 125 K by Electron Paramagnetic Resonance (EPR) Spectroscopy. The investigation of EPR spectra of irradiated single crystals of succinic anhydride showed the presence of two succinic anhydride anion radicals. The anion radicals observed in gamma-irradiated succinic anhydride single crystal were created by the scission of the carbon-oxygen double bond. The structure of EPR spectra demonstrated that the hyperfine splittings arise from the same radical species. The reduction of succinic anhydride was identified which is formed by the addition of an electron to oxygen of the Csbnd O bond. The g values, the hyperfine structure constants and direction cosines of the radiation damage centers observed in succinic anhydride single crystal were obtained.

Correlation effects in fcc-Fe(x)Ni(1-x) alloys investigated by means of the KKR-CPA.

PubMed

Minár, J; Mankovsky, S; Šipr, O; Benea, D; Ebert, H

2014-07-09

The electronic structure and magnetic properties of the disordered alloy system fcc-FexNi1-x (fcc: face centered cubic) have been investigated by means of the KKR-CPA (Korringa-Kohn-Rostoker coherent potential approximation) band structure method. To investigate the impact of correlation effects, the calculations have been performed on the basis of the LSDA (local spin density approximation), the LSDA + U as well as the LSDA + DMFT (dynamical mean field theory). It turned out that the inclusion of correlation effects hardly changed the spin magnetic moments and the related hyperfine fields. The spin-orbit induced orbital magnetic moments and hyperfine fields, on the other hand, show a pronounced and element-specific enhancement. These findings are in full accordance with the results of a recent experimental study.

Hyperfine structure of atomic fluorine (F I)

NASA Astrophysics Data System (ADS)

Huo, Xiaoxue; Deng, Lunhua; Windholz, L.; Mu, Xiuli; Wang, Hailing

2018-01-01

A high resolution absorption spectrum of neutral fluorine(F I) was observed around 800 nm using concentration modulation absorption spectroscopy with a tunable Ti : Sapphire laser. The fluorine atoms were produced by discharging the mixed gases of helium and sulfur hexafluoride (SF6) in a glass tube. Thirty four hyperfine structure (hfs) resolved transitions were analyzed to obtain 23 magnetic dipole hfs constants A for 2p4(3P)3s, 2p4(3P)3p and 2p4(3P)3d configurations. The hfs constants in 2p4(3P)3s and 2p4(3P)3p configurations were compared with those obtained from experiments and calculations. Fifteen constants in 2p4(3P)3d configuration were reported - to our knowledge - for the first time.

Fine Structure in Helium-like Fluorine by Fast-Beam Laser Spectroscopy

NASA Astrophysics Data System (ADS)

Myers, E. G.; Thompson, J. K.; Silver, J. D.

1998-05-01

With the aim of providing an additional precise test of higher-order corrections to high precision calculations of fine structure in helium and helium-like ions(T. Zhang, Z.-C. Yan and G.W.F. Drake, Phys. Rev. Lett. 77), 1715 (1996)., a measurement of the 2^3P_2,F - 2^3P_1,F' fine structure in ^19F^7+ is in progress. The method involves doppler-tuned laser spectroscopy using a CO2 laser on a foil-stripped fluorine ion beam. We aim to achieve a higher precision, compared to an earlier measurement(E.G. Myers, P. Kuske, H.J. Andrae, I.A. Armour, H.A. Klein, J.D. Silver, and E. Traebert, Phys. Rev. Lett. 47), 87 (1981)., by using laser beams parallel and anti-parallel to the ion beam, to obtain partial cancellation of the doppler shift(J.K. Thompson, D.J.H. Howie and E.G. Myers, Phys. Rev. A 57), 180 (1998).. A calculation of the hyperfine structure, allowing for relativistic, QED and nuclear size effects, will be required to obtain the ``hyperfine-free'' fine structure interval from the measurements.

Structural and electronic studies of metal carbide clusterfullerene Sc2C2@Cs-C72

NASA Astrophysics Data System (ADS)

Feng, Yongqiang; Wang, Taishan; Wu, Jingyi; Feng, Lai; Xiang, Junfeng; Ma, Yihan; Zhang, Zhuxia; Jiang, Li; Shu, Chunying; Wang, Chunru

2013-07-01

We present a metal carbide clusterfullerene Sc2C2@Cs(10528)-C72, whose structure has been baffling for many years. A motional endohedral Sc2C2 cluster, special molecule geometry and electronic structure were found in Sc2C2@Cs(10528)-C72. The paramagnetic Sc2C2@Cs-C72 anion radical was successfully prepared by a chemical reduction method and hyperfine couplings in the ESR spectrum were observed.We present a metal carbide clusterfullerene Sc2C2@Cs(10528)-C72, whose structure has been baffling for many years. A motional endohedral Sc2C2 cluster, special molecule geometry and electronic structure were found in Sc2C2@Cs(10528)-C72. The paramagnetic Sc2C2@Cs-C72 anion radical was successfully prepared by a chemical reduction method and hyperfine couplings in the ESR spectrum were observed. Electronic supplementary information (ESI) available: Experimental details, HPLC chromatogram, and DFT calculations. CCDC 917712. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c3nr01739g

Hyperfine Fields of 181Ta in UFe4Al8

NASA Astrophysics Data System (ADS)

Marques, J. G.; Barradas, N. P.; Alves, E.; Ramos, A. R.; Gonçalves, A. P.; da Silva, M. F.; Soares, J. C.

2001-11-01

The γ γ Perturbed Angular Correlation technique was used to study the hyperfine interaction of 181Ta at the Hf site(s) in UFe4Al8 at room temperature and 12 K. The data at room temperature are well described by two electric field gradients, while at low temperature two combined hyperfine interactions have to be considered, one with the magnetic hyperfine field collinear with the c-axis and another with the magnetic hyperfine field in the basal plane. The results are compared with previous Mössbauer and neutron diffraction experiments and the lattice site of Hf is discussed.

Muon contact hyperfine field in metals: A DFT calculation

NASA Astrophysics Data System (ADS)

Onuorah, Ifeanyi John; Bonfà, Pietro; De Renzi, Roberto

2018-05-01

In positive muon spin rotation and relaxation spectroscopy it is becoming customary to take advantage of density functional theory (DFT) based computational methods to aid the experimental data analysis. DFT-aided muon site determination is especially useful for measurements performed in magnetic materials, where large contact hyperfine interactions may arise. Here we present a systematic analysis of the accuracy of the ab initio estimation of muon's hyperfine contact field on elemental transition metals, performing state-of-the-art spin-polarized plane-wave DFT and using the projector-augmented pseudopotential approach, which allows one to include the core state effects due to the spin ordering. We further validate this method in not-so-simple, noncentrosymmetric metallic compounds, presently of topical interest for their spiral magnetic structure giving rise to skyrmion phases, such as MnSi and MnGe. The calculated hyperfine fields agree with experimental values in all cases, provided the spontaneous spin magnetization of the metal is well reproduced within the approach. To overcome the known limits of the conventional mean-field approximation of DFT on itinerant magnets, we adopt the so-called reduced Stoner theory [L. Ortenzi et al., Phys. Rev. B 86, 064437 (2012), 10.1103/PhysRevB.86.064437]. We establish the accuracy of the estimated muon contact field in metallic compounds with DFT and our results show improved agreement with experiments compared to those of earlier publications.

High-resolution molecular-beam spectroscopy of NaCN and Na 13CN

NASA Astrophysics Data System (ADS)

van Vaals, J. J.; Meerts, W. Leo; Dymanus, A.

The sodium cyanide molecule was studied by molecular-beam electric-resonance spectroscopy in the microwave region. We used the seeded-beam technique to produce a supersonic beam with strong translational, rotational and vibrational cooling. In the frequency range 9.5-40 GHz we observed and identified for NaCN 186 and for Na 13CN 107 hyperfine transitions in 20 and 16 rotational transitions, respectively, all in the ground vibrational state. The rotational, the five quartic and three sextic centrifugal distortion constants of NaCN are: A″ = 57921.954(7) MHz; B″ = 8369.312(2) MHz, C″ = 7272.712(2) MHz. All quadrupole and several spin-rotation coupling constants for the hyperfine interaction were evaluated. The quadrupole coupling constants (in MHz) for NaCN are: eQq12(Na) = -5.344(5), eQq12 = 2.397(7). eQq12(N) = 2.148(4), eQq12(N) = -4.142(5). From these constants and those of Na 13CN we have determined the principal components of the quadrupole coupling tensor for potassium and nitrogen. The structure of sodium cyanide evaluated from the rotational constants of NaCN and Na 13CN was found to be T shaped, similar to the structure of KCN but completely different from the linear isocyanide configuration of LiNC. The effective structural parameters for sodium cyanide in the ground vibrational state are: rCN = 1.170(4) Å, rNaC = 2.379(15) Å, rN12N = 2.233(15) Å, in gratifying agreement with ab initio calculations. Both the geometrical structure and the hyperfine coupling justify the conclusion that the CN group in gaseous sodium cyanide approximately can be considered as a free CN - ion.

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, a4d 01 =-133.37 MHz and a5p 01 =-160.25 MHz for 4d45p; a4d 01 =-140.84 MHz, a5p 01 =-170.18 MHz and a5s 10 =-2898 MHz for 4d35s5p; a5s 10 =-2529 (2) MHz and a4d 01 =-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.

Hydrogen bond network around the semiquinone of the secondary quinone acceptor Q(B) in bacterial photosynthetic reaction centers.

PubMed

Taguchi, Alexander T; O'Malley, Patrick J; Wraight, Colin A; Dikanov, Sergei A

2015-05-07

By utilizing a combined pulsed EPR and DFT approach, the high-resolution structure of the QB site semiquinone (SQB) was determined. The development of such a technique is crucial toward an understanding of protein-bound semiquinones on the structural level, as (i) membrane protein crystallography typically results in low resolution structures, and (ii) obtaining protein crystals in the semiquinone form is rarely feasible. The SQB hydrogen bond network was investigated with Q- (∼34 GHz) and X-band (∼9.7 GHz) pulsed EPR spectroscopy on fully deuterated reactions centers from Rhodobacter sphaeroides. Simulations in the SQB g-tensor reference frame provided the principal values and directions of the H-bond proton hyperfine tensors. Three protons were detected, one with an anisotropic tensor component, T = 4.6 MHz, assigned to the histidine NδH of His-L190, and two others with similar anisotropic constants T = 3.2 and 3.0 MHz assigned to the peptide NpH of Gly-L225 and Ile-L224, respectively. Despite the strong similarity in the peptide couplings, all hyperfine tensors were resolved in the Q-band ENDOR spectra. The Euler angles describing the series of rotations that bring the hyperfine tensors into the SQB g-tensor reference frame were obtained by least-squares fitting of the spectral simulations to the ENDOR data. These Euler angles show the locations of the hydrogen bonded protons with respect to the semiquinone. Our geometry optimized model of SQB used in previous DFT work is in strong agreement with the angular constraints from the spectral simulations, providing the foundation for future joint pulsed EPR and DFT semiquinone structural determinations in other proteins.

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

NASA Astrophysics Data System (ADS)

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

2017-05-01

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

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

PubMed

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

2017-05-16

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

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

PubMed Central

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

2017-01-01

Electrons bound in highly charged heavy ions such as hydrogen-like bismuth 209Bi82+ experience electromagnetic fields that are a million times stronger than in light atoms. Measuring the wavelength of light emitted and absorbed by these ions is therefore a sensitive testing ground for quantum electrodynamical (QED) effects and especially the electron–nucleus interaction under such extreme conditions. However, insufficient knowledge of the nuclear structure has prevented a rigorous test of strong-field QED. Here we present a measurement of the so-called specific difference between the hyperfine splittings in hydrogen-like and lithium-like bismuth 209Bi82+,80+ with a precision that is improved by more than an order of magnitude. Even though this quantity is believed to be largely insensitive to nuclear structure and therefore the most decisive test of QED in the strong magnetic field regime, we find a 7-σ discrepancy compared with the theoretical prediction. PMID:28508892

Magnetic interactions in NiO at ultrahigh pressure

DOE PAGES

Potapkin, Vasily; Dubrovinsky, Leonid; Sergueev, I.; ...

2016-05-24

Here, magnetic properties of NiO have been studied in the multimegabar pressure range by nuclear forward scattering of synchrotron radiation using the 67.4 keV M ssbauer transition of 61Ni. The observed magnetic hyperfine splitting confirms the antiferromagnetic state of NiO up to 280 GPa, the highest pressure where magnetism has been observed so far, in any material. Remarkably, the hyperfine field increases from 8.47 T at ambient pressure to ~24 T at the highest pressure, ruling out the possibility of a magnetic collapse. A joint x-ray diffraction and extended x-ray-absorption fine structure investigation reveals that NiO remains in a distortedmore » sodium chloride structure in the entire studied pressure range. Ab initio calculations support the experimental observations, and further indicate a complete absence of Mott transition in NiO up to at least 280 GPa.« less

Hyperfine spin interactions between polarons and nuclei in organic light emitting diodes: Magneto-EL measurements

NASA Astrophysics Data System (ADS)

Crooker, S. A.; Kelley, M. R.; Martinez, N.; Nie, W.; Mohite, A. D.; Smith, D. L.; Tretiak, S.; Ruden, P. P.

2014-03-01

Considerable attention in recent years has focused on the effects of applied magnetic fields on the conductance, photocurrent, electroluminescence (EL), and photoluminescence of nominally nonmagnetic organic semiconductor materials and devices. These magnetic field effects have proven useful in revealing the underlying physical mechanisms and relevant spin interactions that influence the electrical and optical properties in these organic systems (e.g., hyperfine coupling, exchange interactions, and spin-orbit coupling). Here we study the field-dependent properties of organic light-emitting diode (OLEDs) based on MTDATA/LiF/Bphen layered structures, in which exciplex recombination at the interface dominates the EL spectra. Small applied magnetic fields (~10 mT) are found to boost the net EL yield by up to 10%, due to a suppression of the mixing between singlet and triplet polaron pairs which, in turn, arises from hyperfine spin coupling of the polarons to the underlying nuclei of the host molecules. We discuss the dependence of these field-induced effects on the LiF barrier thickness, device bias, and on the orientation of the applied magnetic field, as well as the mechanisms responsible.

Assignment of selected hyperfine proton NMR resonances in the met forms of Glycera dibranchiata monomer hemoglobins and comparisons with sperm whale metmyoglobin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Constantinidis, I.; Satterlee, J.D.; Pandey, R.K.

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 ofmore » 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.« less

29Si-NMR study of magnetic anisotropy and hyperfine interactions in the uranium-bsed ferromagnet UNiSi2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sakai, Hironori; Baek, Seung H; Bauer, Eric 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.more » 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.« less

Fourier transform millimeter-wave spectroscopy of the ethyl radical in the electronic ground state.

PubMed

Kim, Eunsook; Yamamoto, Satoshi

2004-02-15

The pure rotational spectrum of the ethyl radical (C2H5) has been detected for the first time with the Fourier transform millimeter-wave spectrometer. The ethyl radical is produced by discharging the C2H5I gas diluted in Ar. The 1(01)-0(00) rotational transition of the ethyl radical is observed in the frequency range from 43,680 to 43,780 MHz. The observed spectrum shows a very complicated pattern of the fine and hyperfine structures of a doublet radical with the nuclear spins of five protons. The fine and hyperfine components are assigned with the aid of measurements of the Zeeman splittings. As a result, the 22 lines are ascribed to the transitions in the ground vibronic state (A2"). The rotational constant, the spin-rotation interaction constant, and hyperfine interaction constants are determined by the least-squares fit. The Fermi contact term of the alpha-proton is determined to be -64.1654 MHz in the gas phase, indicating that the structure of the -CH2 is essentially planar. The present rotational spectroscopic study further supports that the methyl group of the ethyl radical can be regarded as a nearly free internal rotor with a low energy barrier. A few unassigned lines still remain, which may be vibrational satellites of the internal rotation mode. Copyright 2004 American Institute of Physics

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

Toward laser cooling and trapping lanthanum ions

NASA Astrophysics Data System (ADS)

Olmschenk, Steven; Banner, Patrick; Hankes, Jessie; Nelson, Amanda

2017-04-01

Trapped atomic ions are a leading candidate for applications in quantum information. For scalability and applications in quantum communication, it would be advantageous to interface ions with telecom light. We present progress toward laser cooling doubly-ionized lanthanum, which should require only infrared, telecom-compatible light. Since the hyperfine structure of this ion has not been measured, we are using optogalavanic spectroscopy in a hollow cathode lamp to measure the hyperfine spectrum of transitions in lanthanum. Using laser ablation to directly produce ions from a solid target, we laser cool and trap barium ions, and explore extending this technique to lanthanum ions. This research is supported by the Army Research Office, Research Corporation for Science Advancement, and Denison University.

Electron and nuclear spin interactions in the optical spectra of single GaAs quantum dots.

PubMed

Gammon, D; Efros, A L; Kennedy, T A; Rosen, M; Katzer, D S; Park, D; Brown, S W; Korenev, V L; Merkulov, I A

2001-05-28

Fine and hyperfine splittings arising from electron, hole, and nuclear spin interactions in the magneto-optical spectra of individual localized excitons are studied. We explain the magnetic field dependence of the energy splitting through competition between Zeeman, exchange, and hyperfine interactions. An unexpectedly small hyperfine contribution to the splitting close to zero applied field is described well by the interplay between fluctuations of the hyperfine field experienced by the nuclear spin and nuclear dipole/dipole interactions.

Mössbauer studies of iron hydride at high pressure

NASA Astrophysics Data System (ADS)

Choe, I.; Ingalls, R.; Brown, J. M.; Sato-Sorensen, Y.; Mills, R.

1991-07-01

We have measured in situ Mössbauer spectra of iron hydride made in a diamond anvil cell at high pressure and room temperature. The spectra show a sudden change at 3.5+/-0.5 GPa from a single hyperfine pattern to a superposition of three. The former pattern results from normal α-iron with negligible hydrogen content, and the latter from residual α-iron plus newly formed iron hydride. Between 3.5 and 10.4 GPa, the extra hydride pattern have hyperfine fields for one ranging from 276 to 263 kOe, and the other, from 317 to 309 kOe. Both have isomer shifts of about 0.4 mm/sec, and negligible quadrupole splittings. X-ray studies on quenched samples have shown that iron hydride is of double hexagonal close-packed structure, whose two nonequivalent iron sites may account for the observation of two different patterns. Even allowing for the effect of volume expansion, the observed isomer shifts for the hydride are considerably more positive than those of other metallic phases of iron. At the same time, the hyperfine fields are slightly smaller than that of α-iron. As a possible explanation, one may expect a bonding of hydrogen with iron, which would result in a small reduction of 4s electrons, possibly accompanied by a small increase of 3d electrons compared with the neutral atom in metallic iron. The difference between the hyperfine fields in the two spectra are presumably due to the different symmetry at the two iron sites.

EPR study of a gamma-irradiated (2-hydroxyethyl)triphenylphosphonium chloride single crystal

NASA Astrophysics Data System (ADS)

Karakaş, E.; Türkkan, E.; Dereli, Ö.; Sayιn, Ü.; Tapramaz, R.

2011-12-01

In this study, gamma-irradiated single crystals of (2-hydroxyethyl)triphenylphosphonium chloride [CH2CH2OH P(C6H5)3Cl] were investigated with electron paramagnetic resonance (EPR) spectroscopy at room temperature for different orientations in the magnetic field. The single crystals were irradiated with a 60Co-γ-ray source at 0.818 kGy/h for about 36 h. Taking the chemical structure and the experimental spectra of the irradiated single crystal of the title compound into consideration, a paramagnetic species was produced with the unpaired electron delocalized around 31P and several 1H nuclei. The anisotropic hyperfine values due to the 31P nucleus, slightly anisotropic hyperfine values due to the 1H nuclei and the g-tensor of the radical were measured from the spectra. Depending on the molecular structure and measured parameters, three possible radicals were modeled using the B3LYP/6-31+G(d) level of density-functional theory, and EPR parameters were calculated for modeled radicals using the B3LYP/TZVP method/basis set combination. The calculated hyperfine coupling constants were found to be in good agreement with the observed EPR parameters. The experimental and theoretically simulated spectra for each of the three crystallographic axes were well matched with one of the modeled radicals (discussed in the text). We thus identified the radical C˙H2CH2 P(C 6H5)3 Cl as a paramagnetic species produced in a single crystal of the title compound in two magnetically distinct sites. The experimental g-factor and hyperfine coupling constants of the radical were found to be anisotropic, with the isotropic values g iso = 2.0032, ? G, ? G, ? G and ? G for site 1 and g iso=2.0031, ? G, ? G ? G and ? G for site 2.

Observation of the hyperfine spectrum of antihydrogen.

PubMed

Ahmadi, M; Alves, B X R; Baker, C J; Bertsche, W; Butler, E; Capra, A; Carruth, C; Cesar, C L; Charlton, M; Cohen, S; Collister, R; Eriksson, S; Evans, A; Evetts, N; Fajans, J; Friesen, T; Fujiwara, M C; Gill, D R; Gutierrez, A; Hangst, J S; Hardy, W N; Hayden, M E; Isaac, C A; Ishida, A; Johnson, M A; Jones, S A; Jonsell, S; Kurchaninov, L; Madsen, N; Mathers, M; Maxwell, D; McKenna, J T K; Menary, S; Michan, J M; Momose, T; Munich, J J; Nolan, P; Olchanski, K; Olin, A; Pusa, P; Rasmussen, C Ø; Robicheaux, F; Sacramento, R L; Sameed, M; Sarid, E; Silveira, D M; Stracka, S; Stutter, G; So, C; Tharp, T D; Thompson, J E; Thompson, R I; van der Werf, D P; Wurtele, J S

2017-08-02

The observation of hyperfine structure in atomic hydrogen by Rabi and co-workers and the measurement of the zero-field ground-state splitting at the level of seven parts in 10 13 are important achievements of mid-twentieth-century physics. The work that led to these achievements also provided the first evidence for the anomalous magnetic moment of the electron, inspired Schwinger's relativistic theory of quantum electrodynamics and gave rise to the hydrogen maser, which is a critical component of modern navigation, geo-positioning and very-long-baseline interferometry systems. Research at the Antiproton Decelerator at CERN by the ALPHA collaboration extends these enquiries into the antimatter sector. Recently, tools have been developed that enable studies of the hyperfine structure of antihydrogen-the antimatter counterpart of hydrogen. The goal of such studies is to search for any differences that might exist between this archetypal pair of atoms, and thereby to test the fundamental principles on which quantum field theory is constructed. Magnetic trapping of antihydrogen atoms provides a means of studying them by combining electromagnetic interaction with detection techniques that are unique to antimatter. Here we report the results of a microwave spectroscopy experiment in which we probe the response of antihydrogen over a controlled range of frequencies. The data reveal clear and distinct signatures of two allowed transitions, from which we obtain a direct, magnetic-field-independent measurement of the hyperfine splitting. From a set of trials involving 194 detected atoms, we determine a splitting of 1,420.4 ± 0.5 megahertz, consistent with expectations for atomic hydrogen at the level of four parts in 10 4 . This observation of the detailed behaviour of a quantum transition in an atom of antihydrogen exemplifies tests of fundamental symmetries such as charge-parity-time in antimatter, and the techniques developed here will enable more-precise such tests.

Observation of the hyperfine spectrum of antihydrogen

NASA Astrophysics Data System (ADS)

Ahmadi, M.; Alves, B. X. R.; Baker, C. J.; Bertsche, W.; Butler, E.; Capra, A.; Carruth, C.; Cesar, C. L.; Charlton, M.; Cohen, S.; Collister, R.; Eriksson, S.; Evans, A.; Evetts, N.; Fajans, J.; Friesen, T.; Fujiwara, M. C.; Gill, D. R.; Gutierrez, A.; Hangst, J. S.; Hardy, W. N.; Hayden, M. E.; Isaac, C. A.; Ishida, A.; Johnson, M. A.; Jones, S. A.; Jonsell, S.; Kurchaninov, L.; Madsen, N.; Mathers, M.; Maxwell, D.; McKenna, J. T. K.; Menary, S.; Michan, J. M.; Momose, T.; Munich, J. J.; Nolan, P.; Olchanski, K.; Olin, A.; Pusa, P.; Rasmussen, C. Ø.; Robicheaux, F.; Sacramento, R. L.; Sameed, M.; Sarid, E.; Silveira, D. M.; Stracka, S.; Stutter, G.; So, C.; Tharp, T. D.; Thompson, J. E.; Thompson, R. I.; van der Werf, D. P.; Wurtele, J. S.

2017-08-01

The observation of hyperfine structure in atomic hydrogen by Rabi and co-workers and the measurement of the zero-field ground-state splitting at the level of seven parts in 1013 are important achievements of mid-twentieth-century physics. The work that led to these achievements also provided the first evidence for the anomalous magnetic moment of the electron, inspired Schwinger’s relativistic theory of quantum electrodynamics and gave rise to the hydrogen maser, which is a critical component of modern navigation, geo-positioning and very-long-baseline interferometry systems. Research at the Antiproton Decelerator at CERN by the ALPHA collaboration extends these enquiries into the antimatter sector. Recently, tools have been developed that enable studies of the hyperfine structure of antihydrogen—the antimatter counterpart of hydrogen. The goal of such studies is to search for any differences that might exist between this archetypal pair of atoms, and thereby to test the fundamental principles on which quantum field theory is constructed. Magnetic trapping of antihydrogen atoms provides a means of studying them by combining electromagnetic interaction with detection techniques that are unique to antimatter. Here we report the results of a microwave spectroscopy experiment in which we probe the response of antihydrogen over a controlled range of frequencies. The data reveal clear and distinct signatures of two allowed transitions, from which we obtain a direct, magnetic-field-independent measurement of the hyperfine splitting. From a set of trials involving 194 detected atoms, we determine a splitting of 1,420.4 ± 0.5 megahertz, consistent with expectations for atomic hydrogen at the level of four parts in 104. This observation of the detailed behaviour of a quantum transition in an atom of antihydrogen exemplifies tests of fundamental symmetries such as charge-parity-time in antimatter, and the techniques developed here will enable more-precise such tests.

Permeability studies of redox-sensitive nitroxyl spin probes in corn oil using an L-band ESR spectrometer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jebaraj, D. David; Utsumi, Hideo; Asath, R. Mohamed

Electron spin resonance (ESR) studies were carried out for 2mM {sup 14}N labeled {sup 2}H enriched 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl (MC-PROXYL) and 3–carboxy-2,2,5,5,-tetramethyl-1-pyrrolidinyloxy (carboxy-PROXYL) in pure water and various concentrations of corn oil. The ESR parameters, such as the line width, hyperfine coupling constant, g-factor, rotational correlation time, partition parameter and permeability were reported for the samples. The line width broadening was observed for both nitroxyl radicals in corn oil solutions. The partition parameter for permeable MC-PROXYL in corn oil increases with increasing concentration of corn oil, which reveals that the nitroxyl spin probe permeates into the oil phase. From the results, themore » corn oil concentration was optimized as 50 % for phantom studies. The rotational correlation time also increases with increasing concentration of corn oil. The permeable and impermeable nature of nitroxyl spin probes was demonstrated. These results will be useful for the development of ESR/OMR imaging modalities in in vivo and in vitro studies.« less

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.

Ultrafast Pulse Sequencing for Fast Projective Measurements of Atomic Hyperfine Qubits

NASA Astrophysics Data System (ADS)

Ip, Michael; Ransford, Anthony; Campbell, Wesley

2015-05-01

Projective readout of quantum information stored in atomic hyperfine structure typically uses state-dependent CW laser-induced fluorescence. This method requires an often sophisticated imaging system to spatially filter out the background CW laser light. We present an alternative approach that instead uses simple pulse sequences from a mode-locked laser to affect the same state-dependent excitations in less than 1 ns. The resulting atomic fluorescence occurs in the dark, allowing the placement of non-imaging detectors right next to the atom to improve the qubit state detection efficiency and speed. We also discuss methods of Doppler cooling with mode-locked lasers for trapped ions, where the creation of the necessary UV light is often difficult with CW lasers.

Velocity modulation spectroscopy of molecular ions II: The millimeter/submillimeter-wave spectrum of TiF + ( X3Φr)

NASA Astrophysics Data System (ADS)

Halfen, D. T.; Ziurys, L. M.

2006-11-01

The pure rotational spectrum of the molecular ion TiF + in its 3Φr ground state has been measured in the range 327-542 GHz using millimeter-wave direct absorption techniques combined with velocity modulation spectroscopy. TiF + was made in an AC discharge from a mixture of TiCl 4, F 2 in He, and argon. Ten transitions of this ion were recorded. In every transition, fluorine hyperfine interactions, as well as the fine structure splittings, were resolved. The fine structure pattern was found to be regular with almost equal spacing in frequency between the three spin components, in contrast to TiCl +, which is perturbed in the ground state. The data were fit with a case ( a) Hamiltonian and rotational, fine structure, and hyperfine constants were determined. The bond length established for TiF +, r0 = 1.7775 Å, was found to be shorter than that of TiF, r0 = 1.8342 Å—also established from mm-wave data. The hyperfine parameters determined are consistent with a δ1π1 electron configuration with the electrons primarily located on the titanium nucleus. The nuclear spin-orbit constant a indicates that the unpaired electrons are closer to the fluorine nucleus in TiF + relative to TiF, as expected with the decrease in bond length for the ion. The shorter bond distance is thought to arise from increased charge on the titanium nucleus as a result of a Ti 2+F - configuration. A similar decrease in bond length was found for TiCl + relative to TiCl.

Electronic structure and magnetic properties of dilute U impurities in metals

NASA Astrophysics Data System (ADS)

Mohanta, S. K.; Cottenier, S.; Mishra, S. N.

2016-05-01

The electronic structure and magnetic moment of dilute U impurity in metallic hosts have been calculated from first principles. The calculations have been performed within local density approximation of the density functional theory using Augmented plane wave+local orbital (APW+lo) technique, taking account of spin-orbit coupling and Coulomb correlation through LDA+U approach. We present here our results for the local density of states, magnetic moment and hyperfine field calculated for an isolated U impurity embedded in hosts with sp-, d- and f-type conduction electrons. The results of our systematic study provide a comprehensive insight on the pressure dependence of 5f local magnetism in metallic systems. The unpolarized local density of states (LDOS), analyzed within the frame work of Stoner model suggest the occurrence of local moment for U in sp-elements, noble metals and f-block hosts like La, Ce, Lu and Th. In contrast, U is predicted to be nonmagnetic in most transition metal hosts except in Sc, Ti, Y, Zr, and Hf consistent with the results obtained from spin polarized calculation. The spin and orbital magnetic moments of U computed within the frame of LDA+U formalism show a scaling behavior with lattice compression. We have also computed the spin and orbital hyperfine fields and a detail analysis has been carried out. The host dependent trends for the magnetic moment, hyperfine field and 5f occupation reflect pressure induced change of electronic structure with U valency changing from 3+ to 4+ under lattice compression. In addition, we have made a detailed analysis of the impurity induced host spin polarization suggesting qualitatively different roles of f-band electrons on moment stability. The results presented in this work would be helpful towards understanding magnetism and spin fluctuation in U based alloys.

Charge radii and electromagnetic moments of At-211195

NASA Astrophysics Data System (ADS)

Cubiss, J. G.; Barzakh, A. E.; Seliverstov, M. D.; Andreyev, A. N.; Andel, B.; Antalic, S.; Ascher, P.; Atanasov, D.; Beck, D.; Bieroń, J.; Blaum, K.; Borgmann, Ch.; Breitenfeldt, M.; Capponi, L.; Cocolios, T. E.; Day Goodacre, T.; Derkx, X.; De Witte, H.; Elseviers, J.; Fedorov, D. V.; Fedosseev, V. N.; Fritzsche, S.; Gaffney, L. P.; George, S.; Ghys, L.; Heßberger, F. P.; Huyse, M.; Imai, N.; Kalaninová, Z.; Kisler, D.; Köster, U.; Kowalska, M.; Kreim, S.; Lane, J. F. W.; Liberati, V.; Lunney, D.; Lynch, K. M.; Manea, V.; Marsh, B. A.; Mitsuoka, S.; Molkanov, P. L.; Nagame, Y.; Neidherr, D.; Nishio, K.; Ota, S.; Pauwels, D.; Popescu, L.; Radulov, D.; Rapisarda, E.; Revill, J. P.; Rosenbusch, M.; Rossel, R. E.; Rothe, S.; Sandhu, K.; Schweikhard, L.; Sels, S.; Truesdale, V. L.; Van Beveren, C.; Van den Bergh, P.; Wakabayashi, Y.; Van Duppen, P.; Wendt, K. D. A.; Wienholtz, F.; Whitmore, B. W.; Wilson, G. L.; Wolf, R. N.; Zuber, K.

2018-05-01

Hyperfine-structure parameters and isotope shifts of At-211195 have been measured for the first time at CERN-ISOLDE, using the in-source resonance-ionization spectroscopy method. The hyperfine structures of isotopes were recorded using a triad of experimental techniques for monitoring the photo-ion current. The Multi-Reflection Time-of-Flight Mass Spectrometer, in connection with a high-resolution electron multiplier, was used as an ion-counting setup for isotopes that either were affected by strong isobaric contamination or possessed a long half-life; the ISOLDE Faraday cups were used for cases with high-intensity beams; and the Windmill decay station was used for short-lived, predominantly α -decaying nuclei. The electromagnetic moments and changes in the mean-square charge radii of the astatine nuclei have been extracted from the measured hyperfine-structure constants and isotope shifts. This was only made possible by dedicated state-of-the-art large-scale atomic computations of the electronic factors and the specific mass shift of atomic transitions in astatine that are needed for these extractions. By comparison with systematics, it was possible to assess the reliability of the results of these calculations and their ascribed uncertainties. A strong deviation in the ground-state mean-square charge radii of the lightest astatine isotopes, from the trend of the (spherical) lead isotopes, is interpreted as the result of an onset of deformation. This behavior bears a resemblance to the deviation observed in the isotonic polonium isotopes. Cases for shape coexistence have been identified in At,199197, for which a significant difference in the charge radii for ground (9 /2- ) and isomeric (1 /2+ ) states has been observed.

Zeeman-hyperfine structures and isotope effect in the spectrum of Tl I

NASA Astrophysics Data System (ADS)

Bouazza, Safa; Sobolewski, Łukasz Marek; Kwela, Jerzy

2018-01-01

The Zeeman structures of seventeen lines of 205Tl I (Z = 81) covering the UV-NIR spectral range (351.92-1151.28) nm were investigated. Landé gJ-factors for eighteen levels were determined for the first time. Furthermore, we have performed fine structure studies for both even- and odd-configuration levels and determined the relevant parameters. For the 6 s 6p2 configuration we have refined the suggested level energies and predicted positions for missing levels. With regard to hyperfine structure (hfs), we have justified the surprisingly huge value of the magnetic hfs constant A(6s2 10 s) . Moreover, we have extracted the single-electron hfs constant parameter values for the lowest even-parity configurations of 205Tl I; for instance a10s10 (6s2 10 s) = 1015(9) MHz and a6s10 (6 s 6p2) = 217306(205) MHz. Regarding isotope shift analysis we have observed that Dirac-Fock calculations, preferably chosen to take into account the contribution of the p1/2 contact-electron, are in good agreement with experimental data for low-lying levels of each configuration under study.

The pure rotational spectra of the open-shell diatomic molecules PbI and SnI

DOE Office of Scientific and Technical Information (OSTI.GOV)

Evans, Corey J., E-mail: cje8@le.ac.uk, E-mail: nick.walker@newcastle.ac.uk; Needham, Lisa-Maria E.; Walker, Nicholas R., E-mail: cje8@le.ac.uk, E-mail: nick.walker@newcastle.ac.uk

2015-12-28

Pure rotational spectra of the ground electronic states of lead monoiodide and tin monoiodide have been measured using a chirped pulsed Fourier transform microwave spectrometer over the 7-18.5 GHz region for the first time. Each of PbI and SnI has a X {sup 2}Π{sub 1/2} ground electronic state and may have a hyperfine structure that aids the determination of the electron electric dipole moment. For each species, pure rotational transitions of a number of different isotopologues and their excited vibrational states have been assigned and fitted. A multi-isotopologue Dunham-type analysis was carried out on both species producing values for Y{submore » 01}, Y{sub 02}, Y{sub 11}, and Y{sub 21}, along with Λ-doubling constants, magnetic hyperfine constants and nuclear quadrupole coupling constants. The Born-Oppenheimer breakdown parameters for Pb have been evaluated and the parameter rationalized in terms of finite nuclear field effects. Analysis of the bond lengths and hyperfine interaction indicates that the bonding in both PbI and SnI is ionic in nature. Equilibrium bond lengths have been evaluated for both species.« less

New developments of the in-source spectroscopy method at RILIS/ISOLDE

NASA Astrophysics Data System (ADS)

Marsh, B. A.; Andel, B.; Andreyev, A. N.; Antalic, S.; Atanasov, D.; Barzakh, A. E.; Bastin, B.; Borgmann, Ch.; Capponi, L.; Cocolios, T. E.; Day Goodacre, T.; Dehairs, M.; Derkx, X.; De Witte, H.; Fedorov, D. V.; Fedosseev, V. N.; Focker, G. J.; Fink, D. A.; Flanagan, K. T.; Franchoo, S.; Ghys, L.; Huyse, M.; Imai, N.; Kalaninova, Z.; Köster, U.; Kreim, S.; Kesteloot, N.; Kudryavtsev, Yu.; Lane, J.; Lecesne, N.; Liberati, V.; Lunney, D.; Lynch, K. M.; Manea, V.; Molkanov, P. L.; Nicol, T.; Pauwels, D.; Popescu, L.; Radulov, D.; Rapisarda, E.; Rosenbusch, M.; Rossel, R. E.; Rothe, S.; Schweikhard, L.; Seliverstov, M. D.; Sels, S.; Sjödin, A. M.; Truesdale, V.; Van Beveren, C.; Van Duppen, P.; Wendt, K.; Wienholtz, F.; Wolf, R. N.; Zemlyanoy, S. G.

2013-12-01

At the CERN ISOLDE facility, long isotope chains of many elements are produced by proton-induced reactions in target materials such as uranium carbide. The Resonance Ionization Laser Ion Source (RILIS) is an efficient and selective means of ionizing the reaction products to produce an ion beam of a chosen isotope. Coupling the RILIS with modern ion detection techniques enables highly sensitive studies of nuclear properties (spins, electromagnetic moments and charge radii) along an isotope chain, provided that the isotope shifts and hyperfine structure splitting of the atomic transitions can be resolved. At ISOLDE the campaign to measure the systematics of isotopes in the lead region (Pb, Bi, Tl and Po) has been extended to include the gold and astatine isotope chains. Several developments were specifically required for the feasibility of the most recent measurements: new ionization schemes (Po, At); a remote controlled narrow line-width mode of operation for the RILIS Ti:sapphire laser (At, Au, Po); isobar free ionization using the Laser Ion Source Trap, LIST (Po); isobar selective particle identification using the multi-reflection time-of-flight mass separator (MR-ToF MS) of ISOLTRAP (Au, At). These are summarized as part of an overview of the current status of the in-source resonance ionization spectroscopy setup at ISOLDE.

Experimental and theoretical study of Co sorption in clay montmorillonites

NASA Astrophysics Data System (ADS)

Gil Rebaza, A. V.; Montes, M. L.; Taylor, M. A.; Errico, L. A.; Alonso, R. E.

2018-03-01

Montmorillonite (MMT) clays are 2:1 layered structures which in natural state may allocate different hydrated cations such as M-nH2O (M = Na, Ca, Fe, etc) in its interlayer space. Depending on the capability for ion sorption, these materials are interesting for environmental remediation. In this work we experimentally study the Co sorption in a natural Na-MMT using UV-visible spectrometry and XRD on semi-oriented samples, and then analyze the sorption ability of this clay by means of ab initio calculation performed on pristine MMT. The structural properties of Na-MMT and Co-adsorbed MMT, and the hyperfine parameters at different atomic sites were analyzed and compared with the experimental ones for the first, and for the case of the hyperfine parameters, presented for the first time for the last. The theoretical predictions based on total energy considerations confirm that Co incorporation replacing Na is energetically favorable. Also, the basal spacing d001 experimentally obtained is well reproduced.

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

NASA Astrophysics Data System (ADS)

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

2017-12-01

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

The optical depth of the 158 micron forbidden C-12 II line - Detection of the F = 1 - 0 forbidden C-13 II hyperfine-structure component. [in Orion nebula

NASA Technical Reports Server (NTRS)

Stacey, G. J.; Townes, C. H.; Geis, N.; Madden, S. C.; Herrmann, F.; Genzel, R.; Poglitsch, A.; Jackson, J. M.

1991-01-01

The detection of the F = 1 - 0 hyperfine component of the 158-micron forbidden C-13 II fine-structure line in the interstellar medium is reported. A 12-point intensity map was obtained of the forbidden C-13 distribution over the inner 190-arcsec (R.A.) X 190-arcsec (decl.) regions of the Orion Nebula using an imaging Fabry-Perot interferometer. The forbidden C-12 II/C-13 II line intensity ratio varies significantly over the region mapped. It is highest (86 +/-0) in the core of the Orion H II region, and significantly lower (62 +/-7) in the outer regions of the map, reflecting higher optical depth in the forbidden C-12 II line here. It is suggested that this enhanced optical depth is the result of limb brightening of the optically thin forbidden C-13 II line at the edges of the bowl-shaped H II region blister.

Evidence for changes in the nucleotide conformation in the active site of H(+)-ATPase as determined by pulsed EPR spectroscopy.

PubMed

Schneider, B; Sigalat, C; Amano, T; Zimmermann, J L

2000-12-19

The conformation of di- and triphosphate nucleosides in the active site of ATPsynthase (H(+)-ATPase) from thermophilic Bacillus PS3 (TF1) and their interaction with Mg(2+)/Mn(2+) cations have been investigated using EPR, ESEEM, and HYSCORE spectroscopies. For a ternary complex formed by a stoichiometric mixture of TF1, Mn(2+), and ADP, the ESEEM and HYSCORE data reveal a (31)P hyperfine interaction with Mn(2+) (|A((31)P)| approximately 5.20 MHz), significantly larger than that measured for the complex formed by Mn(2+) and ADP in solution (|A((31)P)| approximately 4.50 MHz). The Q-band EPR spectrum of the Mn.TF1.ADP complex indicates that the Mn(2+) binds in a slightly distorted environment with |D| approximately 180 x 10(-4) cm(-1) and |E| approximately 50 x 10(-4) cm(-1). The increased hyperfine coupling with (31)P in the presence of TF1 reflects the specific interaction between the central Mn(2+) and the ADP beta-phosphate, illustrating the role of the enzyme active site in positioning the phosphate chain of the substrate for efficient catalysis. Results with the ternary Mn.TF1.ATP and Mn.TF1.AMP-PNP complexes are interpreted in a similar way with two hyperfine couplings being resolved for each complex (|A((31)P(beta))| approximately 4.60 MHz and |A((31)P(gamma))| approximately 5.90 MHz with ATP, and |A((31)P(beta))| approximately 4.20 MHz and |A((31)P(gamma))| approximately 5.40 MHz with AMP-PNP). In these complexes, the increased hyperfine coupling with (31)P(gamma) compared with (31)P(beta) reflects the smaller Mn.P distance with the gamma-phosphate compared with the beta-phosphate as found in the crystal structure of the analogous enzyme from mitochondria [3.53 vs 3.70 A (Abrahams, J. P., Leslie, A. G. W., Lutter, R., and Walker, J. E. (1994) Nature 370, 621-628)] and the different binding modes of the two phosphate groups. The ESEEM and HYSCORE data of a complex formed with Mn(2+), ATP, and the isolated beta subunit show that the (31)P hyperfine coupling is close to that measured in the absence of the protein, indicating a poorly structured nucleotide site in the isolated beta subunit in the presence of ATP. The inhibition data obtained for TF1 incubated in the presence of Mg(2+), ADP, Al(NO(3))(3), and NaF indicate the formation of the inhibited complex with the transition state analogue namely Mg.TF1.ADP.AlF(x) with the equilibrium dissociation constant K(D) = 350 microM and rate constant k = 0.02 min(-1). The ESEEM and HYSCORE data obtained for an inhibited TF1 sample, Mn.TF1.ADP.AlF(x), confirm the formation of the transition state analogue with distinct spectroscopic footprints that can be assigned to Mn.(19)F and Mn.(27)Al hyperfine interactions. The (31)P(beta) hyperfine coupling that is measured in the inhibited complex with the transition state analogue (|A((31)P(beta))| approximately 5.10 MHz) is intermediate between those measured in the presence of ADP and ATP and suggests an increase in the bond between Mn and the P(beta) from ADP upon formation of the transition state.

The hyperfine excitation of OH radicals by He

NASA Astrophysics Data System (ADS)

Marinakis, Sarantos; Kalugina, Yulia; Lique, François

2016-04-01

Hyperfine-resolved collisions between OH radicals and He atoms are investigated using quantum scattering calculations and the most recent ab initio potential energy surface, which explicitly takes into account the OH vibrational motion. Such collisions play an important role in astrophysics, in particular in the modelling of OH masers. The hyperfine-resolved collision cross sections are calculated for collision energies up to 2500 cm-1 from the nuclear spin free scattering S-matrices using a recoupling technique. The collisional hyperfine propensities observed are discussed. As expected, the results from our work suggest that there is a propensity for collisions with ΔF = Δj. The new OH-He hyperfine cross sections are expected to significantly help in the modelling of OH masers from current and future astronomical observations. Contribution to the Topical Issue "Atomic Cluster Collisions (7th International Symposium)", edited by Gerardo Delgado Barrio, Andrey Solov'Yov, Pablo Villarreal, Rita Prosmiti.

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 two-electron corrections to the Bethe logarithm are taken into account by a 1/Z expansion method.

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

NASA Astrophysics Data System (ADS)

Baituti, Bernard

2017-11-01

Understanding the structure of oxygen evolving complex (OEC) fully still remains a challenge. Lately computational chemistry with the data from more detailed X-ray diffraction (XRD) OEC structure, has been used extensively in exploring the mechanisms of water oxidation in the OEC (Gatt et al., J. Photochem. Photobiol. B 104(1-2), 80-93 2011). Knowledge of the oxidation states is very crucial for understanding the core principles of catalysis by photosystem II (PSII) and catalytic mechanism of OEC. The present study involves simulation studies of the X-band continuous wave electron-magnetic resonance (CW-EPR) generated S 2 state signals, to investigate whether the data is in agreement with the four manganese ions in the OEC, being organised as a `3 + 1' (trimer plus one) model (Gatt et al., Angew. Chem. Int. Ed. 51, 12025-12028 2012; Petrie et al., Chem. A Eur. J. 21, 6780-6792 2015; Terrett et al., Chem. Commun. (Camb.) 50, 8-11 2014) or `dimer of dimers' model (Terrett et al. 2016). The question that still remains is how much does each Mn ion contribute to the " g2multiline" signal through its hyperfine interactions in OEC also to differentiate between the `high oxidation state (HOS)' and `low oxidation state (LOS)' paradigms? This is revealed in part by the structure of multiline (ML) signal studied in this project. Two possibilities have been proposed for the redox levels of the Mn ions within the catalytic cluster, the so called `HOS' and `LOS' paradigms (Gatt et al., J. Photochem. Photobiol. B 104(1-2), 80-93 2011). The method of data analysis involves numerical simulations of the experimental spectra on relevant models of the OEC cluster. The simulations of the X-band CW-EPR multiline spectra, revealed three manganese ions having hyperfine couplings with large anisotropy. These are most likely Mn III centres and these clearly support the `LOS' OEC paradigm model, with a mean oxidation of 3.25 in the S2 state. This is consistent with the earlier data by Jin et al. (Phys. Chem. Chem. Phys. (PCCP) 16(17), 7799-812 2014), but the present results clearly indicate that heterogeneity in hyperfine couplings exist in samples as typically prepared.

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.

Internal state control of a dense sample of ultracold 23Na87Rb molecules

NASA Astrophysics Data System (ADS)

Ye, Xin; Guo, Mingyang; He, Junyu; Wang, Dajun; Quemener, Goulven; Gonzalez-Martinez, Maykel; Dulieu, Oliver

2017-04-01

We report the optimized production of ultracold 23Na87Rb molecules with completely controlled population distribution among internal states. Starting from a sample of 104 weakly bound Feshbach molecules, we achieved a hyperfine-structure-resolved STIRAP transfer to the ground state with an efficiency up to 95%. By tuning the frequency difference between the Raman lasers and applying an additional microwave signal, we realized the preparation of NaRb samples in different vibrational, rotational, and hyperfine levels. Based on this achievement, some results on molecular collisions with a range of possible loss channels will also be reported. This work was supported by the French ANR/Hong Kong RGC COPOMOL project (Grant No. A-CUHK403/13), the RGC General Research Fund (Grant No. CUHK14301815).

Studies of Landé gJ-factors of singly ionized lanthanum by laser-induced fluorescence spectroscopy

NASA Astrophysics Data System (ADS)

Werbowy, S.; Güney, C.; Windholz, L.

2016-08-01

Laser-induced fluorescence spectroscopy, using a cooled hollow cathode discharge lamp as source of ions, was used to observe the Zeeman splitting of 18 lines of La II in the wavelength range 629.6-680.9 nm, in external intermediate magnetic fields up to 800 G. The recorded hyperfine-Zeeman patterns were analyzed in detail using already known accurate hyperfine structure A- and B-constants. From the recordings the Landé gJ-factors for some levels belonging to the 5d2, 5d6s, 5d6p, 4f5d, 4f6s and 4f6p configurations of La II were determined. The obtained experimental gJ-factors are compared with earlier measurements and theoretical calculations.

Quantum Chemical Calculations of Torsionally Mediated Hyperfine Splittings in States of E Symmetry of Acetaldehyde (CH_{3}CHO)

NASA Astrophysics Data System (ADS)

Xu, Li-Hong; Reid, Elias M.; Guislain, Bradley; Hougen, Jon T.; Alekseev, E. A.; Krapivin, Igor

2017-06-01

Hyperfine splittings in methanol have been revisited in three recent publications. (i) Coudert et al. [JCP 143 (2015) 044304] published an analysis of splittings observed in the low-J range. They calculated 32 spin-rotation, 32 spin-spin, and 16 spin-torsion hyperfine constants using the ACES2 package. Three of these constants were adjusted to fit hyperfine patterns for 12 transitions. (ii) Three present authors and collaborators [JCP 145 (2016) 024307] analyzed medium to high-J experimental Lamb-dip measurements in methanol and presented a theoretical spin-rotation explanation that was based on torsionally mediated spin-rotation hyperfine operators. These contain, in addition to the usual nuclear spin and overall rotational operators, factors in the torsional angle α of the form {e^{plusmn;{inα}}}. Such operators have non-zero matrix elements between the two components of a torsion-rotation ^{tr}E state, but have zero matrix elements within a ^{tr}A state. More than 55 hyperfine splittings were successfully fitted using three parameters and the fitted values agree well with ab initio values obtained in (i). (iii) Lankhaar et al. [JCP 145 (2016) 244301] published a reanalysis of the data set from (i), using CFOUR recalculated hyperfine constants based on their rederivation of the relevant expressions. They explain why their choice of fixed and floated parameters leads to numerical values for all parameters that seem to be more physical than those in (i). The results in (ii) raise the question of whether large torsionally-mediated spin-rotation splittings will occur in other methyl-rotor-containing molecules. This abstract presents ab initio calculations of torsionally mediated hyperfine splittings in the E states of acetaldehyde using the same three operators as in (ii) and spin-rotation constants computed by Gaussian09. We explored the first 13 K states for J from 10 to 40 and ν_{t} = 0, 1, and 2. Our calculations indicate that hyperfine splittings in CH_{3}CHO are just below current measurement capability. This conclusion is confirmed by available experimental measurements.

Electric dipole hyperfine structure of TIF

NASA Astrophysics Data System (ADS)

Hinds, Edward A.; Sandars, P. G. H.

1980-02-01

The authors have calculated the electric dipole interaction energy of the 205TI nucleus in TIF assuming a nonzero electric dipole moment dp on the proton. The result is used in the accompanying experimental paper to obtain a new value of (-1.4+/-6)×10-21 e cm for dp.

Atomic Spectra and the Vector Model

NASA Astrophysics Data System (ADS)

Candler, A. C.

2015-05-01

12. Displaced terms; 13. Combination of several electrons; 14. Short periods; 15. Long periods; 16. Rare earths; 17. Intensity relsations; 18. Sum rules and (jj) coupling; 19. Series limit; 20. Hyperfine structure; 21. Quadripole radiation; 22. Fluorescent crystals; Appendix 5. Key to references; Appendix 6. Bibliography; Subject index; Author index.

High-precision optical measurement of the 2S hyperfine interval in atomic hydrogen.

PubMed

Kolachevsky, N; Fischer, M; Karshenboim, S G; Hänsch, T W

2004-01-23

We have applied an optical method to the measurement of the 2S hyperfine interval in atomic hydrogen. The interval has been measured by means of two-photon spectroscopy of the 1S-2S transition on a hydrogen atomic beam shielded from external magnetic fields. The measured value of the 2S hyperfine interval is equal to 177 556 860(16) Hz and represents the most precise measurement of this interval to date. The theoretical evaluation of the specific combination of 1S and 2S hyperfine intervals D21 is in fair agreement (within 1.4 sigma) with the value for D21 deduced from our measurement.

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.

Theoretical studies of alkyl radicals in the NaY and HY zeolites.

PubMed

Ghandi, Khashayar; Zahariev, Federico E; Wang, Yan Alexander

2005-08-18

Interplay of quantum mechanical calculations and experimental data on hyperfine coupling constants of ethyl radical in zeolites at several temperatures was engaged to study the geometries and binding energies and to predict the temperature dependence of hyperfine splitting of a series of alkyl radicals in zeolites for the first time. The main focus is on the hyperfine interaction of alkyl radicals in the NaY and HY zeolites. The hyperfine splitting for neutral free radicals and free radical cations is predicted for different zeolite environments. This information can be used to establish the nature of the muoniated alkyl radicals in the NaY and HY zeolites via muSR experiments. The muon hyperfine coupling constants of the ethane radical cation in these zeolites are very large with relatively little dependence on temperature. It was found that the intramolecular dynamics of alkyl free radicals are only weakly affected by their strong binding to zeolites. In contrast, the substrate binding has a significant effect on their intermolecular dynamics.

Innovation and reliability of atomic standards for PTTI applications

NASA Technical Reports Server (NTRS)

Kern, R.

1981-01-01

Innovation and reliability in hyperfine frequency standards and clock systems are discussed. Hyperfine standards are defined as those precision frequency sources and clocks which use a hyperfine atomic transition for frequency control and which have realized significant commercial production and acceptance (cesium, hydrogen, and rubidium atoms). References to other systems such as thallium and ammonia are excluded since these atomic standards have not been commercially exploited in this country.

Cold Rydberg molecules

NASA Astrophysics Data System (ADS)

Raithel, Georg

2017-04-01

Cold atomic systems have opened new frontiers in atomic and molecular physics, including several types of Rydberg molecules. Three types will be reviewed. Long-range Rydberg-ground molecules, first predicted in and observed in, are formed via low-energy electron scattering of the Rydberg electron from a ground-state atom within the Rydberg atom's volume. The binding mostly arises from S- and P-wave triplet scattering. We use a Fermi model that includes S-wave and P-wave singlet and triplet scattering, the fine structure coupling of the Rydberg atom and the hyperfine structure coupling of the 5S1/2 atom (in rubidium). The hyperfine structure gives rise to mixed singlet-triplet potentials for both low-L and high-L Rydberg molecules. A classification into Hund's cases will be discussed. The talk further includes results on adiabatic potentials and adiabatic states of Rydberg-Rydberg molecules in Rb and Cs. These molecules, which have even larger bonding length than Rydberg-ground molecules, are formed via electrostatic multipole interactions. The leading interaction of neutral Rydberg-Rydberg molecules is dipole-dipole, while for ionic Rydberg molecules it is dipole-monopole. Higher-order terms are discussed. FUNDING: NSF (PHY-1506093), NNSF of China (61475123).

Comparative analysis of the heme iron electronic structure and stereochemistry in tetrameric rabbit hemoglobin and monomeric soybean leghemoglobin a using Mössbauer spectroscopy with a high velocity resolution

NASA Astrophysics Data System (ADS)

Alenkina, I. V.; Kumar, A.; Berkovsky, A. L.; Oshtrakh, M. I.

2018-02-01

A comparative study of tetrameric rabbit hemoglobin and monomeric soybean leghemoglobin a in the oxy- and deoxy-forms was carried out using 57Fe Mössbauer spectroscopy with a high velocity resolution in order to analyze the heme iron electronic structure and stereochemistry in relation to the Mössbauer hyperfine parameters. The Mössbauer spectra of tetrameric rabbit hemoglobin in both forms were fitted using two quadrupole doublets related to the 57Fe in ɑ- and β-subunits. In contrast, the Mössbauer spectra of monomeric soybean leghemoglobin a were fitted using: (i) two quadrupole doublets for the oxy-form related to two conformational states of the distal His E7 imidazole ring and different hydrogen bonding of oxygen molecule in the oxy-form and (ii) using three quadrupole doublets for deoxy-form related to three conformational states of the proximal His F8 imidazole ring. Small variations of Mössbauer hyperfine parameters related to small differences in the heme iron electronic structure and stereochemistry in tetrameric rabbit hemoglobin and monomeric soybean leghemoglobin a are discussed.

Hyperfine fields and anisotropy of the orbital moment in epitaxial Mn5Ge3 films studied by 55Mn NMR

NASA Astrophysics Data System (ADS)

Kalvig, R.; Jedryka, E.; Wojcik, M.; Allodi, G.; De Renzi, R.; Petit, M.; Michez, L.

2018-05-01

55Mn NMR was used to perform the atomic-scale study of the anisotropic properties of Mn5Ge3 /Ge(111) epitaxial films with thicknesses between 9 and 300 nm. The NMR spectra have been recorded as a function of strong external magnetic field applied in the film plane and perpendicular to it. Two 55Mn NMR resonances have been observed, corresponding to the two manganese sites 4 d and 6 g , in the hexagonal D 88 structure; in zero field their frequency is centered around 207.5 and 428 MHz, respectively. The anisotropy of 55Mn hyperfine fields between the hexagonal c direction and the c plane at both Mn sites was evidenced and attributed to the anisotropic term due to the unquenched Mn orbital momentum. The anisotropy of the orbital contribution to hyperfine fields was determined as 1.52 T in the 4 d site and up to 2.77 T in the 6 g site. The 4 d site reveals a quadrupolar interaction due to the strong electric field gradient: Vz z=5.3 ×1019V/m2 in this site, which is shown to be oriented along the hexagonal c axis.

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

Mineralogical characterization of Greda clays and monitoring of their phase transformations on thermal treatment

NASA Astrophysics Data System (ADS)

Panduro, E. Chavez; Cabrejos, J. Bravo

2010-01-01

The mineralogical characterization of two clay samples from the Central Andean Region of Peru, denominated White Greda and Red Greda, is reported. These clays contain the clay minerals mica and illite respectively. Both clays were treated thermally in an oxidising atmosphere under controlled conditions up to 1,100°C with the purpose of obtaining information about structural changes that may be useful for pottery manufacture. X-ray fluorescence was used for the elemental characterization of the samples and X-ray diffractometry was used to determine the collapse and formation of the mineral phases present in the samples caused by thermal treatment. At temperatures above 1,000°C it is observed the formation of spinel in the case of White Greda and of hematite, corundum and cristobalite in the case of Red Greda. Room temperature transmission Mössbauer spectroscopy allowed the monitoring of the variation of the hyperfine parameters with the thermal treatment temperature; In the case of the evolution of the quadruple splitting of the paramagnetic Fe3 + sites with temperature, in both clays, the analyses reproduced results such as the “camel back” curve shape, found by other workers (Wagner and Wagner, Hyperfine Interact 154:35-82, 2004; Wagner and Kyek, Hyperfine Interact 154:5-33, 2004).

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. Copyright © 2015 Elsevier Inc. All rights reserved.

Methods of Ex Situ and In Situ Investigations of Structural Transformations: The Case of Crystallization of Metallic Glasses.

PubMed

Miglierini, Marcel B; Procházka, Vít; Vrba, Vlastimil; Švec, Peter; Janičkovič, Dušan; Matúš, Peter

2018-06-07

We demonstrate the use of two nuclear-based analytical methods that can follow the modifications of microstructural arrangement of iron-based metallic glasses (MGs). Despite their amorphous nature, the identification of hyperfine interactions unveils faint structural modifications. For this purpose, we have employed two techniques that utilize nuclear resonance among nuclear levels of a stable 57 Fe isotope, namely Mössbauer spectrometry and nuclear forward scattering (NFS) of synchrotron radiation. The effects of heat treatment upon (Fe2.85Co1)77Mo8Cu1B14 MG are discussed using the results of ex situ and in situ experiments, respectively. As both methods are sensitive to hyperfine interactions, information on structural arrangement as well as on magnetic microstructure is readily available. Mössbauer spectrometry performed ex situ describes how the structural arrangement and magnetic microstructure appears at room temperature after the annealing under certain conditions (temperature, time), and thus this technique inspects steady states. On the other hand, NFS data are recorded in situ during dynamically changing temperature and NFS examines transient states. The use of both techniques provides complementary information. In general, they can be applied to any suitable system in which it is important to know its steady state but also transient states.

The millimeter-wave spectrum of the MgH and MgD radicals

NASA Technical Reports Server (NTRS)

Ziurys, L. M.; Barclay, W. L., Jr.; Anderson, M. A.

1993-01-01

The pure rotational spectrum of MgH radical (X 2 Sigma (+)) in its ground state v = 0 and v = 1 vibrational modes has been observed in the laboratory using millimeter/submillimeter direct absorption spectroscopy. The rotational spectra of two isotopically substituted species, MgD and (Mg-26)H, have been detected as well. All six hyperfine components of the N = 0 -1 transition of MgH in its v = 0 and v = 1 states have been directly measured to an accuracy of +/-50 kHz, and the five components have been observed for (Mg-26)H. The N = 0 +/-1 and N = 1 -2 transitions of MgD have also been detected. Rotational, fine structure, and hyperfine constants were determined for all species from a nonlinear least-squared fit to the data using a 2 Sigma Hamiltonian.

Manipulation of individual hyperfine states in cold trapped molecular ions and application to HD+ frequency metrology.

PubMed

Bressel, U; Borodin, A; Shen, J; Hansen, M; Ernsting, I; Schiller, S

2012-05-04

Advanced techniques for manipulation of internal states, standard in atomic physics, are demonstrated for a charged molecular species for the first time. We address individual hyperfine states of rovibrational levels of a diatomic ion by optical excitation of individual hyperfine transitions, and achieve controlled transfer of population into a selected hyperfine state. We use molecular hydrogen ions (HD+) as a model system and employ a novel frequency-comb-based, continuous-wave 5  μm laser spectrometer. The achieved spectral resolution is the highest obtained so far in the optical domain on a molecular ion species. As a consequence, we are also able to perform the most precise test yet of the ab initio theory of a molecule.

Characterization of the hyperfine interaction of the excited D50 state of Eu3 +:Y2SiO5

NASA Astrophysics Data System (ADS)

Cruzeiro, Emmanuel Zambrini; Etesse, Jean; Tiranov, Alexey; Bourdel, Pierre-Antoine; Fröwis, Florian; Goldner, Philippe; Gisin, Nicolas; Afzelius, Mikael

2018-03-01

We characterize the europium (Eu3 +) hyperfine interaction of the excited state (D50) and determine its effective spin Hamiltonian parameters for the Zeeman and quadrupole tensors. An optical free induction decay method is used to measure all hyperfine splittings under a weak external magnetic field (up to 10 mT) for various field orientations. On the basis of the determined Hamiltonian, we discuss the possibility to predict optical transition probabilities between hyperfine levels for the F70⟷D50 transition. The obtained results provide necessary information to realize an optical quantum memory scheme which utilizes long spin coherence properties of 3 + 151Eu :Y2SiO5 material under external magnetic fields.

Comparison of sub-Doppler-width resonances in transmission and reflection spectra of micrometer-thick Cs vapor layers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Krasteva, A., E-mail: anna0kr0stz@gmail.com; Cartaleva, S., E-mail: stefka-c@ie.bas.bg; Vartanyan, T., E-mail: tigran@vartanyan.com

2016-03-25

We report experimental study of resonance sign reversal at the hyperfine F{sub g} = 4 → F{sub e} = 5 transition on D{sub 2} line of {sup 133}Cs. Alkali vapors are confined in an optical cell with micrometric thickness. For circular polarization of the irradiating light, transmission and reflection spectra, recorded at different laser intensities and different temperature of alkali vapor, are studied and compared. At low laser intensity, in the transmission spectra we observe a narrow resonance of increased absorption (bright resonance) at the F{sub g} = 4 → F{sub e} = 5 transition, however in reflection spectra, recordedmore » at the same experimental conditions, this bright resonance transforms into a dark resonance of reduced absorption. A simple explanation is proposed in order to explain the observed difference between the transmission and reflection spectra.« less

Localization of atomic excitation beyond the diffraction limit using electromagnetically induced transparency

NASA Astrophysics Data System (ADS)

Miles, J. A.; Das, Diptaranjan; Simmons, Z. J.; Yavuz, D. D.

2015-09-01

We experimentally demonstrate the localization of excitation between hyperfine ground states of 87Rb atoms to as small as λ /13 -wide spatial regions. We use ultracold atoms trapped in a dipole trap and utilize electromagnetically induced transparency (EIT) for the atomic excitation. The localization is achieved by combining a spatially varying coupling laser (standing wave) with the intensity dependence of EIT. The excitation is fast (150 ns laser pulses) and the dark-state fidelity can be made higher than 94% throughout the standing wave. Because the width of the localized regions is much smaller than the wavelength of the driving light, traditional optical imaging techniques cannot resolve the localized features. Therefore, to measure the excitation profile, we use an autocorrelation-like method where we perform two EIT sequences separated by a time delay, during which we move the standing wave.

Redox-dependent structure change and hyperfine nuclear magnetic resonance shifts in cytochrome c

DOE Office of Scientific and Technical Information (OSTI.GOV)

Feng, Yiquing; Roder, H.; Englander, S.W.

1990-04-10

Proton nuclear magnetic resonance assignments for reduced and oxidized equine cytochrome c show that many individual protons exhibit different chemical shifts in the two protein forms, reflecting diamagnetic shift effects due to structure change, and in addition contact and pseudocontact shifts that occur only in the paramagnetic oxidized form. To evaluate the chemical shift differences for structure change, the authors removed the pseudocontact shift contribution by a calculation based on knowledge of the electron spin g tensor. The g-tensor calculation, when repeated using only 12 available C{sub {alpha}}H proton resonances for cytochrom c from tuna, proved to be remarkably stable.more » The derived g tensor was then used together with spatial coordinates for the oxidized form to calculate the pseudocontact shift contribution to proton resonances at 400 identifiable sites throughout the protein, so that the redox-dependent chemical shift discrepancy, could be evaluated. Large residual changes in chemical shift define the Fermi contact shifts, where are found as expected to be limited to the immediate covalent structure of the heme and its ligands and to be asymmetrically distributed over the heme. The chemical shift discrepancies observed appear in the main to reflect structure-dependent diamagnetic shifts rather than hyperfine effects due to displacements in the pseudocontact shift field. Although 51 protons in 29 different residues exhibit significant chemical shift changes, the general impressions one of small structural adjustments to redox-dependent strain rather than sizeable structural displacements or rearrangements.« less

Extended calculations of energy levels, radiative properties, AJ, BJ hyperfine interaction constants, and Landé gJ-factors for nitrogen-like Ge XXVI

NASA Astrophysics Data System (ADS)

Wang, K.; Zhang, C. Y.; Jönsson, P.; Si, R.; Zhao, X. H.; Chen, Z. B.; Guo, X. L.; Chen, C. Y.; Yan, J.

2018-03-01

Employing two state-of-the-art methods, multiconfiguration Dirac-Hartree-Fock and second-order many-body perturbation theory, highly accurate calculations are performed for the lowest 272 fine-structure levels arising from the 2s22p3, 2s2p4, 2p5, 2s22p23l (l = s , p , d), 2s2p33l (l = s , p , d), and 2p43l (l = s , p , d) configurations in nitrogen-like Ge XXVI. Complete and consistent atomic data, including excitation energies, lifetimes, wavelengths, hyperfine structures, Landé gJ-factors, and E1, E2, M1, M2 line strengths, oscillator strengths, and transition rates among these 272 levels are provided. Comparisons are made between the present two data sets, as well as with other available experimental and theoretical values. The present data are accurate enough for identification and deblending of emission lines involving the n = 3 levels, and are also useful for modeling and diagnosing fusion plasmas.

Niobium hyperfine structure in crystal calcium tungstate

NASA Technical Reports Server (NTRS)

Tseng, D. L.; Kikuchi, C.

1972-01-01

A study of the niobium hyperfine structure in single crystal calcium tungstate was made by the combination of the technique of electron paramagnetic resonance and electron nuclear double resonance (EPR/ENDOR). The microwave frequency was about 9.4 GHz and the radio frequency from 20MHz to 70 MHz. The rare earth ions Nd(3+), U(3+), or Tm(3+) were added as the charge compensator for Nb(5+). To create niobium paramagnetic centers, the sample was irradiated at 77 deg K with a 10 thousand curie Co-60 gamma source for 1 to 2 hours at a dose rate of 200 K rads per hour and then transferred quickly into the cavity. In a general direction of magnetic field, the spectra showed 4 sets of 10 main lines corresponding to 4 nonequivalent sites of niobium with I = 9/2. These 4 sets of lines coalesced into 2 sets of 10 in the ab-plane and into a single set of 10 along the c-axis. This symmetry suggested that the tungsten ions are substituted by the niobium ions in the crystal.

Relativistic coupled-cluster-theory analysis of energies, hyperfine-structure constants, and dipole polarizabilities of Cd+

NASA Astrophysics Data System (ADS)

Li, Cheng-Bin; Yu, Yan-Mei; Sahoo, B. K.

2018-02-01

Roles of electron correlation effects in the determination of attachment energies, magnetic-dipole hyperfine-structure constants, and electric-dipole (E 1 ) matrix elements of the low-lying states in the singly charged cadmium ion (Cd+) have been analyzed. We employ the singles and doubles approximated relativistic coupled-cluster (RCC) method to calculate these properties. Intermediate results from the Dirac-Hartree-Fock approximation,the second-order many-body perturbation theory, and considering only the linear terms of the RCC method are given to demonstrate propagation of electron correlation effects in this ion. Contributions from important RCC terms are also given to highlight the importance of various correlation effects in the evaluation of these properties. At the end, we also determine E 1 polarizabilities (αE 1) of the ground and 5 p 2P1 /2 ;3 /2 states of Cd+ in the ab initio approach. We estimate them again by replacing some of the E 1 matrix elements and energies from the measurements to reduce their uncertainties so that they can be used in the high-precision experiments of this ion.

Determination of the binding energies of the np Rydberg states of H{sub 2}, HD, and D{sub 2} from high-resolution spectroscopic data by multichannel quantum-defect theory

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sprecher, Daniel; Merkt, Frédéric, E-mail: frederic.merkt@phys.chem.ethz.ch; Jungen, Christian

2014-03-14

Multichannel quantum-defect theory (MQDT) is used to calculate the electron binding energies of np Rydberg states of H{sub 2}, HD, and D{sub 2} around n = 60 at an accuracy of better than 0.5 MHz. The theory includes the effects of rovibronic channel interactions and the hyperfine structure, and has been extended to the calculation of the asymmetric hyperfine structure of Rydberg states of a heteronuclear diatomic molecule (HD). Starting values for the eigenquantum-defect parameters of MQDT were extracted from ab initio potential-energy functions for the low-lying p Rydberg states of molecular hydrogen and subsequently refined in a global weighted fitmore » to available experimental data on the singlet and triplet Rydberg states of H{sub 2} and D{sub 2}. The electron binding energies of high-np Rydberg states derived in this work represent important quantities for future determinations of the adiabatic ionization energies of H{sub 2}, HD, and D{sub 2} at sub-MHz accuracy.« less

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.

Hyperfine Fields in Nanocrystalline Fe0.48Al0.52

NASA Astrophysics Data System (ADS)

Szymański, K.; Satuła, D.; Dobrzyński, L.; Voronina, E.; Yelsukov, E. P.

2004-12-01

Mössbauer measurements with circularly polarized radiation were performed on a nanocrystalline, disordered Fe48Al52 alloy. The analysis of the data for various polarization states resulted in the characterization of the hyperfine magnetic field distribution and the dependence of the average z-component of hyperfine field on the chemical environment. An increasing number of Al in the first coordination shell causes not only a decrease of magnetic moments but also introduces noncollinearity.

Electron paramagnetic resonance of a 10B-containing heterocyclic radical

NASA Astrophysics Data System (ADS)

Eaton, Sandra S.; Ngendahimana, Thacien; Eaton, Gareth R.; Jupp, Andrew R.; Stephan, Douglas W.

2018-05-01

Electron paramagnetic resonance measurements for a 10B-containing heterocyclic phenanthrenedione radical, (C6F5)2B(O2C14H8), were made at X-band in 9:1 toluene:dichloromethane from 10 to 293 K and in toluene from 180 to 293 K. In well-deoxygenated 0.1 mM toluene solution at room temperature hyperfine couplings to 10B, four pairs of protons and five pairs of fluorines contribute to a continuous wave spectrum with many resolved lines. Hyperfine couplings were adjusted to provide the best fit for spectra of the radical enriched in 10B and the analogous radical synthesized with 10,11B in natural abundance, resulting in small refinements of the hyperfine coupling constants previously reported for the natural abundance sample. Electron spin relaxation rates at temperatures between 15 and 293 K were similar for samples containing 10B and natural isotope abundance. Analysis of electron spin echo envelope modulation and hyperfine correlation spectroscopy data at 80 K found Axx = -7.5 ± 0.3, Ayy = -8.5 ± 0.3, and Azz = -10.8 ± 0.3 MHz for 11B, which indicates small spin density on the boron. The spin echo and hyperfine spectroscopy data for the 10B -containing radical are consistent with the factor of 2.99 smaller hyperfine values for 10B than for 11B.

Measurement of a heavy-hole hyperfine interaction in InGaAs quantum dots using resonance fluorescence.

PubMed

Fallahi, P; Yilmaz, S T; Imamoğlu, A

2010-12-17

We measure the strength and the sign of hyperfine interaction of a heavy hole with nuclear spins in single self-assembled quantum dots. Our experiments utilize the locking of a quantum dot resonance to an incident laser frequency to generate nuclear spin polarization. By monitoring the resulting Overhauser shift of optical transitions that are split either by electron or exciton Zeeman energy with respect to the locked transition using resonance fluorescence, we find that the ratio of the heavy-hole and electron hyperfine interactions is -0.09 ± 0.02 in three quantum dots. Since hyperfine interactions constitute the principal decoherence source for spin qubits, we expect our results to be important for efforts aimed at using heavy-hole spins in quantum information processing.

Structure of Radicals from X-irradiated Guanine Derivatives: An Experimental and Computational Study of Sodium Guanosine Dihydrate Single Crystals

PubMed Central

Jayatilaka, Nayana; Nelson, William H.

2008-01-01

In sodium guanosine dihydrate single crystals, the guanine moiety is deprotonated at N1 due to growth from high-pH (>12) solutions. EPR and ENDOR study of crystals x-irradiated at 10 K detected evidence for three radical forms. Radical R1,characterized by two proton and two nitrogen hyperfine interactions, was identified as the product of net hydrogenation at N7 of the N1-deprotonated guanine unit. R1 exhibited an unusually distorted structure leading to net positive isotropic components of the hydrogen couplings. Radical R2, characterized by one proton and one nitrogen hyperfine coupling was identified as the primary electron loss product. This product is equivalent to that of deprotonation at N1 by the guanine cation and represents the first ENDOR characterization of that product. Radical R3, characterized by a single hydrogen hyperfine coupling, was identified as the product of net dehydrogenation at C1 of the ribose moiety. The identification of radicals R1-R3 was supported by DFT calculations on several possible structures using the B3LYP/6-311G(2df,p)//6-31G(d,p) approach. Radical R4, detected after warming the crystals to room temperature, was identified as the well-known product of net hydrogenation of C8 of the (N1-deprotonated) guanine component. Radical R1, evidently formed by protonation of the primary electron addition product, was present as roughly 60% of the total radicals detected at 10 K. Radical R2 was present as roughly 27% of the total yield, and the concentration of R3 contributed the remaining 13%. R3 is evidently the product of oneelectron oxidation followed by deprotonation; thus, the balance of oxidation and reduction products is approximately equal within experimental uncertainty. PMID:17249824

Low-temperature binding of NO adsorbed on MIL-100(Al)-A case study for the application of high resolution pulsed EPR methods and DFT calculations.

PubMed

Mendt, Matthias; Barth, Benjamin; Hartmann, Martin; Pöppl, Andreas

2017-12-14

The low-temperature binding of nitric oxide (NO) in the metal-organic framework MIL-100(Al) has been investigated by pulsed electron nuclear double resonance and hyperfine sublevel correlation spectroscopy. Three NO adsorption species have been identified. Among them, one species has been verified experimentally to bind directly to an 27 Al atom and all its relevant 14 N and 27 Al hyperfine interaction parameters have been determined spectroscopically. Those parameters fit well to the calculated ones of a theoretical cluster model, which was derived by density functional theory (DFT) in the present work and describes the low temperature binding of NO to the regular coordinatively unsaturated Al 3+ site of the MIL-100(Al) structure. As a result, the Lewis acidity of that site has been characterized using the NO molecule as an electron paramagnetic resonance active probe. The DFT derived wave function analysis revealed a bent end-on coordination of the NO molecule adsorbed at that site which is almost purely ionic and has a weak binding energy. The calculated flat potential energy surface of this species indicates the ability of the NO molecule to freely rotate at intermediate temperatures while it is still binding to the Al 3+ site. For the other two NO adsorption species, no structural models could be derived, but one of them is indicated to be adsorbed at the organic part of the metal-organic framework. Hyperfine interactions with protons, weakly coupled to the observed NO adsorption species, have also been measured by pulsed electron paramagnetic resonance and found to be consistent with their attribution to protons of the MIL-100(Al) benzenetricarboxylate ligand molecules.

VizieR Online Data Catalog: Rotational frequencies of TiO isotopologues (Lincowski+, 2016)

NASA Astrophysics Data System (ADS)

Lincowski, A. P.; Halfen, D. T.; Ziurys, L. M.

2017-03-01

Pure rotational spectra of the rare isotopologues of titanium oxide, 46TiO, 47TiO, 49TiO, and 50TiO, have been recorded using a combination of Fourier transform millimeter-wave (FTmmW) and millimeter/submillimeter direct absorption techniques in the frequency range 62-538GHz. This study is the first complete spectroscopic characterization of these species in their X3Δr ground electronic states. The isotopologues were created by the reaction of N2O or O2 and titanium vapor, produced either by laser ablation or in a Broida-type oven, and observed in the natural Ti isotopic abundances. Between 10 and 11 rotational transitions J+1<->J were measured for each species, typically in all 3 spin-orbit ladders Ω=1, 2, and 3. For 47TiO and 49TiO, hyperfine structure was resolved, originating from the titanium-47 and titanium-49 nuclear spins of I=5/2 and 7/2, respectively. For the Ω=1 and 3 components, the hyperfine structure was found to follow a classic Lande pattern, while that for Ω=2 appeared to be perturbed, likely a result of mixing with the nearby isoconfigurational a1Δ state. The spectra were analyzed with a case (a) Hamiltonian, and rotational, spin-orbit, and spin-spin parameters were determined for each species, as well as magnetic hyperfine and electric quadrupole constants for the two molecules with nuclear spins. The most abundant species, 48TiO, has been detected in circumstellar envelopes. These measurements will enable other titanium isotopologues to be studied at millimeter wavelengths, providing Ti isotope ratios that can test models of nucleosynthesis. (1 data file).

Millimeter/Submillimeter Spectroscopy of TiO (X3Δr): The Rare Titanium Isotopologues

NASA Astrophysics Data System (ADS)

Lincowski, A. P.; Halfen, D. T.; Ziurys, L. M.

2016-12-01

Pure rotational spectra of the rare isotopologues of titanium oxide, 46TiO, 47TiO, 49TiO, and 50TiO, have been recorded using a combination of Fourier transform millimeter-wave (FTmmW) and millimeter/submillimeter direct absorption techniques in the frequency range 62-538 GHz. This study is the first complete spectroscopic characterization of these species in their X 3Δ r ground electronic states. The isotopologues were created by the reaction of N2O or O2 and titanium vapor, produced either by laser ablation or in a Broida-type oven, and observed in the natural Ti isotopic abundances. Between 10 and 11 rotational transitions J + 1 ≤ftrightarrow J were measured for each species, typically in all 3 spin-orbit ladders Ω = 1, 2, and 3. For 47TiO and 49TiO, hyperfine structure was resolved, originating from the titanium-47 and titanium-49 nuclear spins of I = 5/2 and 7/2, respectively. For the Ω = 1 and 3 components, the hyperfine structure was found to follow a classic Landé pattern, while that for Ω = 2 appeared to be perturbed, likely a result of mixing with the nearby isoconfigurational a 1Δ state. The spectra were analyzed with a case (a) Hamiltonian, and rotational, spin-orbit, and spin-spin parameters were determined for each species, as well as magnetic hyperfine and electric quadrupole constants for the two molecules with nuclear spins. The most abundant species, 48TiO, has been detected in circumstellar envelopes. These measurements will enable other titanium isotopologues to be studied at millimeter wavelengths, providing Ti isotope ratios that can test models of nucleosynthesis.

International Conference on Quantum Chemical Calculations of NMR and EPR Parameters Held in Castle Smolenice, Slovak Republic on September 14-18 1998

DTIC Science & Technology

1998-10-21

site. The electric-field- induced linear shift is also observed in the hyperfine splitting of nuclear quadrupole resonance ( NQR ) spectrum of a nucleus...located at a noncentrosymmetric site in a molecule or in crystal lattice. Thus, the linear electric field effect on the ESR and NQR hyperfine splitting...the electric field effects on ESR and NQR hyperfine couplings. Theoretical methods to calculate the electric field effects within Hartree-Fock

Magneto-optical properties of BaCryFe12-yO19 (0.0 ≤ y ≤ 1.0) hexaferrites

NASA Astrophysics Data System (ADS)

Asiri, S.; Güner, S.; Korkmaz, A. D.; Amir, Md.; Batoo, K. M.; Almessiere, M. A.; Gungunes, H.; Sözeri, H.; Baykal, A.

2018-04-01

In this study, nanocrystalline BaCryFe12-yO19 (0.0 ≤ y ≤ 1.0) hexaferrite powders were prepared by sol-gel auto combustion method and the effect of Cr3+ ion substitution on morphology, structure, optic and magnetic properties of Barium hexaferrite were investigated. X-ray powder diffraction (XRD) analyses confirmed the purity of all samples. The XRD data shows that the average crystallite size lies between 60.95 nm and 50.10 nm and same was confirmed by Transmission electron microscopy. Transmission electron and scanning electron microscopy analyses presented the hexagonal morphology of all products. The characteristic hysteresis (σ-H) curves proved the ferromagnetic feature of as grown nanoparticle samples. Specific saturation magnetization (σs) drops from 46.59 to 34.89 emu/g with increasing Cr content while the coercive field values lie between 770 and 1652 Oe. The large magnitude of the magnetocrystalline (intrinsic) anisotropy field, (Ha) between 11.0 and 12.6 kOe proves that all products are magnetically hard. The energy band gap values decrease from 2.0 eV to 1.84 eV with increasing Cr content. From 57Fe Mössbauer spectroscopy, the variation in line width, isomer shift, quadrupole splitting and hyperfine magnetic field values were determined and discussed.

Two-Photon Absorption Spectroscopy of Rubidium with a Dual-Comb Tequnique

NASA Astrophysics Data System (ADS)

Nishiyama, Akiko; Yoshida, Satoru; Hariki, Takuya; Nakajima, Yoshiaki; Minoshima, Kaoru

2017-06-01

Dual-comb spectroscopies have great potential for high-resolution molecular and atomic spectroscopies, thanks to the broadband comb spectrum consisting of dense narrow modes. In this study, we apply the dual-comb system to Doppler-free two-photon absorption spectroscopy. The outputs of two frequency combs excite several two-photon transitions of rubidium, and we obtained broadband Doppler-free spectra from dual-comb fluorescence signals. The fluorescence detection scheme circumvents the sensitivity limit which is effectively determined by the dynamic range of photodetectors in absorption-based dual-comb spectroscopies. Our system realized high-sensitive, Doppler-free high-resolution and broadband atomic spectroscopy. A part of observed spectra of 5S_{1/2} - 5D_{5/2} transition is shown in the figure. The hyperfine structures of the F" = 1 - F' = 3,2,1 transitions are fully-resolved and the spectral widths are approximately 5 MHz. The absolute frequency axis is precisely calibrated from comb mode frequencies which were stabilized to a GPS-disciplined clock. This work was supported by JST through the ERATO MINOSHIMA Intelligent Optical Synthesizer Project and Grant-in-Aid for JSPS Fellows (16J02345). A. Nishiyama, S. Yoshida, Y. Nakajima, H. Sasada, K. Nakagawa, A. Onae, K. and Minoshima, Opt. Express 24, 25894 (2016). A. Hipke, S. A. Meek, T. Ideguchi, T.W. Hänsch, and N. Picqué, Phys. Rev. A 90, 011805(R) (2014).

Spectroscopy of a Synthetic Trapped Ion Qubit

NASA Astrophysics Data System (ADS)

Hucul, David; Christensen, Justin E.; Hudson, Eric R.; Campbell, Wesley C.

2017-09-01

133Ba+ has been identified as an attractive ion for quantum information processing due to the unique combination of its spin-1 /2 nucleus and visible wavelength electronic transitions. Using a microgram source of radioactive material, we trap and laser cool the synthetic A =133 radioisotope of barium II in a radio-frequency ion trap. Using the same, single trapped atom, we measure the isotope shifts and hyperfine structure of the 62P1 /2↔62S1 /2 and 62P1 /2↔52D3 /2 electronic transitions that are needed for laser cooling, state preparation, and state detection of the clock-state hyperfine and optical qubits. We also report the 62P1 /2↔52D3 /2 electronic transition isotope shift for the rare A =130 and 132 barium nuclides, completing the spectroscopic characterization necessary for laser cooling all long-lived barium II isotopes.

Liquid helium-free cryostat and hermetically sealed cryogenic microwave cavity for hyperfine spectroscopy of antiprotonic helium

PubMed Central

Massiczek, O.; Friedreich, S.; Juhász, B.; Widmann, E.; Zmeskal, J.

2011-01-01

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 4He 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 3He gas volume and different dimensions of the microwave resonator for measuring the 3He 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. PMID:22267883

Confinement and Diffusion Effects in Dynamical Nuclear Polarization in Low Dimensional Nanostructures

NASA Astrophysics Data System (ADS)

Henriksen, Dan; Tifrea, Ionel

2012-02-01

We investigate the dynamic nuclear polarization as it results from the hyperfine coupling between nonequilibrium electronic spins and nuclear spins in semiconductor nanostructures. The natural confinement provided by low dimensional nanostructures is responsible for an efficient nuclear spin - electron spin hyperfine coupling [1] and for a reduced value of the nuclear spin diffusion constant [2]. In the case of optical pumping, the induced nuclear spin polarization is position dependent even in the presence of nuclear spin diffusion. This effect should be measurable via optically induced nuclear magnetic resonance or time-resolved Faraday rotation experiments. We discuss the implications of our calculations for the case of GaAs quantum well structures.[4pt] [1] I. Tifrea and M. E. Flatt'e, Phys. Rev. B 84, 155319 (2011).[0pt] [2] A. Malinowski and R. T. Harley, Solid State Commun. 114, 419 (2000).

Hyperfine coupling constants of the nitrogen and phosphorus atoms: A challenge for exact-exchange density-functional and post-Hartree-Fock methods

NASA Astrophysics Data System (ADS)

Kaupp, Martin; Arbuznikov, Alexei V.; Heßelmann, Andreas; Görling, Andreas

2010-05-01

The isotropic hyperfine coupling constants of the free N(S4) and P(S4) atoms have been evaluated with high-level post-Hartree-Fock and density-functional methods. The phosphorus hyperfine coupling presents a significant challenge to both types of methods. With large basis sets, MP2 and coupled-cluster singles and doubles calculations give much too small values for the phosphorus atom. Triple excitations are needed in coupled-cluster calculations to achieve reasonable agreement with experiment. None of the standard density functionals reproduce even the correct sign of this hyperfine coupling. Similarly, the computed hyperfine couplings depend crucially on the self-consistent treatment in exact-exchange density-functional theory within the optimized effective potential (OEP) method. Well-balanced auxiliary and orbital basis sets are needed for basis-expansion exact-exchange-only OEP approaches to come close to Hartree-Fock or numerical OEP data. Results from the localized Hartree-Fock and Krieger-Li-Iafrate approximations deviate notably from exact OEP data in spite of very similar total energies. Of the functionals tested, only full exact-exchange methods augmented by a correlation functional gave at least the correct sign of the P(S4) hyperfine coupling but with too low absolute values. The subtle interplay between the spin-polarization contributions of the different core shells has been analyzed, and the influence of even very small changes in the exchange-correlation potential could be identified.

EPR and FTIR spectroscopic studies of MO-Al2O3-Bi2O3-B2O3-MnO2(M = Pb, Zn and Cd) glasses

NASA Astrophysics Data System (ADS)

Lalitha Phani, A. V.; Sekhar, K. Chandra; Chakradhar, R. P. S.; Narasimha Chary, M.; Shareefuddin, Md

2018-03-01

Glasses of the system (30-x)MO-xAl2O3-15Bi2O3-54.5B2O3-0.5MnO2 [M = Pb, Zn & Cd] (x = 0, 5, 10 & 15 mol%) were prepared by the normal melt quenching method. The amorphous nature of the prepared glasses was confirmed by the XRD studies. The EPR and FTIR studies were carried out at room temperature (RT). The EPR spectra exhibited three resonance signals at g ≈ 2.0 with a hyperfine structure, an absorption around g = 4.3 and a distinct shoulder at g = 3.3. Deconvoluted spectra were drawn for g ≈ 2.0 to resolve the six hyperfine lines. The electron paramagnetic resonance signal at g ≈ 2.0 indicates that the Mn2+ ions are in nearly perfectly octahedral symmetry. The low field signals at g = 3.3 and g = 4.3 are attributed to the Mn2+ ion which are in distorted rhombic symmetries. The hyperfine (HF) splitting constant (A) values suggested that the bonding between Mn2+ ions and its ligands is ionic in nature. The presence of BO3 and BO4 borate units, metal oxide cation units, Mn2+ and Bi-O bond vibrations in BiO3 units were noticed from the FTIR spectra.

The gamut of alkoxy radicals

NASA Astrophysics Data System (ADS)

Box, Harold C.; Budzinski, Edwin E.; Freund, Harold G.

1984-12-01

It is shown that various radicals exhibiting diverse ESR and ENDOR spectral characteristics are nonetheless a closely related family of alkoxy radicals. The relationship is established by correlating the g tensor with crystal structure and by relating dihedral angles inferred from proton hyperfine couplings to dihedral angles inferred from the g tensor and crystal structure. The analysis also serves to demonstrate that an ESR absorption observed in x-irradiated single crystals of uridine 5'-monophosphate is due to an alkoxy radical.

RADIATIVE TRANSFER MODELING OF THE ENIGMATIC SCATTERING POLARIZATION IN THE SOLAR Na i D{sub 1} LINE

DOE Office of Scientific and Technical Information (OSTI.GOV)

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

2015-12-01

The modeling of the peculiar scattering polarization signals observed in some diagnostically important solar resonance lines requires the consideration of the detailed spectral structure of the incident radiation field as well as the possibility of ground level polarization, along with the atom's hyperfine structure and quantum interference between hyperfine F-levels pertaining either to the same fine structure J-level, or to different J-levels of the same term. Here we present a theoretical and numerical approach suitable for solving this complex non-LTE radiative transfer problem. This approach is based on the density-matrix metalevel theory (where each level is viewed as a continuousmore » distribution of sublevels) and on accurate formal solvers of the transfer equations and efficient iterative methods. We show an application to the D-lines of Na i, with emphasis on the enigmatic D{sub 1} line, pointing out the observable signatures of the various physical mechanisms considered. We demonstrate that the linear polarization observed in the core of the D{sub 1} line may be explained by the effect that one gets when the detailed spectral structure of the anisotropic radiation responsible for the optical pumping is taken into account. This physical ingredient is capable of introducing significant scattering polarization in the core of the Na i D{sub 1} line without the need for ground-level polarization.« less

The g$$p\\atop{2}$$ Experiment: A Measurement of the Proton's Spin Structure Functions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zielinski, Ryan B.

The E08-027 (gmore » $$p\\atop{2}$$) experiment measured the spin structure functions of the proton at Jefferson Laboratory in Newport News, Va. Longitudinally polarized electrons were scattered from a transversely and longitudinally polarized solid ammonia target in Hall A, with the polarized NH$$_3$$ acting as an effective proton target. Focusing on small scattering angle events at the electron energies available at Jefferson Lab, the experiment covered a kinematic phase space of 0.02 GeV$^2$ $< Q^2 <$ 0.20 GeV$^2$ in the proton's resonance region. The spin structure functions, $$g_{1}^p(x,Q^2)$$ and $$g_{2}^p(x,Q^2)$$ , are extracted from an inclusive polarized cross section measurement of the electron-proton interaction. Integrated moments of $$g_1(x,Q^2)$$ are calculated and compared to theoretical predictions made by Chiral Perturbation Theory. The $$g_1(x,Q^2)$$ results are in agreement with previous measurements, but include a significant increase in statistical precision. The spin structure function contributions to the hyperfine energy levels in the hydrogen atom are also investigated. The $$g_2(x,Q^2)$$ measured contribution to the hyperfine splitting is the first ever experimental determination of this quantity. The results of this thesis suggest a disagreement of over 100% with previously published model results.« less

Cold Rydberg molecules

NASA Astrophysics Data System (ADS)

Raithel, Georg; Zhao, Jianming

2017-04-01

Cold atomic systems have opened new frontiers at the interface of atomic and molecular physics. These include research on novel types of Rydberg molecules. Three types of molecules will be reviewed. Long-range, homonuclear Rydberg molecules, first predicted in [1] and observed in [2], are formed via low-energy electron scattering of the Rydberg electron from a ground-state atom within the Rydberg atom's volume. The binding mostly arises from S- and P-wave triplet scattering. We use a Fermi model that includes S-wave and P-wave singlet and triplet scattering, the fine structure coupling of the Rydberg atom and the hyperfine structure coupling of the 5S1/2 atom (in rubidium [3]). The hyperfine structure gives rise to mixed singlet-triplet potentials for both low-L and high-L Rydberg molecules [3]. A classification into Hund's cases [3, 4, 5] will be discussed. The talk further includes results on adiabatic potentials and adiabatic states of Rydberg-Rydberg molecules in Rb and Cs. These molecules, which have even larger bonding length than Rydberg-ground molecules, are formed via electrostatic multipole interactions. The leading interaction term of neutral Rydberg-Rydberg molecules is between two dipoles, while for ionic Rydberg molecules it is between a dipole and a monopole. NSF (PHY-1506093), NNSF of China (61475123).

Hyperfine structure and isotope shift analysis of singly ionized titanium

NASA Astrophysics Data System (ADS)

Bouazza, Safa

2013-04-01

The even-parity low configuration system of Ti II has been considered on the basis of the experimental data found in the literature, and its fine structure has been reanalyzed by simultaneous parameterization of one- and two-body interactions for the model space (3d + 4s)3. Furthermore, the main one-electron hyperfine structure parameters for these configurations have been evaluated. For instance, for 3d24s1, a_{3{\\rm{d}}}^{01} = - {\\rm{63}}.{\\rm{2}}\\left( {{\\rm{3}}.{\\rm{1}}} \\right)\\,{\\rm{MHz}} and a_{4{\\rm{s}}}^{10} = - {\\rm{984}}.{\\rm{1}}\\left( {{\\rm{7}}.{\\rm{1}}} \\right)\\,{\\rm{MHz}} . Field shifts (FS) and specific mass shifts (SMS) of the main Ti II configurations are deduced by means of ab initio estimates combined with a small quantity of experimental isotope shift data available in the literature: FS(3d3) = -63.3 MHz, FS(3d24p1) = -49.7 MHz, FS(3d14s2) = 98.2 MHz, FS(4s24P1) = 163.4 MHz and SMS(3d3) = 1453.3 MHz, SMS(3d14s2) = -2179.7 MHz, …, referred to 3d24s1 for the pair Ti46-Ti48.

Sub-Doppler infrared spectroscopy of propargyl radical (H{sub 2}CCCH) in a slit supersonic expansion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Chih-Hsuan; Nesbitt, David J.

The acetylenic CH stretch mode (ν{sub 1}) of propargyl (H{sub 2}CCCH) radical has been studied at sub-Doppler resolution (∼60 MHz) via infrared laser absorption spectroscopy in a supersonic slit-jet discharge expansion, where low rotational temperatures (T{sub rot} = 13.5(4) K) and lack of spectral congestion permit improved determination of band origin and rotational constants for the excited state. For the lowest J states primarily populated in the slit jet cooled expansion, fine structure due to the unpaired electron spin is resolved completely, which permits accurate analysis of electron spin-rotation interactions in the vibrationally excited states (ε{sub aa} = − 518.1(1.8),more » ε{sub bb} = − 13.0(3), ε{sub cc} = − 1.8(3) MHz). In addition, hyperfine broadening in substantial excess of the sub-Doppler experimental linewidths is observed due to nuclear spin–electron spin contributions at the methylenic (—CH{sub 2}) and acetylenic (—CH) positions, which permits detailed modeling of the fine/hyperfine structure line contours. The results are consistent with a delocalized radical spin density extending over both methylenic and acetylenic C atoms, in excellent agreement with simple resonance structures as well as ab initio theoretical calculations.« less

Structural investigation and electron paramagnetic resonance of vanadyl doped alkali niobium borate glasses.

PubMed

Agarwal, A; Sheoran, A; Sanghi, S; Bhatnagar, V; Gupta, S K; Arora, M

2010-03-01

Glasses with compositions xNb(2)O(5).(30-x)M(2)O.69B(2)O(3) (where M=Li, Na, K; x=0, 4, 8 mol%) doped with 1 mol% V(2)O(5) have been prepared using normal melt quench technique. The IR transmission spectra of the glasses have been studied over the range 400-4000 cm(-1). The changes caused by the addition of Nb(2)O(5) on the structure of these glasses have been reported. The electron paramagnetic resonance spectra of VO(2+) ions in these glasses have been recorded in X-band (9.14 GHz) at room temperature (300 K). The spin Hamiltonian parameters, dipolar hyperfine coupling parameter and Fermi contact interaction parameter have been calculated. It is observed that the resultant resonance spectra contain hyperfine structures (hfs) due to V(4+) ions which exist as VO(2+) ions in octahedral coordination with a tetragonal compression in the present glasses. The tetragonality of V(4+)O(6) complex decreases with increasing concentration of Nb(2)O(5). The 3d(xy) orbit contracts with increase in Nb(2)O(5):M(2)O ratio. Values of the theoretical optical basicity, Lambda(th), have also been reported. Copyright 2009 Elsevier B.V. All rights reserved.

Research on Spectroscopy, Opacity, and Atmospheres

NASA Astrophysics Data System (ADS)

Kurucz, Robert L.

1996-01-01

The main accomplishment was the merging of all the atomic line data into one wavelength-sorted list that is simple to use. We have combined all the atomic files from a CDROM into 534,910 line files GFALL.DAT and GFELEN.DAT. These are the data we use to compute spectra. They are not up to date. References are given in GFALL.REF or GFELEK.REF. There are no references after 1988, and for light elements there are no references after 1979. One new development is the inclusion of hyperfine splitting for the iron group elements using hyperfine data from the literature through 1993. The data are very incomplete. We have supplied a program for splitting the line list for a species. It reads the hyperfine and isotopic splitting parameters for levels and computes the splittings whenever those levels appear. Lines with no splitting data are copied untouched. Because Sc, Mn, and Co are monoisotopic, only the hyperfine splittings are needed. Since 51V is much more abundant than 50V, the isotope shifts are small for 51V, and we approximate V with 51V. GFALLHYP.DAT has 754,946 lines including hyperfine Sc I, V I, Mn I, and Co I.

Single crystal X- and Q-band EPR spectroscopy of a binuclear Mn(2)(III,IV) complex relevant to the oxygen-evolving complex of photosystem II.

PubMed

Yano, Junko; Sauer, Kenneth; Girerd, Jean-Jacques; Yachandra, Vittal K

2004-06-23

The anisotropic g and hyperfine tensors of the Mn di-micro-oxo complex, [Mn(2)(III,IV)O(2)(phen)(4)](PF(6))(3).CH(3)CN, were derived by single-crystal EPR measurements at X- and Q-band frequencies. This is the first simulation of EPR parameters from single-crystal EPR spectra for multinuclear Mn complexes, which are of importance in several metalloenzymes; one of them is the oxygen-evolving complex in photosystem II (PS II). Single-crystal [Mn(2)(III,IV)O(2)(phen)(4)](PF(6))(3).CH(3)CN EPR spectra showed distinct resolved (55)Mn hyperfine lines in all crystal orientations, unlike single-crystal EPR spectra of other Mn(2)(III,IV) di-micro-oxo bridged complexes. We measured the EPR spectra in the crystal ab- and bc-planes, and from these spectra we obtained the EPR spectra of the complex along the unique a-, b-, and c-axes of the crystal. The crystal orientation was determined by X-ray diffraction and single-crystal EXAFS (Extended X-ray Absorption Fine Structure) measurements. In this complex, the three crystallographic axes, a, b, and c, are parallel or nearly parallel to the principal molecular axes of Mn(2)(III,IV)O(2)(phen)(4) as shown in the crystallographic data by Stebler et al. (Inorg. Chem. 1986, 25, 4743). This direct relation together with the resolved hyperfine lines significantly simplified the simulation of single-crystal spectra in the three principal directions due to the reduction of free parameters and, thus, allowed us to define the magnetic g and A tensors of the molecule with a high degree of reliability. These parameters were subsequently used to generate the solution EPR spectra at both X- and Q-bands with excellent agreement. The anisotropic g and hyperfine tensors determined by the simulation of the X- and Q-band single-crystal and solution EPR spectra are as follows: g(x) = 1.9887, g(y) = 1.9957, g(z) = 1.9775, and hyperfine coupling constants are A(III)(x) = |171| G, A(III)(y) = |176| G, A(III)(z) = |129| G, A(IV)(x) = |77| G, A(IV)(y) = |74| G, A(IV)(z) = |80| G.

Magnetic properties and hyperfine interactions in Cr{sub 8}, Cr{sub 7}Cd, and Cr{sub 7}Ni molecular rings from {sup 19}F-NMR

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bordonali, L.; Borsa, F.; Consorzio INSTM, Via Giusti 9, I-50121 Firenze

2014-04-14

A detailed experimental investigation of the {sup 19}F nuclear magnetic resonance is made on single crystals of the homometallic Cr{sub 8} antiferromagnetic molecular ring and heterometallic Cr{sub 7}Cd and Cr{sub 7}Ni rings in the low temperature ground state. Since the F{sup −} ion is located midway between neighboring magnetic metal ions in the ring, the {sup 19}F-NMR spectra yield information about the local electronic spin density and {sup 19}F hyperfine interactions. In Cr{sub 8}, where the ground state is a singlet with total spin S{sub T} = 0, the {sup 19}F-NMR spectra at 1.7 K and low external magnetic fieldmore » display a single narrow line, while when the magnetic field is increased towards the first level crossing field, satellite lines appear in the {sup 19}F-NMR spectrum, indicating a progressive increase in the Boltzmann population of the first excited state S{sub T} = 1. In the heterometallic rings, Cr{sub 7}Cd and Cr{sub 7}Ni, whose ground state is magnetic with S{sub T} = 3/2 and S{sub T} = 1/2, respectively, the {sup 19}F-NMR spectrum has a complicated structure which depends on the strength and orientation of the magnetic field, due to both isotropic and anisotropic transferred hyperfine interactions and classical dipolar interactions. From the {sup 19}F-NMR spectra in single crystals we estimated the transferred hyperfine constants for both the F{sup −}-Ni{sup 2+} and the F{sup −}-Cd{sup 2+} bonds. The values of the hyperfine constants compare well to the ones known for F{sup −}-Ni{sup 2+} in KNiF{sub 3} and NiF{sub 2} and for F{sup −}-Cr{sup 3+} in K{sub 2}NaCrF{sub 6}. The results are discussed in terms of hybridization of the 2s, 2p orbitals of the F{sup −} ion and the d orbitals of the magnetic ion. Finally, we discuss the implications of our results for the electron-spin decoherence.« less

An ultra-stable optical frequency standard for telecommunication purposes based upon the 5S1/2 → 5D5/2 two-photon transition in rubidium

NASA Astrophysics Data System (ADS)

Terra, Osama; Hussein, Hatem

2016-02-01

In this study, we report the development of a frequency standard for optical fiber communication applications based on a two-photon transition in rubidium at 385.2 THz. This standard kills two birds with one stone in the sense it is capable of providing us with two highly stable serviceable wavelengths at 778.1 and 1556.2 nm. In this system, we exploit the narrow line-width of a fiber laser emitting at 1556.2 nm in conjunction with an erbium-doped fiber amplifier to generate a sufficient second harmonic laser beam at 778.1 nm in a periodically polled lithium niobate waveguide mixer in order to probe and frequency-lock the laser to the 5S1/2 ( F g = 3)-5D5/2 ( F e = 5) hyperfine two-photon transition component in 85Rb. The metrological performance of the standard is evaluated with the aid of an optical frequency comb synthesizer. Allan variance measurement shows a stability of 4 × 10-12 at 1 s (limited by the comb stability), reaching a floor of 6.8 × 10-13 at 1000 s. After correction of all the major systematic frequency shifts including the light shift, the absolute frequency is found to be 385 285 142 374.0 (5.0) kHz. Moreover, the absolute frequencies of most of the hyperfine components of the 5S1/2-5D5/2 transition of the two naturally existing rubidium isotopes are measured using a femtosecond frequency comb synthesizer after stabilizing a laser on each component.

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.

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

NASA Astrophysics Data System (ADS)

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

2016-07-01

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.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Belov, S. P.; Golubiatnikov, G. Yu.; Lapinov, A. V.

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.,more » 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{sup ±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 A{sub 1} and A{sub 2} 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.« less

Mixing of the lowest-lying qqq configurations with JP =1/2- in different hyperfine interaction models

NASA Astrophysics Data System (ADS)

Chen, Jia; An, Chunsheng; Chen, Hong

2018-02-01

We investigate mixing of the lowest-lying qqq configurations with JP = 1/2- caused by the hyperfine interactions between quarks mediated by Goldstone Boson Exchange, One Gluon Exchange, and both Goldstone Boson and One Gluon exchange, respectively. The first orbitally excited nucleon, Σ, Λ and Ξ states are considered. Contributions of both the contact term and tensor term are taken into account. Our numerical results show that mixing of the studied configurations in the two employed hyperfine interaction models are very different. Therefore, the present results, which should affect the strong and electromagnetic decays of baryon resonances, may be used to examine the present employed hyperfine interaction models. Supported by National Natural Science Foundation of China (11675131,11645002), Chongqing Natural Science Foundation (cstc2015jcyjA00032) and Fundamental Research Funds for the Central Universities (SWU115020)

Ab initio calculations of torsionally mediated hyperfine splittings in E states of acetaldehyde

NASA Astrophysics Data System (ADS)

Xu, Li-Hong; Reid, E. M.; Guislain, B.; Hougen, J. T.; Alekseev, E. A.; Krapivin, I.

2017-12-01

Quantum chemistry packages can be used to predict with reasonable accuracy spin-rotation hyperfine interaction constants for methanol, which contains one methyl-top internal rotor. In this work we use one of these packages to calculate components of the spin-rotation interaction tensor for acetaldehyde. We then use torsion-rotation wavefunctions obtained from a fit to the acetaldehyde torsion-rotation spectrum to calculate the expected magnitude of hyperfine splittings analogous to those observed at relatively high J values in the E symmetry states of methanol. We find that theory does indeed predict doublet splittings at moderate J values in the acetaldehyde torsion-rotation spectrum, which closely resemble those seen in methanol, but that the factor of three decrease in hyperfine spin-rotation constants compared to methanol puts the largest of the acetaldehyde splittings a factor of two below presently available Lamb-dip resolution.

Scanning nuclear resonance imaging of a hyperfine-coupled quantum Hall system.

PubMed

Hashimoto, Katsushi; Tomimatsu, Toru; Sato, Ken; Hirayama, Yoshiro

2018-06-07

Nuclear resonance (NR) is widely used to detect and characterise nuclear spin polarisation and conduction electron spin polarisation coupled by a hyperfine interaction. While the macroscopic aspects of such hyperfine-coupled systems have been addressed in most relevant studies, the essential role of local variation in both types of spin polarisation has been indicated in 2D semiconductor systems. In this study, we apply a recently developed local and highly sensitive NR based on a scanning probe to a hyperfine-coupled quantum Hall (QH) system in a 2D electron gas subject to a strong magnetic field. We succeed in imaging the NR intensity and Knight shift, uncovering the spatial distribution of both the nuclear and electron spin polarisation. The results reveal the microscopic origin of the nonequilibrium QH phenomena, and highlight the potential use of our technique in microscopic studies on various electron spin systems as well as their correlations with nuclear spins.

High-resolution internal state control of ultracold 23Na87Rb molecules

NASA Astrophysics Data System (ADS)

Guo, Mingyang; Ye, Xin; He, Junyu; Quéméner, Goulven; Wang, Dajun

2018-02-01

We report the full internal state control of ultracold 23Na87Rb molecules, including vibrational, rotational, and hyperfine degrees of freedom. Starting from a sample of weakly bound Feshbach molecules, we realize the creation of molecules in single hyperfine levels of both the rovibrational ground and excited states with a high-efficiency and high-resolution stimulated Raman adiabatic passage. This capability brings broad possibilities for investigating ultracold polar molecules with different chemical reactivities and interactions with a single molecular species. Moreover, starting from the rovibrational and hyperfine ground state, we achieve rotational and hyperfine control with one- and two-photon microwave spectroscopy to reach levels not accessible by the stimulated Raman transfer. The combination of these two techniques results in complete control over the internal state of ultracold polar molecules, which paves the way to study state-dependent molecular collisions and state-controlled chemical reactions.

Molecules in high spin states III: The millimeter/submillimeter-wave spectrum of the MnCl radical (X 7Σ+)

NASA Astrophysics Data System (ADS)

Halfen, D. T.; Ziurys, L. M.

2005-02-01

The pure rotational spectrum of the MnCl radical (X 7Σ+) has been recorded in the range 141-535 GHz using millimeter-submillimeter direct absorption spectroscopy. This work is the first time the molecule has been studied with rotational resolution in its ground electronic state. MnCl was synthesized by the reaction of manganese vapor, produced in a Broida-type oven, with Cl2. Transitions of both chlorine isotopomers were measured, as well as lines originating in several vibrationally excited states. The presence of several spin components and manganese hyperfine interactions resulted in quite complex spectra, consisting of multiple blended features. Because 42 rotational transitions were measured for Mn35Cl over a wide range of frequencies with high signal-to-noise, a very accurate set of rotational, fine structure, and hyperfine constants could be determined with the aid of spectral simulations. Spectroscopic constants were also determined for Mn37Cl and several vibrationally excited states. The values of the spin-rotation and spin-spin parameters were found to be relatively small (γ=11.2658 MHz and λ=1113.10 MHz for Mn35Cl); in the case of λ, excited electronic states contributing to the second-order spin-orbit interaction may be canceling each other. The Fermi contact hyperfine term was found to be large in manganese chloride with bF(Mn35Cl)=397.71 MHz, a result of the manganese 4s character mixing into the 12σ orbital. This orbital is spσ hybridized, and contains some Mn 4pσ character, as well. Hence, it also contributes to the dipolar constant c, which is small and positive for this radical (c=32.35 MHz for Mn35Cl). The hyperfine parameters in MnCl are similar to those of MnH and MnF, suggesting that the bonding in these three molecules is comparable.

Calculation of the spin-polarized electronic structure of an interstitial iron impurity in silicon

NASA Astrophysics Data System (ADS)

Katayama-Yoshida, H.; Zunger, Alex

1985-06-01

We apply our self-consistent, all-electron, spin-polarized Green's-function method within an impurity-centered, dynamic basis set to study the interstitial iron impurity in silicon. We use two different formulations of the interelectron interactions: the local-spin-density (LSD) formalism and the self-interaction-corrected (SIC) local-spin-density (SIC-LSD) formalism. We find that the SIC-LSD approach is needed to obtain the correct high-spin ground state of Si:Fe+. We propose a quantitative explanation to the observed donor ionization energy and the high-spin ground states for Si:Fe+ within the SIC-LSD approach. For both Si:Fe0 and Si:Fe+, this approach leads to a hyperfine field, contact spin density, and ionization energy in better agreement with experiments than the simple LSD approach. The apparent dichotomy between the covalently delocalized nature of Si:Fe as suggested on the one hand by its reduced hyperfine field (relative to the free atom) and extended spin density and by the occurrence of two closely spaced, stable charge states (within 0.4 eV) and on the other hand by the atomically localized picture (suggested, for example, by the stability of a high-spin, ground-state configuration) is resolved. We find a large reduction in the hyperfine field and contact spin density due to the covalent hybridization between the impurity 3d orbitals and the tails of the delocalized sp3 hybrid orbitals of the surrounding silicon atoms. Using the calculated results, we discuss (i) the underlying mechanism for the stability and plurality of charged states, (ii) the covalent reduction in the hyperfine field, (iii) the remarkable constancy of the impurity Mössbauer isomer shift for different charged states, (iv) comparison with the multiple charged states in ionic crystals, and (v) some related speculation about the mechanism of (Fe2+/Fe3+) oxidation-reduction ionizations in heme proteins and electron-transporting biological systems.

Molecules in high spin states III: the millimeter/submillimeter-wave spectrum of the MnCl radical (X (7)Sigma(+)).

PubMed

Halfen, D T; Ziurys, L M

2005-02-01

The pure rotational spectrum of the MnCl radical (X (7)Sigma(+)) has been recorded in the range 141-535 GHz using millimeter-submillimeter direct absorption spectroscopy. This work is the first time the molecule has been studied with rotational resolution in its ground electronic state. MnCl was synthesized by the reaction of manganese vapor, produced in a Broida-type oven, with Cl(2). Transitions of both chlorine isotopomers were measured, as well as lines originating in several vibrationally excited states. The presence of several spin components and manganese hyperfine interactions resulted in quite complex spectra, consisting of multiple blended features. Because 42 rotational transitions were measured for Mn(35)Cl over a wide range of frequencies with high signal-to-noise, a very accurate set of rotational, fine structure, and hyperfine constants could be determined with the aid of spectral simulations. Spectroscopic constants were also determined for Mn(37)Cl and several vibrationally excited states. The values of the spin-rotation and spin-spin parameters were found to be relatively small (gamma=11.2658 MHz and lambda=1113.10 MHz for Mn(35)Cl); in the case of lambda, excited electronic states contributing to the second-order spin-orbit interaction may be canceling each other. The Fermi contact hyperfine term was found to be large in manganese chloride with b(F)(Mn(35)Cl)=397.71 MHz, a result of the manganese 4s character mixing into the 12sigma orbital. This orbital is spsigma hybridized, and contains some Mn 4psigma character, as well. Hence, it also contributes to the dipolar constant c, which is small and positive for this radical (c=32.35 MHz for Mn(35)Cl). The hyperfine parameters in MnCl are similar to those of MnH and MnF, suggesting that the bonding in these three molecules is comparable.

57Fe Mössbauer study of stoichiometric iron-based superconductor CaKFe 4As 4: a comparison to KFe 2As 2 and CaFe 2As 2

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bud’ko, Sergey L.; Kong, Tai; Meier, William R.

57Fe Mössbauer spectra at different temperatures between ~5 and ~300 K were measured on an oriented mosaic of single crystals of CaKFe 4 As 4. The data indicate that is a well formed compound with narrow spectral lines, no traces of other, Fe – containing, secondary phases in the spectra and no static magnetic order. There is no discernible feature at the superconducting transition temperature in any of the hyperfine parameters. The temperature dependence of the quadrupole splitting approximately follows the empirical ‘ T 3/2 law’. Furthermore, the hyperfine parameters of CaKFe 4 As 4 are compared with those formore » measured in this work, and the literature data for CaFe 2 As 2, and were found to be in between those for these two, ordered, 122 compounds, in agreement with the gross view of CaKFe 4 As 4 as a structural analog of KFe 2 As 2 and CaFe 2 As 2 that has alternating Ca- and K-layers in the structure.« less

Effect of WO3 on EPR, structure and electrical conductivity of vanadyl doped WO3·M2O·B2O3 (M=Li, Na) glasses

NASA Astrophysics Data System (ADS)

Sheoran, A.; Agarwal, A.; Sanghi, S.; Seth, V. P.; Gupta, S. K.; Arora, M.

2011-12-01

Glasses with composition xWO3·(30-x)M2O·70B2O3 (M=Li, Na; 0≤x≤15) doped with 2 mol% V2O5 have been prepared using the melt-quench technique. The electron paramagnetic resonance spectra have been recorded in X-band (ν≈9.14 GHz) at room temperature (RT). The spin Hamiltonian parameters, dipolar hyperfine coupling parameter and Fermi contact interaction parameter have been calculated. It is observed that the resultant resonance spectra contain hyperfine structures (hfs) only due to V4+ ions, which exist as VO2+ ions in octahedral coordination with a tetragonal compression in the present glass system. The tetragonality increases with WO3:M2O ratio and also there is an expansion of 3dxy orbit of unpaired electron in the vanadium ion. The study of IR transmission spectra over a range 400-4000 cm-1 depicts the presence of WO6 group. The DC conductivity (σ) has been measured in the temperature range 423-623 K and is found to be predominantly ionic.

Properties of Gd{sub 2}O{sub 3} nanoparticles studied by hyperfine interactions and magnetization measurements

DOE Office of Scientific and Technical Information (OSTI.GOV)

Correa, E. L., E-mail: eduardo.correa@usp.br; Bosch-Santos, B.; Cavalcante, F. H. M.

2016-05-15

The magnetic behavior of Gd{sub 2}O{sub 3} 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 {sup 111}In({sup 111}Cd) 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 particlesmore » 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.« less

57Fe Mössbauer study of stoichiometric iron-based superconductor CaKFe 4As 4: a comparison to KFe 2As 2 and CaFe 2As 2

DOE PAGES

Bud’ko, Sergey L.; Kong, Tai; Meier, William R.; ...

2017-07-06

57Fe Mössbauer spectra at different temperatures between ~5 and ~300 K were measured on an oriented mosaic of single crystals of CaKFe 4 As 4. The data indicate that is a well formed compound with narrow spectral lines, no traces of other, Fe – containing, secondary phases in the spectra and no static magnetic order. There is no discernible feature at the superconducting transition temperature in any of the hyperfine parameters. The temperature dependence of the quadrupole splitting approximately follows the empirical ‘ T 3/2 law’. Furthermore, the hyperfine parameters of CaKFe 4 As 4 are compared with those formore » measured in this work, and the literature data for CaFe 2 As 2, and were found to be in between those for these two, ordered, 122 compounds, in agreement with the gross view of CaKFe 4 As 4 as a structural analog of KFe 2 As 2 and CaFe 2 As 2 that has alternating Ca- and K-layers in the structure.« less

Ground state spectrum of methylcyanide

NASA Astrophysics Data System (ADS)

Šimečková, Marie; Urban, Štěpán; Fuchs, Ulrike; Lewen, Frank; Winnewisser, Gisbert; Morino, Isamu; Yamada, Koichi M. T.

2004-08-01

The rotational spectrum of methylcyanide (acetonitrile) in the ground vibrational state was measured in the spectral region from 91 to 810 GHz using the Cologne and Tsukuba spectrometers operated in the Doppler-limited and sub-Doppler saturation layouts. The resolution of the saturation Lamb-dip measurements is estimated to be about 1 kHz at the best of circumstances and the measuring accuracy of 10-60 kHz depending very sensitively on the quality of the spectrum. In the cases of rotational transitions with the low quantum number J ( J<18) and with a low difference of the rotational quantum numbers J- K, the resolved or partly resolved hyperfine structures of the rotational transitions were observed. Together with the most accurate data from the literature, the newly measured experimental data were analyzed using the traditional polynomial energy formula as well as the Padè approximant for the effective rotational Hamiltonian. The resulting rotational, centrifugal distortion, and hyperfine structure spectroscopic constants were obtained with a significantly higher accuracy than the ones listed in the literature. In addition, an anomalous accidental resonance was detected between the K=14 ground state levels and the K=12, + l levels in the excited v8=1 vibrational state.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Davaasuren, Bambar; Dashjav, Enkhtsetseg; Kreiner, Guido

The carboferrates RE{sub 15}[Fe{sub 8}C{sub 25}] (RE=Dy, Ho) were prepared from mixtures of the elements by arc-melting followed with subsequent annealing at 1373 K. The crystal structures were determined from single crystal X-ray diffraction data and revealed an isotypic relationship to Er{sub 15}[Fe{sub 8}C{sub 25}] (hP48, P321). The main feature of the crystal structure is given by Fe{sub 6} cluster units characterized by covalent Fe–Fe bonding interactions. {sup 57}Fe Mössbauer spectra of Dy{sub 15}[Fe{sub 8}C{sub 25}] were fitted by three subspectra with relative spectral weights of about 3:3:2 which is in general agreement with the crystal structure. Below 50 K,more » an onset of magnetic hyperfine fields at the three iron sites is observed which is supposed to be caused by dipolar fields arising from neighboring, slowly relaxing Dy magnetic moments. - Graphical abstract: Fe{sub 6}-cluster in the crystal structure of RE{sub 15}[Fe{sub 8}C{sub 25}], RE=Dy, Ho. - Highlights: • New carboferrates RE{sub 15}[Fe{sub 8}C{sub 25}] with RE=Dy, Ho have been synthesized. • The crystal structures were refined using single crystal X-ray data. • An orientational relationship between Fe{sub 6}-clusters and Fe in γ-Fe is outlined. • {sup 57}Fe Mössbauer spectra are in agreement with structural data from X-rays. • Magnetic hyperfine fields below 50 K are explained by dipolar fields from Dy atoms.« less

Microstructure and spectroscopic investigations of calcium zinc bismuth phosphate glass ceramics doped with manganese ions

NASA Astrophysics Data System (ADS)

Suneel Kumar, A.; Sambasiva Rao, M. V.; Chinna Ram, G.; Krishna Rao, D.

2018-01-01

Multi-component 10CaF2-20ZnO-(15 - x)Bi2O3-55P2O5:xMnO (0 ≤ x ≤ 2.5) glass ceramics were synthesised by melt quenching technique and heat treatment. The prepared glass ceramics were characterised by XRD, DTA, EDS and SEM. Spectroscopic studies such as optical absorption, EPR, FTIR and Raman were also carried out on these glass ceramics. The XRD and SEM studies have indicated that ceramic samples contain well defined and randomly distributed grains of different crystalline phases. The observed increase of enthalpy from DTA patterns up to 1 mol% of MnO indicates that the crystallisation starts initially from the surface of the material then gradually it is extended to the volume of the material and this influence is meagre at higher concentrations of MnO. The absorption spectra of manganese doped glass ceramics have exhibited two types of conventional bands; one due to Mn2+ ions and other due to Mn3+ ions. The EPR spectra of MnO doped glass ceramics showed a resonance signal around g2 = 2.023 with a six line hyperfine structure and another signal at about g1 = 4.314. The relative intensity and half-width of these two signals are observed to increase with the increase in the concentration of manganese ions up to 1 mol% beyond this concentration it is found to decrease. Such observation indicates the conversion of part of Mn2+ ions into Mn3+ ions in the glass ceramic matrix. The observed increase in the intensity of symmetrical structural units at the expense of asymmetrical structural units from the FTIR and Raman spectra at higher concentration of MnO indicating that Mn2+ ions occupy the network forming positions in the glass ceramic structure.

Quantum versus classical hyperfine-induced dynamics in a quantum dota)

NASA Astrophysics Data System (ADS)

Coish, W. A.; Loss, Daniel; Yuzbashyan, E. A.; Altshuler, B. L.

2007-04-01

In this article we analyze spin dynamics for electrons confined to semiconductor quantum dots due to the contact hyperfine interaction. We compare mean-field (classical) evolution of an electron spin in the presence of a nuclear field with the exact quantum evolution for the special case of uniform hyperfine coupling constants. We find that (in this special case) the zero-magnetic-field dynamics due to the mean-field approximation and quantum evolution are similar. However, in a finite magnetic field, the quantum and classical solutions agree only up to a certain time scale t <τc, after which they differ markedly.

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.

Structural and magnetic study of Al{sup 3+} doped Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4} nanoferrites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wang, L.; Rai, B.K.; Mishra, S.R.

2015-05-15

Graphical abstract: Hyperfine field of individual sites (inset) and weighted average hyperfine field as a function of Al{sup 3+} content for Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4}. - Highlights: • Grain size reduction with Al{sup 3+} substitution. • Preferred occupancy of Al{sup 3+} at B site for higher Al{sup 3+} content. • Reduction in Ms, Tc, and hyperfine field with increasing Al{sup 3+} content. • Size dependent variation in coercivity. • Changes in isomer shift due to competing effect of volume and substitution. - Abstract: Nanostructured Al{sup 3+} doped Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4} (x = 0.0, 0.2, 0.4,more » 0.6, 0.8, and 1.0) ferrites were synthesized via the wet chemical method. X-ray diffraction, transmission electron microscopy, and magnetization measurements have been used to investigate the structural and magnetic properties of spinel ferrites calcined at 950 °C. With the doping of Al{sup 3+}, the particle size of Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4} first increased to 47 nm at x = 0.4 and then decreased down to 37 nm at x = 1. The main two absorption bands in IR spectra were observed around 600 cm{sup −1} and 400 cm{sup −1} corresponding to stretching vibration of tetrahedral and octahedral group Fe{sup 3+}–O{sup 2−}. Saturation magnetization and hyperfine field values decreased linearly with Al{sup 3+} due to magnetic dilution and the relative strengths of Fe–O–Me (Me = Fe, Ni, Zn, and Al) superexchanges. The coercive field showed an inverse dependence on ferrite particle size with minimum value of 82 Oe for x = 0.4. A continuous drop in Curie temperature was observed with the Al{sup 3+} substitution. From the Moessbauer spectral analysis and X-ray diffraction analysis, it is deduced that Al{sup 3+} for x < 0.4 has no obvious preference for either tetrahedral or octahedral site but has a greater preference for the B site for x > 0.4. In nutshell the study presents detailed structural and magnetic, and Moessbauer analysis of Ni{sub 0.75}Zn{sub 0.25}Fe{sub 2−x}Al{sub x}O{sub 4} ferrites.« less

A single dopant atom in silicon sees the light

NASA Astrophysics Data System (ADS)

Rogge, Sven

2014-03-01

Optical access to a single qubit is very attractive since it allows for readout with unprecedented high spectral resolution and long distance coupling. Substantial progress has been demonstrated for nitrogen-vacancy centers in diamond (Bernien, Nature, 2013). Optical access to qubits in silicon been an important goal but has to date only been achieved in the ensemble limit (Steger, Science, 2012). Here, we present the photoionization of an individual erbium dopant in silicon (Yin, Nature, 2013). A single-electron transistor is used as a single-shot charge detector to observe the resonant ionization of a single atom as a function of photon energy. This allows for optical addressing and electrical detection of individual erbium dopants with exceptionally narrow line width. The hyperfine coupling is clearly resolved which paves the way to single shot readout of the nuclear spin. This hybrid approach is a first step towards an optical interface to dopants in silicon. in collaboration with Chunming Yin, Milos Rancic, Gabriele G. de Boo, Nikolas Stavrias, Jeffrey C. McCallum, Matthew J. Sellars.

Effect of ionophores on the rate of intramolecular cation exchange in durosemiquinone ion pairs

NASA Technical Reports Server (NTRS)

Eastman, M. P.; Bruno, G. V.; Mcguyer, C. A.; Gutierrez, A. R.; Shannon, J. M.

1979-01-01

The effects of the ionophores 15-crown-5 (15C5), 18-crown-6 (18C6), dibenzo-18-crown-6 (DBC) and cryptand 222 (C222) on intramolecular cation exchange in ion pairs of the sodium salt of the durosemiquinone anion in benzene solution are investigated. Electron paramagnetic resonance spectra of the 18C6 and 15C5 complexes with durosemiquinone reduced by contact with a sodium mirror show an alternating line width which indicates that the sodium ion is being exchanged between equivalent sites near the oxygens of the semiquinone with activation energies of 8.7 and 6.0 kcal/mole and Arrhenius preexponential factors of 9 x 10 to the 12th/sec and 10 to the 12th/sec, respectively. Spectra obtained for the DBC complexes show no evidence of exchange, while those of C222 indicate rapid exchange. It is also noted that the hyperfine splitting constants measured do not change over the 50-K temperature interval studied.

Performance of a GaAlAs laser diode stabilized on a hyperfine component of two-photon transitions in rubidium at 778 nm

NASA Astrophysics Data System (ADS)

Felder, Raymond; Touahri, D.; Acef, Ouali; Hilico, L.; Zondy, Jean-Jacques; Clairon, Andre; de Beauvoir, Beatrice; Biraben, Francois; Julien, Lucile; Nez, Francois; Millerioux, Yves P.

1995-04-01

The absolute frequency measurement of each hyperfine component of the 5S3/2 and 5S5/2 levels in rubidium was done at ENS more than one year ago using Ti-Sa lasers. We built two devices based on diode lasers to study some metrological properties. We measure the frequency differences between hyperfine components of the 5S5/2 level and we calculate the corresponding hyperfine constants. We also measure the frequency interval between the 5S3/2 and 5S5/2 levels using a Schottky diode. The measured stability in terms of Allan variance is 3*10-13t-1/2 up to 2000 s. The light shift is investigated and the difference between our two systems is 1.7 kHz. The repeatability of one system is better than 10-12 and will allow the absolute frequency measurement at this level via the LPTF frequency synthesis chain.

The optical pumping of alkali atoms using coherent radiation from semi-conductor injection lasers and incoherent radiation from resonance lamps

NASA Technical Reports Server (NTRS)

Singh, G.

1973-01-01

An experimental study for creating population differences in the ground states of alkali atoms (Cesium 133) is presented. Studies made on GaAs-junction lasers and the achievement of population inversions among the hyperfine levels in the ground state of Cs 133 by optically pumping it with radiation from a GaAs diode laser. Laser output was used to monitor the populations in the ground state hyperfine levels as well as to perform the hyperfine pumping. A GaAs laser operated at about 77 K was used to scan the 8521 A line of Cs 133. Experiments were performed both with neon-filled and with paraflint-coated cells containing the cesium vapor. Investigations were also made for the development of the triple resonance coherent pulse technique and for the detection of microwave induced hyperfine trasistions by destroying the phase relationships produced by a radio frequency pulse. A pulsed cesium resonance lamp developed, and the lamp showed clean and reproducible switching characteristics.

Influence of Fe-substitution on structural, magnetic and magnetocaloric properties of Nd2Fe17-xCox solid solutions

NASA Astrophysics Data System (ADS)

Bouchaala, N.; Jemmali, M.; Bartoli, T.; Nouri, K.; Hentech, I.; Walha, S.; Bessais, L.; Salah, A. Ben

2018-02-01

Nd2Fe17-xCox (x = 0 , 1 , 2 , 3 , 4) intermetallic compounds, obtained under arc-melting conditions, have been investigated by means of X-ray diffraction analysis (XRD), Mössbauer spectrometry and magnetic measurements. The Rietveld refinement revealed that the sample is a pure compound with rhombohedral Th2Zn17-type structure (R 3 bar m space group) with the following lattice parameters: a = 8.5792 (2) Å, c = 12.4615 (2) Å. Using Mössbauer spectrometry analysis coupled with structural consideration we have unambiguously determined the cobalt atoms preferred inequivalent crystallographic site. Nd2Fe17 show an increase of 3.5 T in their weighted average hyperfine fields upon cobalt substitution. Whatever the cobalt content, the hyperfine field of these compounds follow this sequence Hhf { 6 c } >Hhf { 9 d } >Hhf { 18 f } >Hhf { 18 h }. The magnetic measurements showed that the Curie temperature increases with the Co content. The magnetic entropy change (ΔSM) was estimated from isothermal magnetization curves and it increases from 3.35 J/Kg K for x = 0 to 5.83 J/Kg K for x = 2 at μ0 H = 1.6 T . The relative cooling power (RCP) is in the range of 11.6 J/kg (x = 0) and 16 J/kg (x = 2).

Electronic and Magnetic Structures, Magnetic Hyperfine Fields and Electric Field Gradients in UX3 (X = In, Tl, Pb) Intermetallic Compounds

NASA Astrophysics Data System (ADS)

Khan, Sajid; Yazdani-Kachoei, Majid; Jalali-Asadabadi, Saeid; Farooq, Muhammad Bilal; Ahmad, Iftikhar

2018-02-01

Cubic uranium compounds such as UX3 (X is a non-transition element of groups IIIA or IVA) exhibit highly diverse magnetic properties, including Pauli paramagnetism, spin fluctuation and anti-ferromagnetism. In the present paper, we explore the structural, electronic and magnetic properties as well as the hyperfine fields (HFFs) and electric field gradients (EFGs) with quadrupole coupling constant of UX3 (X = In, Tl, Pb) compounds using local density approximation, Perdew-Burke-Ernzerhof parametrization of generalized gradient approximation (PBE-GGA) including the Hubbard U parameter (GGA + U), a revised version of PBE-GGA that improves equilibrium properties of densely packed solids and their surfaces (PBEsol-GGA), and a hybrid functional (HF-PBEsol). The spin orbit-coupling calculations have been added to investigate the relativistic effect of electrons in these materials. The comparison between the experimental parameters and our calculated structural parameters we confirm the consistency and effectiveness of our theoretical tools. The computed magnetic moments show that magnetic moment increases from indium to lead in the UX3 family, and all these compounds are antiferromagnetic in nature. The EFGs and HFFs, as well as the quadrupole coupling constant of UX3 (X = In, Tl, Pb), are discussed in detail. These properties primarily originate from f and p states of uranium and post-transition sites.

NMR studies of electronic structure in crystalline and amorphous Zr2PdH/x/

NASA Technical Reports Server (NTRS)

Bowman, R. C., Jr.; Johnson, W. L.; Maeland, A. J.; Rhim, W.-K.

1983-01-01

The proton Knight shifts and spin-lattice relaxation times have been measured in crystalline and amorphous Ze2PdH(x). Core polarization from the Zr d-band dominates the proton hyperfine interactions. The density of Fermi level d-electron states is reduced in the amorphous phase relative to the electron density in crystalline Zr2PdH(x).

Laser isotope separation of erbium and other isotopes

DOEpatents

Haynam, Christopher A.; Worden, Earl F.

1995-01-01

Laser isotope separation is accomplished using at least two photoionization pathways of an isotope simultaneously, where each pathway comprises two or more transition steps. This separation method has been applied to the selective photoionization of erbium isotopes, particularly for the enrichment of .sup.167 Er. The hyperfine structure of .sup.167 Er was used to find two three-step photoionization pathways having a common upper energy level.

Constraints on Exotic Spin-Dependent Interactions Between Matter and Antimatter from Antiprotonic Helium Spectroscopy

NASA Astrophysics Data System (ADS)

Ficek, Filip; Fadeev, Pavel; Flambaum, Victor V.; Jackson Kimball, Derek F.; Kozlov, Mikhail G.; Stadnik, Yevgeny V.; Budker, Dmitry

2018-05-01

Heretofore undiscovered spin-0 or spin-1 bosons can mediate exotic spin-dependent interactions between standard model particles. Here, we carry out the first search for semileptonic spin-dependent interactions between matter and antimatter. We compare theoretical calculations and spectroscopic measurements of the hyperfine structure of antiprotonic helium to constrain exotic spin- and velocity-dependent interactions between electrons and antiprotons.

Constraints on Exotic Spin-Dependent Interactions Between Matter and Antimatter from Antiprotonic Helium Spectroscopy.

PubMed

Ficek, Filip; Fadeev, Pavel; Flambaum, Victor V; Jackson Kimball, Derek F; Kozlov, Mikhail G; Stadnik, Yevgeny V; Budker, Dmitry

2018-05-04

Heretofore undiscovered spin-0 or spin-1 bosons can mediate exotic spin-dependent interactions between standard model particles. Here, we carry out the first search for semileptonic spin-dependent interactions between matter and antimatter. We compare theoretical calculations and spectroscopic measurements of the hyperfine structure of antiprotonic helium to constrain exotic spin- and velocity-dependent interactions between electrons and antiprotons.

NUCLEAR CHEMISTRY ANNUAL REPORT 1970

DOE Office of Scientific and Technical Information (OSTI.GOV)

Authors, Various

Papers are presented for the following topics: (1) Nuclear Structure and Nuclear Properties - (a) Nuclear Spectroscopy and Radioactivity; (b) Nuclear Reactions and Scattering; (c) Nuclear Theory; and (d) Fission. (2) Chemical and Atomic Physics - (a) Atomic and Molecular Spectroscopy; and (b) Hyperfine Interactions. (3) Physical, Inorganic, and Analytical Chemistry - (a) X-Ray Crystallography; (b) Physical and Inorganic Chemistry; (c) Radiation Chemistry; and (d) Chemical Engineering. (4) Instrumentation and Systems Development.

Matrix effects on copper(II)phthalocyanine complexes. A combined continuous wave and pulse EPR and DFT study.

PubMed

Finazzo, Cinzia; Calle, Carlos; Stoll, Stefan; Van Doorslaer, Sabine; Schweiger, Arthur

2006-04-28

The effect of the electron withdrawing or donating character of groups located at the periphery of the phthalocyanine ligand, as well as the influence of polar and nonpolar solvents are of importance for the redox chemistry of metal phthalocyanines. Continuous wave and pulse electron paramagnetic resonance and pulse electron nuclear double resonance spectroscopy at X- and Q-band are applied to investigate the electronic structure of the complexes Cu(II)phthalocyanine (CuPc), copper(II) 2,9,16,23-tetra-tert-butyl-29H,31H-phthalocyanine (CuPc(t)), and copper(II) 1,2,3,4,8,9,10,11,15,16,17,18,22,23,24,25-hexadecafluoro-29H,31H-phthalocyanine (CuPc(F)) in various matrices. Isotope substitutions are used to determine the g values, the copper hyperfine couplings and the hyperfine interactions with the 14N, 1H and 19F nuclei of the macrocycle and the surrounding matrix molecules. Simulations and interpretations of the spectra are shown and discussed, and a qualitative analysis of the data using previous theoretical models is given. Density functional computations facilitate the interpretation of the EPR parameters. The experimental g, copper and nitrogen hyperfine and nuclear quadrupole values are found to be sensitive to changes of the solvent and the structure of the macrocycle. To elucidate the electronic, structural and bonding properties the changes in the g principal values are related to data from UV/Vis spectroscopy and to density functional theory (DFT) computations. The analysis of the EPR data indicates that the in-plane metal-ligand sigma bonding is more covalent for CuPc(t) in toluene than in sulfuric acid. Furthermore, the out-of-plane pi bonding is found to be less covalent in the case of a polar sulfuric acid environment than with nonpolar toluene or H2Pc environment, whereby the covalency of this bonding is increased upon addition of tert-butyl groups. No contribution from in-plane pi bonding is found.

Development of a sensitive setup for laser spectroscopy studies of very exotic calcium isotopes

NASA Astrophysics Data System (ADS)

Garcia Ruiz, R. F.; Gorges, C.; Bissell, M.; Blaum, K.; Gins, W.; Heylen, H.; Koenig, K.; Kaufmann, S.; Kowalska, M.; Krämer, J.; Lievens, P.; Malbrunot-Ettenauer, S.; Neugart, R.; Neyens, G.; Nörtershäuser, W.; Yordanov, D. T.; Yang, X. F.

2017-04-01

An experimental setup for sensitive high-resolution measurements of hyperfine structure spectra of exotic calcium isotopes has been developed and commissioned at the COLLAPS beam line at ISOLDE, CERN. The technique is based on the radioactive detection of decaying isotopes after optical pumping and state selective neutralization (ROC) (Vermeeren et al 1992 Phys. Rev. Lett. 68 1679). The improvements and developments necessary to extend the applicability of the experimental technique to calcium isotopes produced at rates as low as few ions s-1 are discussed. Numerical calculations of laser-ion interaction and ion-beam simulations were explored to obtain the optimum performance of the experimental setup. Among the implemented features are a multi-step optical pumping region for sensitive measurements of isotopes with hyperfine splitting, a high-voltage platform for adequate control of low-energy ion beams and simultaneous β-detection of neutralized and remaining ions. The commissioning of the experimental setup, and the first online results on neutron-rich calcium isotopes are presented.

Calculating hyperfine couplings in large ionic crystals containing hundreds of QM atoms: subsystem DFT is the key.

PubMed

Kevorkyants, Ruslan; Wang, Xiqiao; Close, David M; Pavanello, Michele

2013-11-14

We present an application of the linear scaling frozen density embedding (FDE) formulation of subsystem DFT to the calculation of isotropic hyperfine coupling constants (hfcc's) of atoms belonging to a guanine radical cation embedded in a guanine hydrochloride monohydrate crystal. The model systems range from an isolated guanine to a 15,000 atom QM/MM cluster where the QM region is comprised of 36 protonated guanine cations, 36 chlorine anions, and 42 water molecules. Our calculations show that the embedding effects of the surrounding crystal cannot be reproduced by small model systems nor by a pure QM/MM procedure. Instead, a large QM region is needed to fully capture the complicated nature of the embedding effects in this system. The unprecedented system size for a relativistic all-electron isotropic hfcc calculation can be approached in this work because the local nature of the electronic structure of the organic crystals considered is fully captured by the FDE approach.

High-Resolution Rotational Spectrum, Dunham Coefficients, and Potential Energy Function of NaCl.

PubMed

Cabezas, C; Cernicharo, J; Quintana-Lacaci, G; Peña, I; Agundez, M; Prieto, L Velilla; Castro-Carrizo, A; Zuñiga, J; Bastida, A; Alonso, J L; Requena, A

2016-07-13

We report laboratory spectroscopy for the first time of the J = 1-0 and J = 2-1 lines of Na 35 Cl and Na 37 Cl in several vibrational states. The hyperfine structure has been resolved in both transitions for all vibrational levels, which permit us to predict with high accuracy the hyperfine splitting of the rotational transitions of the two isotopologues at higher frequencies. The new data have been merged with all previous works at microwave, millimeter, and infrared wavelengths and fitted to a series of mass-independent Dunham parameters and to a potential energy function. The obtained parameters have been used to compute a new dipole moment function, from which the dipole moment for infrared transitions up to Δ v = 8 has been derived. Frequency and intensity predictions are provided for all rovibrational transitions up to J = 150 and v = 8, from which the ALMA data of evolved stars can be modeled and interpreted.

Crack width monitoring of concrete structures based on smart film

NASA Astrophysics Data System (ADS)

Zhang, Benniu; Wang, Shuliang; Li, Xingxing; Zhang, Xu; Yang, Guang; Qiu, Minfeng

2014-04-01

Due to its direct link to structural security, crack width is thought to be one of the most important parameters reflecting damage conditions of concrete structures. However, the width problem is difficult to solve with the existing structural health monitoring methods. In this paper, crack width monitoring by means of adhering enameled copper wires with different ultimate strains on the surface of structures is proposed, based on smart film crack monitoring put forward by the present authors. The basic idea of the proposed method is related to a proportional relationship between the crack width and ultimate strain of the broken wire. Namely, when a certain width of crack passes through the wire, some low ultimate strain wires will be broken and higher ultimate strain wires may stay non-broken until the crack extends to a larger scale. Detection of the copper wire condition as broken or non-broken may indicate the width of the structural crack. Thereafter, a multi-layered stress transfer model and specimen experiment are performed to quantify the relationship. A practical smart film is then redesigned with this idea and applied to Chongqing Jiangjin Yangtze River Bridge.

High-resolution laser spectroscopy between 0.9 and 14.3 THz in a supersonic beam: Rydberg-Rydberg transitions of atomic Xe at intermediate n values

DOE Office of Scientific and Technical Information (OSTI.GOV)

Haase, Christa; Agner, Josef A.; Merkt, Frederic

2013-06-28

A laser-based, pulsed, narrow-band source of submillimeter-wave radiation has been developed that is continuously tunable from 0.1 THz to 14.3 THz. The source is based on difference-frequency mixing in the nonlinear crystal trans-4{sup Prime }-(dimethylamino)-N-methyl-4-stilbazolium tosylate. By varying the pulse length, the bandwidth of the submillimeter-wave radiation can be adjusted between 85 MHz and 2.8 MHz. This new radiation source has been integrated in a vacuum-ultraviolet-submillimeter-ware double-resonance spectrometer, with which low-frequency transitions of atoms and molecules in supersonic beams can be detected mass-selectively by photoionization and time-of-flight mass spectrometry. The properties of the radiation source and spectrometer are demonstrated inmore » a study of 33f Leftwards-Arrow nd Rydberg-Rydberg transitions in Xe with n in the range 16-31. The frequency calibration of the submillimeter-wave radiation was performed with an accuracy of 2.8 MHz. The narrowest lines observed experimentally have a full-width at half-maximum of {approx}3 MHz, which is sufficient to fully resolve the hyperfine structure of the Rydberg-Rydberg transitions of {sup 129}Xe and {sup 131}Xe. A total of 72 transitions were measured in the range between 0.937 THz and 14.245 THz and their frequencies are compared with frequencies calculated by multichannel quantum defect theory.« less

Selective Reflection of Potassium Vapor Nanolayers in a Magnetic Field

NASA Astrophysics Data System (ADS)

Sargsyan, A.; Tonoyan, A.; Keaveney, J.; Hughes, I. G.; Adams, C. S.; Sarkisyan, D.

2018-03-01

The selective reflection of laser radiation from the interface between a dielectric window and the atomic vapors confined in a nanocell of thickness L ≈ 350 nm is used to develop effective Doppler-broadening- free spectroscopy of potassium atoms. A small atomic line width and a relation between the signal intensity and the transition probability allowed us to resolve four lines of atomic transitions responsible for the D1 lines of the 39K and 41K isotopes. Two groups containing four atomic transitions form in an applied magnetic field upon pumping by radiation with circular polarization σ+ or σ-. Different intensities (probabilities) of transitions for the σ+ and σ- excitations are detected in magnetic field B 0 ≈ A hfs /μB ≈ 165 G ( A hfs is the magnetic dipole constant for the ground state and μB is the Bohr magneton). A substantially different situation is observed at B ≫ B 0, since high symmetry appears for the two groups formed by radiation with circular polarization σ+ or σ-. Each group is the mirror image of the other group with respect to the frequency of the 42 S 1/2-42 P 1/2 transition, which additionally proves the occurrence of the complete Paschen-Back regime of the hyperfine structure at B ≈ 2.5 kG. A developed theoretical model well reproduces the experimental results. Possible practical applications are described. The results obtained can also be applied to the D 1 lines of 87Rb and 23Na.

Resolving the limitations of using glycine as EPR dosimeter in the intermediate level of gamma dose

NASA Astrophysics Data System (ADS)

Aboelezz, E.; Hassan, G. M.

2018-04-01

The dosimetric properties of the simplest amino acid "glycine"- using EPR technique- were investigated in comparison to reference standard alanine dosimeter. The EPR spectrum of glycine at room temperature is complex, but immediately after irradiation, it appears as a triplet hyperfine structure probably due to the dominant contribution of the (•CH2COO-) radical. The dosimetric peak of glycine is at g-factor 2.0026 ± 0.0015 and its line width is 9 G at large modulation amplitude (7 G). The optimum microwave was studied and was found to be as alanine 8 mW; the post-irradiation as well as the dose rate effects were discussed. Dosimetric peak intensity of glycine fades rapidly to be about one quarter of its original value during 20 days for dried samples and it stabilizes after that. The dose response study in an intermediate range (2-1000 Gy) reveals that the glycine SNR is about 2 times more than that of alanine pellets when measured immediately after irradiation and 4 times more than that of glycine itself after 22 days of irradiation. The effect of energy dependence was studied and interpreted theoretically by calculation of mass energy absorption coefficient. The calculated combined uncertainties for glycine and alanine are nearly the same and were found to be 2.42% and 2.33%, respectively. Glycine shows interesting dosimetric properties in the range of ionizing radiation doses investigated.

Magnetism and Hyperfine Parameters in Iron Rich Gd_2Fe_{17-x}Si_x Intermetallics

NASA Astrophysics Data System (ADS)

Nouri, K.; Bartoli, T.; Chrobak, A.; Moscovici, J.; Bessais, L.

2018-04-01

Gd_2Fe_{17-x}Si_x (x = 0.25 , 0.5 and 1) samples were synthesized by arc melting and annealed at 1073 K for 1 week. X-ray diffraction analysis by the Rietveld method has shown that these materials crystallize in the rhombohedral Th_2Zn_{17} -type structure (space group R\\bar{3}m ). The Curie temperature increases with Si content x, whereas the unit-cell parameters decrease slightly. The temperature dependence of magnetization data revealed that Gd_2Fe_{17-x}Si_x exhibits a second-order ferromagnetic to paramagnetic phase transition in the vicinity of the Curie temperature. Exchange coupling parameters of R-R, M-M and R-M (R—rare earth, M—transition metal) have been determined from M(T) magnetization curves based on the mean field theory calculation. The magnetic entropy change Δ S_M and the relative cooling power were estimated from isothermal magnetization curves for all samples. In the proximity of {T}_C and in an applied field of 1.56 T, Δ S_M reached a maximum values of 1.38, 1.67 and 3.07 J/kg K for x = 0.25, 0.5 and 1, respectively. We have calculated the magnetic moment per Fe atom from magnetization measurements at 293 K up to 17 kOe, and it decreases with Si content. These results are verified by the Mössbauer spectrometry measurements obtained at the same temperature. The Mössbauer spectra analysis is based on the correlation between the Wigner-Seitz volume and the isomer-shift evolution of each specific site 6c, 9d, 18f, and 18h of the R\\bar{3} m structure. For all Si concentrations, the magnitude of the hyperfine fields are {H_HF}{6c} > {H_HF}{9d} > {H_HF}{18f} > {H_HF}{18h} . The mean hyperfine field decreases with the Si content.

Magnetism and Hyperfine Parameters in Iron Rich Gd_2Fe_{17-x}Si_x Intermetallics

NASA Astrophysics Data System (ADS)

Nouri, K.; Bartoli, T.; Chrobak, A.; Moscovici, J.; Bessais, L.

2018-07-01

Gd_2Fe_{17-x}Si_x (x = 0.25, 0.5 and 1) samples were synthesized by arc melting and annealed at 1073 K for 1 week. X-ray diffraction analysis by the Rietveld method has shown that these materials crystallize in the rhombohedral Th_2Zn_{17}-type structure (space group R\\bar{3}m). The Curie temperature increases with Si content x, whereas the unit-cell parameters decrease slightly. The temperature dependence of magnetization data revealed that Gd_2Fe_{17-x}Si_x exhibits a second-order ferromagnetic to paramagnetic phase transition in the vicinity of the Curie temperature. Exchange coupling parameters of R- R, M- M and R- M ( R—rare earth, M—transition metal) have been determined from M( T) magnetization curves based on the mean field theory calculation. The magnetic entropy change Δ S_M and the relative cooling power were estimated from isothermal magnetization curves for all samples. In the proximity of {T}_C and in an applied field of 1.56 T, Δ S_M reached a maximum values of 1.38, 1.67 and 3.07 J/kg K for x = 0.25, 0.5 and 1, respectively. We have calculated the magnetic moment per Fe atom from magnetization measurements at 293 K up to 17 kOe, and it decreases with Si content. These results are verified by the Mössbauer spectrometry measurements obtained at the same temperature. The Mössbauer spectra analysis is based on the correlation between the Wigner-Seitz volume and the isomer-shift evolution of each specific site 6 c, 9 d, 18 f, and 18 h of the R\\bar{3}m structure. For all Si concentrations, the magnitude of the hyperfine fields are {H_HF}{6c} > {H_HF}{9d} > {H_HF}{18f} > {H_HF}{18h}. The mean hyperfine field decreases with the Si content.

Synthesis, X-ray structure, magnetic resonance, and DFT analysis of a soluble copper(II) phthalocyanine lacking C-H bonds.

PubMed

Moons, Hans; Łapok, Łukasz; Loas, Andrei; Van Doorslaer, Sabine; Gorun, Sergiu M

2010-10-04

The synthesis, crystal structure, and electronic properties of perfluoro-isopropyl-substituted perfluorophthalocyanine bearing a copper atom in the central cavity (F(64)PcCu) are reported. While most halogenated phthalocyanines do not exhibit long-term order sufficient to form large single crystals, this is not the case for F(64)PcCu. Its crystal structure was determined by X-ray analysis and linked to the electronic properties determined by electron paramagnetic resonance (EPR). The findings are corroborated by density functional theory (DFT) computations, which agree well with the experiment. X-band continuous-wave EPR spectra of undiluted F(64)PcCu powder, indicate the existence of isolated metal centers. The electron-withdrawing effect of the perfluoroalkyl (R(f)) groups significantly enhances the complexes solubility in organic solvents like alcohols, including via their axial coordination. This coordination is confirmed by X-band (1)H HYSCORE experiments and is also seen in the solid state via the X-ray structure. Detailed X-band CW-EPR, X-band Davies and Mims ENDOR, and W-band electron spin-echo-detected EPR studies of F(64)PcCu in ethanol allow the determination of the principal g values and the hyperfine couplings of the metal, nitrogen, and fluorine nuclei. Comparison of the g and metal hyperfine values of F(64)PcCu and other PcCu complexes in different matrices reveals a dominant effect of the matrix on these EPR parameters, while variations in the ring substituents have only a secondary effect. The relatively strong axial coordination occurs despite the diminished covalency of the C-N bonds and potentially weakening Jahn-Teller effects. Surprisingly, natural abundance (13)C HYSCORE signals could be observed for a frozen ethanol solution of F(64)PcCu. The (13)C nuclei contributing to the HYSCORE spectra could be identified as the pyrrole carbons by means of DFT. Finally, (19)F ENDOR and easily observable paramagnetic NMR were found to relate well to the DFT computations, revealing negligible isotropic hyperfine (Fermi contact) contributions. The single-site isolation in solution and solid state and the relatively strong coordination of axial ligands, both attributed to the introduction of R(f) groups, are features important for materials and catalyst design.

Hyperfine-Structure-Induced Depolarization of Impulsively Aligned I2 Molecules

NASA Astrophysics Data System (ADS)

Thomas, Esben F.; Søndergaard, Anders A.; Shepperson, Benjamin; Henriksen, Niels E.; Stapelfeldt, Henrik

2018-04-01

A moderately intense 450 fs laser pulse is used to create rotational wave packets in gas phase I2 molecules. The ensuing time-dependent alignment, measured by Coulomb explosion imaging with a delayed probe pulse, exhibits the characteristic revival structures expected for rotational wave packets but also a complex nonperiodic substructure and decreasing mean alignment not observed before. A quantum mechanical model attributes the phenomena to coupling between the rotational angular momenta and the nuclear spins through the electric quadrupole interaction. The calculated alignment trace agrees very well with the experimental results.

New Tests for Variations of the Fine Structure Constant

NASA Technical Reports Server (NTRS)

Prestage, John D.

1995-01-01

We describe a new test for possible variations of the fine structure constant, by comparisons of rates between clocks based on hyperfine transitions in alkali atomos with different atomic number Z. H- maser, Cs and Hg+ clocks have a different dependence on ia relativistic contributions of order (Z. Recent H-maser vs Hg+ clock comparison data improves laboratory limits on a time variation by 100-fold to giveFuture laser cooled clocks (Be+, Rb, Cs, Hg+, etc.), when compared, will yield the most senstive of all tests for.

Investigation of Rubidium Hyperfine Structure Frequency Stabilization Mechanisms.

DTIC Science & Technology

1984-08-01

Frueholtz, and C. H. Volk, Phys. Rev. A 27, 1914 (1983). 4. C. Cohen-Tannoudji, Metrologia 13, 161 (1977). 5. W. Happer, and A. C. Tam, Phys. Rev. A 16, 1877...w U C) ED W mF w c M0 -0 Dm U(i2 DOW V) ZivF 00. LA *I U-(JL OLLIAJ - (I 0 7 a I I ~w..-..- ~ * * ~ -~.’,** ~-, .*h4w.’.-* .- ,-~-. . .- * 8

Laser isotope separation of erbium and other isotopes

DOEpatents

Haynam, C.A.; Worden, E.F.

1995-08-22

Laser isotope separation is accomplished using at least two photoionization pathways of an isotope simultaneously, where each pathway comprises two or more transition steps. This separation method has been applied to the selective photoionization of erbium isotopes, particularly for the enrichment of {sup 167}Er. The hyperfine structure of {sup 167}Er was used to find two three-step photoionization pathways having a common upper energy level. 3 figs.

Abundances of Copper and Zinc in Stars of the Galactic Thin and Thick Disks

NASA Astrophysics Data System (ADS)

Gorbaneva, T. I.; Mishenina, T. V.; Basak, N. Yu.; Soubiran, C.; Kovtyukh, V. V.

The spectra of studied stars were obtained with the ELODIE spectrograph at the 1.93-m telescope of the Observatoire de Haute Provence (France). The determination of Cu and Zn abundances was carried out in LTE assumption by model atmosphere method, for Cu the hyperfine structure was taken into account. Cu and Zn abundance trends for thin and thick disk's stars are presented.

Modification of structural and magnetic properties of soft magnetic multi-component metallic glass by 80 MeV 16O6+ ion irradiation

NASA Astrophysics Data System (ADS)

Kane, S. N.; Shah, M.; Satalkar, M.; Gehlot, K.; Kulriya, P. K.; Avasthi, D. K.; Sinha, A. K.; Modak, S. S.; Ghodke, N. L.; Reddy, V. R.; Varga, L. K.

2016-07-01

Effect of 80 MeV 16O6+ ion irradiation in amorphous Fe77P8Si3C5Al2Ga1B4 alloy is reported. Electronic energy loss induced modifications in the structural and, magnetic properties were monitored by synchrotron X-ray diffraction (SXRD), Mössbauer and, magnetic measurements. Broad amorphous hump seen in SXRD patterns reveals the amorphous nature of the studied specimens. Mössbauer measurements suggest that: (a) alignment of atomic spins within ribbon plane, (b) changes in average hyperfine field suggests radiation-induced decrease in the inter atomic distance around Mössbauer (Fe) atom, (c) hyperfine field distribution confirms the presence of non-magnetic elements (e.g. - B, P, C) in the first near-neighbor shell of the Fe atom, thus reducing its magnetic moment, and (d) changes in isomer shift suggests variation in average number of the metalloid near neighbors and their distances. Minor changes in soft magnetic behavior - watt loss and, coercivity after an irradiation dose of 2 × 1013 ions/cm2 suggests prospective application of Fe77P8Si3C5Al2Ga1B4 alloy as core material in accelerators (radio frequency cavities).

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.

Whither HFI/NQI?

NASA Astrophysics Data System (ADS)

Bharuth-Ram, K.

2013-05-01

A brief review is given of the Hyperfine Interactions Conference series and, in particular, of the Joint meetings of the Hyperfine Interactions and Nuclear Quadrupole Interaction (HFI/NQI) Conferences, with respect to number of participants, contributed papers and participant countries. Trends are traced and recommendations are offered to attract a wider participation at future HFI/NQI conferences.

New Nuclear Magnetic Moment of ^{209}Bi: Resolving the Bismuth Hyperfine Puzzle.

PubMed

Skripnikov, Leonid V; Schmidt, Stefan; Ullmann, Johannes; Geppert, Christopher; Kraus, Florian; Kresse, Benjamin; Nörtershäuser, Wilfried; Privalov, Alexei F; Scheibe, Benjamin; Shabaev, Vladimir M; Vogel, Michael; Volotka, Andrey V

2018-03-02

A recent measurement of the hyperfine splitting in the ground state of Li-like ^{208}Bi^{80+} has established a "hyperfine puzzle"-the experimental result exhibits a 7σ deviation from the theoretical prediction [J. Ullmann et al., Nat. Commun. 8, 15484 (2017)NCAOBW2041-172310.1038/ncomms15484; J. P. Karr, Nat. Phys. 13, 533 (2017)NPAHAX1745-247310.1038/nphys4159]. We provide evidence that the discrepancy is caused by an inaccurate value of the tabulated nuclear magnetic moment (μ_{I}) of ^{209}Bi. We perform relativistic density functional theory and relativistic coupled cluster calculations of the shielding constant that should be used to extract the value of μ_{I}(^{209}Bi) and combine it with nuclear magnetic resonance measurements of Bi(NO_{3})_{3} in nitric acid solutions and of the hexafluoridobismuthate(V) BiF_{6}^{-} ion in acetonitrile. The result clearly reveals that μ_{I}(^{209}Bi) is much smaller than the tabulated value used previously. Applying the new magnetic moment shifts the theoretical prediction into agreement with experiment and resolves the hyperfine puzzle.

New Nuclear Magnetic Moment of 209Bi: Resolving the Bismuth Hyperfine Puzzle

NASA Astrophysics Data System (ADS)

Skripnikov, Leonid V.; Schmidt, Stefan; Ullmann, Johannes; Geppert, Christopher; Kraus, Florian; Kresse, Benjamin; Nörtershäuser, Wilfried; Privalov, Alexei F.; Scheibe, Benjamin; Shabaev, Vladimir M.; Vogel, Michael; Volotka, Andrey V.

2018-03-01

A recent measurement of the hyperfine splitting in the ground state of Li-like 80+208Bi has established a "hyperfine puzzle"—the experimental result exhibits a 7 σ deviation from the theoretical prediction [J. Ullmann et al., Nat. Commun. 8, 15484 (2017), 10.1038/ncomms15484; J. P. Karr, Nat. Phys. 13, 533 (2017), 10.1038/nphys4159]. We provide evidence that the discrepancy is caused by an inaccurate value of the tabulated nuclear magnetic moment (μI) of 209Bi. We perform relativistic density functional theory and relativistic coupled cluster calculations of the shielding constant that should be used to extract the value of μI(209ipts>) and combine it with nuclear magnetic resonance measurements of Bi (NO3 )3 in nitric acid solutions and of the hexafluoridobismuthate(V) BiF6- ion in acetonitrile. The result clearly reveals that μI(209Bi) is much smaller than the tabulated value used previously. Applying the new magnetic moment shifts the theoretical prediction into agreement with experiment and resolves the hyperfine puzzle.

ENDOR/ESR of Mn atoms and MnH molecules in solid argon

NASA Astrophysics Data System (ADS)

van Zee, R. J.; Garland, D. A.; Weltner, W., Jr.

1986-09-01

Mn atoms and MnH molecules, the latter formed by reaction between metal and hydrogen atoms, were trapped in solid argon and their ESR/ENDOR spectra measured at 4 K. At each pumping magnetic field two ENDOR lines were observed for 55Mn(I=5/2) atoms, corresponding to hyperfine transitions within the MS =±1/2 levels. Values of the hyperfine interaction constant and nuclear moment of 55Mn were derived from the six sets of data. For MnH, three sets of signals were detected: a proton ``matrix ENDOR'' line, transitions in the MS =0,±1 levels involving MI (55Mn)=1/2, 3/2, 5/2 levels, and proton transitions corresponding to νH and νH±aH. Analysis yielded the hyperfine constant aH =6.8(1) MHz and the nuclear quadrupole coupling constant Q'(55Mn)=-11.81(2) MHz. The latter compared favorably with a theoretical value derived earlier by Bagus and Schaefer. A higher term in the spin Hamiltonian appeared to be necessary to fit the proton hyperfine data.

Determining the Topology of Integral Membrane Peptides Using EPR Spectroscopy

PubMed Central

Inbaraj, Johnson J.; Cardon, Thomas B.; Laryukhin, Mikhail; Grosser, Stuart M.

2008-01-01

This paper reports on the development of a new structural biology technique for determining the membrane topology of an integral membrane protein inserted into magnetically aligned phospholipid bilayers (bicelles) using EPR spectroscopy. The nitroxide spin probe, 2,2,6,6-tetramethylpiperidine-1-oxyl-4-amino-4-carboxylic acid (TOAC) was attached to the pore-lining transmembrane domain (M2δ) of the nicotinic acetylcholine receptor (AChR) and incorporated into a bicelle. The corresponding EPR spectra revealed hyperfine splittings that were highly dependent on the macroscopic orientation of the bicelles with respect to the static magnetic field. The helical tilt of the peptide can be easily calculated using the hyperfine splittings gleaned from the orientational dependent EPR spectra. A helical tilt of 14° was calculated for the M2δ peptide with respect to the bilayer normal of the membrane, which agrees well with previous 15N solid-state NMR studies. The helical tilt of the peptide was verified by simulating the corresponding EPR spectra using the standardized MOMD approach. This new method is advantageous because: (1) bicelle samples are easy to prepare, (2) the helical tilt can be directly calculated from the orientational-dependent hyperfine splitting in the EPR spectra, and (3) EPR spectroscopy is approximately 1000 fold more sensitive than 15N solid-state NMR spectroscopy; thus, the helical tilt of an integral membrane peptide can be determined with only 100 μg of peptide. The helical tilt can be determined more accurately by placing TOAC spin labels at several positions with this technique. PMID:16848493

Research on Spectroscopy, Opacity, and Atmospheres

NASA Astrophysics Data System (ADS)

Kurucz, Robert L.; Bell, Barbara

1996-01-01

This line list is a replacement for the Kurucz-Peytremann line list. We have combined all the atomic files from CDROM 18 into 534910 line files GFALL.DAT and GFELEM.DAT. These are the data we actually use to compute spectra. They are not up to date. References are given in GFALL.REF or GFELEN.REF. There are no references after 1988. For light elements there are no references after 1979. We have the literature into the 1990's but have not had manpower or funding to update everything. Our current plan is to make a new semiempirical calculation for each species and at that time to include all the data from the literature. One new development is the inclusion of hyperfine splitting for the iron group elements using hyperfine data from the literature through 1993. The data are very incomplete. We have not yet included data for isotopic splitting. We supply a program for splitting the line list for a species. It reads the hyperfine and isotopic splitting parameters for levels and computes the oplittings whenever those levels appear. Lines with no splitting data are copied untouched. Because Sc, Mn, and Co are monoisotopic, only the hyperfine splittings are needed. Since 51V is much more abundant than S0V, the isotope shifts are small for 51V, and we approximate V with 51V. GFALLKYP.DAT has 754946 lines including hyperfine Sc(I), V(I), Mn(I), and Co(I). A bibliography for last year (1994-1995) is also attached.

Hyperfine quenching of the 2s2 2p5 3 s3P2 state of Ne-like ions

NASA Astrophysics Data System (ADS)

Safronova, U. I.; Stafford, A.; Safronova, A. S.

2017-04-01

The many-body perturbation theory (RMBPT) is used to calculate energies and multipole matrix elements to evaluate hyperfine quenching of the 2s2 2p5 3 s 3P2 state in Ne-like ions. In particular, the 3P2 excited state decays to the 1S0 ground state by M2 emission, while both 1P1 and 3P1 states decay to the ground-state by E1 emission, which is substantially faster. For odd-A nuclei, the hyperfine interaction induces admixtures of 3P1 and 1P1 states into the 3P2 state, resulting in an increase of the 3P2 transition rate and a corresponding reduction of the 3P2 lifetime. We consider 22 Ne like ions with Z = 14 - 94 and nuclear moment I =1/2. We found that the largess hyperfine quenching contribution by a factor of 2 are for Ne-like 31P and 203Tl. The smallest (less than 1%) induced contribution are the following Ne-like ions: 57Fe, 107Ag, 109Ag, 183W, and 187Os ions. For another 15 Ne-like ions the hyperfine quenching contribution is between 15% and 35%. Applications to x-ray line polarization of Ne-like lines is considered. This work is supported by the Department of Energy, National Nuclear Security Administration, under Award Number DE-NA0002954.

Electronic structure and magnetic properties of disordered Co{sub 2}FeAl Heusler alloy

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jain, Vishal, E-mail: vjain045@gmail.com; Jain, Vivek, E-mail: vjain045@gmail.com; Sudheesh, V. D., E-mail: vjain045@gmail.com

The effects of disorder on the magnetic properties of Co{sub 2}FeAl alloy are reported. X-ray diffraction exhibit A2-type disordered structure. Room temperature Mössbauer studies show the presence of two sextets with hyperfine field values of 31T and 30T along with a nonmagnetic singlet. The electronic structure of ordered and disordered Co{sub 2}FeAl alloys, investigated by means of the KKR Green's-function method shows that the magnetic moment of the ordered structure is 5.08μ{sub B} and is 5.10μ{sub B} when disordered. However, a much higher magnetic moment of 5.74μ{sub B} is observed experimentally.

The Structure of the Elusive Simplest Dipeptide Gly-Gly.

PubMed

Cabezas, Carlos; Varela, Marcelino; Alonso, José L

2017-06-01

Among the hundreds of peptide compounds for which conformations have been determined by using different spectroscopic techniques, the structure of the simplest dipeptide glycylglycine (Gly-Gly) is conspicuously absent. Herein, for the first time, solid samples of Gly-Gly have been vaporized by laser ablation and three different structures have been revealed in a supersonic expansion by Fourier transform microwave spectroscopy. The intramolecular hydrogen bonding interactions that stabilize the observed forms have been established based on the 14 N nuclear quadrupole hyperfine structure. We have illustrated how conformer interconversion distorts the equilibrium conformational distribution, giving rise to missing conformers in the conformational landscape. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Determination of the fine structure constant using helium fine structure.

PubMed

Smiciklas, Marc; Shiner, David

2010-09-17

We measure 31,908,131.25(30) kHz for the 2(3)}P J=0 to 2 fine structure interval in helium. The difference between this and theory to order mα7 (20 Hz numerical uncertainty) implies 0.22(30) kHz for uncalculated terms. The measurement is performed by using atomic beam and electro-optic laser techniques. Various checks include a 3He 2{3}S hyperfine measurement. We can obtain an independent value for the fine structure constant α with a 5 ppb experimental uncertainty. However, dominant mα8 terms (potentially 1.2 kHz) limit the overall uncertainty to a less competitive 20 ppb in α.

Limits on estimating the width of thin tubular structures in 3D images.

PubMed

Wörz, Stefan; Rohr, Karl

2006-01-01

This work studies limits on estimating the width of thin tubular structures in 3D images. Based on nonlinear estimation theory we analyze the minimal stochastic error of estimating the width. Given a 3D analytic model of the image intensities of tubular structures, we derive a closed-form expression for the Cramér-Rao bound of the width estimate under image noise. We use the derived lower bound as a benchmark and compare it with three previously proposed accuracy limits for vessel width estimation. Moreover, by experimental investigations we demonstrate that the derived lower bound can be achieved by fitting a 3D parametric intensity model directly to the image data.

Role of the He I and He II metastables in the resonance 2p 2P°1/2, 3/2 B III level population

NASA Astrophysics Data System (ADS)

Djeniže, S.; Srećković, A.; Bukvić, S.

2007-01-01

Aims:The aim of this work is to present atomic processes which lead to an extra population of the 2p ~^2P°1/2, 3/2 B III resonance levels in helium plasma generating intense radiation in the B III 206.578 nm and 206.723 nm lines. Methods: The line profiles were recorded using a step-by-step (7.3 pm) technique which provides monitoring of the line shapes continually during the plasma decay and gives the possibility to compare line shapes at various times in the same plasma. Results: On the basis of the line intensity decays of the doubly ionized boron resonance spectral lines in laboratory nitrogen and helium plasmas, we have found the existence of a permanent energy transfer from He I and He II metastables to the 2p ^2P°1/2, 3/2 B III resonance levels. The shapes of the mentioned lines are also observed. At electron temperatures of about 18 000 K and electron densities about 1.1× 1023 m-3, the Stark broadening was found as a main B III line broadening mechanism. The measured Stark widths (W) are compared with the Doppler width (W_D) and with the splitting in the hyperfine structure (Δ_hfs). Our measured W data are found to be much higher than results obtained by means of various theoretical approaches. Conclusions: . The He I and He II metastables over populate the B III resonance levels leading to populations higher than predicted by LTE model. Consequently, the emitted B III resonance lines are more intense than expected from LTE model. This fact can be of importance if B III resonance line intensities are used for abundance determination purposes in astrophysics. Similar behavior can be expected for some lines emitted by astrophysical interesting emitters: Al III, Si III, Sc III, Cr III, V III, Ti III, Fe III, Co III, Ni III, Ga III, Zr III, Y III, Nb III, In III, Sn III, Sb III, Au III, Pb III and Bi III in hot and dense helium plasmas.

Local magnetic moment formation at 119Sn Mössbauer impurity in RCo2 (R=Gd,Tb,Dy,Ho,Er) Laves phase compounds

NASA Astrophysics Data System (ADS)

de Oliveira, A. L.; de Oliveira, N. A.; Troper, A.

2008-04-01

In this work, we theoretically study the local magnetic moment formation and the systematics of the magnetic hyperfine fields at a Mösbauer Sn119 impurity diluted at the R site (R=Gd,Tb,Dy,Ho,Er) of the cubic Laves phase intermetallic compounds RCo2. One considers that the magnetic hyperfine fields have two contributions, (i) the contribution from R ions, calculated via an extended Daniel-Friedel [J. Phys. Chem. Solids 24, 1601 (1963)] model, and (ii) the contribution from the induced magnetic moments arising from the Co neighboring sites. Our calculated self-consistent total magnetic hyperfine fields are in a good agreement with recent experimental data.

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.

A portable version of the program of nettar and villafranca for the simulation of electron paramagnetic resonance spectra of powders

NASA Astrophysics Data System (ADS)

Soulié, Edgar; Gaugenot, Jacques

1995-04-01

Nettar and Villafranca wrote in the FORTRAN programming language a computer program which simulates the electron paramagnetic resonance (EPR) spectra of powders (Journal of Magnetic Resonance, vol. 64 (1985) pp. 61-65). The spin Hamiltonian which their program can handle includes the Zeeman electronic interaction, the fine interaction up to the sixth order in the electron spin, a general hyperfine interaction, an isotropic nuclear Zeeman term; anisotropic ligand hyperfine terms are treated to first order in perturbation. The above Hamiltonian, without the ligand hyperfine terms, is treated exactly, i.e. the resonance equation for a transition between states labeled i and j is solved numerically: h.ν=Ei(H)-Ej(H).

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

NASA Astrophysics Data System (ADS)

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

2017-06-01

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

Electron spin resonance identification di-carbon-related centers in irradiated silicon

NASA Astrophysics Data System (ADS)

Hayashi, S.; Saito, H.; Itoh, K. M.; Vlasenko, M. P.; Vlasenko, L. S.

2018-04-01

A previously unreported electron spin resonance (ESR) spectrum was found in γ-ray irradiated silicon by the detection of the change in microwave photoconductivity arising from spin-dependent recombination (SDR). In the specially prepared silicon crystals doped by 13C isotope, a well resolved hyperfine structure of SDR-ESR lines due to the interaction between electrons and two equivalent carbon atoms having nuclear spin I = 1/2 was observed. The Si-KU4 spectrum is described by spin Hamiltonian for spin S = 1 and of g and D tensors of orthorhombic symmetry with principal values g1 = 2.008, g2 = 2.002, and g3 =2.007; and D1 = ± 103 MHz, D2 = ∓170 MHz, and D3 = ± 67 MHz where axes 1, 2, and 3 are parallel to the [1 1 ¯ 0 ], [110], and [001] crystal axes, respectively. The hyperfine splitting arising from 13C nuclei is about 0.35 mT. A possible microstructure of the detect leading to the Si-KU4 spectrum is discussed.

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

PubMed

Tabrizi, Shadan Ghassemi; Pelmenschikov, Vladimir; Noodleman, Louis; Kaupp, Martin

2016-01-12

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, (57)Fe 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 (57)Fe 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.

Interface influence on the properties of Co90Fe10 films on soft magnetic underlayers - Magnetostrictive and Mössbauer spectrometry studies

NASA Astrophysics Data System (ADS)

Szumiata, Tadeusz; Gzik-Szumiata, Małgorzata; Brzózka, Katarzyna; Górka, Bogumił; Gawroński, Michał; Caruana Finkel, Anastasia; Reeves-McLaren, Nik; Morley, Nicola A.

2016-03-01

The main aim of the work was to show the correlation between magnetostrictive properties and microstructure of 25 nm thick Co90Fe10 films deposited on soft magnetic underlayers. A special attention was paid to the role of the interface region. In the case of Co90Fe10 on 25 nm and 35 nm thick METGLAS underlayers one can resolve in conversion electron Mössbauer spectra two hyperfine field distributions (high-field and medium-field ones) corresponding to both constituents of bilayers. Analogical distributions describe the spectra of Co90Fe10 on 25 nm and 35 nm thick Ni81Fe19 underlayers, however an additional low-field, smeared component has been observed. It has been attributed to the interface layer (of partially disordered structure) between magnetostrictive layer and soft magnetic layer. Such interpretation is backed up by the obtained strong correlation between mean hyperfine field value and magnetostriction constant of the films. The investigated bilayers are good candidates for MRAM devices.

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

PubMed

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

2017-06-12

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

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

PubMed Central

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

2017-01-01

Antihydrogen, the lightest atom consisting purely of antimatter, is an ideal laboratory to study the CPT symmetry by comparison with hydrogen. With respect to absolute precision, transitions within the ground-state hyperfine structure (GS-HFS) are most appealing by virtue of their small energy separation. ASACUSA proposed employing a beam of cold antihydrogen atoms in a Rabi-type experiment, to determine the GS-HFS in a field-free region. Here we present a measurement of the zero-field hydrogen GS-HFS using the spectroscopy apparatus of ASACUSA's antihydrogen experiment. The measured value of νHF=1,420,405,748.4(3.4) (1.6) Hz with a relative precision of 2.7 × 10−9 constitutes the most precise determination of this quantity in a beam and verifies the developed spectroscopy methods for the antihydrogen HFS experiment to the p.p.b. level. Together with the recently presented observation of antihydrogen atoms 2.7 m downstream of the production region, the prerequisites for a measurement with antihydrogen are now available within the ASACUSA collaboration. PMID:28604657

Integration of optically active Neodymium ions in Niobium devices (Nd:Nb): quantum memory for hybrid quantum entangled systems

NASA Astrophysics Data System (ADS)

Nayfeh, O. M.; Chao, D.; Djapic, N.; Sims, P.; Liu, B.; Sharma, S.; Lerum, L.; Fahem, M.; Dinh, V.; Zlatanovic, S.; Lynn, B.; Torres, C.; Higa, B.; Moore, J.; Upchurch, A.; Cothern, J.; Tukeman, M.; Barua, R.; Davidson, B.; Ramirez, A. D.; Rees, C. D.; Anant, V.; Kanter, G. S.

2017-08-01

Optically active rare-earth Neodymium (Nd) ions are integrated in Niobium (Nb) thin films forming a new quantum memory device (Nd:Nb) targeting long-lived coherence times and multi-functionality enabled by both spin and photon storage properties. Nb is implanted with Nd spanning 10-60 keV energy and 1013-1014 cm-2 dose producing a 1- 3% Nd:Nb concentration as confirmed by energy-dispersive X-ray spectroscopy. Scanning confocal photoluminescence (PL) at 785 nm excitation are made and sharp emission peaks from the 4F3/2 -< 4I11/2 Nd3+ transition at 1064-1070 nm are examined. In contrast, un-implanted Nb is void of any peaks. Line-shapes at room temperature are fit with Lorentzian profiles with line-widths of 4-5 nm and 1.3 THz bandwidth and the impacts of hyperfine splitting via the metallic crystal potential are apparent and the co-contribution of implant induced defects. With increasing Nd from 1% to 3%, there is a 0.3 nm red shift and increased broadening to a 4.8 nm linewidth. Nd:Nb is photoconductive and responds strongly to applied fields. Furthermore, optically detected magnetic resonance (ODMR) measurements are presented spanning near-infrared telecom band. The modulation of the emission intensity with magnetic field and microwave power by integration of these magnetic Kramer type Nd ions is quantified along with spin echoes under pulsed microwave π-π/2 excitation. A hybrid system architecture is proposed using spin and photon quantum information storage with the nuclear and electron states of the Nd3+ and neighboring Nb atoms that can couple qubit states to hyperfine 7/2 spin states of Nd:Nb and onto NIR optical levels excitable with entangled single photons, thus enabling implementation of computing and networking/internet protocols in a single platform.

Electron-Nuclear Quantum Information Processing

DTIC Science & Technology

2008-11-13

quantum information processing that exploits the anisotropic hyperfine coupling. This scheme enables universal control over a 1-electron, N-nuclear spin...exploits the anisotropic hyperfine coupling. This scheme enables universal control over a 1-electron, N-nuclear spin system, addressing only a...sample of irradiated malonic acid. (a) Papers published in peer-reviewed journals (N/A for none) Universal control of nuclear spins via anisotropic

An EPR investigation of the dynamic Jahn-Teller effect in SrCl2:y(2 plus) and SrCl2:Sc(2 plus)

NASA Technical Reports Server (NTRS)

Herrington, J. R.; Estle, T. L.; Boatner, L. A.

1972-01-01

EPR spectra have been observed for SrCl2:Y(2+) and SrCl2:Sc(2+) at liquid helium temperatures. At 1.2 K the spectra were dominated by anisotropic hyperfine patterns whose lineshapes and angular dependences were explained using second order solutions of the effective Hamiltonian for an isolated 2Eg state split by large random internal strains. Pronounced asymmetries in some of the strin produced lineshapes for Srcl2:Sc(2+) are shown to result from second order terms in the solution of the effective Hamiltonian. Coexisting with the anisotropic hyperfine patterns are weak nearly isotropic hyperfine patterns with typical lineshapes. Variations in the apparent intensity of lines in these weak hyperfine patterns as functions of the applied magnetic field direction and temperature imply that these lines result from averaging by vibronic relaxation of a portion of the anisotropic pattern. The effective Hamiltonian parameters for SrCl2:La(2+), SrCl2:y(2+), and SrCl2:SC(2+) are analyzed in terms of crystal field theory modified to include a dynamic Jahn-Teller effect.

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, and the Leverhulme Trust.[1] J. C. Pickering, F. Liggins, C. Clear, M. Ruffoni, G. Nave, C. Sansonetti (this meeting)[2] R. A. Holt, T. J. Scholl & S. D. Rosner, MNRAS 306, 107 (1999)

Fine and hyperfine collisional excitation of C6H by He

NASA Astrophysics Data System (ADS)

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

2018-01-01

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

The pure rotational spectrum of TiF (X 4Φr): 3d transition metal fluorides revisited

NASA Astrophysics Data System (ADS)

Sheridan, P. M.; McLamarrah, S. K.; Ziurys, L. M.

2003-11-01

The pure rotational spectrum of TiF in its X 4Φr (v=0) ground state has been measured using millimeter/sub-millimeter wave direct absorption techniques in the range 140-530 GHz. In ten out of the twelve rotational transitions recorded, all four spin-orbit components were observed, confirming the 4Φr ground state assignment. Additional small splittings were resolved in several of the spin components in lower J transitions, which appear to arise from magnetic hyperfine interactions of the 19F nucleus. In contrast, no evidence for Λ-doubling was seen in the data. The rotational transitions of TiF were analyzed using a case (a) Hamiltonian, resulting in the determination of rotational and fine structure constants, as well as hyperfine parameters for the fluorine nucleus. The data were readily fit in a case (a) basis, indicating strong first order spin-orbit coupling and minimal second-order effects, as also evidenced by the small value of λ, the spin-spin parameter. Moreover, only one higher order term, η, the spin-orbit/spin-spin interaction term, was needed in the analysis, again suggesting limited perturbations in the ground state. The relative values of the a, b, and c hyperfine constants indicate that the three unpaired electrons in this radical lie in orbitals primarily located on the titanium atom and support the molecular orbital picture of TiF with a σ1δ1π1 single electron configuration. The bond length of TiF (1.8342 Å) is significantly longer than that of TiO, suggesting that there are differences in the bonding between 3d transition metal fluorides and oxides.

Substrate Oxide Layer Thickness Optimization for a Dual-Width Plasmonic Grating for Surface-Enhanced Raman Spectroscopy (SERS) Biosensor Applications

PubMed Central

Bauman, Stephen J.; Brawley, Zachary T.; Darweesh, Ahmad A.; Herzog, Joseph B.

2017-01-01

This work investigates a new design for a plasmonic SERS biosensor via computational electromagnetic models. It utilizes a dual-width plasmonic grating design, which has two different metallic widths per grating period. These types of plasmonic gratings have shown larger optical enhancement than standard single-width gratings. The new structures have additional increased enhancement when the spacing between the metal decreases to sub-10 nm dimensions. This work integrates an oxide layer to improve the enhancement even further by carefully studying the effects of the substrate oxide thickness on the enhancement and reports ideal substrate parameters. The combined effects of varying the substrate and the grating geometry are studied to fully optimize the device’s enhancement for SERS biosensing and other plasmonic applications. The work reports the ideal widths and substrate thickness for both a standard and a dual-width plasmonic grating SERS biosensor. The ideal geometry, comprising a dual-width grating structure atop an optimal SiO2 layer thickness, improves the enhancement by 800%, as compared to non-optimized structures with a single-width grating and a non-optimal oxide thickness. PMID:28665308

Formation of Ni3Fe nanoparticles as studied using Mössbauer spectroscopy

NASA Astrophysics Data System (ADS)

Parvathy, N. S.; Govindaraj, R.; Vinod, K.; Amarendra, G.

2018-05-01

Nickel and iron in the ratio of 3:1 have been taken and subjected to high energy ball milling and systematic post annealing treatments to obtain Ni3Fe. Structural and bulk magnetic properties have been deduced using XRD and magnetization studies, while the results of Mössbauer studies are used to deduce distinct 57Fe sites based on the hyperfine parameters. Formation of disordered Ni3Fe has been elucidated based on this study.

Laser-sodium interaction for the polychromatic laser guide star project

NASA Astrophysics Data System (ADS)

Bellanger, Veronique; Petit, Alain D.

2002-02-01

We developed a code aimed at determining the laser parameters leading to the maximum return flux of photons at 0.33 micrometers for a polychromatic sodium Laser Guide Star. This software relies upon a full 48-level collisionless and magnetic-field-free density-matrix description of the hyperfine structure of Na and includes Doppler broadening and Zeeman degeneracy. Experimental validation of BEACON was conducted on the SILVA facilities and will also be discussed in this paper.

Revealing the Cu(2+) ions localization at low symmetry Bi sites in photorefractive Bi12GeO20 crystals doped with Cu and V by high frequency EPR.

PubMed

Nistor, Sergiu V; Stefan, Mariana; Goovaerts, Etienne; Ramaz, François; Briat, Bernard

2015-10-01

The sites of incorporation of Cu(2+) impurity ions in Bi12GeO20 single crystals co-doped with copper and vanadium have been investigated by electron paramagnetic resonance (EPR). While the X-band EPR spectra consist of a simple broad (ΔB ∼50 mT) line with anisotropic lineshape, the W-band EPR spectra exhibit well resolved, strongly anisotropic lines, due to transitions within the 3d(9)-(2)D ground manifold of the Cu(2+) ions. The most intense group of lines, attributed to the dominant Cu(2+)(I) center, displays a characteristic four components hyperfine structure for magnetic field orientations close to a 〈110〉 direction. The g and A tensor main axes are very close to one of the 12 possible sets of orthogonal 〈1-10〉, 〈00-1〉 and 〈110〉 crystal directions. Several less intense lines, with unresolved hyperfine structure and similar symmetry properties, mostly overlapped by the Cu(2+)(I) spectrum, were attributed to Cu(2+)(II) centers. The two paramagnetic centers are identified as substitutional Cu(2+) ions at Bi(3+) sites with low C1 symmetry, very likely resulting from different configurations of neighboring charge compensating defects. Copyright © 2015 Elsevier Inc. All rights reserved.

Development of alternative plasma sources for cavity ring-down measurements of mercury.

PubMed

Duan, Yixiang; Wang, Chuji; Scherrer, Susan T; Winstead, Christopher B

2005-08-01

We have been exploring innovative technologies for elemental and hyperfine structure measurements using cavity ring-down spectroscopy (CRDS) combined with various plasma sources. A laboratory CRDS system utilizing a tunable dye laser is employed in this work to demonstrate the feasibility of the technology. An in-house fabricated sampling system is used to generate aerosols from solution samples and introduce the aerosols into the plasma source. The ring-down signals are monitored using a photomultiplier tube and recorded using a digital oscilloscope interfaced to a computer. Several microwave plasma discharge devices are tested for mercury CRDS measurement. Various discharge tubes have been designed and tested to reduce background interference and increase the sample path length while still controlling turbulence generated from the plasma gas flow. Significant background reduction has been achieved with the implementation of the newly designed tube-shaped plasma devices, which has resulted in a detection limit of 0.4 ng/mL for mercury with the plasma source CRDS. The calibration curves obtained in this work readily show that linearity over 2 orders of magnitude can be obtained with plasma-CRDS for mercury detection. In this work, the hyperfine structure of mercury at the experimental plasma temperatures is clearly identified. We expect that plasma source cavity ring-down spectroscopy will provide enhanced capabilities for elemental and isotopic measurements.

ISOTROPIC INELASTIC COLLISIONS IN A MULTITERM ATOM WITH HYPERFINE STRUCTURE

DOE Office of Scientific and Technical Information (OSTI.GOV)

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 ismore » 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.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wood, M. P.; Lawler, J. E.; Den Hartog, E. A.

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 fittingmore » 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.« less

Energy Levels, wavelengths and hyperfine structure measurements of Sc II

NASA Astrophysics Data System (ADS)

Hala, Fnu; Nave, Gillian

2018-01-01

Lines of singly ionized Scandium (Sc II) along with other Iron group elements have been observed [1] in the region surrounding the massive star Eta Carinae [2,3] called the strontium filament (SrF). The last extensive analysis of Sc II was the four-decade old work of Johansson & Litzen [4], using low-resolution grating spectroscopy. To update and extend the Sc II spectra, we have made observation of Sc/Ar, Sc/Ne and Sc/Ge/Ar hollow cathode emission spectrum on the NIST high resolution FT700 UV/Vis and 2 m UV/Vis/IR Fourier transform spectrometers (FTS). More than 850 Sc II lines have been measured in the wavelength range of 187 nm to 3.2 μm. connecting a total of 152 energy levels. The present work also focuses to resolve hyperfine structure (HFS) in Sc II lines. We aim to obtain accurate transition wavelengths, improved energy levels and HFS constants of Sc II. The latest results from work in progress will be presented.Reference[1] Hartman H, Gull T, Johansson S and Smith N 2004 Astron. Astrophys. 419 215[2] Smith N, Morse J A and Gull T R 2004 Astrophys. J. 605 405[3] Davidson K and Humphreys R M 1997 Annu. Rev. Astron. Astrophys. 35[4] Johansson S and Litzén U 1980 Phys. Scr. 22 49

The influence of coordinated defects on inhomogeneous broadening in cubic lattices

NASA Astrophysics Data System (ADS)

Matheson, P. L.; Sullivan, Francis P.; Evenson, William E.

2016-12-01

The joint probability distribution function (JPDF) of electric field gradient (EFG) tensor components in cubic materials is dominated by coordinated pairings of defects in shells near probe nuclei. The contributions from these inner shell combinations and their surrounding structures contain the essential physics that determine the PAC-relevant quantities derived from them. The JPDF can be used to predict the nature of inhomogeneous broadening (IHB) in perturbed angular correlation (PAC) experiments by modeling the G 2 spectrum and finding expectation values for V zz and η. The ease with which this can be done depends upon the representation of the JPDF. Expanding on an earlier work by Czjzek et al. (Hyperfine Interact. 14, 189-194, 1983), Evenson et al. (Hyperfine Interact. 237, 119, 2016) provide a set of coordinates constructed from the EFG tensor invariants they named W 1 and W 2. Using this parameterization, the JPDF in cubic structures was constructed using a point charge model in which a single trapped defect (TD) is the nearest neighbor to a probe nucleus. Individual defects on nearby lattice sites pair with the TD to provide a locus of points in the W 1- W 2 plane around which an amorphous-like distribution of probability density grows. Interestingly, however, marginal, separable PDFs appear adequate to model IHB relevant cases. We present cases from simulations in cubic materials illustrating the importance of these near-shell coordinations.

Stark broadening parameters and transition probabilities of persistent lines of Tl II

NASA Astrophysics Data System (ADS)

de Andrés-García, I.; Colón, C.; Fernández-Martínez, F.

2018-05-01

The presence of singly ionized thallium in the stellar atmosphere of the chemically peculiar star χ Lupi was reported by Leckrone et al. in 1999 by analysis of its stellar spectrum obtained with the Goddard High Resolution Spectrograph (GHRS) on board the Hubble Space Telescope. Atomic data about the spectral line of 1307.50 Å and about the hyperfine components of the spectral lines of 1321.71 Å and 1908.64 Å were taken from different sources and used to analyse the isotopic abundance of thallium II in the star χ Lupi. From their results the authors concluded that the photosphere of the star presents an anomalous isotopic composition of Tl II. A study of the atomic parameters of Tl II and of the broadening by the Stark effect of its spectral lines (and therefore of the possible overlaps of these lines) can help to clarify the conclusions about the spectral abundance of Tl II in different stars. In this paper we present calculated values of the atomic transition probabilities and Stark broadening parameters for 49 spectral lines of Tl II obtained by using the Cowan code including core polarization effects and the Griem semiempirical approach. Theoretical values of radiative lifetimes for 11 levels (eight with experimental values in the bibliography) are calculated and compared with the experimental values in order to test the quality of our results. Theoretical trends of the Stark width and shift parameters versus the temperature for spectral lines of astrophysical interest are displayed. Trends of our calculated Stark width for the isoelectronic sequence Tl II-Pb III-Bi IV are also displayed.

Low-frequency ESR studies on permeable and impermeable deuterated nitroxyl radicals in corn oil solution.

PubMed

David Jebaraj, D; Utsumi, Hideo; Milton Franklin Benial, A

2018-04-01

Low-frequency electron spin resonance studies were performed for 2 mM concentration of deuterated permeable and impermeable nitroxyl spin probes, 3-methoxycarbonyl-2,2,5,5-tetramethyl-pyrrolidine-1-oxyl and 3-carboxy-2,2,5,5,-tetramethyl-1-pyrrolidinyloxy in pure water and various concentrations of corn oil solution. The electron spin resonance parameters such as the line width, hyperfine coupling constant, g factor, rotational correlation time, permeability, and partition parameter were estimated. The broadening of line width was observed for nitroxyl radicals in corn oil mixture. The rotational correlation time increases with increasing concentration of corn oil, which indicates the less mobile nature of spin probe in corn oil mixture. The membrane permeability and partition parameter values were estimated as a function of corn oil concentration, which reveals that the nitroxyl radicals permeate equally into the aqueous phase and oil phase at the corn oil concentration of 50%. The electron spin resonance spectra demonstrate the permeable and impermeable nature of nitroxyl spin probes. From these results, the corn oil concentration was optimized as 50% for phantom studies. In this work, the corn oil and pure water mixture phantom models with various viscosities correspond to plasma membrane, and whole blood membrane with different hematocrit levels was studied for monitoring the biological characteristics and their interactions with permeable nitroxyl spin probe. These results will be useful for the development of electron spin resonance and Overhauser-enhanced magnetic resonance imaging modalities in biomedical applications. Copyright © 2017 John Wiley & Sons, Ltd.

Infrared laser induced population transfer and parity selection in 14NH3: A proof of principle experiment towards detecting parity violation in chiral molecules

NASA Astrophysics Data System (ADS)

Dietiker, P.; Miloglyadov, E.; Quack, M.; Schneider, A.; Seyfang, G.

2015-12-01

We have set up an experiment for the efficient population transfer by a sequential two photon—absorption and stimulated emission—process in a molecular beam to prepare quantum states of well defined parity and their subsequent sensitive detection. This provides a proof of principle for an experiment which would allow for parity selection and measurement of the time evolution of parity in chiral molecules, resulting in a measurement of the parity violating energy difference ΔpvE between enantiomers of chiral molecules. Here, we present first results on a simple achiral molecule demonstrating efficient population transfer (about 80% on the average for each step) and unperturbed persistence of a selected excited parity level over flight times of about 1.3 ms in the beam. In agreement with model calculations with and without including nuclear hyperfine structure, efficient population transfer can be achieved by a rather simple implementation of the rapid adiabatic passage method of Reuss and coworkers and considering also the stimulated Raman adiabatic passage technique of Bergmann and coworkers as an alternative. The preparation step uses two powerful single mode continuous wave optical parametric oscillators of high frequency stability and accuracy. The detection uses a sensitive resonantly enhanced multiphoton ionization method after free flight lengths of up to 0.8 m in the molecular beam. Using this technique, we were able to also resolve the nuclear hyperfine structure in the rovibrational levels of the ν1 and ν3 fundamentals as well as the 2ν4 overtone of 14NH3, for which no previous data with hyperfine resolution were available. We present our new results on the quadrupole coupling constants for the ν1, ν3, and 2ν4 levels in the context of previously known data for ν2 and its overtone, as well as ν4, and the ground state. Thus, now, 14N quadrupole coupling constants for all fundamentals and some overtones of 14NH3 are known and can be used for further theoretical analysis.

Infrared laser induced population transfer and parity selection in (14)NH3: A proof of principle experiment towards detecting parity violation in chiral molecules.

PubMed

Dietiker, P; Miloglyadov, E; Quack, M; Schneider, A; Seyfang, G

2015-12-28

We have set up an experiment for the efficient population transfer by a sequential two photon-absorption and stimulated emission-process in a molecular beam to prepare quantum states of well defined parity and their subsequent sensitive detection. This provides a proof of principle for an experiment which would allow for parity selection and measurement of the time evolution of parity in chiral molecules, resulting in a measurement of the parity violating energy difference ΔpvE between enantiomers of chiral molecules. Here, we present first results on a simple achiral molecule demonstrating efficient population transfer (about 80% on the average for each step) and unperturbed persistence of a selected excited parity level over flight times of about 1.3 ms in the beam. In agreement with model calculations with and without including nuclear hyperfine structure, efficient population transfer can be achieved by a rather simple implementation of the rapid adiabatic passage method of Reuss and coworkers and considering also the stimulated Raman adiabatic passage technique of Bergmann and coworkers as an alternative. The preparation step uses two powerful single mode continuous wave optical parametric oscillators of high frequency stability and accuracy. The detection uses a sensitive resonantly enhanced multiphoton ionization method after free flight lengths of up to 0.8 m in the molecular beam. Using this technique, we were able to also resolve the nuclear hyperfine structure in the rovibrational levels of the ν1 and ν3 fundamentals as well as the 2ν4 overtone of (14)NH3, for which no previous data with hyperfine resolution were available. We present our new results on the quadrupole coupling constants for the ν1, ν3, and 2ν4 levels in the context of previously known data for ν2 and its overtone, as well as ν4, and the ground state. Thus, now, (14)N quadrupole coupling constants for all fundamentals and some overtones of (14)NH3 are known and can be used for further theoretical analysis.

Implication for using heme methyl hyperfine shifts as indicators of heme seating as related to stereoselectivity in the catabolism of heme by heme oxygenase: in-plane heme versus axial his rotation.

PubMed

Ogura, Hiroshi; Evans, John P; de Montellano, Paul R Ortiz; La Mar, Gerd N

2008-01-08

The triple mutant of the solubilized, 265-residue construct of human heme oxygenase, K18E/E29K/R183E-hHO, has been shown to redirect the exclusive alpha-regioselectivity of wild-type hHO to primarily beta,delta-selectivity in the cleavage of heme (Wang, J., Evans, J. P., Ogura, H., La Mar, G. N., and Ortiz de Montellano, P. R. (2006) Biochemistry 45, 61-73). The 1H NMR hyperfine shift pattern for the substrate and axial His CbetaH's and the substrate-protein contacts of the cyanide-inhibited protohemin and 2,4-dimethyldeuterohemin complexes of the triple mutant have been analyzed in detail and compared to data for the WT complex. It is shown that protein contacts for the major solution isomers for both substrates in the mutant dictate approximately 90 degrees in-plane clockwise rotation relative to that in the WT. The conventional interpretation of the pattern of substrate methyl hyperfine shifts, however, indicates substrate rotations of only approximately 50 degrees . This paradox is resolved by demonstrating that the axial His25 imidazole ring also rotates counterclockwise with respect to the protein matrix in the mutant relative to that in the WT. The axial His25 CbetaH hyperfine shifts are shown to serve as independent probes of the imidazole plane orientation relative to the protein matrix. The analysis indicates that the pattern of heme methyl hyperfine shifts cannot be used alone to determine the in-plane orientation of the substrate as it relates to the stereospecificity of heme cleavage, without explicit consideration of the orientation of the axial His imidazole plane relative to the protein matrix.

Hyperfine excitation of C2H in collisions with ortho- and para-H2

NASA Astrophysics Data System (ADS)

Dagdigian, Paul J.

2018-06-01

Accurate estimation of the abundance of the ethynyl (C2H) radical requires accurate radiative and collisional rate coefficients. Hyperfine-resolved rate coefficients for (de-)excitation of C2H in collisions with ortho- and para-H2 are presented in this work. These rate coefficients were computed in time-independent close-coupling quantum scattering calculations that employed a potential energy surface recently computed at the coupled-clusters level of theory that describes the interaction of C2H with H2. Rate coefficients for temperatures from 10 to 300 K were computed for all transitions among the first 40 hyperfine energy levels of C2H in collisions with ortho- and para-H2. These rate coefficients were employed in simple radiative transfer calculations to simulate the excitation of C2H in typical molecular clouds.

Hyperfine excitation of CH in collisions with atomic and molecular hydrogen

NASA Astrophysics Data System (ADS)

Dagdigian, Paul J.

2018-04-01

We investigate here the excitation of methylidene (CH) induced by collisions with atomic and molecular hydrogen (H and H2). The hyperfine-resolved rate coefficients were obtained from close coupling nuclear-spin-free scattering calculations. The calculations are based upon recent, high-accuracy calculations of the CH(X2Π)-H(2S) and CH(X2Π)-H2 potential energy surfaces. Cross-sections and rate coefficients for collisions with atomic H, para-H2, and ortho-H2 were computed for all transitions between the 32 hyperfine levels for CH(X2Π) involving the n ≤ 4 rotational levels for temperatures between 10 and 300 K. These rate coefficients should significantly aid in the interpretation of astronomical observations of CH spectra. As a first application, the excitation of CH is simulated for conditions in typical molecular clouds.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

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.

NMR studies of field induced magnetism in CeCoIn5

DOE Office of Scientific and Technical Information (OSTI.GOV)

Graf, Matthias; Curro, Nicholas J; Young, Ben - Li

2009-01-01

Recent Nuclear Magnetic Resonance and elastic neutron scattering experiments have revealed conclusively the presence of static incommensurate magnetism in the field-induced B phase of CeCoIns, We analyze the NMR data assuming the hyperfine coupling to the 1n(2) nuclei is anisotropic and simulate the spectra for several different magnetic structures, The NMR data are consistent with ordered Ce moments along the [001] direction, but are relatively insensitive to the direction of the incommensurate wavevector.

Theoretical explanation of spin-Hamiltonian parameters and local structure for the orthorhombic MnO2 -4 clusters in K2CrO4 : Mn6 + crystal

NASA Astrophysics Data System (ADS)

Wang, Ning; Xie, Linhua

2017-12-01

In this paper, the spin-Hamiltonian parameters (g factors gx, gy, gz and hyperfine structure constants A Ax, Ay, Az) and the absorption spectrum of K2CrO4 : Mn6 + crystal are theoretically explained by using the high-order perturbation theory, the double-spin-orbit-coupling model theory and the double-mechanism theory (the crystal field mechanism and the charge-transfer (CT) mechanism). The calculation results show that the contribution of the CT mechanism cannot be neglected for Mn6 + ions in orthorhombic clusters with the ground state ?.

Atomic Clocks and Variations of the FIne Structure Constant

NASA Technical Reports Server (NTRS)

Prestage, John D.; Tjoelker, Robert L.; Maleki, Lute

1995-01-01

We describe a new test for possible variations of the fine structure constant alpha by comparisons of rates between clocks based on hyperfine transitions in alkali atoms with different atomic number Z. H-maser, Cs, and Hg(+) clocks have a different dependence on alpha via relativistic contributions of order (Z-alpha)(sup 2). Recent H-maser vs Hg(+) clock comparison data improve laboratory limits on a time variation by 100-fold to give dot-alpha less than or equal to 3.7 x 10(exp -14)/yr. Future laser cooled clocks (Be(+), Rb, Cs, Hg(+), etc.), when compared, will yield the most sensitive of all tests for dot-alpha/alpha.

Laser-spectroscopy studies of the nuclear structure of neutron-rich radium

NASA Astrophysics Data System (ADS)

Lynch, K. M.; Wilkins, S. G.; Billowes, J.; Binnersley, C. L.; Bissell, M. L.; Chrysalidis, K.; Cocolios, T. E.; Goodacre, T. Day; de Groote, R. P.; Farooq-Smith, G. J.; Fedorov, D. V.; Fedosseev, V. N.; Flanagan, K. T.; Franchoo, S.; Garcia Ruiz, R. F.; Gins, W.; Heinke, R.; Koszorús, Á.; Marsh, B. A.; Molkanov, P. L.; Naubereit, P.; Neyens, G.; Ricketts, C. M.; Rothe, S.; Seiffert, C.; Seliverstov, M. D.; Stroke, H. H.; Studer, D.; Vernon, A. R.; Wendt, K. D. A.; Yang, X. F.

2018-02-01

The neutron-rich radium isotopes, Ra-233222, were measured with Collinear Resonance Ionization Spectroscopy (CRIS) at the ISOLDE facility, CERN. The hyperfine structure of the 7 s2S10→7 s 7 p P31 transition was probed, allowing measurement of the magnetic moments, quadrupole moments, and changes in mean-square charge radii. These results are compared to existing literature values, and the new moments and change in mean-square charge radii of 231Ra are presented. Low-resolution laser spectroscopy of the very neutron-rich 233Ra has allowed the isotope shift and relative charge radius to be determined for the first time.

Predicting the intrauterine fetal death of fetuses with cystic hygroma in early pregnancy.

PubMed

Shimura, Mai; Ishikawa, Hiroshi; Nagase, Hiromi; Mochizuki, Akihiko; Sekiguchi, Futoshi; Koshimizu, Naho; Itai, Toshiyuki; Odagami, Mizuha

2018-01-11

We investigated whether it was possible to predict the prognosis of fetuses with cystic hygroma in early pregnancy based on the degree of neck thickening. We retrospectively analyzed 57 singleton pregnancies with fetuses with cystic hygroma who were examined before the 22nd week of pregnancy. The fetuses were categorized according to the outcome, structural abnormalities at birth, and chromosomal abnormalities. Here, we proposed a new sonographic predictor with which we assessed neck thickening by dividing the width of the neck thickening by the biparietal diameter, which is expressed as the cystic hygroma width/biparietal diameter ratio. The median cystic hygroma width/biparietal diameter ratio in the intrauterine fetal death group (0.51) was significantly higher than that in the live birth group (0.27). No significant difference in the median cystic hygroma width/biparietal diameter ratio was found between the structural abnormalities group at birth and the no structural abnormalities group, and no significant difference in the median cystic hygroma width/biparietal diameter ratio was found between the chromosomal abnormality group and the no chromosomal abnormality group. We used receiver operating characteristic analysis to evaluate the cystic hygroma width/biparietal diameter ratio to predict intrauterine fetal death. When the cystic hygroma width/biparietal diameter ratio cut-off value was 0.5, intrauterine fetal death could be predicted with a sensitivity of 52.9% and a specificity of 100%. It is possible to predict intrauterine fetal death in fetuses with cystic hygroma in early pregnancy if cystic hygroma width/biparietal diameter ratio is measured. However, even if cystic hygroma width/biparietal diameter ratio is measured, predicting the presence or absence of a structural abnormality at birth or a chromosomal abnormality is difficult. © 2018 Japanese Teratology Society.

First determination of ground state electromagnetic moments of Fe 53

DOE Office of Scientific and Technical Information (OSTI.GOV)

Miller, A. J.; Minamisono, K.; Rossi, D. M.

Here, the hyperfine coupling constants of neutron deficient 53Fe were deduced from the atomic hyperfine spectrum measured using the bunched-beam collinear laser spectroscopy technique. The low-energy 53Fe beam was produced by projectile-fragmentation reactions followed by gas stopping, and used for the first time for laser spectroscopy. Ground state magnetic-dipole and electric-quadrupole moments were determined as μ= –0.65(1)μ N and Q=+35(15)e 2fm 2, respectively. The multiconfiguration Dirac-Fock method was used to calculate the electric field gradient to deduce Q from the quadrupole hyperfine coupling constant, since the quadrupole coupling constant has not been determined for any Fe isotopes. Both experimental valuesmore » agree well with nuclear shell model calculations using the GXPF1A effective interaction performed in a full fp shell model space, which support the soft nature of the 56Ni nucleus.« less

Polaron spin echo envelope modulations in an organic semiconducting polymer

DOE PAGES

Mkhitaryan, V. V.; Dobrovitski, V. V.

2017-06-01

Here, we present a theoretical analysis of the electron spin echo envelope modulation (ESEEM) spectra of polarons in semiconducting π -conjugated polymers. We show that the contact hyperfine coupling and the dipolar interaction between the polaron and the proton spins give rise to different features in the ESEEM spectra. Our theory enables direct selective probe of different groups of nuclear spins, which affect the polaron spin dynamics. Namely, we demonstrate how the signal from the distant protons (coupled to the polaron spin via dipolar interactions) can be distinguished from the signal coming from the protons residing on the polaron sitemore » (coupled to the polaron spin via contact hyperfine interaction). We propose a method for directly probing the contact hyperfine interaction, that would enable detailed study of the polaron orbital state and its immediate environment. Lastly, we also analyze the decay of the spin echo modulation, and its connection to the polaron transport.« less

First determination of ground state electromagnetic moments of Fe 53

DOE PAGES

Miller, A. J.; Minamisono, K.; Rossi, D. M.; ...

2017-11-16

Here, the hyperfine coupling constants of neutron deficient 53Fe were deduced from the atomic hyperfine spectrum measured using the bunched-beam collinear laser spectroscopy technique. The low-energy 53Fe beam was produced by projectile-fragmentation reactions followed by gas stopping, and used for the first time for laser spectroscopy. Ground state magnetic-dipole and electric-quadrupole moments were determined as μ= –0.65(1)μ N and Q=+35(15)e 2fm 2, respectively. The multiconfiguration Dirac-Fock method was used to calculate the electric field gradient to deduce Q from the quadrupole hyperfine coupling constant, since the quadrupole coupling constant has not been determined for any Fe isotopes. Both experimental valuesmore » agree well with nuclear shell model calculations using the GXPF1A effective interaction performed in a full fp shell model space, which support the soft nature of the 56Ni nucleus.« less

Mean link versus average plaquette tadpoles in lattice NRQCD

NASA Astrophysics Data System (ADS)

Shakespeare, Norman H.; Trottier, Howard D.

1999-03-01

We compare mean-link and average plaquette tadpole renormalization schemes in the context of the quarkonium hyperfine splittings in lattice NRQCD. Simulations are done for the three quarkonium systems c overlinec, b overlinec, and b overlineb. The hyperfine splittings are computed both at leading and at next-to-leading order in the relativistic expansion. Results are obtained at a large number of lattice spacings. A number of features emerge, all of which favor tadpole renormalization using mean links. This includes much better scaling of the hyperfine splittings in the three quarkonium systems. We also find that relativistic corrections to the spin splittings are smaller with mean-link tadpoles, particularly for the c overlinec and b overlinec systems. We also see signs of a breakdown in the NRQCD expansion when the bare quark mass falls below about one in lattice units (with the bare quark masses turning out to be much larger with mean-link tadpoles).

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.

Comparing Zeeman qubits to hyperfine qubits in the context of the surface code: +174Yb and +171Yb

NASA Astrophysics Data System (ADS)

Brown, Natalie C.; Brown, Kenneth R.

2018-05-01

Many systems used for quantum computing possess additional states beyond those defining the qubit. Leakage out of the qubit subspace must be considered when designing quantum error correction codes. Here we consider trapped ion qubits manipulated by Raman transitions. Zeeman qubits do not suffer from leakage errors but are sensitive to magnetic fields to first order. Hyperfine qubits can be encoded in clock states that are insensitive to magnetic fields to first order, but spontaneous scattering during the Raman transition can lead to leakage. Here we compare a Zeeman qubit (+174Yb) to a hyperfine qubit (+171Yb) in the context of the surface code. We find that the number of physical qubits required to reach a specific logical qubit error can be reduced by using +174Yb if the magnetic field can be stabilized with fluctuations smaller than 10 μ G .

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Accurate determination of the fine-structure intervals in the 3P ground states of C-13 and C-12 by far-infrared laser magnetic resonance

NASA Technical Reports Server (NTRS)

Cooksy, A. L.; Saykally, R. J.; Brown, J. M.; Evenson, K. M.

1986-01-01

Accurate values are presented for the fine-structure intervals in the 3P ground state of neutral atomic C-12 and C-13 as obtained from laser magnetic resonance spectroscopy. The rigorous analysis of C-13 hyperfine structure, the measurement of resonant fields for C-12 transitions at several additional far-infrared laser frequencies, and the increased precision of the C-12 measurements, permit significant improvement in the evaluation of these energies relative to earlier work. These results will expedite the direct and precise measurement of these transitions in interstellar sources and should assist in the determination of the interstellar C-12/C-13 abundance ratio.

Structure and magnetic properties of Sm1-xZrx Fe10Si2 (x=0.2-0.6) alloys

NASA Astrophysics Data System (ADS)

Gjoka, M.; Sarafidis, C.; Psycharis, V.; Devlin, E.; Niarchos, D.; Hadjipanayis, G.

2017-10-01

Structure and magnetic properties of Sm1-xZrxFe10Si2 (0.1 ≤ x ≤ 0.6) alloys have been characterized using X-ray diffraction, thermomagnetic analysis and Mössbauer spectroscopy. The formation of the tetragonal ThMn12 -type structure was been observed in all alloys, without further annealing. The Curie temperature decreases linearly with Zr substitution from 322 °C for x=0.1 to 395 °C for x=0.6. Mössbauer spectroscopy showed the iron hyperfine field values decrease with increasing Zr content, and also confirmed changes to the magnetic anisotropy with increasing Zr content observed by XRD on oriented samples.

Polarization effects in the interaction between multi-level atoms and two optical fields

NASA Astrophysics Data System (ADS)

Colín-Rodríguez, R.; Flores-Mijangos, J.; Hernández-Gómez, S.; Jáuregui, R.; López-Hernández, O.; Mojica-Casique, C.; Ponciano-Ojeda, F.; Ramírez-Martínez, F.; Sahagún, D.; Volke-Sepúlveda, K.; Jiménez-Mier, J.

2015-06-01

Polarized velocity selective spectra for rubidium atoms in a room temperature cell are presented. The experiments were performed in the lambda configuration (D2 manifold) and in the 5s\\to 5{{p}3/2}\\to 5{{d}j} ladder configuration. For the lambda configuration the effect of the probe beam intensity in the absorption and polarization spectra are compared with results of a rate equation approximation. Good overall agreement between experiment and theory is found. The results indicate different saturation rates for each of the atomic transitions. Distinctive polarization signals with hyperfine-resolved components are found for the ladder 5{{d}3/2} and 5{{d}5/2} upper states. Fluorescence detection of the 420 nm that results from the second step in the cascade decay 5{{d}j}\\to 6{{p}{{j\\prime }}}\\to 5s was used in the ladder experiments. This fluorescence was also used for the detection of the 5{{p}3/2}\\to 6{{p}3/2} electric dipole forbidden transition in atomic rubidium that occurs at 911 nm. The 6{{p}3/2} hyperfine structure was resolved in this continuous wave, non-dipole excitation.

Ultranarrow Optical Inhomogeneous Linewidth in a Stoichiometric Rare-Earth Crystal.

PubMed

Ahlefeldt, R L; Hush, M R; Sellars, M J

2016-12-16

We obtain a low optical inhomogeneous linewidth of 25 MHz in the stoichiometric rare-earth crystal EuCl_{3}·6H_{2}O by isotopically purifying the crystal in ^{35}Cl. With this linewidth, an important limit for stoichiometric rare-earth crystals is surpassed: the hyperfine structure of ^{153}Eu is spectrally resolved, allowing the whole population of ^{153}Eu^{3+} ions to be prepared in the same hyperfine state using hole-burning techniques. This material also has a very high optical density, and can have long coherence times when deuterated. This combination of properties offers new prospects for quantum information applications. We consider two of these: quantum memories and quantum many-body studies. We detail the improvements in the performance of current memory protocols possible in these high optical depth crystals, and describe how certain memory protocols, such as off-resonant Raman memories, can be implemented for the first time in a solid-state system. We explain how the strong excitation-induced interactions observed in this material resemble those seen in Rydberg systems, and describe how these interactions can lead to quantum many-body states that could be observed using standard optical spectroscopy techniques.

Centralization or decentralization of facial structures in Korean young adults.

PubMed

Yoo, Ja-Young; Kim, Jeong-Nam; Shin, Kang-Jae; Kim, Soon-Heum; Choi, Hyun-Gon; Jeon, Hyun-Soo; Koh, Ki-Seok; Song, Wu-Chul

2013-05-01

It is well known that facial beauty is dictated by facial type, and harmony between the eyes, nose, and mouth. Furthermore, facial impression is judged according to the overall facial contour and the relationship between the facial structures. The aims of the present study were to determine the optimal criteria for the assessment of gathering or separation of the facial structures and to define standardized ratios for centralization or decentralization of the facial structures.Four different lengths were measured, and 2 indexes were calculated from standardized photographs of 551 volunteers. Centralization and decentralization were assessed using the width index (interpupillary distance / facial width) and height index (eyes-mouth distance / facial height). The mean ranges of the width index and height index were 42.0 to 45.0 and 36.0 to 39.0, respectively. The width index did not differ with sex, but males had more decentralized faces, and females had more centralized faces, vertically. The incidence rate of decentralized faces among the men was 30.3%, and that of centralized faces among the women was 25.2%.The mean ranges in width and height indexes have been determined in a Korean population. Faces with width and height index scores under and over the median ranges are determined to be "centralized" and "decentralized," respectively.

Solving radiative transfer with line overlaps using Gauss-Seidel algorithms

NASA Astrophysics Data System (ADS)

Daniel, F.; Cernicharo, J.

2008-09-01

Context: The improvement in observational facilities requires refining the modelling of the geometrical structures of astrophysical objects. Nevertheless, for complex problems such as line overlap in molecules showing hyperfine structure, a detailed analysis still requires a large amount of computing time and thus, misinterpretation cannot be dismissed due to an undersampling of the whole space of parameters. Aims: We extend the discussion of the implementation of the Gauss-Seidel algorithm in spherical geometry and include the case of hyperfine line overlap. Methods: We first review the basics of the short characteristics method that is used to solve the radiative transfer equations. Details are given on the determination of the Lambda operator in spherical geometry. The Gauss-Seidel algorithm is then described and, by analogy to the plan-parallel case, we see how to introduce it in spherical geometry. Doing so requires some approximations in order to keep the algorithm competitive. Finally, line overlap effects are included. Results: The convergence speed of the algorithm is compared to the usual Jacobi iterative schemes. The gain in the number of iterations is typically factors of 2 and 4 for the two implementations made of the Gauss-Seidel algorithm. This is obtained despite the introduction of approximations in the algorithm. A comparison of results obtained with and without line overlaps for N2H^+, HCN, and HNC shows that the J=3-2 line intensities are significantly underestimated in models where line overlap is neglected.

Magnetism of the 35 K superconductor CsEuFe4As4

NASA Astrophysics Data System (ADS)

Albedah, Mohammed A.; Nejadsattari, Farshad; Stadnik, Zbigniew M.; Liu, Yi; Cao, Guang-Han

2018-04-01

The results of ab initio hyperfine-interaction parameters calculations, and of x-ray diffraction and 57Fe and 151Eu Mössbauer spectroscopy study of the new 35 K superconductor CsEuFe4As4 are reported. The superconductor crystallizes in the tetragonal space group P4/mmm with the lattice parameters a = 3.8956(1) Å and c = 13.6628(5) Å. It is demonstrated unequivocally that there is no magnetic order of the Fe magnetic moments down to 2.1 K and that the ferromagnetic order is associated with the Eu magnetic moments. The Curie temperature TC = 15.97(8) K determined from the temperature dependence of the hyperfine magnetic field at 151Eu nuclei is shown to be compatible with the temperature dependence of the transferred hyperfine magnetic field at 57Fe nuclei that is induced by the ferromagnetically ordered Eu sublattice. The Eu magnetic moments are shown to be perpendicular to the crystallographic c-axis. The temperature dependence of the principal component of the electric field gradient tensor, both at Fe and Eu sites, is well described by a T 3/2 power-law relation. Good agreement between the calculated and measured hyperfine-interaction parameters is observed. The Debye temperature of CsEuFe4As4 is found to be 295(3) K.

Mössbauer spectroscopy measurements on the 35.5 K superconductor Rb1 -δEuFe4As4

NASA Astrophysics Data System (ADS)

Albedah, Mohammed A.; Nejadsattari, Farshad; Stadnik, Zbigniew M.; Liu, Yi; Cao, Guang-Han

2018-04-01

The results of x-ray diffraction and 57Fe and 151Eu Mössbauer spectroscopy measurements, supplemented with ab initio hyperfine-interaction parameter calculations, on the new 35.5 K superconductor Rb1 -δEuFe4As4 are presented. The superconductor crystallizes in the tetragonal space group P 4 /m m m with the lattice parameters a =3.8849 (1 ) Å and c =13.3370 (3 ) Å. It is shown that there is no magnetic order of the Fe magnetic moments down to 2.1 K and that the ferromagnetic order is associated solely with the Eu magnetic moments. The Curie temperature TC=16.54 (8 ) K is determined from the temperature dependence of both the hyperfine magnetic field at 151Eu nuclei and the transferred hyperfine magnetic field at 57Fe nuclei that is induced by the ferromagnetically ordered Eu sublattice. The Eu magnetic moments are demonstrated to be perpendicular to the crystallographic c axis. The temperature dependence of the principal component of the electric field gradient tensor, at both Fe and Eu sites, is well described by a T3 /2 power-law relation. Good agreement between the calculated and measured hyperfine-interaction parameters is observed. The Debye temperature of Rb1 -δEuFe4As4 is found to be 391(8) K.

Structural, optical and magnetic studies of CuFe2O4, MgFe2O4 and ZnFe2O4 nanoparticles prepared by hydrothermal/solvothermal method

NASA Astrophysics Data System (ADS)

Kurian, Jessyamma; Mathew, M. Jacob

2018-04-01

In this paper we report the structural, optical and magnetic studies of three spinel ferrites namely CuFe2O4, MgFe2O4 and ZnFe2O4 prepared in an autoclave under the same physical conditions but with two different liquid medium and different surfactant. We use water as the medium and trisodium citrate as the surfactant for one method (Hydrothermal method) and ethylene glycol as the medium and poly ethylene glycol as the surfactant for the second method (solvothermal method). The phase identification and structural characterization are done using XRD and morphological studies are carried out by TEM. Cubical and porous spherical morphologies are obtained for hydrothermal and solvothermal process respectively without any impurity phase. The optical studies are carried out using FTIR and UV-Vis reflectance spectra. In order to elucidate the nonlinear optical behaviour of the prepared nanomaterial, open aperture z-scan technique is used. From the fitted z-scan curves nonlinear absorption coefficient and the saturation intensity are determined. The magnetic characterization of the samples is performed at room temperature using vibrating sample magnetometer measurements. The M-H curves obtained are fitted using theoretical equation and the different components of magnetization are determined. Nanoparticles with high saturation magnetization are obtained for MgFe2O4 and ZnFe2O4 prepared under solvothermal reaction. The magnetic hyperfine parameters and the cation distribution of the prepared materials are determined using room temperature Mössbauer spectroscopy. The fitted spectra reveal the difference in the magnetic hyperfine parameters owing to the change in size and morphology.

Convergence of QM/MM and Cluster Models for the Spectroscopic Properties of the Oxygen-Evolving Complex in Photosystem II.

PubMed

Retegan, Marius; Neese, Frank; Pantazis, Dimitrios A

2013-08-13

The latest crystal structure of photosystem II at 1.9 Å resolution, which resolves the topology of the Mn4CaO5 oxygen evolving complex (OEC) at atomistic detail, enables a better correlation between structural features and spectroscopic properties than ever before. Building on the refined crystallographic model of the OEC and the protein, we present combined quantum mechanical/molecular mechanical (QM/MM) studies of the spectroscopic properties of the natural catalyst embedded in the protein matrix. Focusing on the S2 state of the catalytic cycle, we examine the convergence of not only structural parameters but also of the intracluster magnetic interactions in terms of exchange coupling constants and of experimentally relevant (55)Mn, (17)O, and (14)N hyperfine coupling constants with respect to QM/MM partitioning using five QM regions of increasing size. This enables us to assess the performance of the method and to probe second sphere effects by identifying amino acid residues that principally affect the spectroscopic properties of the OEC. Comparison between QM-only and QM/MM treatments reveals that whereas QM/MM models converge quickly to stable values, the QM cluster models need to incorporate significantly larger parts of the second coordination sphere and surrounding water molecules to achieve convergence for certain properties. This is mainly due to the sensitivity of the QM-only models to fluctuations in the hydrogen bonding network and ligand acidity. Additionally, a hydrogen bond that is typically omitted in QM-only treatments is shown to determine the hyperfine coupling tensor of the unique Mn(III) ion by regulating the rotation plane of the ligated D1-His332 imidazole ring, the only N-donor ligand of the OEC.

The Effects of Internal Rotation and 14N Quadrupole Coupling in N-Methyldiacetamide

NASA Astrophysics Data System (ADS)

Kannengießer, Raphaela; Eibl, Konrad; Nguyen, Ha Vinh Lam; Stahl, Wolfgang

2015-06-01

Acetyl- and nitrogen containing substances play an important role in chemical, physical, and especially biological systems. This applies in particular for acetamides, which are structurally related to peptide bonds. In this work, N-methyldiacetamide, CH_3N(COCH_3)_2, was investigated by a combination of molecular beam Fourier transform microwave spectroscopy and quantum chemical calculations. In N-methyldiacetamide, at least three large amplitude motions are possible: (1) the internal rotation of the methyl group attached to the nitrogen atom and (2, 3) the internal rotations of both acetyl methyl groups. This leads to a rather complicated torsional fine structure of all rotational transitions with additional quadrupole hyperfine splittings caused by the 14N nucleus. Quantum chemical calculations were carried out at the MP2/6-311++G(d,p) level of theory to support the spectral assignment. Conformational analysis was performed by calculating a full potential energy surface depending on the orientation of the two acetyl groups. This yielded three stable conformers with a maximum energy difference of 35.2 kJ/mol. The spectrum of the lowest energy conformer was identified in the molecular beam. The quadrupole hyperfine structure as well as the internal rotation of two methyl groups could be assigned. For the N-methyl group and for one of the two acetyl methyl groups, barriers to internal rotation of 147 cm-1 and of 680 cm-1, respectively, were determined. The barrier of the last methyl group seems to be so high that no additional splittings could be resolved. Using the XIAM program, a global fit with a standard deviation on the order of our experimental accuracy could be achieved.

Transient nutation electron spin resonance spectroscopy on spin-correlated radical pairs: A theoretical analysis on hyperfine-induced nuclear modulations

NASA Astrophysics Data System (ADS)

Weber, Stefan; Kothe, Gerd; Norris, James R.

1997-04-01

The influence of anisotropic hyperfine interaction on transient nutation electron paramagnetic resonance (EPR) of light-induced spin-correlated radical pairs is studied theoretically using the density operator formalism. Analytical expressions for the time evolution of the transient EPR signal during selective microwave excitation of single transitions are derived for a model system comprised of a weakly coupled radical pair and one hyperfine-coupled nucleus with I=1/2. Zero-quantum electron coherence and single-quantum nuclear coherence are created as a result of the sudden light-induced generation of the radical pair state from a singlet-state precursor. Depending on the relative sizes of the nuclear Zeeman frequency and the secular and pseudo-secular parts of the hyperfine coupling, transitions between levels with different nuclear spin orientations are predicted to modulate the time-dependent EPR signal. These modulations are in addition to the well-known transient nutations and electron zero-quantum precessions. Our calculations provide insight into the mechanism of recent experimental observations of coherent nuclear modulations in the time-resolved EPR signals of doublets and radical pairs. Two distinct mechanisms of the modulations are presented for various microwave magnetic field strengths. The first modulation scheme arises from electron and nuclear coherences initiated by the laser excitation pulse and is "read out" by the weak microwave magnetic field. While the relative modulation depth of these oscillations with respect to the signal intensity is independent of the Rabi frequency, ω1, the frequencies of this coherence phenomenon are modulated by the effective microwave amplitude and determined by the nuclear Zeeman interaction and hyperfine coupling constants as well as the electron-electron spin exchange and dipolar interactions between the two radical pair halves. In a second mechanism the modulations are both created and detected by the microwave radiation. Here, the laser pulse merely defines the beginning of the microwave-induced coherent time evolution. This second mechanism appears the most consistent with current experimental observations.

Magnetic moment of {sup 104}Ag{sup m} and the hyperfine magnetic field of Ag in Fe using nuclear magnetic resonance on oriented nuclei

DOE Office of Scientific and Technical Information (OSTI.GOV)

Golovko, V. V.; Kraev, I. S.; Phalet, T.

2010-05-15

Nuclear magnetic resonance (NMR/ON) measurements with beta- and gamma-ray detection have been performed on oriented {sup 104}Ag{sup g,m} nuclei with the NICOLE {sup 3}He-{sup 4}He dilution refrigerator setup at ISOLDE/CERN. For {sup 104}Ag{sup g} (I{sup p}i=5{sup +}) the gamma-NMR/ON resonance signal was found at nu=266.70(5) MHz. Combining this result with the known magnetic moment for this isotope, the magnetic hyperfine field of Ag impurities in an Fe host at low temperature (<1 K) is found to be |B{sub hf}(AgFe)|=44.709(35) T. A detailed analysis of other relevant data available in the literature yields three more values for this hyperfine field. Averagingmore » all four values yields a new and precise value for the hyperfine field of Ag in Fe; that is, |B{sub hf}(AgFe)|=44.692(30) T. For {sup 104}Ag{sup m} (I{sup p}i=2{sup +}), the anisotropy of the beta particles provided the NMR/ON resonance signal at nu=627.7(4) MHz. Using the new value for the hyperfine field of Ag in Fe, this frequency corresponds to the magnetic moment mu({sup 104m}Ag)=+3.691(3) mu{sub N}, which is significantly more precise than previous results. The magnetic moments of the even-A {sup 102-110}Ag isotopes are discussed in view of the competition between the (pig{sub 9/2}){sub 7/2}{sup +-3}(nud{sub 5/2}nug{sub 7/2}){sub 5/2}{sup +} and the (pig{sub 9/2}){sub 9/2}{sup +-3}(nud{sub 5/2}nug{sub 7/2}){sub 5/2}{sup +} configurations. The magnetic moments of the ground and isomeric states of {sup 104}Ag can be explained by an almost complete mixing of these two configurations.« less

Structure and properties of bis(1-phenyl-1h-tetrazole-5-thiolate)diiron tetranitrosyl

NASA Astrophysics Data System (ADS)

Sanina, N. A.; Kozub, G. I.; Kondrat'eva, T. A.; Shilov, G. V.; Korchagin, D. V.; Emel'yanova, N. S.; Poleshchuk, O. Kh.; Chernyak, A. V.; Kulikov, A. V.; Mushenok, F. B.; Ovanesyan, N. S.; Aldoshin, S. M.

2013-06-01

New tetranitrosyl binuclear iron complex [Fe2(SС7H5N4)2(NO)4] (I) has been synthesized by interaction of aqueous solutions of anionic salts [Fе(S2O3)2(NO)2]3- and [SС7H5N4]-. The latter one was synthesized by reduction of bis-(1-phenyl-1H-tetrazole-5-yl) disulfide with hydrazine hydrate in ethanol at T = 25 °C. Molecular and crystalline structure of I was determined by X-ray analysis; the complex has binuclear structure of "μ-SCN" type with ˜4.02 Å between the iron atoms. Shortened О⋯О contacts (2.81 Å) between the NO groups of similar type are observed. Parameters of Mössbauer spectrum for I are: isomer shift δFe = 0.311(1) mm/s, quadrupole splitting ΔEQ = 1.044(1) mm/s, line width Γ = 0.267(1) mm/s at 85 K. From SQUID magnetometry data, the temperature and field dependences of the magnetic moment of I are well described in the frame of a simple model of binuclear iron complex with magnetic centers S1 = S2 = ½. In solution, binuclear structure of the complex remains, though the NO groups are non-equivalent. For solutions of I five-line hyperfine structure of spectrum (HFS) is observed, g-factor = 2.03. For polycrystals of I, no HFS was observed due to averaged exchange interaction between the electron spins of adjacent complexes. In polycrystals of I, the number of spins per one binuclear complex is <2, this being the evidence of antiferromagnetic exchange interaction of unpaired electrons of two iron atoms. The average number of spins in crystals (0.65) and solutions (0.55) are close. The maximum amount of NO generated by I in 1% dimethylsulfoxide (DMSO) aqueous solution is ˜13.8 nM, it halves in 8 min after decomposition starts, and reaches ˜3.8 nM in anaerobic conditions at Т = 25 °С, pH 7.0. This is due, according to quantum-chemical calculations, to the presence of a more stable Fesbnd NO bond in I than in its isostructural analog - nitrosyl iron complex with 1-methyltetrazole-5-yl (II).

X-ray diffraction-based electronic structure calculations and experimental x-ray analysis for medical and materials applications

NASA Astrophysics Data System (ADS)

Mahato, Dip Narayan

This thesis includes x-ray experiments for medical and materials applications and the use of x-ray diffraction data in a first-principles study of electronic structures and hyperfine properties of chemical and biological systems. Polycapillary focusing lenses were used to collect divergent x rays emitted from conventional x-ray tubes and redirect them to form an intense focused beam. These lenses are routinely used in microbeam x-ray fluorescence analysis. In this thesis, their potential application to powder diffraction and focused beam orthovoltage cancer therapy has been investigated. In conventional x-ray therapy, very high energy (˜ MeV) beams are used, partly to reduce the skin dose. For any divergent beam, the dose is necessarily highest at the entry point, and decays exponentially into the tissue. To reduce the skin dose, high energy beams, which have long absorption lengths, are employed, and rotated about the patient to enter from different angles. This necessitates large expensive specialized equipment. A focused beam could concentrate the dose within the patient. Since this is inherently skin dose sparing, lower energy photons could be employed. A primary concern in applying focused beams to therapy is whether the focus would be maintained despite Compton scattering within the tissue. To investigate this, transmission and focal spot sizes as a function of photon energy of two polycapillary focusing lenses were measured. The effects of tissue-equivalent phantoms of different thicknesses on the focal spot size were studied. Scatter fraction and depth dose were calculated. For powder diffraction, the polycapillary optics provide clean Gaussian peaks, which result in angular resolution that is much smaller than the peak width due to the beam convergence. Powder diffraction (also called coherent scatter) without optics can also be used to distinguish between tissue types that, because they have different nanoscale structures, scatter at different angles. Measurements were performed on the development of coherent scatter imaging to provide tissue type information in mammography. Atomic coordinates from x-ray diffraction data were used to study the nuclear quadrupole interactions and nature of molecular binding in DNA/RNA nucleobases and molecular solid BF3 systems.

Diode Laser Velocity Measurements by Modulated Filtered Rayleigh Scattering

NASA Technical Reports Server (NTRS)

Mach, J. J.; Varghese, P. L.; Jagodzinski, J. J.

1999-01-01

The ability of solid-state lasers to be tuned in operating frequency at MHz rates by input current modulation, while maintaining a relatively narrow line-width, has made them useful for spectroscopic measurements. Their other advantages include low cost, reliability, durability, compact size, and modest power requirements, making them a good choice for a laser source in micro-gravity experiments in drop-towers and in flight. For their size, they are also very bright. In a filtered Rayleigh scattering (FRS) experiment, a diode laser can be used to scan across an atomic or molecular absorption line, generating large changes in transmission at the resonances for very small changes in frequency. The hyperfine structure components of atomic lines of alkali metal vapors are closely spaced and very strong, which makes such atomic filters excellent candidates for sensitive Doppler shift detection and therefore for high-resolution velocimetry. In the work we describe here we use a Rubidium vapor filter, and work with the strong D(sub 2) transitions at 780 nm that are conveniently accessed by near infrared diode lasers. The low power output of infrared laser diodes is their primary drawback relative to other laser systems commonly used for velocimetry. However, the capability to modulate the laser frequency rapidly and continuously helps mitigate this. Using modulation spectroscopy and a heterodyne detection scheme with a lock-in amplifier, one can extract sub-microvolt signals occurring at a specific frequency from a background that is orders of magnitude stronger. The diode laser modulation is simply achieved by adding a small current modulation to the laser bias current. It may also be swept repetitively in wavelength using an additional lower frequency current ramp.

Laser cooling at resonance

NASA Astrophysics Data System (ADS)

Yudkin, Yaakov; Khaykovich, Lev

2018-05-01

We show experimentally that three-dimensional laser cooling of lithium atoms on the D2 line is possible when the laser light is tuned exactly to resonance with the dominant atomic transition. Qualitatively, it can be understood by applying simple Doppler cooling arguments to the specific hyperfine structure of the excited state of lithium atoms, which is both dense and inverted. However, to build a quantitative theory, we must resolve to a full model which takes into account both the entire atomic structure of all 24 Zeeman sublevels and the laser light polarization. Moreover, by means of Monte Carlo simulations, we show that coherent processes play an important role in showing consistency between the theory and the experimental results.

Diode laser spectroscopy of the MnD radical ( 7Σ) and the determination of mass-independent parameters

NASA Astrophysics Data System (ADS)

Urban, Rolf-Dieter; Jones, Harold

1991-03-01

The infrared spectrum of the manganese deuteride radical has been observed in its ground electronic state ( 7Σ) using a diode-laser spectrometer. The hyperfine structure of a number of infrared transitions in the bands ν=1←0, ν=2←1 and ν=3←2 were measured with a nominal accuracy of ±0.001 cm -1. In all cases, the complete structure was easily resolved. Dunham parameters, spin—rotation and spin—spin coupling parameters were determined from the MnD data. A simultaneous fit of these data with those determined previously for MnH was carried out to determine mass-independent parameters and mass-scaling coefficients.

Continuous modulations of femtosecond laser-induced periodic surface structures and scanned line-widths on silicon by polarization changes.

PubMed

Han, Weina; Jiang, Lan; Li, Xiaowei; Liu, Pengjun; Xu, Le; Lu, YongFeng

2013-07-01

Large-area, uniform laser-induced periodic surface structures (LIPSS) are of wide potential industry applications. The continuity and processing precision of LIPSS are mainly determined by the scanning intervals of adjacent scanning lines. Therefore, continuous modulations of LIPSS and scanned line-widths within one laser scanning pass are of great significance. This study proposes that by varying the laser (800 nm, 50 fs, 1 kHz) polarization direction, LIPSS and the scanned line-widths on a silicon (111) surface can be continuously modulated with high precision. It shows that the scanned line-width reaches the maximum when the polarization direction is perpendicular to the scanning direction. As an application example, the experiments show large-area, uniform LIPSS can be fabricated by controlling the scanning intervals based on the one-pass scanned line-widths. The simulation shows that the initially formed LIPSS structures induce directional surface plasmon polaritons (SPP) scattering along the laser polarization direction, which strengthens the subsequently anisotropic LIPSS fabrication. The simulation results are in good agreement with the experiments, which both support the conclusions of continuous modulations of the LIPSS and scanned line-widths.

EPR study of free radical in gamma-irradiated bis(cyclopentadienyl)zirconium dichloride single crystal

NASA Astrophysics Data System (ADS)

Caliskan, Betul; Caliskan, Ali Cengiz

2017-06-01

Bis(cyclopentadienyl)zirconium dichloride (BCZD; zirconocene dichloride) single crystals were exposed to 60Co-γ irradiation at room temperature. The irradiated single crystals were investigated between 125 and 470 K by electron paramagnetic resonance spectroscopy. The spectra of the crystals were found to be temperature independent. The paramagnetic center was attributed to the cyclopentadienyl radical. The g values of the radiation damage center observed in BCZD single crystal and the hyperfine structure constants of the free electron with nearby protons were obtained.

21-cm radiation: a new probe of variation in the fine-structure constant.

PubMed

Khatri, Rishi; Wandelt, Benjamin D

2007-03-16

We investigate the effect of variation in the value of the fine-structure constant (alpha) at high redshifts (recombination > z > 30) on the absorption of the cosmic microwave background (CMB) at 21 cm hyperfine transition of the neutral atomic hydrogen. We find that the 21 cm signal is very sensitive to the variations in alpha and it is so far the only probe of the fine-structure constant in this redshift range. A change in the value of alpha by 1% changes the mean brightness temperature decrement of the CMB due to 21 cm absorption by >5% over the redshift range z < 50. There is an effect of similar magnitude on the amplitude of the fluctuations in the brightness temperature. The redshift of maximum absorption also changes by approximately 5%.

Local structure study of Fe dopants in Ni-deficit Ni 3Al alloys

DOE Office of Scientific and Technical Information (OSTI.GOV)

V. N. Ivanovski; Umicevic, A.; Belosevic-Cavor, J.

2015-08-24

We found that the local electronic and magnetic structure, hyperfine interactions, and phase composition of polycrystalline Ni–deficient Ni 3-x FexAl (x = 0.18 and 0.36) were investigated by means of 57 Fe Mössbauer spectroscopy. The samples were characterized by X–ray diffraction and magnetization measurements. The ab initio calculations performed with the projector augmented wave method and the calculations of the energies of iron point defects were done to elucidate the electronic structure and site preference of Fe doped Ni 3 Al. Moreover, the value of calculated electric field gradient tensor V zz=1.6 10 21Vm -2 matches well with the resultsmore » of Mössbauer spectroscopy and indicates that the Fe atoms occupy Ni sites.« less

Hyperfine interaction mechanism of magnetic field effects in sequential fluorophore and exciplex fluorescence.

PubMed

Dodin, Dmitry V; Ivanov, Anatoly I; Burshtein, Anatoly I

2013-03-28

The magnetic field effect on the fluorescence of the photoexcited electron acceptor, (1)A∗, and the exciplex, (1)[D(+δ)A(-δ)] formed at contact of (1)A∗ with an electron donor (1)D, is theoretically explored in the framework of Integral Encounter Theory. It is assumed that the excited fluorophore is equilibrated with the exciplex that reversibly dissociates into the radical-ion pair. The magnetic field sensitive stage is the spin conversion in the resulting geminate radical-ion pair, (1, 3)[D(+)...A(-)] that proceeds due to hyperfine interaction. We confirm our earlier conclusion (obtained with a rate description of spin conversion) that in the model with a single nucleus spin 1/2 the magnitude of the Magnetic Field Effect (MFE) also vanishes in the opposite limits of low and high dielectric permittivity of the solvent. Moreover, it is shown that MFE being positive at small hyperfine interaction A, first increases with A but approaching the maximum starts to decrease and even changes the sign.

Angular distribution and polarization of X-ray radiation in highly charged He-like ions: hyperfine-induced transition

NASA Astrophysics Data System (ADS)

Chen, Zhan-Bin; Dong, Chen-Zhong

2018-06-01

The angular distribution and polarization properties of the X-rays produced by the hyperfine-induced transition are investigated within a fully relativistic distorted-wave approximation. The calculations are performed for the 1 s2 p 3/2 3P2 F i = 3/2 → 1 s 2 1S0 F f = 1/2 component of the Kα 1 decay for highly charged He-like 119Sn48+ and 207Tl79+ ions with nuclear spin I = 1/2 following impact excitations by an un-polarized and a completely longitudinally-polarized electron beam, respectively. The Breit interaction and mutipole mixing between the leading M2 decay and the hyperfine-induced E1 decay corrections to both linear and circular polarizations of the emitted X-ray radiations are evaluated. All these effects are found to be significant and may potentially explain the disagreement between the theories and experiments related to the polarization properties of the X-ray radiation.

Single-resonance optical pumping spectroscopy and application in dressed-state measurement with atomic vapor cell at room temperature.

PubMed

Liang, Qiangbing; Yang, Baodong; Zhang, Tiancai; Wang, Junmin

2010-06-21

By monitoring the transmission of probe laser beam (also served as coupling laser beam) which is locked to a cycling hyperfine transition of cesium D(2) line, while pumping laser is scanned across cesium D(1) or D(2) lines, the single-resonance optical pumping (SROP) spectra are obtained with atomic vapor cell. The SROP spectra indicate the variation of the zero-velocity atoms population of one hyperfine fold of ground state, which is optically pumped into another hyperfine fold of ground state by pumping laser. With the virtue of Doppler-free linewidth, high signal-to-noise ratio (SNR), flat background and elimination of crossover resonance lines (CRLs), the SROP spectra with atomic vapor cell around room temperature can be employed to measure dressed-state splitting of ground state, which is normally detected with laser-cooled atomic sample only, even if the dressed-state splitting is much smaller than the Doppler-broaden linewidth at room temperature.

Theory of long-range interactions for Rydberg states attached to hyperfine-split cores

NASA Astrophysics Data System (ADS)

Robicheaux, F.; Booth, D. W.; Saffman, M.

2018-02-01

The theory is developed for one- and two-atom interactions when the atom has a Rydberg electron attached to a hyperfine-split core state. This situation is relevant for some of the rare-earth and alkaline-earth atoms that have been proposed for experiments on Rydberg-Rydberg interactions. For the rare-earth atoms, the core electrons can have a very substantial total angular momentum J and a nonzero nuclear spin I . In the alkaline-earth atoms there is a single (s ) core electron whose spin can couple to a nonzero nuclear spin for odd isotopes. The resulting hyperfine splitting of the core state can lead to substantial mixing between the Rydberg series attached to different thresholds. Compared to the unperturbed Rydberg series of the alkali-metal atoms, the series perturbations and near degeneracies from the different parity states could lead to qualitatively different behavior for single-atom Rydberg properties (polarizability, Zeeman mixing and splitting, etc.) as well as Rydberg-Rydberg interactions (C5 and C6 matrices).

DOE Office of Scientific and Technical Information (OSTI.GOV)

van den Berg, R.; Brandino, G. P.; El Araby, O.

In this study, we introduce an integrability-based method enabling the study of semiconductor quantum dot models incorporating both the full hyperfine interaction as well as a mean-field treatment of dipole-dipole interactions in the nuclear spin bath. By performing free induction decay and spin echo simulations we characterize the combined effect of both types of interactions on the decoherence of the electron spin, for external fields ranging from low to high values. We show that for spin echo simulations the hyperfine interaction is the dominant source of decoherence at short times for low fields, and competes with the dipole-dipole interactions atmore » longer times. On the contrary, at high fields the main source of decay is due to the dipole-dipole interactions. In the latter regime an asymmetry in the echo is observed. Furthermore, the non-decaying fraction previously observed for zero field free induction decay simulations in quantum dots with only hyperfine interactions, is destroyed for longer times by the mean-field treatment of the dipolar interactions.« less

Competing interactions in semiconductor quantum dots

DOE PAGES

van den Berg, R.; Brandino, G. P.; El Araby, O.; ...

2014-10-14

In this study, we introduce an integrability-based method enabling the study of semiconductor quantum dot models incorporating both the full hyperfine interaction as well as a mean-field treatment of dipole-dipole interactions in the nuclear spin bath. By performing free induction decay and spin echo simulations we characterize the combined effect of both types of interactions on the decoherence of the electron spin, for external fields ranging from low to high values. We show that for spin echo simulations the hyperfine interaction is the dominant source of decoherence at short times for low fields, and competes with the dipole-dipole interactions atmore » longer times. On the contrary, at high fields the main source of decay is due to the dipole-dipole interactions. In the latter regime an asymmetry in the echo is observed. Furthermore, the non-decaying fraction previously observed for zero field free induction decay simulations in quantum dots with only hyperfine interactions, is destroyed for longer times by the mean-field treatment of the dipolar interactions.« less

Spin-Orbit Interactions and Quantum Spin Dynamics in Cold Ion-Atom Collisions

NASA Astrophysics Data System (ADS)

Tscherbul, Timur V.; Brumer, Paul; Buchachenko, Alexei A.

2016-09-01

We present accurate ab initio and quantum scattering calculations on a prototypical hybrid ion-atom system Yb+ -Rb, recently suggested as a promising candidate for the experimental study of open quantum systems, quantum information processing, and quantum simulation. We identify the second-order spin-orbit (SO) interaction as the dominant source of hyperfine relaxation in cold Yb+ -Rb collisions. Our results are in good agreement with recent experimental observations [L. Ratschbacher et al., Phys. Rev. Lett. 110, 160402 (2013)] of hyperfine relaxation rates of trapped Yb+ immersed in an ultracold Rb gas. The calculated rates are 4 times smaller than is predicted by the Langevin capture theory and display a weak T-0.3 temperature dependence, indicating significant deviations from statistical behavior. Our analysis underscores the deleterious nature of the SO interaction and implies that light ion-atom combinations such as Yb+ -Li should be used to minimize hyperfine relaxation and decoherence of trapped ions in ultracold atomic gases.

Spin-state transfer in laterally coupled quantum-dot chains with disorders

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yang Song; Key Laboratory of Quantum Information, University of Science and Technology of China, Hefei 230026; Bayat, Abolfazl

2010-08-15

Quantum dot arrays are a promising medium for transferring quantum information between two distant points without resorting to mobile qubits. Here we study the two most common disorders, namely hyperfine interaction and exchange coupling fluctuations, in quantum dot arrays and their effects on quantum communication through these chains. Our results show that the hyperfine interaction is more destructive than the exchange coupling fluctuations. The average optimal time for communication is not affected by any disorder in the system and our simulations show that antiferromagnetic chains are much more resistive than the ferromagnetic ones against both kind of disorders. Even whenmore » time modulation of a coupling and optimal control is employed to improve the transmission, the antiferromagnetic chain performs much better. We have assumed the quasistatic approximation for hyperfine interaction and time-dependent fluctuations in the exchange couplings. Particularly for studying exchange coupling fluctuations we have considered the static disorder, white noise, and 1/f noise.« less

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Adam, Ahmad Y.; Jensen, Per, E-mail: jensen@uni-wuppertal.de; Yachmenev, Andrey

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 verymore » 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.« less

First determination of ground state electromagnetic moments of 53Fe

NASA Astrophysics Data System (ADS)

Miller, A. J.; Minamisono, K.; Rossi, D. M.; Beerwerth, R.; Brown, B. A.; Fritzsche, S.; Garand, D.; Klose, A.; Liu, Y.; Maaß, B.; Mantica, P. F.; Müller, P.; Nörtershäuser, W.; Pearson, M. R.; Sumithrarachchi, C.

2017-11-01

The hyperfine coupling constants of neutron deficient 53Fe were deduced from the atomic hyperfine spectrum of the 3 d64 s25D4↔3 d64 s 4 p 5F5 transition, measured using the bunched-beam collinear laser spectroscopy technique. The low-energy 53Fe beam was produced by projectile-fragmentation reactions followed by gas stopping, and used for the first time for laser spectroscopy. Ground state magnetic-dipole and electric-quadrupole moments were determined as μ =-0.65 (1 ) μN and Q =+35 (15 ) e2fm2 , respectively. The multiconfiguration Dirac-Fock method was used to calculate the electric field gradient to deduce Q from the quadrupole hyperfine coupling constant, since the quadrupole coupling constant has not been determined for any Fe isotopes. Both experimental values agree well with nuclear shell model calculations using the GXPF1A effective interaction performed in a full f p shell model space, which support the soft nature of the 56Ni nucleus.

Infrared laser induced population transfer and parity selection in {sup 14}NH{sub 3}: A proof of principle experiment towards detecting parity violation in chiral molecules

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dietiker, P.; Miloglyadov, E.; Quack, M., E-mail: Martin@Quack.ch

We have set up an experiment for the efficient population transfer by a sequential two photon—absorption and stimulated emission—process in a molecular beam to prepare quantum states of well defined parity and their subsequent sensitive detection. This provides a proof of principle for an experiment which would allow for parity selection and measurement of the time evolution of parity in chiral molecules, resulting in a measurement of the parity violating energy difference Δ{sub pv}E between enantiomers of chiral molecules. Here, we present first results on a simple achiral molecule demonstrating efficient population transfer (about 80% on the average for eachmore » step) and unperturbed persistence of a selected excited parity level over flight times of about 1.3 ms in the beam. In agreement with model calculations with and without including nuclear hyperfine structure, efficient population transfer can be achieved by a rather simple implementation of the rapid adiabatic passage method of Reuss and coworkers and considering also the stimulated Raman adiabatic passage technique of Bergmann and coworkers as an alternative. The preparation step uses two powerful single mode continuous wave optical parametric oscillators of high frequency stability and accuracy. The detection uses a sensitive resonantly enhanced multiphoton ionization method after free flight lengths of up to 0.8 m in the molecular beam. Using this technique, we were able to also resolve the nuclear hyperfine structure in the rovibrational levels of the ν{sub 1} and ν{sub 3} fundamentals as well as the 2ν{sub 4} overtone of {sup 14}NH{sub 3}, for which no previous data with hyperfine resolution were available. We present our new results on the quadrupole coupling constants for the ν{sub 1}, ν{sub 3}, and 2ν{sub 4} levels in the context of previously known data for ν{sub 2} and its overtone, as well as ν{sub 4}, and the ground state. Thus, now, {sup 14}N quadrupole coupling constants for all fundamentals and some overtones of {sup 14}NH{sub 3} are known and can be used for further theoretical analysis.« less

Propagation properties of cylindrical sinc Gaussian beam

NASA Astrophysics Data System (ADS)

Eyyuboğlu, Halil T.; Bayraktar, Mert

2016-09-01

We investigate the propagation properties of cylindrical sinc Gaussian beam in turbulent atmosphere. Since an analytic solution is hardly derivable, the study is carried out with the aid of random phase screens. Evolutions of the beam intensity profile, beam size and kurtosis parameter are analysed. It is found that on the source plane, cylindrical sinc Gaussian beam has a dark hollow appearance, where the side lobes also start to emerge with increase in width parameter and Gaussian source size. During propagation, beams with small width and Gaussian source size exhibit off-axis behaviour, losing the dark hollow shape, accumulating the intensity asymmetrically on one side, whereas those with large width and Gaussian source size retain dark hollow appearance even at long propagation distances. It is seen that the beams with large widths expand more in beam size than the ones with small widths. The structure constant values chosen do not seem to alter this situation. The kurtosis parameters of the beams having small widths are seen to be larger than the ones with the small widths. Again the choice of the structure constant does not change this trend.

Measurements of deuterium quadrupole coupling in propiolic acid and fluorobenzenes using pulsed-beam Fourier transform microwave spectrometers

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sun, Ming; Sargus, Bryan A.; Carey, Spencer J.

The pure rotational spectra of deuterated propiolic acids (HCCCOOD and DCCCOOH), 1-fluorobenzene (4-d{sub 1}), and 1,2-difluorobenzene (4-d{sub 1}) in their ground states have been measured using two Fourier transform microwave (FTMW) spectrometers at the University of Arizona. For 1-fluorobenzene (4-d{sub 1}), nine hyperfine lines of three different ΔJ = 0 and 1 transitions were measured to check the synthesis method and resolution. For 1,2-difluorobenzene (4-d{sub 1}), we obtained 44 hyperfine transitions from 1 to 12 GHz, including 14 different ΔJ = 0, 1 transitions. Deuterium quadrupole coupling constants along the three principal inertia axes were well determined. For deuterated propiolicmore » acids, 37 hyperfine lines of Pro-OD and 59 hyperfine lines of Pro-CD, covering 11 and 12 different ΔJ = − 1, 0, 1 transitions, respectively, were obtained from 5 to 16 GHz. Deuterium quadrupole coupling constants along the three inertia axes were well resolved for Pro-OD. For Pro-CD, only eQq{sub aa} was determined due to the near coincidence of the CD bond and the least principal inertia axis. Some measurements were made using a newer FTMW spectrometer employing multiple free induction decays as well as background subtraction. For 1-fluorobenzene (4-d{sub 1}) and 1,2-difluorobenzene (4-d{sub 1}), a very large-cavity (1.2 m mirror dia.) spectrometer yielded very high resolution (2 kHz) spectra.« less

Global kinetic simulations of neoclassical toroidal viscosity in low-collisional perturbed tokamak plasmas

NASA Astrophysics Data System (ADS)

Matsuoka, Seikichi; Idomura, Yasuhiro; Satake, Shinsuke

2017-10-01

The neoclassical toroidal viscosity (NTV) caused by a non-axisymmetric magnetic field perturbation is numerically studied using two global kinetic simulations with different numerical approaches. Both simulations reproduce similar collisionality ( νb*) dependencies over wide νb * ranges. It is demonstrated that resonant structures in the velocity space predicted by the conventional superbanana-plateau theory exist in the small banana width limit, while the resonances diminish when the banana width becomes large. It is also found that fine scale structures are generated in the velocity space as νb* decreases in the large banana width simulations, leading to the νb* -dependency of the NTV. From the analyses of the particle orbit, it is found that the finite k∥ mode structure along the bounce motion appears owing to the finite orbit width, and it suffers from bounce phase mixing, suggesting the generation of the fine scale structures by the similar mechanism as the parallel phase mixing of passing particles.

Pulsed EPR investigations of systems modeling molybdenum enzymes: hyperfine and quadrupole parameters of oxo-17O in [Mo 17O(SPh)4]-.

PubMed

Astashkin, Andrei V; Neese, Frank; Raitsimring, Arnold M; Cooney, J Jon A; Bultman, Eric; Enemark, John H

2005-11-30

Ka band ESEEM spectroscopy was used to determine the hyperfine (hfi) and nuclear quadrupole (nqi) interaction parameters for the oxo-17O ligand in [Mo 17O(SPh)4]-, a spectroscopic model of the oxo-Mo(V) centers of enzymes. The isotropic hfi constant of 6.5 MHz found for the oxo-17O is much smaller than the values of approximately 20-40 MHz typical for the 17O nucleus of an equatorial OH(2) ligand in molybdenum enzymes. The 17O nqi parameter (e2qQ/h = 1.45 MHz, eta approximately = 0) is the first to be obtained for an oxo group in a metal complex. The parameters of the oxo-17O ligand, as well as other magnetic resonance parameters of [Mo 17O(SPh)4]- predicted by quasi-relativistic DFT calculations, were in good agreement with those obtained in experiment. From the electronic structure of the complex revealed by DFT, it follows that the SOMO is almost entirely molybdenum d(xy) and sulfur p, while the spin density on the oxo-17O is negative, determined by spin polarization mechanisms. The results of this work will enable direct experimental identification of the oxo ligand in a variety of chemical and biological systems.

Collective nuclear stabilization in single quantum dots by noncollinear hyperfine interaction

NASA Astrophysics Data System (ADS)

Yang, Wen; Sham, L. J.

2012-06-01

We present a theory of efficient suppression of the collective nuclear spin fluctuation, which prolongs the electron spin coherence time through the noncollinear hyperfine interaction between the nuclear spins and the hole spin. This provides a general paradigm to combat decoherence by direct control of environmental noise, and a possible solution to the puzzling observation of symmetric broadening of the absorption spectra in two recent experiments [Xu , Nature (London)NATUAS0028-083610.1038/nature08120 459, 1105 (2009) and Latta , Nature Phys.1745-247310.1038/nphys1363 5, 758 (2009)].

Hyperfine-resolved transition frequency list of fundamental vibration bands of H35Cl and H37Cl

NASA Astrophysics Data System (ADS)

Iwakuni, Kana; Sera, Hideyuki; Abe, Masashi; Sasada, Hiroyuki

2014-12-01

Sub-Doppler resolution spectroscopy of the fundamental vibration bands of H35Cl and H37Cl has been carried out from 87.1 to 89.9 THz. We have determined the absolute transition frequencies of the hyperfine-resolved R(0) to R(4) transitions with a typical uncertainty of 10 kHz. We have also yielded six molecular constants for each isotopomer in the vibrational excited state, which reproduce the determined frequencies with a standard deviation of about 10 kHz.

Assessment of the dental and skeletal effects of fan-type rapid maxillary expansion screw and Hyrax screw on craniofacial structures.

PubMed

Gopalakrishnan, Umarevathi; Sridhar, Premkumar

2017-01-01

The purpose of the study was to assess the skeletal and dental effects of fan-type rapid maxillary expansion (RME) appliance and Hyrax RME appliance on the craniofacial structures. The sample of the study included 12 patients with constricted maxillary arches. Acrylic bonded type of attachment was used for both groups. Changes in sagittal, vertical, and transverse relationship were assessed with lateral and frontal cephalograms, respectively. Intercanine and intermolar widths were measured with stone models. Pre- and immediate post-treatment records were statistically analyzed with Wilcoxon signed-rank test. The differences between the groups were evaluated using Mann-Whitney U-test. Since the data pertaining to intercanine width and intermolar width were normally distributed, parametric test of significance (unpaired t -test) was used to compare them. Results showed that Hyrax presented with significantly greater increments for both nasal cavity width and maxillary width when compared to fan-type RME. Both groups had retroclination of incisors. The increase in the intercanine width was almost similar in both groups. Fan-type RME caused only minimal expansion of the intermolar width when compared to the Hyrax. The ratio between the intercanine and intermolar width expansion was nearly 4:1 in the fan-type RME and 0.75:1 in Hyrax.

ANTIHYDROGEN PRODUCTION AND PRECISION SPECTROSCOPY WITH ATHENA/AD-1

DOE Office of Scientific and Technical Information (OSTI.GOV)

M. HOLZSCHEITER; C. AMSLER; ET AL

2000-11-01

CPT invariance is a fundamental property of quantum field theories in flat space-time. Principal consequences include the predictions that particles and their antiparticles have equal masses and lifetimes, and equal and opposite electric charges and magnetic moments. It also follows that the fine structure, hyperfine structure, and Lamb shifts of matter and antimatter bound systems should be identical. It is proposed to generate new stringent tests of CPT using precision spectroscopy on antihydrogen atoms. An experiment to produce antihydrogen at rest has been approved for running at the Antiproton Decelerator (AD) at CERN. We describe the fundamental features of thismore » experiment and the experimental approach to the first phase of the program, the formation and identification of low energy antihydrogen.« less

Methods for constraining fine structure constant evolution with OH microwave transitions.

PubMed

Darling, Jeremy

2003-07-04

We investigate the constraints that OH microwave transitions in megamasers and molecular absorbers at cosmological distances may place on the evolution of the fine structure constant alpha=e(2)/ variant Planck's over 2pi c. The centimeter OH transitions are a combination of hyperfine splitting and lambda doubling that can constrain the cosmic evolution of alpha from a single species, avoiding systematic errors in alpha measurements from multiple species which may have relative velocity offsets. The most promising method compares the 18 and 6 cm OH lines, includes a calibration of systematic errors, and offers multiple determinations of alpha in a single object. Comparisons of OH lines to the HI 21 cm line and CO rotational transitions also show promise.

Mössbauer analysis of the magnetic structure of a high-carbon austenitic steel upon deformation and under pressure

NASA Astrophysics Data System (ADS)

Shabashov, V. A.; Korshunov, L. G.; Zamatovskii, A. E.; Litvinov, A. V.

2007-10-01

A large plastic deformation of Hadfield steel (frictional action, shear under pressure, filing, and rolling) leads to the growth of an internal effective field at 57Fe nuclei, magnetic-degeneracy removal in the spectra, and delay of the paraprocess up to room temperature. In the Mössbauer spectrum of the 120G13 Hadfield steel, the reversible formation of a hyperfine structure, which is supposedly connected with magnetic ordering, has been detected in situ upon quasi-hydrostatic compression to 26 GPa. The observed growth of magnetic characteristics upon deformation and under high pressure is explained by the deformation-induced redistribution of carbon with the formation of short-range ordering of oxygen and manganese.

Studies of the spin Hamiltonian parameters and local structure for ZnO:Cu2+.

PubMed

Wu, Shao-Yi; Wei, Li-Hua; Zhang, Zhi-Hong; Wang, Xue-Feng; Hu, Yue-Xia

2008-12-15

The spin Hamiltonian parameters (the g factors and the hyperfine structure constants) and local structure for ZnO:Cu2+ are theoretically studied from the perturbation formulas of these parameters for a 3d9 ion under trigonally distorted tetrahedra. The ligand orbital and spin-orbit coupling contributions are taken into account from the cluster approach due to the significant covalency of the [CuO4](6-) cluster. According to the investigations, the impurity Cu2+ is suggested not to locate on the ideal Zn2+ site in ZnO but to undergo a slight outward displacement (approximately 0.01 angstroms) away from the ligand triangle along C3 axis. The calculated spin Hamiltonian parameters are in good agreement with the observed values. The validity of the above impurity displacement is also discussed.

Charge and Spin Currents in Open-Shell Molecules:  A Unified Description of NMR and EPR Observables.

PubMed

Soncini, Alessandro

2007-11-01

The theory of EPR hyperfine coupling tensors and NMR nuclear magnetic shielding tensors of open-shell molecules in the limit of vanishing spin-orbit coupling (e.g., for organic radicals) is analyzed in terms of spin and charge current density vector fields. The ab initio calculation of the spin and charge current density response has been implemented at the Restricted Open-Shell Hartree-Fock, Unrestricted Hartree-Fock, and unrestricted GGA-DFT level of theory. On the basis of this formalism, we introduce the definition of nuclear hyperfine coupling density, a scalar function of position providing a partition of the EPR observable over the molecular domain. Ab initio maps of spin and charge current density and hyperfine coupling density for small radicals are presented and discussed in order to illustrate the interpretative advantages of the newly introduced approach. Recent NMR experiments providing evidence for the existence of diatropic ring currents in the open-shell singlet pancake-bonded dimer of the neutral phenalenyl radical are directly assessed via the visualization of the induced current density.

One-electron oxidation of individual DNA bases and DNA base stacks.

PubMed

Close, David M

2010-02-04

In calculations performed with DFT there is a tendency of the purine cation to be delocalized over several bases in the stack. Attempts have been made to see if methods other than DFT can be used to calculate localized cations in stacks of purines, and to relate the calculated hyperfine couplings with known experimental results. To calculate reliable hyperfine couplings it is necessary to have an adequate description of spin polarization which means that electron correlation must be treated properly. UMP2 theory has been shown to be unreliable in estimating spin densities due to overestimates of the doubles correction. Therefore attempts have been made to use quadratic configuration interaction (UQCISD) methods to treat electron correlation. Calculations on the individual DNA bases are presented to show that with UQCISD methods it is possible to calculate hyperfine couplings in good agreement with the experimental results. However these UQCISD calculations are far more time-consuming than DFT calculations. Calculations are then extended to two stacked guanine bases. Preliminary calculations with UMP2 or UQCISD theory on two stacked guanines lead to a cation localized on a single guanine base.

133Cs-NMR study on aligned powder of competing spin chain compound Cs2Cu2Mo3O12

NASA Astrophysics Data System (ADS)

Yagi, A.; Matsui, K.; Goto, T.; Hase, M.; Sasaki, T.

2018-03-01

S = 1/2 competing spin chain compound Cs2Cu2Mo3O12 has two dominant exchange interactions of the nearest neighbouring ferromagnetic J 1 = 93 K and the second nearest neighbouring antiferromagnetic J 2 = +33 K, and is expected to show the nematic Tomonaga-Luttinger liquid (TLL) state under high magnetic field region. The recent theoretical study by Sato et al. has shown that in the nematic TLL state, the spin fluctuations are expected to be highly anisotropic, that is, its transverse component is suppressed. Our previous NMR study on the present system showed that the dominant contribution to nuclear spin relaxation comes from the longitudinal component. In order to conclude that the transverse component of spin fluctuations is suppressed, the knowledge of hyperfine coupling is indispensable. This article is solely devoted to investigate the hyperfine coupling of 133Cs-NMR site to prove that the anisotropic part of hyperfine coupling, which connects the nuclear spin relaxation with the transverse spin fluctuations is considerably large to be A an = +770 Oe/μB.

Optimised frequency modulation for continuous-wave optical magnetic resonance sensing using nitrogen-vacancy ensembles.

PubMed

El-Ella, Haitham A R; Ahmadi, Sepehr; Wojciechowski, Adam M; Huck, Alexander; Andersen, Ulrik L

2017-06-26

Magnetometers based on ensembles of nitrogen-vacancy centres are a promising platform for continuously sensing static and low-frequency magnetic fields. Their combination with phase-sensitive (lock-in) detection creates a highly versatile sensor with a sensitivity that is proportional to the derivative of the optical magnetic resonance lock-in spectrum, which is in turn dependant on the lock-in modulation parameters. Here we study the dependence of the lock-in spectral slope on the modulation of the spin-driving microwave field. Given the presence of the intrinsic nitrogen hyperfine spin transitions, we experimentally show that when the ratio between the hyperfine linewidth and their separation is ≳ 1/4, square-wave based frequency modulation generates the steepest slope at modulation depths exceeding the separation of the hyperfine lines, compared to sine-wave based modulation. We formulate a model for calculating lock-in spectra which shows excellent agreement with our experiments, and which shows that an optimum slope is achieved when the linewidth/separation ratio is ≲ 1/4 and the modulation depth is less then the resonance linewidth, irrespective of the modulation function used.

Temporal complexity in emission from Anderson localized lasers

NASA Astrophysics Data System (ADS)

Kumar, Randhir; Balasubrahmaniyam, M.; Alee, K. Shadak; Mujumdar, Sushil

2017-12-01

Anderson localization lasers exploit resonant cavities formed due to structural disorder. The inherent randomness in the structure of these cavities realizes a probability distribution in all cavity parameters such as quality factors, mode volumes, mode structures, and so on, implying resultant statistical fluctuations in the temporal behavior. Here we provide direct experimental measurements of temporal width distributions of Anderson localization lasing pulses in intrinsically and extrinsically disordered coupled-microresonator arrays. We first illustrate signature exponential decays in the spatial intensity distributions of the lasing modes that quantify their localized character, and then measure the temporal width distributions of the pulsed emission over several configurations. We observe a dependence of temporal widths on the disorder strength, wherein the widths show a single-peaked, left-skewed distribution in extrinsic disorder and a dual-peaked distribution in intrinsic disorder. We propose a model based on coupled rate equations for an emitter and an Anderson cavity with a random mode structure, which gives excellent quantitative and qualitative agreement with the experimental observations. The experimental and theoretical analyses bring to the fore the temporal complexity in Anderson-localization-based lasing systems.

Probing the coordination environment of Ti(3+) ions coordinated to nitrogen-containing Lewis bases.

PubMed

Morra, E; Maurelli, S; Chiesa, M; Van Doorslaer, S

2015-08-28

Multi-frequency continuous-wave and pulsed EPR techniques are employed to investigate the coordination of nitrogen-containing ligands to Ti(3+)-chloro complexes. Frozen solutions of TiCl3 and TiCl3(Py)3 dissolved in nitrogen-containing solvents have been investigated together with the TiCl3(Py)3 solid-state complex. For these different systems, the hyperfine and nuclear quadrupole data of Ti(3+)-bound (14)N nuclei are reported and discussed in the light of DFT computations, allowing for a detailed description of the microscopic structure of these systems.

Long-Lived Ultracold Molecules with Electric and Magnetic Dipole Moments.

PubMed

Rvachov, Timur M; Son, Hyungmok; Sommer, Ariel T; Ebadi, Sepehr; Park, Juliana J; Zwierlein, Martin W; Ketterle, Wolfgang; Jamison, Alan O

2017-10-06

We create fermionic dipolar ^{23}Na^{6}Li molecules in their triplet ground state from an ultracold mixture of ^{23}Na and ^{6}Li. Using magnetoassociation across a narrow Feshbach resonance followed by a two-photon stimulated Raman adiabatic passage to the triplet ground state, we produce 3×10^{4} ground state molecules in a spin-polarized state. We observe a lifetime of 4.6 s in an isolated molecular sample, approaching the p-wave universal rate limit. Electron spin resonance spectroscopy of the triplet state was used to determine the hyperfine structure of this previously unobserved molecular state.

Long-Lived Ultracold Molecules with Electric and Magnetic Dipole Moments

NASA Astrophysics Data System (ADS)

Rvachov, Timur M.; Son, Hyungmok; Sommer, Ariel T.; Ebadi, Sepehr; Park, Juliana J.; Zwierlein, Martin W.; Ketterle, Wolfgang; Jamison, Alan O.

2017-10-01

We create fermionic dipolar 23Na 6Li molecules in their triplet ground state from an ultracold mixture of 23Na and 6Li. Using magnetoassociation across a narrow Feshbach resonance followed by a two-photon stimulated Raman adiabatic passage to the triplet ground state, we produce 3 ×1 04 ground state molecules in a spin-polarized state. We observe a lifetime of 4.6 s in an isolated molecular sample, approaching the p -wave universal rate limit. Electron spin resonance spectroscopy of the triplet state was used to determine the hyperfine structure of this previously unobserved molecular state.

How water interacts with halogenated anesthetics: the rotational spectrum of isoflurane-water.

PubMed

Gou, Qian; Feng, Gang; Evangelisti, Luca; Vallejo-López, Montserrat; Spada, Lorenzo; Lesarri, Alberto; Cocinero, Emilio J; Caminati, Walther

2014-02-10

The rotational spectra of several isotopologues of the 1:1 complex between the inhaled anesthetic isoflurane and water have been recorded and analyzed by using Fourier transform microwave spectroscopy. The rotational spectrum showed a single rotamer, corresponding to the configuration in which the most stable conformer of isolated isoflurane is linked to the water molecule through an almost linear C-H⋅⋅⋅O weak hydrogen bond. All transitions display a hyperfine structure due to the (35)Cl (or (37)Cl) nuclear quadrupole effects. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Joint CPT and N resonance in compact atomic time standards

NASA Astrophysics Data System (ADS)

Crescimanno, Michael; Hohensee, Michael; Xiao, Yanhong; Phillips, David; Walsworth, Ron

2008-05-01

Currently development efforts towards small, low power atomic time standards use current-modulated VCSELs to generate phase-coherent optical sidebands that interrogate the hyperfine structure of alkali atoms such as rubidium. We describe and use a modified four-level quantum optics model to study the optimal operating regime of the joint CPT- and N-resonance clock. Resonant and non-resonant light shifts as well as modulation comb detuning effects play a key role in determining the optimal operating point of such clocks. We further show that our model is in good agreement with experimental tests performed using Rb-87 vapor cells.

Development of high-power dye laser chain

NASA Astrophysics Data System (ADS)

Konagai, Chikara; Kimura, Hironobu; Fukasawa, Teruichiro; Seki, Eiji; Abe, Motohisa; Mori, Hideo

2000-01-01

Copper vapor laser (CVL) pumped dye laser (DL) system, both in a master oscillator power amplifier (MOPA) configuration, has been developed for Atomic Vapor Isotope Separation program in Japan. Dye laser output power of about 500 W has been proved in long-term operations over 200 hours. High power fiber optic delivery system is utilized in order to efficiently transport kilowatt level CVL beams to the DL MOPA. Single model CVL pumped DL oscillator has been developed and worked for 200 hours within +/- 0.1 pm wavelength stability. Phase modulator for spreading spectrum to the linewidth of hyperfine structure has been developed and demonstrated.

Spin relaxation in quantum dots due to electron exchange with leads.

PubMed

Vorontsov, A B; Vavilov, M G

2008-11-28

We calculate spin relaxation rates in lateral quantum dot systems due to electron exchange between dots and leads. Using rate equations, we develop a theoretical description of the experimentally observed electric current in the spin blockade regime of double quantum dots. A single expression fits the entire current profile and describes the structure of both the conduction peaks and the suppressed ("valley") region. Extrinsic rates calculated here have to be taken into account for accurate extraction of intrinsic relaxation rates due to the spin-orbit and hyperfine spin scattering mechanisms from spin blockade measurements.

Pump-probe differencing technique for cavity-enhanced, noise-canceling saturation laser spectroscopy.

PubMed

de Vine, Glenn; McClelland, David E; Gray, Malcolm B; Close, John D

2005-05-15

We present an experimental technique that permits mechanical-noise-free, cavity-enhanced frequency measurements of an atomic transition and its hyperfine structure. We employ the 532-nm frequency-doubled output from a Nd:YAG laser and an iodine vapor cell. The cell is placed in a folded ring cavity (FRC) with counterpropagating pump and probe beams. The FRC is locked with the Pound-Drever-Hall technique. Mechanical noise is rejected by differencing the pump and probe signals. In addition, this differenced error signal provides a sensitive measure of differential nonlinearity within the FRC.

Design of multiplier-less sharp transition width non-uniform filter banks using gravitational search algorithm

NASA Astrophysics Data System (ADS)

Bindiya T., S.; Elias, Elizabeth

2015-01-01

In this paper, multiplier-less near-perfect reconstruction tree-structured filter banks are proposed. Filters with sharp transition width are preferred in filter banks in order to reduce the aliasing between adjacent channels. When sharp transition width filters are designed as conventional finite impulse response filters, the order of the filters will become very high leading to increased complexity. The frequency response masking (FRM) method is known to result in linear-phase sharp transition width filters with low complexity. It is found that the proposed design method, which is based on FRM, gives better results compared to the earlier reported results, in terms of the number of multipliers when sharp transition width filter banks are needed. To further reduce the complexity and power consumption, the tree-structured filter bank is made totally multiplier-less by converting the continuous filter bank coefficients to finite precision coefficients in the signed power of two space. This may lead to performance degradation and calls for the use of a suitable optimisation technique. In this paper, gravitational search algorithm is proposed to be used in the design of the multiplier-less tree-structured uniform as well as non-uniform filter banks. This design method results in uniform and non-uniform filter banks which are simple, alias-free, linear phase and multiplier-less and have sharp transition width.

Laser magnetic resonance in supersonic plasmas - The rotational spectrum of SH(+)

NASA Technical Reports Server (NTRS)

Hovde, David C.; Saykally, Richard J.

1987-01-01

The rotational spectrum of v = 0 and v = 1X3Sigma(-)SH(+) was measured by laser magnetic resonance. Rotationally cold (Tr = 30 K), vibrationally excited (Tv = 3000 K) ions were generated in a corona excited supersonic expansion. The use of this source to identify ion signals is described. Improved molecular parameters were obtained; term values are presented from which astrophysically important transitions may be calculated. Accurate hyperfine parameters for both vibrational levels were determined and the vibrational dependence of the Fermi contact interaction was resolved. The hyperfine parameters agree well with recent many-body perturbation theory calculations.

Radiation effects in x-irradiated hydroxy compounds

NASA Astrophysics Data System (ADS)

Budzinski, Edwin E.; Potter, William R.; Box, Harold C.

1980-01-01

Radiation effects are compared in single crystals of xylitol, sorbitol, and dulcitol x-irradiated at 4.2 °K. In xylitol and dulcitol, but not in sorbitol, a primary oxidation product is identified as an alkoxy radical. ENDOR measurements detected three proton hyperfine couplings associated with the alkoxy ESR absorption, one of which is attributed to a proton three bond lengths removed from the seat of unpaired spin density. Intermolecular trapping of electrons is observed in all three crystals. ENDOR measurements were made of the hyperfine couplings between the trapped electron and the hydroxy protons forming the trap.

Radiative improvement of the lattice nonrelativistic QCD action using the background field method and application to the hyperfine splitting of quarkonium states.

PubMed

Hammant, T C; Hart, A G; von Hippel, G M; Horgan, R R; Monahan, C J

2011-09-09

We present the first application of the background field method to nonrelativistic QCD (NRQCD) on the lattice in order to determine the one-loop radiative corrections to the coefficients of the NRQCD action in a manifestly gauge-covariant manner. The coefficients of the σ·B term in the NRQCD action and the four-fermion spin-spin interaction are computed at the one-loop level; the resulting shift of the hyperfine splitting of bottomonium is found to bring the lattice predictions in line with experiment.

Parallel Low-Loss Measurement of Multiple Atomic Qubits

NASA Astrophysics Data System (ADS)

Kwon, Minho; Ebert, Matthew F.; Walker, Thad G.; Saffman, M.

2017-11-01

We demonstrate low-loss measurement of the hyperfine ground state of rubidium atoms by state dependent fluorescence detection in a dipole trap array of five sites. The presence of atoms and their internal states are minimally altered by utilizing circularly polarized probe light and a strictly controlled quantization axis. We achieve mean state detection fidelity of 97% without correcting for imperfect state preparation or background losses, and 98.7% when corrected. After state detection and correction for background losses, the probability of atom loss due to the state measurement is <2 % and the initial hyperfine state is preserved with >98 % probability.

Split-cross-bridge resistor for testing for proper fabrication of integrated circuits

NASA Technical Reports Server (NTRS)

Buehler, M. G. (Inventor)

1985-01-01

An electrical testing structure and method is described whereby a test structure is fabricated on a large scale integrated circuit wafer along with the circuit components and has a van der Pauw cross resistor in conjunction with a bridge resistor and a split bridge resistor, the latter having two channels each a line width wide, corresponding to the line width of the wafer circuit components, and with the two channels separated by a space equal to the line spacing of the wafer circuit components. The testing structure has associated voltage and current contact pads arranged in a two by four array for conveniently passing currents through the test structure and measuring voltages at appropriate points to calculate the sheet resistance, line width, line spacing, and line pitch of the circuit components on the wafer electrically.

Addressable-Matrix Integrated-Circuit Test Structure

NASA Technical Reports Server (NTRS)

Sayah, Hoshyar R.; Buehler, Martin G.

1991-01-01

Method of quality control based on use of row- and column-addressable test structure speeds collection of data on widths of resistor lines and coverage of steps in integrated circuits. By use of straightforward mathematical model, line widths and step coverages deduced from measurements of electrical resistances in each of various combinations of lines, steps, and bridges addressable in test structure. Intended for use in evaluating processes and equipment used in manufacture of application-specific integrated circuits.

Solar system history as recorded in the Saturnian ring structure

NASA Technical Reports Server (NTRS)

Alfven, H.

1983-01-01

Holberg's analysis of the Voyager Saturn photographs in reflected and transparent light, and occultation data of stars seen through the rings are discussed. A hyperfine structure with 10,000 ringlets can be explained by the Baxter-Thompson negative diffusion. This gives the ringlets a stability which makes it possible to interpret them as fossils which originated at cosmogonic times. It is shown that the bulk structure can be explained by the combined cosmogonic shadows of the satellites Mimas and Janus and the Shepherd satellites. This structure originated at the transition from the plasma phase to the planetesimal phase. The shadows are not simple void regions but exhibit a characteristic signature. Parts of the fine structure, explained by Holberg as resonances with satellites, are interpreted as cosmogonic shadow effects. However, there are a number of ringlets which can neither be explained by cosmogonic nor by resonance effects. Analysis of ring data can reconstruct the plasma-planetesimal transition with an accuracy of a few percent. Previously announced in STAR as N84-12013

Solar system history as recorded in the Saturnian ring structure

NASA Technical Reports Server (NTRS)

Alfven, H.

1983-01-01

Holberg's analysis of the Voyager Saturn photographs in reflected and transparent light, and occultation data of stars seen through the rings are discussed. A hyperfine structure, with 10,000 ringlets can be explained by the Baxter-Thompson negative diffusion. This gives the ringlets a stability which makes it possible to interpret them as fossils, which originated at cosmogonic times. It is shown that the bulk structure can be explained by the combined cosmogonic shadows of the satellites Mimas, Janus and the Shepherd satellites. This structure originated at the transition from the plasma phase to the planetesimal phase. The shadows are not simple void regions but exhibit a characteristic signature. Parts of the fine structure, explained by Holberg as resonances with satellites, are interpreted as cosmogonic shadow effects. However, there are a number of ringlets which can neither be explained by cosmogonic nor by resonance effects. Analysis of ring data can reconstruct the plasma-planetesimal transition with an accuracy of a few percent.

Magnetic ordering in TmGa.

PubMed

Cadogan, J M; Stewart, G A; Muñoz Pérez, S; Cobas, R; Hansen, B R; Avdeev, M; Hutchison, W D

2014-03-19

We have determined the magnetic structure of the intermetallic compound TmGa by high-resolution neutron powder diffraction and (169)Tm Mössbauer spectroscopy. This compound crystallizes in the orthorhombic (Cmcm) CrB-type structure and its magnetic structure is characterized by magnetic order of the Tm sublattice along the a-axis. The initial magnetic ordering occurs at 15(1) K and yields an incommensurate antiferromagnetic structure described by the propagation vector k1 = [0 0.275(2) 0]. At 12 K the dominant ferromagnetic ordering of the Tm sublattice along the a-axis develops in what appears to be a first-order transition. At 3 K the magnetic structure of TmGa is predominantly ferromagnetic but a weakened incommensurate component remains. The ferromagnetic Tm moment reaches 6.7(2) μB at 3 K and the amplitude of the remaining incommensurate component is 2.7(4) μB. The (169)Tm hyperfine magnetic field at 5 K is 631(1) T.

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

NASA Astrophysics Data System (ADS)

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

2017-10-01

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

A review of atomic clock technology, the performance capability of present spaceborne and terrestrial atomic clocks, and a look toward the future

NASA Technical Reports Server (NTRS)

Vessot, Robert F. C.

1989-01-01

Clocks have played a strong role in the development of general relativity. The concept of the proper clock is presently best realized by atomic clocks, whose development as precision instruments has evolved very rapidly in the last decades. To put a historical prospective on this progress since the year AD 1000, the time stability of various clocks expressed in terms of seconds of time error over one day of operation is shown. This stability of operation must not be confused with accuracy. Stability refers to the constancy of a clock operation as compared to that of some other clocks that serve as time references. Accuracy, on the other hand, is the ability to reproduce a previously defined frequency. The issues are outlined that must be considered when accuracy and stability of clocks and oscillators are studied. In general, the most widely used resonances result from the hyperfine interaction of the nuclear magnetic dipole moment and that of the outermost electron, which is characteristic of hydrogen and the alkali atoms. During the past decade hyperfine resonances of ions have also been used. The principal reason for both the accuracy and the stability of atomic clocks is the ability of obtaining very narrow hyperfine transition resonances by isolating the atom in some way so that only the applied stimulating microwave magnetic field is a significant source of perturbation. It is also important to make resonance transitions among hyperfine magnetic sublevels where separation is independent, at least to first order, of the magnetic field. In the case of ions stored in traps operating at high magnetic fields, one selects the trapping field to be consistent with a field-independent transition of the trapped atoms.

High-field Overhauser dynamic nuclear polarization in silicon below the metal-insulator transition.

PubMed

Dementyev, Anatoly E; Cory, David G; Ramanathan, Chandrasekhar

2011-04-21

Single crystal silicon is an excellent system to explore dynamic nuclear polarization (DNP), as it exhibits a continuum of properties from metallic to insulating as a function of doping concentration and temperature. At low doping concentrations DNP has been observed to occur via the solid effect, while at very high-doping concentrations an Overhauser mechanism is responsible. Here we report the hyperpolarization of (29)Si in n-doped silicon crystals, with doping concentrations in the range of (1-3) × 10(17) cm(-3). In this regime exchange interactions between donors become extremely important. The sign of the enhancement in our experiments and its frequency dependence suggest that the (29)Si spins are directly polarized by donor electrons via an Overhauser mechanism within exchange-coupled donor clusters. The exchange interaction between donors only needs to be larger than the silicon hyperfine interaction (typically much smaller than the donor hyperfine coupling) to enable this Overhauser mechanism. Nuclear polarization enhancement is observed for a range of donor clusters in which the exchange energy is comparable to the donor hyperfine interaction. The DNP dynamics are characterized by a single exponential time constant that depends on the microwave power, indicating that the Overhauser mechanism is a rate-limiting step. Since only about 2% of the silicon nuclei are located within 1 Bohr radius of the donor electron, nuclear spin diffusion is important in transferring the polarization to all the spins. However, the spin-diffusion time is much shorter than the Overhauser time due to the relatively weak silicon hyperfine coupling strength. In a 2.35 T magnetic field at 1.1 K, we observed a DNP enhancement of 244 ± 84 resulting in a silicon polarization of 10.4 ± 3.4% following 2 h of microwave irradiation.

Using Hyperfine Electron Paramagnetic Resonance Spectroscopy to Define the Proton-Coupled Electron Transfer Reaction at Fe-S Cluster N2 in Respiratory Complex I.

PubMed

Le Breton, Nolwenn; Wright, John J; Jones, Andrew J Y; Salvadori, Enrico; Bridges, Hannah R; Hirst, Judy; Roessler, Maxie M

2017-11-15

Energy-transducing respiratory complex I (NADH:ubiquinone oxidoreductase) is one of the largest and most complicated enzymes in mammalian cells. Here, we used hyperfine electron paramagnetic resonance (EPR) spectroscopic methods, combined with site-directed mutagenesis, to determine the mechanism of a single proton-coupled electron transfer reaction at one of eight iron-sulfur clusters in complex I, [4Fe-4S] cluster N2. N2 is the terminal cluster of the enzyme's intramolecular electron-transfer chain and the electron donor to ubiquinone. Because of its position and pH-dependent reduction potential, N2 has long been considered a candidate for the elusive "energy-coupling" site in complex I at which energy generated by the redox reaction is used to initiate proton translocation. Here, we used hyperfine sublevel correlation (HYSCORE) spectroscopy, including relaxation-filtered hyperfine and single-matched resonance transfer (SMART) HYSCORE, to detect two weakly coupled exchangeable protons near N2. We assign the larger coupling with A( 1 H) = [-3.0, -3.0, 8.7] MHz to the exchangeable proton of a conserved histidine and conclude that the histidine is hydrogen-bonded to N2, tuning its reduction potential. The histidine protonation state responds to the cluster oxidation state, but the two are not coupled sufficiently strongly to catalyze a stoichiometric and efficient energy transduction reaction. We thus exclude cluster N2, despite its proton-coupled electron transfer chemistry, as the energy-coupling site in complex I. Our work demonstrates the capability of pulse EPR methods for providing detailed information on the properties of individual protons in even the most challenging of energy-converting enzymes.

Second rank direction cosine spherical tensor operators and the nuclear electric quadrupole hyperfine structure Hamiltonian of rotating molecules

NASA Astrophysics Data System (ADS)

di Lauro, C.

2018-03-01

Transformations of vector or tensor properties from a space-fixed to a molecule-fixed axis system are often required in the study of rotating molecules. Spherical components λμ,ν of a first rank irreducible tensor can be obtained from the direction cosines between the two axis systems, and a second rank tensor with spherical components λμ,ν(2) can be built from the direct product λ × λ. It is shown that the treatment of the interaction between molecular rotation and the electric quadrupole of a nucleus is greatly simplified, if the coefficients in the axis-system transformation of the gradient of the electric field of the outer charges at the coupled nucleus are arranged as spherical components λμ,ν(2). Then the reduced matrix elements of the field gradient operators in a symmetric top eigenfunction basis, including their dependence on the molecule-fixed z-angular momentum component k, can be determined from the knowledge of those of λ(2) . The hyperfine structure Hamiltonian Hq is expressed as the sum of terms characterized each by a value of the molecule-fixed index ν, whose matrix elements obey the rule Δk = ν. Some of these terms may vanish because of molecular symmetry, and the specific cases of linear and symmetric top molecules, orthorhombic molecules, and molecules with symmetry lower than orthorhombic are considered. Each ν-term consists of a contraction of the rotational tensor λ(2) and the nuclear quadrupole tensor in the space-fixed frame, and its matrix elements in the rotation-nuclear spin coupled representation can be determined by the standard spherical tensor methods.

Mössbauer spectroscopy and the structure of interfaces on the atomic scale in metallic nanosystems

NASA Astrophysics Data System (ADS)

Uzdin, V. M.

2007-10-01

A microscopic model of the formation of an alloy on the interface has been constructed, which takes into account the exchange of atoms with the substrate atoms and the “floating up” of the latter into the upper layers in the process of epitaxial growth. The self-consistent calculations of atomic magnetic moments of spatially inhomogeneous structures obtained in this case are used for the interpretation of data of Mössbauer spectroscopy. The proposed scenario of mixing leads to the appearance of a preferred direction in the sample and the asymmetry of interfaces in the direction of epitaxial growth. In the multilayer M 1/ M 2 ( M 1,2 = Fe, Cr, V, Sn, or Ag) systems, this asymmetry makes it possible to understand the difference in the magnetic behavior of M 1-on M 2 and M 2-on- M 1 interfaces which has been observed experimentally. The correlation between the calculated distributions of magnetic moments and the measured distributions of hyperfine fields at iron atoms confirms the assumption about their proportionality for a broad class of metallic multilayer systems. However, a linear decrease of hyperfine fields at the 57Fe nuclei with increasing number of impurity atoms among the nearest and next-nearest neighbors is not confirmed for Fe/Cr systems, although is correct in Fe/V superlattices. In the Fe/Cr multilayer systems, the experimentally measured value of magnetoresistance grows with increasing fraction of the “floated up” atoms of 57Fe. Thus, it is the bulk scattering by impurity atoms that gives the basic contribution to the effect of giant magnetoresistance. The problem of the influence of mixing and adsorption of hydrogen in the vanadium layers on the state of the spin-density wave in V/Cr superlattices has been considered.

Terahertz Spectroscopy of CrH (X 6Σ+) and AlH (X 1Σ+)

NASA Astrophysics Data System (ADS)

Halfen, D. T.; Ziurys, L. M.

2016-12-01

New laboratory measurements of hydrides have been carried out using terahertz direct absorption spectroscopy. Spin components of the N=2≤ftarrow 1 transition of the free radical CrH (X 6Σ+) have been recorded in the range 730-734 GHz, as well as a new measurement of the J=2≤ftarrow 1 line of AlH (X 1Σ+) near 755 GHz. Both species were created in an AC discharge of H2, argon, and metal vapor. For CrH, the chromium source was Cr(CO)6, while AlH was produced from Al(CH3)3. The J=4.5≤ftarrow 3.5 and 3.5≤ftarrow 2.5 fine-structure components were recorded for CrH, each which consists of resolved proton hyperfine doublets. For AlH, the two main quadrupole components, F=4.5≤ftarrow 3.5 and 3.5≤ftarrow 2.5, of the J=2≤ftarrow 1 transition were observed as blended features. These data were analyzed with previous 1≤ftarrow 0 millimeter/submillimeter measurements with 6Σ and 1Σ Hamiltonians for chromium and aluminum hydrides, respectively, and rotational, fine-structure (CrH only), and hyperfine constants were derived. The new measurements have resulted in refined spectroscopic parameters for both species, as well as direct measurement of the respective 2≤ftarrow 1 rotational transitions. This work also resolves a 10 MHz discrepancy in the frequency of the AlH line. CrH and AlH have already been observed in the photospheres of stars via their electronic transitions. These data will facilitate their discovery at submillimeter/terahertz wavelengths in circumstellar envelopes and perhaps in diffuse clouds.

Collisional Processes Probed by using Resonant Four-Wave Mixing Spectroscopy

NASA Astrophysics Data System (ADS)

McCormack, E. F.; Stampanoni, A.; Hemmerling, B.

2000-06-01

Collisionally-induced decay processes in excited-state nitric oxide (NO) have been measured by using time-resolved two-color, resonant four-wave mixing (TC-RFWM) spectroscopy and polarization spectroscopy (PS). Markedly different time dependencies were observed in the data obtained by using TC-RFWM when compared to PS. Oscillations in the PS signal as a function of delay between the pump and probe laser pulses were observed and it was determined that their characteristics depend very sensitively on laser polarization. Analysis reveals that the oscillations in the decay curves are due to coherent excitation of unresolved hyperfine structure in the A state of NO. A comparison of beat frequencies obtained by taking Fourier transforms of the time data to the predicted hyperfine structure of the A state support this explanation. Further, based on a time-dependent model of PS as a FWM process, the signal’s dependence as a function of time on polarization configuration and excitation scheme can be predicted. By using the beat frequency values, fits of the model results to experimental decay curves for different pressures allows a study of the quenching rate in the A state due to collisional processes. A comparison of the PS data to laser-induced fluorescence decay measurements reveals different decay rates which suggests that the PS signal decay depends on the orientation and alignment of the excited molecules. The different behavior of the decay curves obtained by using TC-RFWM and PS can be understood in terms of the various contributions to the decay as described by the model and this has a direct bearing on which technique is preferable for a given set of experimental parameters.

Electron paramagnetic resonance and density-functional theory studies of Cu(II)-bis(oxamato) complexes.

PubMed

Bräuer, Björn; Weigend, Florian; Fittipaldi, Maria; Gatteschi, Dante; Reijerse, Edward J; Guerri, Annalisa; Ciattini, Samuele; Salvan, Georgeta; Rüffer, Tobias

2008-08-04

In this work we present the investigation of the influence of electronic and structural variations induced by varying the N,N'-bridge on the magnetic properties of Cu(II)- bis(oxamato) complexes. For this study the complexes [Cu(opba)] (2-) ( 1, opba = o-phenylene- bis(oxamato)), [Cu(nabo)] (2-) ( 2, nabo = 2,3-naphthalene- bis(oxamato)), [Cu(acbo)] (2-) ( 3, acbo = 2,3-anthrachinone- bis(oxamato)), [Cu(pba)] (2-) ( 4, pba = propylene- bis(oxamato)), [Cu(obbo)] (2-) ( 5, obbo = o-benzyl- bis(oxamato)), and [Cu(npbo)] (2-) ( 6, npbo = 1,8-naphthalene- bis(oxamato)), and the respective structurally isomorphic Ni(II) complexes ( 8- 13) have been prepared as ( (n)Bu 4N) (+) salts. The new complex ( (n)Bu 4N) 2[Cu(R-bnbo)].2H 2O ( 7, R-bnbo = (R)-1,1'-binaphthalene-2,2'- bis(oxamato)) was synthesized and is the first chiral complex in the series of Cu(II)-bis(oxamato) complexes. The molecular structure of 7 has been determined by single crystal X-ray analysis. The Cu(II) ions of the complexes 1- 7 are eta (4)(kappa (2) N, kappa (2) O) coordinated with a more or less distorted square planar geometry for 1- 6 and a distorted tetrahedral geometry for 7. Using pulsed Electron Nuclear Double Resonance on complex 6, detailed information about the relative orientation of the hyperfine ( A) and nuclear quadrupole tensors ( Q) of the coordinating nitrogens with respect to the g tensor were obtained. Electron Paramagnetic Resonance studies in the X, Q, and W-band at variable temperatures were carried out to extract g and A values of N ligands and Cu ion for 1- 7. The hyperfine values were interpreted in terms of spin population on the corresponding atoms. The obtained trends of the spin population for the monomeric building blocks were shown to correlate to the trends obtained in the dependence of the exchange interaction of the corresponding trinuclear complexes on their geometry.

7 CFR 29.1085 - Width.

Code of Federal Regulations, 2010 CFR

2010-01-01

....) Elements Degrees Maturity Immature Unripe Mature Ripe Mellow. Leaf structure Tight Close Firm Open Body... Type 92) § 29.1085 Width. The relative breadth of a tobacco leaf expressed in relation to its length...

7 CFR 29.1085 - Width.

Code of Federal Regulations, 2013 CFR

2013-01-01

....) Elements Degrees Maturity Immature Unripe Mature Ripe Mellow. Leaf structure Tight Close Firm Open Body... Type 92) § 29.1085 Width. The relative breadth of a tobacco leaf expressed in relation to its length...

7 CFR 29.1085 - Width.

Code of Federal Regulations, 2011 CFR

2011-01-01

....) Elements Degrees Maturity Immature Unripe Mature Ripe Mellow. Leaf structure Tight Close Firm Open Body... Type 92) § 29.1085 Width. The relative breadth of a tobacco leaf expressed in relation to its length...

7 CFR 29.1085 - Width.

Code of Federal Regulations, 2014 CFR

2014-01-01

....) Elements Degrees Maturity Immature Unripe Mature Ripe Mellow. Leaf structure Tight Close Firm Open Body... Type 92) § 29.1085 Width. The relative breadth of a tobacco leaf expressed in relation to its length...

7 CFR 29.1085 - Width.

Code of Federal Regulations, 2012 CFR

2012-01-01

....) Elements Degrees Maturity Immature Unripe Mature Ripe Mellow. Leaf structure Tight Close Firm Open Body... Type 92) § 29.1085 Width. The relative breadth of a tobacco leaf expressed in relation to its length...

Zeeman structure of red lines of lanthanum observed by laser spectroscopy methods

NASA Astrophysics Data System (ADS)

Sobolewski, Ł. M.; Windholz, L.; Kwela, J.

2017-11-01

Laser Induced Fluorescence (LIF) Spectroscopy and Optogalvanic (OG) Spectroscopy were used for the investigation of the Zeeman hyperfine (hf) structures of 27 spectral lines of La I in the wavelength range between 633.86 and 667.54 nm. As a source of free La atoms a hollow cathode discharge lamp was used. Spectra were recorded in the presence of a relatively weak magnetic field (about 800G) produced by a permanent magnet, for two linear polarization directions of the exciting laser beam. As a result of the measurements, we determined for the first time the Landé gJ- factors of 18 levels of La I. The Landé gJ- factors of 12 other levels were re-investigated and determined with higher accuracy.

Structural and Mössbauer analysis of pure and Ce-Dy doped cobalt ferrite nanoparticles

NASA Astrophysics Data System (ADS)

Hashim, Mohd.; Meena, Sher Singh; Kumar, Shalendra; Ahmed, Ateeq; Bhatt, Pramod

2018-05-01

Ce and Dy doped Cobalt ferrites with the chemical composition CoCexDyxFe2-2xO4 (x = 0.00 and 0.04) were synthesized via the chemical route using citrate-gel auto-combustion method. The structural analysis has been carried out with the help of x-ray diffraction (XRD). Formation of spinel cubic structure of the ferrites was confirmed by XRD analysis. Mössbauer spectra were recorded for both samples at room temperature. Presence of the well resolved sextet spectra corresponding to A and B sub-lattice clearly shows that both the samples have ferrimagnetic ordering at room temperature. Isomer shift observed from fitting of the Mössbauer spectra infers that Fe3+ ions are in high valence state. The decrease in the hyperfine field due to the doping of Ce and Dy clearly showed that magnetic interactions diluted due to the doping of Ce and Dy ions.

Evaluation of Spin Hamiltonian Parameters and Local Structure of Cu2+-doped Ion in xK2SO4-(50 - x)Na2SO4-50ZnSO4 Glasses with Various K2SO4 Concentrations

NASA Astrophysics Data System (ADS)

Ding, Ch.-Ch.; Wu, Sh.-Y.; Xu, Y.-Q.; Zhang, L.-J.; He, J.-J.

2018-03-01

The spin Hamiltonian parameters (SHPs), i.e., g factors and hyperfine structure constants, and local structures are theoretically studied by analyzing tetragonally elongated 3d9 clusters for Cu2+ in xK2SO4-(50 - x)Na2SO4-50ZnSO4 glasses with various K2SO4 concentrations x. The concentration dependences of the SHPs are attributed to the parabolic decreases of the cubic field parameter Dq, orbital reduction factor k, relative tetragonal elongation ratio τ, and core polarization constant κ with x. The [CuO6]10- clusters are found to undergo significant elongations of about 17% due to the Jahn-Teller effect. The calculated cubic field splittings and the SHPs at various concentrations agree well with the experimental data.

Structure of massive star forming clumps from the Red MSX Source Survey

NASA Astrophysics Data System (ADS)

Figura, Charles C.; Urquhart, J. S.; Morgan, L.

2014-01-01

We present ammonia (1,1) and (2,2) emission maps of 61 high-mass star forming regions drawn from the Red MSX Source (RMS) Survey and observed with the Green Bank Telescope's K-Band Focal Plane Array. We use these observations to investigate the spatial distribution of the environmental conditions associated with this sample of embedded massive young stellar objects (MYSOs). Ammonia is an excellent high-density tracer of star-forming regions as its hyperfine structure allows relatively simple characterisation of the molecular environment. These maps are used to measure the column density, kinetic gas temperature distributions and velocity structure across these regions. We compare the distribution of these properties to that of the associated dust and mid-infrared emission traced by the ATLASGAL 870 micron emission maps and the Spitzer GLIMPSE IRAC images. We present a summary of these results and highlight some of more interesting finds.

Stabilized 1762 nm Laser for Barium Ion Qubit Readout via Adiabatic Passage

NASA Astrophysics Data System (ADS)

Salacka, Joanna

2008-05-01

Trapped ions are one of the most promising candidates for the implementation of quantum computation. We are trapping single ions of Ba^137 to serve as our qubit, because the hyperfine structure of its ground state and its various visible-wavelength transitions make it favorable for quantum computation. The two hyperfine ground levels will serve as our |1> and |0> qubit states. The readout of the qubit will be accomplished by first selectively shelving the ion directly to the metastable 5D5/2 state using a 1762 nm narrow band fiber laser. Next, the cooling and repumping lasers are turned on and the fluorescence of the ion is measured. Since the 5D5/2 state is decoupled from the laser cooling transitions, the ion will remain dark when shelved. Thus if fluorescence is seen we know that the qubit was in the |0> state, and if no fluorescence is seen it was in the |1> state. The laser is actively stabilized to a temperature-controlled, high-finesse 1.76 um Zerodur optical cavity. The shelving to the 5D5/2 state is most efficiently achieved with adiabatic passage, which requires a smooth scan of the laser frequency across the transition resonance. To accomplish this, the laser frequency is modulated by an AOM driven by a smooth frequency sweep of adjustable amplitude and duration.

Characterization of methanol as a magnetic field tracer in star-forming regions

NASA Astrophysics Data System (ADS)

Lankhaar, Boy; Vlemmings, Wouter; Surcis, Gabriele; van Langevelde, Huib Jan; Groenenboom, Gerrit C.; van der Avoird, Ad

2018-02-01

Magnetic fields play an important role during star formation1. Direct magnetic field strength observations have proven particularly challenging in the extremely dynamic protostellar phase2-4. Because of their occurrence in the densest parts of star-forming regions, masers, through polarization observations, are the main source of magnetic field strength and morphology measurements around protostars2. Of all maser species, methanol is one of the strongest and most abundant tracers of gas around high-mass protostellar disks and in outflows. However, as experimental determination of the magnetic characteristics of methanol has remained largely unsuccessful5, a robust magnetic field strength analysis of these regions could hitherto not be performed. Here, we report a quantitative theoretical model of the magnetic properties of methanol, including the complicated hyperfine structure that results from its internal rotation6. We show that the large range in values of the Landé g factors of the hyperfine components of each maser line lead to conclusions that differ substantially from the current interpretation based on a single effective g factor. These conclusions are more consistent with other observations7,8 and confirm the presence of dynamically important magnetic fields around protostars. Additionally, our calculations show that (nonlinear) Zeeman effects must be taken into account to further enhance the accuracy of cosmological electron-to-proton mass ratio determinations using methanol9-12.

Electron paramagnetic resonance study of neutral Mg acceptors in β-Ga2O3 crystals

NASA Astrophysics Data System (ADS)

Kananen, B. E.; Halliburton, L. E.; Scherrer, E. M.; Stevens, K. T.; Foundos, G. K.; Chang, K. B.; Giles, N. C.

2017-08-01

Electron paramagnetic resonance (EPR) is used to directly observe and characterize neutral Mg acceptors ( M gGa0 ) in a β-Ga2O3 crystal. These acceptors, best considered as small polarons, are produced when the Mg-doped crystal is irradiated at or near 77 K with x rays. During the irradiation, neutral acceptors are formed when holes are trapped at singly ionized Mg acceptors ( M gGa- ). Unintentionally present Fe3+ (3d5) and Cr3+ (3d3) transition-metal ions serve as the corresponding electron traps. The hole is localized in a nonbonding p orbital on a threefold-coordinated oxygen ion adjacent to an Mg ion at a sixfold-coordinated Ga site. These M gGa0 acceptors (S = 1/2) have a slightly anisotropic g matrix (principal values are 2.0038, 2.0153, and 2.0371). There is also partially resolved 69Ga and 71Ga hyperfine structure resulting from unequal interactions with the two Ga ions adjacent to the hole. With the magnetic field along the a direction, hyperfine parameters are 2.61 and 1.18 mT for the 69Ga nuclei at the two inequivalent neighboring Ga sites. The M gGa0 acceptors thermally convert back to their nonparamagnetic M gGa- charge state when the temperature of the crystal is raised above approximately 250 K.

Studies of radiative transfer in planetary atmospheres

NASA Technical Reports Server (NTRS)

Irvine, W. M.; Schloerb, F. P.

1986-01-01

The research emphasis during the period of this report has been on radio observations of comets, related to the International Halley Watch. Observations of the 18 cm lambda-doublet of OH have been carried out monthly. Both of the 1667 and 1665 MHz lines have been repeatedly detected for Comets Halley, Giacobini-Zinner, Thiele, and Hartley-Good. The first astronomical detection of the weak satellite line at 1720 MHz was made for P/Halley. These data promise to supply the highest signal-to-noise-ratio data over an extended period ever obtained for cometary radio observations. Analysis will provide gas production rates as a function of heliocentric distance and allow for detailed comparisons with the OH excitation model involving ultraviolet pumping. In the case of Halley, the lines appear quite symmetric, usually being centered within 0.1 km/s with respect to the nominal nuclear velocity. Line widths have been typically within 10% of 2 km/s. There is thus little evidence for asymmetric emission in the data obtained to date. It seems likely that non-steady-state models of the coma will be required to interpret the data. Evidence for significant departures from the LTE hyperfine ratios was found for Comet Giacobini-Zinner. Smaller, but nonetheless significant, deviations have been found for Comet Halley.

Rubidium Cloud Size in a Magneto-Optical Trap

NASA Astrophysics Data System (ADS)

Chatwin-Davies, A.; Kong, T.; Behr, J. A.; Gorelov, A.; Pearson, M.

2008-05-01

Preparations for a search for exotic 20 - 556 keV-mass particles emitted during the nuclear 2-body decay of ^86Rb confined in a magneto-optical trap (MOT) are underway at TRIUMF. Such emissions would correspond to a peak in the recoil momentum distribution at a momentum lower than that caused by 556 keV γ emission. The stable isotope ^85Rb is being used to optimize the experimental apparatus since its atomic hyperfine splitting is similar to that of ^86Rb, producing similar laser cooling properties. The size of the cloud of trapped atoms directly affects the achievable momentum resolution of the recoil and must hence be minimized. A Doppler-limited model for cloud size ignoring cooling beyond that generated by the photon scattering force is presented and compared with experimental data. Analysis suggested reducing the intensity and red-detuning from resonance of the trapping light from optimal values for atom collection. We also better balanced the power in the trapping beams. Recent data in disagreement with a Doppler-limited theory indicate sub-Doppler cooling mechanisms (J. Dalibard and C. Cohen-Tannoudji, J. Opt. Soc. Am. B 6, 2023 (1989)) are now at work. A cloud full width at half-maximum of less than 0.25 mm has since been achieved.

Structural, magneto-optical properties and cation distribution of SrBi{sub x}La{sub x}Y{sub x}Fe{sub 12−3x}O{sub 19} (0.0 ≤ x ≤ 0.33) hexaferrites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Auwal, I.A.; Güngüneş, H.; Güner, S.

Highlights: • SrBi{sub x}La{sub x}Y{sub x}Fe{sub 12−3x}O{sub 19} (0.0 ≤ x ≤ 0.33) hexaferrites have been prepared by sol-gel autocombustion. • XRD patterns show that SrBi{sub x}La{sub x}Y{sub x}Fe{sub 12−3x}O{sub 19} (0.0 ≤ x ≤ 0.33) hexaferrites exhibit hexagonal structure. • The intrinsic coercivity (H{sub ci}) above 15000 Oe reveals that all samples are magnetically hard materials. - Abstract: SrBi{sub x}La{sub x}Y{sub x}Fe{sub 12−3x}O{sub 19} (0.0 ≤ x ≤ 0.33) hexaferrites were produced via sol-gel auto combustion. XRD patterns show that all the samples are single-phase M-type strontium hexaferrite (SrM). The magnetic hysteresis (σ-H) loops revealed the ferromagnetic nature ofmore » nanoparticles (NPs). The coercive field decreases from 4740 Oe to 2720 Oe with increasing ion content. In particular, SrBi{sub x}La{sub x}Y{sub x}Fe{sub 12−3x}O{sub 19} NPs with x = 0.0, 0.1, 0.2 have suitable magnetic characteristics (σ{sub s} = 62.03–64.72 emu/g and H{sub c} = 3105–4740 Oe) for magnetic recording. The intrinsic coercivity (H{sub ci}) above 15000 Oe reveals that all samples are magnetically hard materials. Tauc plots were used to specify the direct optical energy band gap (E{sub g}) of NPs. The E{sub g} values are between 1.76 eV and 1.85 eV. {sup 57}Fe Mössbauer spectroscopy data, the variation in line width, isomer shift, quadrupole splitting, relative area and hyperfine magnetic field values on Bi{sup 3+} La{sup 3+} and Y{sup 3+} substitutions have been determined.« less

Low-bias flat band-stop filter based on velocity modulated gaussian graphene superlattice

NASA Astrophysics Data System (ADS)

Sattari-Esfahlan, S. M.; Shojaei, S.

2018-05-01

Transport properties of biased planar Gaussian graphene superlattice (PGGSL) with Fermi velocity barrier is investigated by transfer matrix method (TMM). It is observed that enlargement of bias voltage over miniband width breaks the miniband to WSLs leads to suppressing resonant tunneling. Transmission spectrum shows flat wide stop-band property controllable by external bias voltage with stop-band width of near 200 meV. The simulations demonstrate that strong velocity barriers prevent tunneling of Dirac electrons leading to controllable enhancement of stop-band width. By increasing ratio of Fermi velocity in barriers to wells υc stop-band width increase. As wide transmission stop-band width (BWT) of filter is tunable from 40 meV to 340 meV is obtained by enhancing ratio of υc from 0.2 to 1.5, respectively. Proposed structure suggests easy tunable wide band-stop electronic filter with a modulated flat stop-band characteristic by height of electrostatic barrier and structural parameters. Robust sensitivity of band width to velocity barrier intensity in certain bias voltages and flat band feature of proposed filter may be opens novel venue in GSL based flat band low noise filters and velocity modulation devices.

Ultra-short beam expander with segmented curvature control: the emergence of a semi-lens

DOE PAGES

Abbaslou, Siamak; Gatdula, Robert; Lu, Ming; ...

2017-01-01

We introduce direct curvature control in designing a segmented beam expander, and explore novel design possibilities for ultra-compact beam expanders. Assisted by the particle swarm optimization algorithm, we search for an optimal curvature-controlled multi-segment taper that maintains width continuity. Counterintuitively, the optimization yields a structure with abrupt width discontinuity and width compression features. Through spatial phase and parameterized analysis, a semi-lens feature is revealed that helps to flatten the wavefront at the output end for higher coupling efficiency. Such functionality cannot be achieved by normal tapers in a short distance. The structure is fabricated and characterized experimentally. By a figuremore » of merit that accounts for expansion ratio, length, and efficiency, this structure outperforms an adiabatic taper by 9 times.« less

Hartree-Fock investigation of muon trapping in the chemical ferromagnet 4-(/p-chlorobenzylideneamino)-TEMPO

NASA Astrophysics Data System (ADS)

Jeong, Junho; Briere, Tina M.; Sahoo, N.; Das, T. P.; Ohira, Seiko; Nishiyama, K.; Nagamine, K.

2000-08-01

First-principles unrestricted Hartree-Fock theory is used to obtain the trapping sites for muon and muonium in ferromagnetic p-Cl-Ph-CHN-TEMPO (4-( p-chlorobenzylideneamino)- 2,2,6,6-tetramethylpiperidin-1-yloxyl) and the hyperfine interaction tensors for these sites. Using the calculated hyperfine interactions to fit the two experimentally observed muon spin rotation frequencies, it has been concluded that the two most likely candidates for explaining the experimental data are a muon trapped at the chlorine site and a singlet muonium state at the radical oxygen. The direction of the easy axis is also determined.

Hyperfine state entanglement of spinor BEC and scattering atom

NASA Astrophysics Data System (ADS)

Li, Zhibing; Bao, Chengguang; Zheng, Wei

2018-05-01

Condensate of spin-1 atoms frozen in a unique spatial mode may possess large internal degrees of freedom. The scattering amplitudes of polarized cold atoms scattered by the condensate are obtained with the method of fractional parentage coefficients that treats the spin degrees of freedom rigorously. Channels with scattering cross sections enhanced by the square of the atom number of the condensate are found. Entanglement between the condensate and the propagating atom can be established by scattering. Entanglement entropy is analytically obtained for arbitrary initial states. Our results also give a hint for the establishment of quantum thermal ensembles in the hyperfine space of spin states.

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.

High-Fidelity Quantum Logic Gates Using Trapped-Ion Hyperfine Qubits.

PubMed

Ballance, C J; Harty, T P; Linke, N M; Sepiol, M A; Lucas, D M

2016-08-05

We demonstrate laser-driven two-qubit and single-qubit logic gates with respective fidelities 99.9(1)% and 99.9934(3)%, significantly above the ≈99% minimum threshold level required for fault-tolerant quantum computation, using qubits stored in hyperfine ground states of calcium-43 ions held in a room-temperature trap. We study the speed-fidelity trade-off for the two-qubit gate, for gate times between 3.8  μs and 520  μs, and develop a theoretical error model which is consistent with the data and which allows us to identify the principal technical sources of infidelity.

Iron Atoms in Cr-Mn Antiferromagnetic Matrix

NASA Astrophysics Data System (ADS)

Szymański, K.; Satuła, D.; Dobrzyński, L.; Biernacka, M.; Perzyńska, K.; Zaleski, P.

2002-06-01

The results of the Mössbauer effect measurements on bcc Cr rich Cr-Fe-Mn alloys in temperature range 12-296 K in zero- and in applied magnetic fields are reported. Monochromatic, circularly polarized radiation was used for investigation of iron moments alignment. Strong enhancement of internal hyperfine magnetic field induced by the applied magnetic field was detected and explained as due to dynamical effects. At high temperatures alignment of iron moments in antiferromagnetic phase is weakly magnetic field-dependent. At low temperatures the average hyperfine magnetic field is antiparallel to the net magnetization showing that iron moments are partly ordered by the applied field.

Local magnetic moment formation at 119Sn Mössbauer impurity in RFe2 ( R=rare-earth metals) Laves phases compounds

NASA Astrophysics Data System (ADS)

de Oliveira, A. L.; de Oliveira, N. A.; Troper, A.

2010-05-01

The purpose of the present work is to theoretically study the local magnetic moment formation and the systematics of the magnetic hyperfine fields at a non-magnetic s-p Mössbauer 119Sn impurity diluted on R sites ( R=rare-earth metals) of the cubic Laves phases intermetallic compounds RFe2. One considers that the magnetic hyperfine field has two contributions (i) the contribution from R ions, calculated via an extended Daniel-Friedel [J. Phys. Chem. Solids 24 (1963) 1601] model and (ii) the contribution from the induced magnetic moments arising from the Fe neighboring sites. We have in this case a two-center Blandin-Campbell-like [Phys. Rev. Lett. 31 (1973) 51; J. Magn. Magn. Mater. 1 (1975) 1] problem, where a magnetic 3d-element located at a distance from the 119Sn impurity gives an extra magnetization to a polarized electron gas which is strongly charge perturbed at the 119Sn impurity site. We also include in the model, the nearest-neighbor perturbation due to the translational invariance breaking introduced by the impurity. Our self-consistent total magnetic hyperfine field calculations are in a very good agreement with recent experimental data.

Development of a collinear laser spectrometer facility at VECC: First test result

NASA Astrophysics Data System (ADS)

Ali, Md Sabir; Ray, Ayan; Raja, Waseem; Bandyopadhyay, Arup; Naik, Vaishali; Polley, Asish; Chakrabarti, Alok

2018-04-01

We report here the development of collinear laser spectroscopy (CLS) system at VECC for the study of hyperfine spectrum and isotopic shift of stable and unstable isotopes. The facility is first of its kind in the country allowing measurement of hyperfine splitting of atomic levels using atomic beams. The CLS system is installed downstream of the focal plane of the existing isotope separator online (ISOL) facility at VECC and is recently commissioned by successfully resolving the fluorescence spectrum of the hyperfine levels in ^{85,87}Rb. The atomic beams of Rb were produced by charge exchange of 8 keV Rb ion beam which were produced, extracted and transported to the charge exchange cell using the ion sources, extractor and the beam-line magnets of the ISOL facility. The laser propagating opposite to the ion / atom beam direction was allowed to interact with the atom beam and fluorescence spectrum was recorded. The experimental set-up and the experiment conducted are reported in detail. The measures needed to be carried out for improving the sensitivity to a level necessary for studying short-lived exotic nuclei have also been discussed.

Magnitude of finite-nucleus-size effects in relativistic density functional computations of indirect NMR nuclear spin-spin coupling constants.

PubMed

Autschbach, Jochen

2009-09-14

A spherical Gaussian nuclear charge distribution model has been implemented for spin-free (scalar) and two-component (spin-orbit) relativistic density functional calculations of indirect NMR nuclear spin-spin coupling (J-coupling) constants. The finite nuclear volume effects on the hyperfine integrals are quite pronounced and as a consequence they noticeably alter coupling constants involving heavy NMR nuclei such as W, Pt, Hg, Tl, and Pb. Typically, the isotropic J-couplings are reduced in magnitude by about 10 to 15 % for couplings between one of the heaviest NMR nuclei and a light atomic ligand, and even more so for couplings between two heavy atoms. For a subset of the systems studied, viz. the Hg atom, Hg(2) (2+), and Tl--X where X=Br, I, the basis set convergence of the hyperfine integrals and the coupling constants was monitored. For the Hg atom, numerical and basis set calculations of the electron density and the 1s and 6s orbital hyperfine integrals are directly compared. The coupling anisotropies of TlBr and TlI increase by about 2 % due to finite-nucleus effects.

Detecting primordial gravitational waves with circular polarization of the redshifted 21 cm line. I. Formalism

NASA Astrophysics Data System (ADS)

Hirata, Christopher M.; Mishra, Abhilash; Venumadhav, Tejaswi

2018-05-01

We propose a new method to measure the tensor-to-scalar ratio r using the circular polarization of the 21 cm radiation from the pre-reionization epoch. Our method relies on the splitting of the F =1 hyperfine level of neutral hydrogen due to the quadrupole moment of the cosmic microwave background (CMB). We show that unlike the Zeeman effect, where MF=±1 have opposite energy shifts, the CMB quadrupole shifts MF=±1 together relative to MF=0 . This splitting leads to a small circular polarization of the emitted 21 cm radiation. In this paper (Paper I in a series on this effect), we present calculations on the microphysics behind this effect, accounting for all processes that affect the hyperfine transition. We conclude with an analytic formula for the circular polarization from the Dark Ages as a function of pre-reionization parameters and the value of the remote quadrupole of the CMB. We also calculate the splitting of the F =1 hyperfine level due to other anisotropic radiation sources and show that they are not dominant. In a companion paper (Paper II) we make forecasts for measuring the tensor-to-scalar ratio r using future radio arrays.

Crater property in two-particle bound states: When and why

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chow, Chi-Keung

2000-06-01

Crater has shown that, for two particles (with masses m{sub 1} and m{sub 2}) in a Coulombic bound state, the charge distribution is equal to the sum of the two charge distributions obtained by taking m{sub 1}{yields}{infinity} and m{sub 2}{yields}{infinity}, respectively, while keeping the same Coulombic potential. We provide a simple scaling criterion to determine whether an arbitrary Hamiltonian possesses this property. In particular, we show that, for a Coulombic system, fine structure corrections preserve this Crater property while two-particle relativistic corrections and/or hyperfine corrections may destroy it. (c) 2000 American Association of Physics Teachers.

Conventional electron paramagnetic resonance of Mn2+ in synthetic hydroxyapatite at different concentrations of the doped manganese

NASA Astrophysics Data System (ADS)

Murzakhanov, F.; Mamin, G.; Voloshin, A.; Klimashina, E.; Putlyaev, V.; Doronin, V.; Bakhteev, S.; Yusupov, R.; Gafurov, M.; Orlinskii, S.

2018-05-01

Powders of synthetic hydroxyapatite doped with Mn2+ ions in concentrations from 0.05 till 5 wt. % were investigated by conventional electron paramagnetic resonance (EPR). The parameters of the spin-Hamiltonian are derived. Partially resolved hyperfine structure in the magnetic fields corresponding to g ≈ 4.3 and g ≈ 9.4 is observed. The narrowing of the central peak with concentration is reported. A possibility to use the linewidth and intensity of the central peak for concentration measurements are discussed. The results could be used for the identification and qualification of Mn2+ in oil, mining and ore formations.

Bichromatic laser cooling in a three-level system

NASA Astrophysics Data System (ADS)

Gupta, R.; Xie, C.; Padua, S.; Batelaan, H.; Metcalf, H.

1993-11-01

We report a 1D study of optical forces on atoms in a two-frequency laser field. The light couples two ground state hyperfine structure levels to a common excited state of 85Rb, thus forming a Λ system. We observe a new type of sub-Doppler coupling with blue-tuned light that uses neither polarization gradients nor magnetic fields, efficient heating with red tuning, and the spatial phase dependence of these. We observed deflection from a rectified dipole force and determined its velocity dependence and capture range. We report velocity selective resonances associated with Raman transitions. A simplified semiclassical calculation agrees qualitatively with our measurements.

Laser ablated hydantoin: A high resolution rotational study.

PubMed

Alonso, Elena R; Kolesniková, Lucie; Alonso, José L

2017-09-28

Laser ablation techniques coupled with broadband and narrowband Fourier transform microwave spectroscopies have allowed the high resolution rotational study of solid hydantoin, an important target in astrochemistry as a possible precursor of glycine. The complicated hyperfine structure arising from the presence of two 14 N nuclei in non-equivalent positions has been resolved and interpreted in terms of the nuclear quadrupole coupling interactions. The results reported in this work provide a solid base for the interstellar searches of hydantoin in the astrophysical surveys. The values of the nuclear quadrupole coupling constants have been also discussed in terms of the electronic environment around the respective nitrogen atom.

Density functional calculations of the Mössbauer parameters in hexagonal ferrite SrFe12O19

NASA Astrophysics Data System (ADS)

Ikeno, Hidekazu

2018-03-01

Mössbauer parameters in a magnetoplumbite-type hexagonal ferrite, SrFe12O19, are computed using the all-electron band structure calculation based on the density functional theory. The theoretical isomer shift and quadrupole splitting are consistent with experimentally obtained values. The absolute values of hyperfine splitting parameters are found to be underestimated, but the relative scale can be reproduced. The present results validate the site-dependence of Mössbauer parameters obtained by analyzing experimental spectra of hexagonal ferrites. The results also show the usefulness of theoretical calculations for increasing the reliability of interpretation of the Mössbauer spectra.

Oxygen-17 and molybdenum-95 coupling in spectroscopic models of molybdoenzymes

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilson, G.L.; Kony, M.; Tiekink, E.R.

1988-09-28

Assignment of (Mo/sup V/OS) and cis-(Mo/sup V/O(SH)) centers in active xanthine oxidase (very rapid and rapid ESR signals) are supported by generation of these species in solution. The ESR parameters were measured using /sup 17/O and /sup 95/Mo and are reported herein. The data revealed variations in relative magnitudes of the hyperfine components, and the different patterns of angles reflect significant differences in electronic structure. The same electronic differences appear to be responsible for the variations in magnitude and anisotropy of the /sup 17/O coupling, assigned to bound product Mo-/sup 17/OR in both enzyme signals.

Manganese Abundances in the Stars with Metallicities -1 <[Fe/H]< +0.3

NASA Astrophysics Data System (ADS)

Mishenina, T.; Gorbaneva, T.; Pignatari, M.; Thielemann, F.-K.; Korotin, S.

2018-01-01

We estimate the Mn abundances in the atmospheres of 247 F-G-K-type dwarf stars belonging to the thin and thick disk populations in the metallicity range -1 < [Fe/H] < +0.3. The observations were conducted using the 1.93 m telescope at Observatoire de Haute-Provence (OHP, France) equipped with the echelle type spectrographs ELODIE and SOPHIE. The abundances were derived under the LTE approximation; the synthetic spectrum for the Mn lines was computed accounting for the hyperfine structure. Starting from the results obtained, we discuss the evolution of the [Mn/Fe] ratio with respect to [Fe/H] in the galactic disk.

Laser-stimulated electric quadrupole transitions in the molecular hydrogen ion H2+

NASA Astrophysics Data System (ADS)

Korobov, V. I.; Danev, P.; Bakalov, D.; Schiller, S.

2018-03-01

Molecular hydrogen ions are of metrological relevance due to the possibility of precise theoretical evaluation of their spectrum and of external-field-induced shifts. We report the results of the calculations of the rate of laser-induced electric quadrupole transitions between a large set of ro-vibrational states of H2+. The hyperfine and Zeeman structure of the E 2 transition spectrum and the effects of the laser polarization are treated in detail. The treatment is generally applicable to molecules in 2Σ states. We also present the nuclear spin-electron spin-coupling constants, computed with a precision ten times higher than previously obtained.

Laboratory detection of the rotational-tunnelling spectrum of the hydroxymethyl radical, CH2OH

NASA Astrophysics Data System (ADS)

Bermudez, C.; Bailleux, S.; Cernicharo, J.

2017-02-01

Context. Of the two structural isomers of CH3O, methoxy is the only radical whose astronomical detection has been reported through the observation of several rotational lines at 2 and 3 mm wavelengths. Although the hydroxymethyl radical, CH2OH, is known to be thermodynamically the most stable (by 3300 cm-1), it has so far eluded rotational spectroscopy presumably because of its high chemical reactivity. Aims: Recent high-resolution ( 10 MHz) sub-Doppler rovibrationally resolved infrared spectra of CH2OH (symmetric CH stretching a-type band) provided accurate ground vibrational state rotational constants, thus reviving the quest for its millimeter-wave spectrum in laboratory and subsequently in space. Methods: The search and assignment of the rotational spectrum of this fundamental species were guided by our quantum chemical calculations and by using rotational constants derived from high-resolution IR data. The hydroxymethyl radical was produced by hydrogen abstraction from methanol by atomic chlorine. Results: Ninety-six b-type rotational transitions between the v = 0 and v = 1 tunnelling sublevels involving 25 fine-structure components of Q branches (with Ka = 1 ← 0) and 4 fine-structure components of R branches (assigned to Ka = 0 ← 1) were measured below 402 GHz. Hyperfine structure alternations due to the two identical methylenic hydrogens were observed and analysed based on the symmetry and parity of the rotational levels. A global fit including infrared and millimeter-wave lines has been conducted using Pickett's reduced axis system Hamiltonian. The recorded transitions (odd ΔKa) did not allow us to evaluate the Coriolis tunnelling interaction term. The comparison of the experimentally determined constants for both tunnelling levels with their computed values secures the long-awaited first detection of the rotational-tunnelling spectrum of this radical. In particular, a tunnelling rate of 139.73 ± 0.10 MHz (4.6609(32) × 10-3 cm-1) was obtained along with the rotational constants, electron spin-rotation interaction parameters and several hyperfine coupling terms. Conclusions: The laboratory characterization of CH2OH by millimeter-wave spectroscopy now offers the possibility for its astronomical detection for the first time.

Statistical self-similarity of width function maxima with implications to floods

USGS Publications Warehouse

Veitzer, S.A.; Gupta, V.K.

2001-01-01

Recently a new theory of random self-similar river networks, called the RSN model, was introduced to explain empirical observations regarding the scaling properties of distributions of various topologic and geometric variables in natural basins. The RSN model predicts that such variables exhibit statistical simple scaling, when indexed by Horton-Strahler order. The average side tributary structure of RSN networks also exhibits Tokunaga-type self-similarity which is widely observed in nature. We examine the scaling structure of distributions of the maximum of the width function for RSNs for nested, complete Strahler basins by performing ensemble simulations. The maximum of the width function exhibits distributional simple scaling, when indexed by Horton-Strahler order, for both RSNs and natural river networks extracted from digital elevation models (DEMs). We also test a powerlaw relationship between Horton ratios for the maximum of the width function and drainage areas. These results represent first steps in formulating a comprehensive physical statistical theory of floods at multiple space-time scales for RSNs as discrete hierarchical branching structures. ?? 2001 Published by Elsevier Science Ltd.

Modified ferrite core-shell nanoparticles magneto-structural characterization

NASA Astrophysics Data System (ADS)

Klekotka, Urszula; Piotrowska, Beata; Satuła, Dariusz; Kalska-Szostko, Beata

2018-06-01

In this study, ferrite nanoparticles with core-shell structures and different chemical compositions of both the core and shell were prepared with success. Proposed nanoparticles have in the first and second series magnetite core, and the shell is composed of a mixture of ferrites with Fe3+, Fe2+ and M ions (where M = Co2+, Mn2+ or Ni2+) with a general composition of M0.5Fe2.5O4. In the third series, the composition is inverted, the core is composed of a mixture of ferrites and as a shell magnetite is placed. Morphology and structural characterization of nanoparticles were done using Transmission Electron Microscopy (TEM), X-ray diffraction (XRD), and Infrared spectroscopy (IR). While room temperature magnetic properties were measured using Mössbauer spectroscopy (MS). It is seen from Mössbauer measurements that Co always increases hyperfine magnetic field on Fe atoms at RT, while Ni and Mn have opposite influences in comparison to pure Fe ferrite, regardless of the nanoparticles structure.

Theoretical studies of the EPR parameters and local structures for Cu2+-doped cobalt ammonium phosphate hexahydrate

NASA Astrophysics Data System (ADS)

Li, Chao-Ying; Liu, Shi-Fei; Fu, Jin-Xian

2015-11-01

High-order perturbation formulas for a 3d9 ion in rhombically elongated octahedral was applied to calculate the electron paramagnetic resonance (EPR) parameters (the g factors, gi, and the hyperfine structure constants Ai, i = x, y, z) of the rhombic Cu2+ center in CoNH4PO4.6H2O. In the calculations, the required crystal-field parameters are estimated from the superposition model which enables correlation of the crystal-field parameters and hence the EPR parameters with the local structure of the rhombic Cu2+ center. Based on the calculations, the ligand octahedral (i.e. [Cu(H2O)6]2+ cluster) are found to experience the local bond length variations ΔZ (≈0.213 Å) and δr (≈0.132 Å) along axial and perpendicular directions due to the Jahn-Teller effect. Theoretical EPR parameters based on the above local structure are in good agreement with the observed values; the results are discussed.

Magnetic structures and magnetocaloric effect in R VO4 (R =Gd , Nd )

NASA Astrophysics Data System (ADS)

Palacios, E.; Evangelisti, M.; Sáez-Puche, R.; Dos Santos-García, A. J.; Fernández-Martínez, F.; Cascales, C.; Castro, M.; Burriel, R.; Fabelo, O.; Rodríguez-Velamazán, J. A.

2018-06-01

We report the magnetic properties and magnetic structure of the zircon-type compound GdVO4, together with the magnetic structure of the isostructural NdVO4. At T ≃2.5 K, GdVO4 undergoes a phase transition to antiferromagnetic Gz, driven mainly by the exchange interactions, while the magnetic anisotropy and dipolar interactions are minor contributions. Near the liquid-helium boiling temperature, the magnetocaloric effect of GdVO4 is nearly as large as that of the structurally closely related GdPO4. It is noteworthy that GdVO4 has been recently proposed as a good passive regenerator in Gifford-McMahon cryocoolers, since adding a magnetization-demagnetization stage to the cryocooler refrigeration cycle would increase its efficiency for liquefying helium. NdVO4 is a canted Gz-type antiferromagnet and shows enhancement of the magnetic reflections in neutron diffraction below ca. 500 mK, due to the polarization of the Nd nuclei by the hyperfine field.

Slow light effect analysis excited by plasmon-induced transparency in metal-dielectric-metal waveguide

NASA Astrophysics Data System (ADS)

Jin, Gui; Huang, Xiaoyi

2018-02-01

We propose and demonstrate a metal-dielectric-metal(MDM) waveguide side coupled with two stubs to realize plasmon induced transparency (PIT) effect. The dispersion relation of the structure has been plotted by solving the dispersion equation of MDM three layer structure, the transmission spectrum is investigated by coupled mode theory (CMT) and Finite Element Method (FEM) simulation, the CMT results can. The surface plasmon device can also be used as a EIT-like filter with a variable full width of half-maximum (FWHM) and highest transmission over 88%. The maximum group index ng is 42 with a group velocity of 0.023ܿ and transmission of 48%, The normalized delay-bandwidth product (NDBP) can be modulated through changing the gap width of resonators and waveguide bus, the highest is 0.641 at gap width 10 nm, and lowest is 0.246 at 30 nm. The dispersion of group velocity (GVD) changes drastically at narrow gap width and becomes more and more flat at broader gap width, this opens up an avenue for designing optical buffers, switches and modulators.

Quantifying inter- and intra-population niche variability using hierarchical bayesian stable isotope mixing models.

PubMed

Semmens, Brice X; Ward, Eric J; Moore, Jonathan W; Darimont, Chris T

2009-07-09

Variability in resource use defines the width of a trophic niche occupied by a population. Intra-population variability in resource use may occur across hierarchical levels of population structure from individuals to subpopulations. Understanding how levels of population organization contribute to population niche width is critical to ecology and evolution. Here we describe a hierarchical stable isotope mixing model that can simultaneously estimate both the prey composition of a consumer diet and the diet variability among individuals and across levels of population organization. By explicitly estimating variance components for multiple scales, the model can deconstruct the niche width of a consumer population into relevant levels of population structure. We apply this new approach to stable isotope data from a population of gray wolves from coastal British Columbia, and show support for extensive intra-population niche variability among individuals, social groups, and geographically isolated subpopulations. The analytic method we describe improves mixing models by accounting for diet variability, and improves isotope niche width analysis by quantitatively assessing the contribution of levels of organization to the niche width of a population.

Effects of aluminum hinged shoes on the structure of contracted feet in Thoroughbred yearlings.

PubMed

Tanaka, Kousuke; Hiraga, Atsushi; Takahashi, Toshiyuki; Kuwano, Atsutoshi; Morrison, Scott Edward

2015-01-01

We applied aluminum hinged shoes (AHSs) to the club foot-associated contracted feet of 11 Thoroughbred yearlings to examine the effects of the shoes on the shape of the hoof and third phalanx (P III). After 3 months of AHS use, the size of the affected hooves increased significantly, reaching the approximate size of the healthy contralateral hooves with respect to the maximum lateral width of the foot, the mean ratio of the bearing border width to the coronary band width, and the mean ratio of the solar surface width to the articular surface width. These results suggest that the AHSs corrected the contracted feet in these yearling horses.

Effects of ballet training of children in Turkey on foot anthropometric measurements and medial longitudinal arc development.

PubMed

Ozdinc, Sevgi Anar; Turan, Fatma Nesrin

2016-07-01

To investigate the effects of ballet training on foot structure and the formation of the medial longitudinal arc in childhood, and the association of body mass index with structural change secondary to ballet training. This study was conducted at Öykü Ballet and Dance School and Trakya University, Edirne, Turkey, from September 2007 to November 2008, and comprised girl students who were taking ballet classes, and a group of those who were not taking such who acted as the controls. Static footprints of both feet of all participants were taken with an ink paedogram. Parameters evaluated from footprints included foot length, metatarsal width, heel width and medial longitudinal arch. The relationship between the parameters, the ballet starting age, training duration and body mass index was investigated. Of the 67 participants, there were 36(53.7%) in the experimental group and 31(48.3%) in the control group. The difference between age, height, weight and body mass index between the two groups was insignificant (p>0.05). The average ballet starting age was 6.47±1.55 years and duration was 4.36±2.002 years. Positive correlations were found between body mass index and foot length, metatarsal width, heel width, medial longitudinal arch contact width and halluxvalgus angle; between ballet starting age and metatarsal width, heel width; between duration of training and foot length, metatarsal width and hallux valgus angle (p?0.05 each). Evidence supporting the education in children on foot anthropometric measurements and medial longitudinal arc development could not be found.

The microwave spectrum of a triplet carbene: HCCN in the X 3Sigma - state

NASA Astrophysics Data System (ADS)

Saito, Shuji; Endo, Yasuki; Hirota, Eizi

1984-02-01

A simple carbene, the HCCN radical, has been identified in the gas phase using a microwave spectroscopic method. The HCCN molecule was generated in a free space absorption cell by the reaction of CH3CN with the microwave discharge products of CF4. Five rotational transitions, each split into three fine structure components, were observed in the region of 110 to 198 GHz. No hyperfine structure was resolved, although some of the observed lines showed broadening. The rotational constant, the centrifugal distortion constant, the spin-spin coupling constant, and the spin-rotation coupling constant were determined with good precision. The observed spectrum is completely consistent with that expected for a linear molecule in a 3Σ state, in agreement with an earlier matrix EPR study of Bernheim et al. [J. Chem. Phys. 43, 196 (1965)].

Astronomical constraints on the cosmic evolution of the fine structure constant and possible quantum dimensions.

PubMed

Carilli, C L; Menten, K M; Stocke, J T; Perlman, E; Vermeulen, R; Briggs, F; de Bruyn , A G; Conway, J; Moore, C P

2000-12-25

We present measurements of absorption by the 21 cm hyperfine transition of neutral hydrogen toward radio sources at substantial look-back times. These data are used in combination with observations of rotational transitions of common interstellar molecules to set limits on the evolution of the fine structure constant: alpha/ alpha<3.5x10(-15) yr(-1), to a look-back time of 4.8 Gyr. In the context of string theory, the limit on the secular evolution of the scale factor of the compact dimensions, R, is &Rdot/ R<10(-15) yr(-1). Including terrestrial and other astronomical measurements places 2sigma limits on slow oscillations of R from the present to the epoch of cosmic nucleosynthesis, just seconds after the big bang, of DeltaR /R<10(-5).

Interplay of stereoelectronic and enviromental effects in tuning the structural and magnetic properties of a prototypical spin probe: further insights from a first principle dynamical approach.

PubMed

Pavone, Michele; Cimino, Paola; De Angelis, Filippo; Barone, Vincenzo

2006-04-05

The nitrogen isotropic hyperfine coupling constant (hcc) and the g tensor of a prototypical spin probe (di-tert-butyl nitroxide, DTBN) in aqueous solution have been investigated by means of an integrated computational approach including Car-Parrinello molecular dynamics and quantum mechanical calculations involving a discrete-continuum embedding. The quantitative agreement between computed and experimental parameters fully validates our integrated approach. Decoupling of the structural, dynamical, and environmental contributions acting onto the spectral observables allows an unbiased judgment of the role played by different effects in determining the overall experimental observables and highlights the importance of finite-temperature vibrational averaging. Together with their intrinsic interest, our results pave the route toward more reliable interpretations of EPR parameters of complex systems of biological and technological relevance.

Observation of photoassociation of ultracold sodium and cesium at the asymptote Na (3S1/2) + Cs (6P1/2)

NASA Astrophysics Data System (ADS)

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

2018-05-01

We report on the production of ultracold heteronuclear NaCs* molecules in a dual-species magneto-optical trap through photoassociation. The electronically excited molecules are formed below the Na (3S1/2) + Cs (6P1/2) dissociation limit. 12 resonance lines are detected using trap-loss spectroscopy based on a highly sensitive modulation technique. The highest observed rovibrational level exhibits clear hyperfine structure, which is detected for the first time. This structure is simulated within a simplified model consisting of 4 coupled levels belonging to the initially unperturbed Hund's case "a" electronic states, which have been explored in our previous work that dealt with the Na (3S1/2) + Cs (6P3/2) asymptote [W. Liu et al., Phys. Rev. A 94, 032518 (2016)].

Theoretical investigations of the local distortion and spectral properties for VO2+ in SiO2 Glass

NASA Astrophysics Data System (ADS)

Li, Mu-Neng; Zhang, Zhi-Hong; Wu, Shao-Yi

2017-11-01

The local distortions and the spin Hamiltonian parameters g factors g∥, g⊥ and the hyperfine structure constants A∥ and A⊥ for isolated vanadyl ions VO2+ doped in SiO2 glass at 700°C are theoretically investigated from the perturbation formulas of these parameters for a 3d1 ion in tetragonally compressed octahedra. In these formulas, the relationships between local structure of VO2+ ions center and the tetragonal crystal field parameters are established. As a result, the distortion of the ligand octahedron is attributed to the strong axial crystal-fields associated with the short V4+-O2- bond due to the strong V=O bonding in the silica matrix. The theoretical spin Hamiltonian parameters obtained in this work show reasonable agreement with the experimental data.

A variable temperature EPR study of Mn(2+)-doped NH(4)Cl(0.9)I(0.1) single crystal at 170 GHz: zero-field splitting parameter and its absolute sign.

PubMed

Misra, Sushil K; Andronenko, Serguei I; Chand, Prem; Earle, Keith A; Paschenko, Sergei V; Freed, Jack H

2005-06-01

EPR measurements have been carried out on a single crystal of Mn(2+)-doped NH(4)Cl(0.9)I(0.1) at 170-GHz in the temperature range of 312-4.2K. The spectra have been analyzed (i) to estimate the spin-Hamiltonian parameters; (ii) to study the temperature variation of the zero-field splitting (ZFS) parameter; (iii) to confirm the negative absolute sign of the ZFS parameter unequivocally from the temperature-dependent relative intensities of hyperfine sextets at temperatures below 10K; and (iv) to detect the occurrence of a structural phase transition at 4.35K from the change in the structure of the EPR lines with temperature below 10K.

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.

Frequency-Comb Based Double-Quantum Two-Dimensional Spectrum Identifies Collective Hyperfine Resonances in Atomic Vapor Induced by Dipole-Dipole Interactions

NASA Astrophysics Data System (ADS)

Lomsadze, Bachana; Cundiff, Steven T.

2018-06-01

Frequency-comb based multidimensional coherent spectroscopy is a novel optical method that enables high-resolution measurement in a short acquisition time. The method's resolution makes multidimensional coherent spectroscopy relevant for atomic systems that have narrow resonances. We use double-quantum multidimensional coherent spectroscopy to reveal collective hyperfine resonances in rubidium vapor at 100 °C induced by dipole-dipole interactions. We observe tilted and elongated line shapes in the double-quantum 2D spectra, which have never been reported for Doppler-broadened systems. The elongated line shapes suggest that the signal is predominately from the interacting atoms that have a near zero relative velocity.

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.

Double resonance calibration of g factor standards: Carbon fibers as a high precision standard

NASA Astrophysics Data System (ADS)

Herb, Konstantin; Tschaggelar, Rene; Denninger, Gert; Jeschke, Gunnar

2018-04-01

The g factor of paramagnetic defects in commercial high performance carbon fibers was determined by a double resonance experiment based on the Overhauser shift due to hyperfine coupled protons. Our carbon fibers exhibit a single, narrow and perfectly Lorentzian shaped ESR line and a g factor slightly higher than gfree with g = 2.002644 =gfree · (1 + 162ppm) with a relative uncertainty of 15ppm . This precisely known g factor and their inertness qualify them as a high precision g factor standard for general purposes. The double resonance experiment for calibration is applicable to other potential standards with a hyperfine interaction averaged by a process with very short correlation time.

Kobayashi-Kondo-Maskawa-'t Hooft interaction in pentaquarks

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dmitrasinovic, V.

2005-05-01

We review critically the predictions of pentaquarks in the quark model, in particular, those based on the flavor-spin-dependent (Glozman-Riska) hyperfine interaction and the color-spin (one-gluon-exchange Fermi-Breit) one. We include the antiquark interactions and find that: (1) the exotic SU(3) multiplets are not substantially affected in the flavor-spin model, whereas some of the nonexotic multiplets are; and (2) the variational upper bound on the {xi}{sup --}-{theta}{sup +} mass difference in the color-spin hyperfine interaction model is substantially reduced. This leads us to the U{sub A}(1) symmetry breaking Kobayashi-Kondo-Maskawa-'tHooft interaction. We discuss some of its phenomenological consequences for pentaquarks.

Dipole, quadrupole, and octupole terms in the long-range hyperfine frequency shift for hydrogen in the presence of inert gases

NASA Astrophysics Data System (ADS)

Greenwood, W. G.; Tang, K. T.

1987-03-01

The R-6, R-8, and R-10 terms in the long-range expansion for the hyperfine frequency shift are calculated for hydrogen in the presence of He, Ne, Ar, Kr, and Xe. The R-6 terms are based on the dipole oscillator strength sums. For helium, the R-8 and R-10 terms are based on quadrupole and octupole oscillator strength sums. For the heavier inert gases, the results for the R-8 and R-10 terms are obtained from the sum rules and the static polarizabilities. Upper bounds are also determined for the R-8 and R-10 terms.

Electromagnetically induced absorption and transparency in degenerate two level systems of metastable Kr atoms and measurement of Landé g-factor

NASA Astrophysics Data System (ADS)

Kale, Y. B.; Tiwari, V. B.; Mishra, S. R.; Singh, S.; Rawat, H. S.

2016-12-01

We report electromagnetically induced absorption (EIA) and transparency (EIT) resonances of sub-natural linewidth in degenerate two level systems (DTLSs) of metastable 84Kr (84Kr*) and 83Kr (83Kr*) atoms. Using the spectrally narrow EIA signals obtained corresponding to the closed hyperfine transition 4p55s[3/2]2(F=13/2) to 4p55p[5/2]3(F‧ = 15 / 2) in 83Kr* atom, we have measured the Landé g-factor (gF) for the lower hyperfine level involved in this transition by application of small values of magnetic field of few Gauss.

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.

Nuclear Resonance Scattering of Circularly Polarized SR

NASA Astrophysics Data System (ADS)

Szymanski, K.; Satula, D.; Dobrzynski, L.; Kalska, B.

2004-09-01

Results of the experiments with nuclear resonance scattering of synchrotron radiation aiming at construction of the circularly polarized beam suitable for nuclear hyperfine studies are reported. Si(4 0 0) single crystal slab, 100 μ m thick, was used as a quarter wave plate. Observed twofold reduction of the intensity in proposed geometry is due to the Si crystal itself. Hyperfine interactions are used to probe polarization state of the synchrotron beam. Too large angular beam divergence did not allow for achieving full circular polarization of photons. Consequently, further experiments are proposed to overcame beam divergence problems. A number of calculations presented in the paper show that cheap and easily available Si plate can serve as an effective desired polarizer.

Dark state polarizing a nuclear spin in the vicinity of a nitrogen-vacancy center

NASA Astrophysics Data System (ADS)

Wang, Yang-Yang; Qiu, Jing; Chu, Ying-Qi; Zhang, Mei; Cai, Jianming; Ai, Qing; Deng, Fu-Guo

2018-04-01

The nuclear spin in the vicinity of a nitrogen-vacancy (NV) center possesses long coherence time and convenient manipulation assisted by the strong hyperfine interaction with the NV center. It is suggested for the subsequent quantum information storage and processing after appropriate initialization. However, current experimental schemes are either sensitive to the inclination and magnitude of the magnetic field or require thousands of repetitions to achieve successful realization. Here, we propose a method to polarize a 13C nuclear spin in the vicinity of an NV center via a dark state. We demonstrate theoretically and numerically that it is robust to polarize various nuclear spins with different hyperfine couplings and noise strengths.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Manjura Hoque, S.; Liba, S. I.; Akhter, Shireen

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 fieldmore » (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.« less

Ultra-soft magnetic properties and correlated phase analysis by 57Fe Mössbauer spectroscopy of Fe74Cu0.8Nb2.7Si15.5B7 alloy

NASA Astrophysics Data System (ADS)

Manjura Hoque, S.; Liba, S. I.; Anirban, A.; Choudhury, Shamima; Akhter, Shireen

2016-02-01

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 Fe74Cu0.8Nb2.7Si15.5B7 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.

Theoretical study of the hyperfine-interaction constants and the isotope-shift factors for the 3 s21S0-3 s 3 p 3,1P1o transitions in Al+

NASA Astrophysics Data System (ADS)

Zhang, Tingxian; Xie, Luyou; Li, Jiguang; Lu, Zehuang

2017-07-01

We calculated the magnetic dipole and the electric quadrupole hyperfine interaction constants of 3 s 3 p 3,1P1o states and the isotope shift, including mass and field shift, factors for transitions from these two states to the ground state 3 s 2 1S0 in Al+ ions using the multiconfiguration Dirac-Hartree-Fock method. The effects of the electron correlations and the Breit interaction on these physical quantities were investigated in detail based on the active space approach. It is found that the core-core and the higher order correlations are considerable for evaluating the uncertainties of the atomic parameters concerned. The uncertainties of the hyperfine interaction constants in this work are less than 1.6%. Although the isotope shift factors are highly sensitive to the electron correlations, reasonable uncertainties were obtained by exploring the effects of the electron correlations. Moreover, we found that the relativistic nuclear recoil corrections to the mass shift factors are very small and insensitive to the electron correlations for Al+. These atomic parameters present in this work are valuable for extracting the nuclear electric quadrupole moments and the mean-square charge radii of Al isotopes.

Electron-nuclear coherent spin oscillations probed by spin-dependent recombination

NASA Astrophysics Data System (ADS)

Azaizia, S.; Carrère, H.; Sandoval-Santana, J. C.; Ibarra-Sierra, V. G.; Kalevich, V. K.; Ivchenko, E. L.; Bakaleinikov, L. A.; Marie, X.; Amand, T.; Kunold, A.; Balocchi, A.

2018-04-01

We demonstrate the triggering and detection of coherent electron-nuclear spin oscillations related to the hyperfine interaction in Ga deep paramagnetic centers in GaAsN by band-to-band photoluminescence without an external magnetic field. In contrast to other point defects such as Cr4 + in SiC, Ce3 + in yttrium aluminum garnet crystals, nitrogen-vacancy centers in diamond, and P atoms in silicon, the bound-electron spin in Ga centers is not directly coupled to the electromagnetic field via the spin-orbit interaction. However, this apparent drawback can be turned into an advantage by exploiting the spin-selective capture of conduction band electrons to the Ga centers. On the basis of a pump-probe photoluminescence experiment we measure directly in the temporal domain the hyperfine constant of an electron coupled to a gallium defect in GaAsN by tracing the dynamical behavior of the conduction electron spin-dependent recombination to the defect site. The hyperfine constants and the relative abundance of the nuclei isotopes involved can be determined without the need of an electron spin resonance technique and in the absence of any magnetic field. Information on the nuclear and electron spin relaxation damping parameters can also be estimated from the oscillation amplitude decay and the long-time-delay behavior.

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.

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.

Hyperfine induced transition probabilities from 4{f}^{14}5s5p{}^{3}{{\\rm{P}}}_{0,2}^{o} states in Sm-like ions

NASA Astrophysics Data System (ADS)

Zhou, Fuyang; Li, Jiguang; Qu, Yizhi; Wang, Jianguo

2017-11-01

The hyperfine induced 4{f}145s5p{}3{{{P}}}0,2o-4{f}145{s}2{}1{{{S}}}0 transition probabilities for highly charged Sm-like ions are calculated within the framework of the multiconfiguration Dirac-Hartree-Fock method. Electron correlation, the Breit interaction and quantum electrodynamical effects are taken into account. For ions ranging from Z = 79 to Z=94,4{f}145s5p{}3{{{P}}}0o is the first excited state, and the hyperfine induced transition (HIT) is a dominant decay channel. For the 4{f}145s5p{}3{{{P}}}2o state, the HIT rates of Sm-like ions with Z=82-94 are reported as well as the magnetic dipole (M1) {}3{{{P}}}2o-{}3{{{P}}}1o, the electric quadrupole (E2) {}3{{{P}}}2o-{}3{{{P}}}0,1o, and the magnetic quadrupole (M2) {}3{{{P}}}2o-{}1{{{S}}}0 transition probabilities. It is found that M1 transition from the 4{f}145s5p{}3{{{P}}}2o state is the most important decay channel in this range on Z≥slant 82.

Fabrication and In Situ Transmission Electron Microscope Characterization of Free-Standing Graphene Nanoribbon Devices.

PubMed

Wang, Qing; Kitaura, Ryo; Suzuki, Shoji; Miyauchi, Yuhei; Matsuda, Kazunari; Yamamoto, Yuta; Arai, Shigeo; Shinohara, Hisanori

2016-01-26

Edge-dependent electronic properties of graphene nanoribbons (GNRs) have attracted intense interests. To fully understand the electronic properties of GNRs, the combination of precise structural characterization and electronic property measurement is essential. For this purpose, two experimental techniques using free-standing GNR devices have been developed, which leads to the simultaneous characterization of electronic properties and structures of GNRs. Free-standing graphene has been sculpted by a focused electron beam in transmission electron microscope (TEM) and then purified and narrowed by Joule heating down to several nanometer width. Structure-dependent electronic properties are observed in TEM, and significant increase in sheet resistance and semiconducting behavior become more salient as the width of GNR decreases. The narrowest GNR width we obtained with the present method is about 1.6 nm with a large transport gap of 400 meV.

Structure and performance of anisotropic nanocrystalline Nd-Fe-B magnets fabricated by high-velocity compaction followed by deformation

NASA Astrophysics Data System (ADS)

Zhao, L. Z.; Deng, X. X.; Yu, H. Y.; Guan, H. J.; Li, X. Q.; Xiao, Z. Y.; Liu, Z. W.; Greneche, J. M.

2017-12-01

High-velocity compaction (HVC) has been proposed as an effective approach for the fabrication of nanocrystalline Nd-Fe-B magnets. In this work, the effect of powder size on the density of HVCed magnets has been studied and the anisotropic nanocrystalline Nd-Fe-B magnets were prepared by HVC followed by hot deformation (HD). It is found that a proper particle size range is beneficial to high density. The investigations on the microstructure, magnetic domain structure, and hyperfine structure, indicate that the deformed grain structure and the magnetic domain structure with uniform paramagnetic grain boundary phase give good magnetic properties of HVC + HDed magnets. These magnets also have good mechanical and anti-corrosion properties. The results indicate that HVC is not only a near-net-shape, room temperature and binder-free process but is also able to maintain uniform nanostructure and to achieve good magnetic properties in both isotropic and anisotropic magnets. As a result, HVC can be employed as an ideal alternative process for bonding or hot pressing for the conventional MQI, MQII and MQIII magnets.

Doppler-free spectroscopy of the atomic rubidium fine structure using ultrafast spatial coherent control method

NASA Astrophysics Data System (ADS)

Kim, Minhyuk; Kim, Kyungtae; Lee, Woojun; Kim, Hyosub; Ahn, Jaewook

2017-04-01

Spectral programming solutions for the ultrafast spatial coherent control (USCC) method to resolve the fine-structure energy levels of atomic rubidium are reported. In USCC, a pair of counter-propagating ultrashort laser pulses are programmed to make a two-photon excitation pattern specific to particular transition pathways and atom species, thus allowing the involved transitions resolvable in space simultaneously. With a proper spectral phase and amplitude modulation, USCC has been also demonstrated for the systems with many intermediate energy levels. Pushing the limit of system complexity even further, we show here an experimental demonstration of the rubidium fine-structure excitation pattern resolvable by USCC. The spectral programming solution for the given USCC is achieved by combining a double-V-shape spectral phase function and a set of phase steps, where the former distinguishes the fine structure and the latter prevents resonant transitions. The experimental results will be presented along with its application in conjunction with the Doppler-free frequency-comb spectroscopy for rubidium hyperfine structure measurements. Samsung Science and Technology Foundation [SSTFBA1301-12].

OH 18 cm TRANSITION AS A THERMOMETER FOR MOLECULAR CLOUDS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ebisawa, Yuji; Inokuma, Hiroshi; Yamamoto, Satoshi

We have observed the four hyperfine components of the 18 cm OH transition toward the translucent cloud eastward of Heiles Cloud 2 (HCL2E), the cold dark cloud L134N, and the photodissociation region of the ρ-Ophiuchi molecular cloud with the Effelsberg 100 m telescope. We have found intensity anomalies among the hyperfine components in all three regions. In particular, an absorption feature of the 1612 MHz satellite line against the cosmic microwave background has been detected toward HCL2E and two positions of the ρ-Ophiuchi molecular cloud. On the basis of statistical equilibrium calculations, we find that the hyperfine anomalies originate frommore » the non-LTE population of the hyperfine levels, and can be used to determine the kinetic temperature of the gas over a wide range of H{sub 2} densities (10{sup 2}–10{sup 7} cm{sup −3}). Toward the center of HCL2E, the gas kinetic temperature is determined to be 53 ± 1 K, and it increases toward the cloud peripheries (∼60 K). The ortho-to-para ratio of H{sub 2} is determined to be 3.5 ± 0.9 from the averaged spectrum for the eight positions. In L134N, a similar increase of the temperature is also seen toward the periphery. In the ρ-Ophiuchi molecular cloud, the gas kinetic temperature decreases as a function of the distance from the exciting star HD 147889. These results demonstrate a new aspect of the OH 18 cm line that can be used as a good thermometer of molecular cloud envelopes. The OH 18 cm line can be used to trace a new class of warm molecular gas surrounding a molecular cloud, which is not well traced by the emission of CO and its isotopologues.« less

Mixing efficiency inside micro-droplets coalesced by two components in cross-structure

NASA Astrophysics Data System (ADS)

Ren, Yanlin; Liu, Zhaomiao; Pang, Yan

2017-11-01

The mixing of micro-droplets is used in analytical chemistry, medicine production and material synthesis owing to its advantages including the encapsulation and narrow time residence distribution. In this work, droplets are coalesced by two dispersed phase with different flow rates, generated in cross-structure and mixed in planar serpentine structure. The mixing efficiency of micro-droplets under control characters including the width of entrance and the flow rate of dispersed phases have been investigated by experiments and numerical simulations. The UDS (user-defined scalar) as dimensionless concentration of the solution is adopted in simulation, and is used to calculate the concentration and the mixing effect. By changing the flow rates and the entrances` width, the changing rules of the mixing characters have been obtained. The asymmetry distributions of components make rapid mixing process in half part of each droplet when travel through a straight channel. Increasing of the ratio of entrance width result into larger droplet and weaken the chaotic mixing effect. Meanwhile, the coalesced mechanism can be performed by ranging the ratio of flow rates, the ranges are also determined by the widths of entrances. The authors gratefully acknowledge the support of National Natural Science Foundation of China (Grant No. 11572013).

Electronic Structure and I- V Characteristics of InSe Nanoribbons

NASA Astrophysics Data System (ADS)

Yao, A.-Long; Wang, Xue-Feng; Liu, Yu-Shen; Sun, Ya-Na

2018-04-01

We have studied the electronic structure and the current-voltage ( I-V) characteristics of one-dimensional InSe nanoribbons using the density functional theory combined with the nonequilibrium Green's function method. Nanoribbons having bare or H-passivated edges of types zigzag (Z), Klein (K), and armchair (A) are taken into account. Edge states are found to play an important role in determining their electronic properties. Edges Z and K are usually metallic in wide nanoribbons as well as their hydrogenated counterparts. Transition from semiconductor to metal is observed in hydrogenated nanoribbons HZZH as their width increases, due to the strong width dependence of energy difference between left and right edge states. Nevertheless, electronic structures of other nanoribbons vary with the width in a very limited scale. The I-V characteristics of bare nanoribbons ZZ and KK show strong negative differential resistance, due to spatial mismatch of wave functions in energy bands around the Fermi energy. Spin polarization in these nanoribbons is also predicted. In contrast, bare nanoribbons AA and their hydrogenated counterparts HAAH are semiconductors. The band gaps of nanoribbons AA (HAAH) are narrower (wider) than that of two-dimensional InSe monolayer and increase (decrease) with the nanoribbon width.

The Lamb-shift experiment in Muonic helium

NASA Astrophysics Data System (ADS)

Nebel, T.; Amaro, F. D.; Antognini, A.; Biraben, F.; Cardoso, J. M. R.; Covita, D. S.; Dax, A.; Fernandes, L. M. P.; Gouvea, A. L.; Graf, T.; Hänsch, T. W.; Hildebrandt, M.; Indelicato, P.; Julien, L.; Kirch, K.; Kottmann, F.; Liu, Y.-W.; Monteiro, C. M. B.; Nez, F.; Santos, J. M. F. dos; Schuhmann, K.; Taqqu, D.; Veloso, J. F. C. A.; Voss, A.; Pohl, R.

2012-12-01

We propose to measure several transition frequencies between the 2 S and the 2 P states (Lamb shift) in muonic helium ions ( μ 4He + and μ 3He + ) by means of laser spectroscopy, in order to determine the alpha-particle and helion root-mean-square (rms) charge radius. In addition, the fine and hyperfine structure components will be revealed, and the magnetic moment distribution radius will be determined. The contribution of the finite size effect to the Lamb shift (2 S - 2 P energy difference) in μHe + is as high as 20 %. Therefore a measurement of the transition frequencies with a moderate (for laser spectroscopy) precision of 50 ppm (corresponding to 1/20 of the linewidth) will lead to a determination of the nuclear rms charge radii with a relative accuracy of 3 ×10 - 4 (equivalent to 0.0005 fm). The limiting factor for the extraction of the radii from the Lamb shift measurements is given by the uncertainty of the nuclear polarizability contribution. Combined with an ongoing experiment at MPQ aiming to measure the 1 S - 2 S transition frequency in the helium ion, the Lamb shift measurement in μHe + will lead to a sensitive test of problematic and challenging bound-state QED terms. This measurement will also help to clarify the discrepancy found in our previous μ p experiment. Additionally, a precise knowledge of the absolute nuclear radii of the He isotopes and the hyperfine splitting of μ 3He + provide a relevant test of few-nucleon theories.

The Lamb-shift experiment in Muonic helium

NASA Astrophysics Data System (ADS)

Nebel, T.; Amaro, F. D.; Antognini, A.; Biraben, F.; Cardoso, J. M. R.; Covita, D. S.; Dax, A.; Fernandes, L. M. P.; Gouvea, A. L.; Graf, T.; Hänsch, T. W.; Hildebrandt, M.; Indelicato, P.; Julien, L.; Kirch, K.; Kottmann, F.; Liu, Y.-W.; Monteiro, C. M. B.; Nez, F.; Santos, J. M. F. dos; Schuhmann, K.; Taqqu, D.; Veloso, J. F. C. A.; Voss, A.; Pohl, R.

We propose to measure several transition frequencies between the 2S and the 2P states (Lamb shift) in muonic helium ions (μ 4He + and μ 3He + ) by means of laser spectroscopy, in order to determine the alpha-particle and helion root-mean-square (rms) charge radius. In addition, the fine and hyperfine structure components will be revealed, and the magnetic moment distribution radius will be determined. The contribution of the finite size effect to the Lamb shift (2S - 2P energy difference) in μHe + is as high as 20 %. Therefore a measurement of the transition frequencies with a moderate (for laser spectroscopy) precision of 50 ppm (corresponding to 1/20 of the linewidth) will lead to a determination of the nuclear rms charge radii with a relative accuracy of 3 ×10 - 4 (equivalent to 0.0005 fm). The limiting factor for the extraction of the radii from the Lamb shift measurements is given by the uncertainty of the nuclear polarizability contribution. Combined with an ongoing experiment at MPQ aiming to measure the 1S - 2S transition frequency in the helium ion, the Lamb shift measurement in μHe + will lead to a sensitive test of problematic and challenging bound-state QED terms. This measurement will also help to clarify the discrepancy found in our previous μ p experiment. Additionally, a precise knowledge of the absolute nuclear radii of the He isotopes and the hyperfine splitting of μ 3He + provide a relevant test of few-nucleon theories.

Self-trapped holes in β-Ga2O3 crystals

NASA Astrophysics Data System (ADS)

Kananen, B. E.; Giles, N. C.; Halliburton, L. E.; Foundos, G. K.; Chang, K. B.; Stevens, K. T.

2017-12-01

We have experimentally observed self-trapped holes (STHs) in a β-Ga2O3 crystal using electron paramagnetic resonance (EPR). These STHs are an intrinsic defect in this wide-band-gap semiconductor and may serve as a significant deterrent to producing usable p-type material. In our study, an as-grown undoped n-type β-Ga2O3 crystal was initially irradiated near room temperature with high-energy neutrons. This produced gallium vacancies (acceptors) and lowered the Fermi level. The STHs (i.e., small polarons) were then formed during a subsequent irradiation at 77 K with x rays. Warming the crystal above 90 K destroyed the STHs. This low thermal stability is a strong indicator that the STH is the correct assignment for these new defects. The S = 1/2 EPR spectrum from the STHs is easily observed near 30 K. A holelike angular dependence of the g matrix (the principal values are 2.0026, 2.0072, and 2.0461) suggests that the defect's unpaired spin is localized on one oxygen ion in a nonbonding p orbital aligned near the a direction in the crystal. The EPR spectrum also has resolved hyperfine structure due to equal and nearly isotropic interactions with 69,71Ga nuclei at two neighboring Ga sites. With the magnetic field along the a direction, the hyperfine parameters are 0.92 mT for the 69Ga nuclei and 1.16 mT for the 71Ga nuclei.

Theoretical energies, transition rates, lifetimes, hyperfine interaction constants and Lande´ gJ-factors for the Se XXVII spectrum of fusion interest

NASA Astrophysics Data System (ADS)

Chen, Zhan-Bin; Guo, Xue-Ling; Wang, Kai

2018-02-01

An extensive set of level energies, wavelengths, line strengths, oscillator strengths, lifetimes, hyperfine structures, Lande´ gJ-factors, electric dipole (E1), magnetic dipole (M1), electric quadrupole (E2), and magnetic quadrupole (M2) radiative transition rates among the lowest 318 states arising from the 2s22p4, 2s2p5, 2p6, 2s22p33l (l = 0, 1, 2), 2s2p43l (l = 0, 1, 2), 2p53l (l = 0, 1, 2), and 2s22p34l (l = 0, 1, 2, 3) configurations has been obtained for Se XXVII. These new data, calculated within the frameworks of the multi-configuration Dirac-Hartree-Fock method and the second-order many-body perturbation theory, fill in the gap existing in the atomic data needed for the diagnostic processes of tokamak plasmas. Using two methods allowed us to make an intercomparison and to estimate the uncertainties on the obtained data. The results arising in the two sets of calculations are quite close, suggesting that there is a high degree of convergence achieved in our work. i.e., our two sets of energies agree to better than 0.02%, and the lifetimes mostly agree to within 2%. Comparison is also made with the limited number of experimental data and previous computations to assess the accuracy of our calculations.

Effective field theories for muonic hydrogen

NASA Astrophysics Data System (ADS)

Peset, Clara

2017-03-01

Experimental measurements of muonic hydrogen bound states have recently started to take place and provide a powerful setting in which to study the properties of QCD. We profit from the power of effective field theories (EFTs) to provide a theoretical framework in which to study muonic hydrogen in a model independent fashion. In particular, we compute expressions for the Lamb shift and the hyperfine splitting. These expressions include the leading logarithmic O(mμα6) terms, as well as the leading {\\cal O}≤ft( {{m_μ }{α ^5}{{m_μ ^2} \\over {Λ {{QCD}}^2}}} \\right) hadronic effects. Most remarkably, our analyses include the determination of the spin-dependent and spin-independent structure functions of the forward virtualphoton Compton tensor of the proton to O(p3) in HBET and including the Delta particle. Using these results we obtain the leading hadronic contributions to the Wilson coeffcients of the lepton-proton four fermion operators in NRQED. The spin-independent coeffcient yields a pure prediction for the two-photon exchange contribution to the muonic hydrogen Lamb shift, which is the main source of uncertainty in our computation. The spindependent coeffcient yields the prediction of the hyperfine splitting. The use of EFTs crucially helps us organizing the computation, in such a way that we can clearly address the parametric accuracy of our result. Furthermore, we review in the context of NRQED all the contributions to the energy shift of O(mμα5, as well as those that scale like mrα6× logarithms.

Computational Studies of Magnetically Doped Semiconductor Nanoclusters

NASA Astrophysics Data System (ADS)

Gutsev, Lavrenty Gennady

Spin-polarized unrestricted density functional theory is used to calculate the molecular properties of magnetic semiconductor quantum dots doped with 3d-metal atoms. We calculate total energies of the low spin antiferromagnetically coupled states using a spin-flipping algorithm leading to the broken-symmetry states. Given the novel nature of the materials studied, we simulate experimental observables such as hyperfine couplings, ionization/ energies, electron affinities, first and second order polarizabilities, band gaps and exchange coupling constants. Specifically, we begin our investigation with pure clusters of (CdSe )16 and demonstrate the dependence of molecular observables on geometrical structures. We also show that the many isomers of this cluster are energetically quite closely spaced, and thus it would be necessary to employ a battery of tests to experimentally distinguish them. Next, we discuss Mn-doping into the cage (CdSe)9 cluster as well as the zinc-blende stacking type cluster (CdSe)36. We show that the local exchange coupling mechanism is ligand-mediated superexchange and simulate the isotropic hyperfine constants. Finally, we discuss a novel study where (CdSe)9 is doped with Mn or Fe up to a full replacement of all the Cd's and discuss the transition points for the magnetic behavior and specifically the greatly differing band-gap shifts. We also outline an unexpected pattern in the polarizability of the material as metals are added and compare our results with the results from theoretical studies of the bulk material.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Dalal, M.; Mallick, A.; Mahapatra, A.S.

Highlights: • Cation distribution in tetrahedral and octahedral sites of spinel Ni{sub 0.4}Zn{sub 0.4}Co{sub 0.2}Fe{sub 2}O{sub 4}. • Structural analysis of observed X-ray diffraction pattern using Rietveld method. • Study of hyperfine behaviour using Mössbauer spectroscopy. • Static and dynamic magnetic measurements. • Correlation of cation distributions obtained from Rietveld analysis with the results of magnetic and Mössbauer effect measurements. - Abstract: Nanoparticles of Ni{sub 0.4}Zn{sub 0.4}Co{sub 0.2}Fe{sub 2}O{sub 4} are prepared by a simple co-precipitation method. The as dried sample is heat treated at 400, 500, 600, 700 and 800 °C to obtain different sizes of nanoparticles. The crystallographicmore » phase of the samples is confirmed analyzing observed X-ray diffraction (XRD) by Rietveld method. Hyperfine parameters of the samples are derived from room temperature (RT) Mössbauer spectra of the samples. Magnetic properties of the samples are investigated by static and dynamic hysteresis loops. Different magneto-crystalline parameters are calculated from the variation of magnetization with temperature (M–T curve) under zero field cooled (ZFC) and field cooled (FC) conditions of the as dried sample. The cation distribution estimated from Rietveld analysis are correlated with the results of magnetic and Mössbauer effect measurements. The observed high value of saturation magnetization (72.7 emu/g at RT) of the sample annealed at 800 °C would be interesting for applications in different electromagnetic devices.« less

EVOLUTION OF FAST MAGNETOACOUSTIC PULSES IN RANDOMLY STRUCTURED CORONAL PLASMAS

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yuan, D.; Li, B.; Pascoe, D. J.

2015-02-01

We investigate the evolution of fast magnetoacoustic pulses in randomly structured plasmas, in the context of large-scale propagating waves in the solar atmosphere. We perform one-dimensional numerical simulations of fast wave pulses propagating perpendicular to a constant magnetic field in a low-β plasma with a random density profile across the field. Both linear and nonlinear regimes are considered. We study how the evolution of the pulse amplitude and width depends on their initial values and the parameters of the random structuring. Acting as a dispersive medium, a randomly structured plasma causes amplitude attenuation and width broadening of the fast wavemore » pulses. After the passage of the main pulse, secondary propagating and standing fast waves appear. Width evolution of both linear and nonlinear pulses can be well approximated by linear functions; however, narrow pulses may have zero or negative broadening. This arises because narrow pulses are prone to splitting, while broad pulses usually deviate less from their initial Gaussian shape and form ripple structures on top of the main pulse. Linear pulses decay at an almost constant rate, while nonlinear pulses decay exponentially. A pulse interacts most efficiently with a random medium with a correlation length of about half of the initial pulse width. This detailed model of fast wave pulses propagating in highly structured media substantiates the interpretation of EIT waves as fast magnetoacoustic waves. Evolution of a fast pulse provides us with a novel method to diagnose the sub-resolution filamentation of the solar atmosphere.« less

Impact of surface nanostructure on ice nucleation.

PubMed

Zhang, Xiang-Xiong; Chen, Min; Fu, Ming

2014-09-28

Nucleation of water on solid surface can be promoted noticeably when the lattice parameter of a surface matches well with the ice structure. However, the characteristic length of the surface lattice reported is generally less than 0.5 nm and is hardly tunable. In this paper, we show that a surface with nanoscale roughness can also remarkably promote ice nucleation if the characteristic length of the surface structure matches well with the ice crystal. A series of surfaces composed of periodic grooves with same depth but different widths are constructed in molecular dynamics simulations. Water cylinders are placed on the constructed surfaces and frozen at constant undercooling. The nucleation rates of the water cylinders are calculated in the simulation using the mean first-passage time method and then used to measure the nucleation promotion ability of the surfaces. Results suggest that the nucleation behavior of the supercooled water is significantly sensitive to the width of the groove. When the width of the groove matches well with the specific lengths of the ice crystal structure, the nucleation can be promoted remarkably. If the width does not match with the ice crystal, this kind of promotion disappears and the nucleation rate is even smaller than that on the smooth surface. Simulations also indicate that even when water molecules are adsorbed onto the surface structure in high-humidity environment, the solid surface can provide promising anti-icing ability as long as the characteristic length of the surface structure is carefully designed to avoid geometric match.

First principles calculations of the magnetic and hyperfine properties of Fe/N/Fe and Fe/O/Fe multilayers in the ground state of cohesive energy

NASA Astrophysics Data System (ADS)

dos Santos, A. V.; Samudio Pérez, C. A.; Muenchen, D.; Anibele, T. P.

2015-01-01

The ground state properties of Fe/N/Fe and Fe/O/Fe multilayers were investigated using the first principles calculations. The calculations were performed using the Linearized Augmented Plane Wave (LAPW) method implemented in the Wien2k code. A supercell consisting of one layer of nitride (or oxide) between two layers of Fe in the bcc structure was used to model the structure of the multilayer. The research in new materials also stimulated theoretical and experimental studies of iron-based nitrides due to their variety of structural and magnetic properties for the potential applications as in high strength steels and for high corrosion resistance. It is obvious from many reports that magnetic iron nitrides such as γ-Fe4N and α-Fe16N2 have interesting magnetic properties, among these a high magnetisation saturation and a high density crimp. However, although Fe-N films and multilayers have many potential applications, they can be produced in many ways and are being extensively studied from the theoretical point of view there is no detailed knowledge of their electronic structure. Clearly, efforts to understand the influence of the nitrogen atoms on the entire electronic structure are needed as to correctly interpret the observed changes in the magnetic properties when going from Fe-N bulk compounds to multilayer structures. Nevertheless, the N atoms are not solely responsible for electronics alterations in solid compounds. Theoretical results showed that Fe4X bulk compounds, where X is a variable atom with increasing atomic number (Z), the nature of bonding between X and adjacent Fe atoms changes from more covalent to more ionic and the magnetic moments of Fe also increase for Z=7, i.e. N. This is an indicative that atoms with a Z number higher than 7, i.e., O, can produce several new alterations in the entire magnetic properties of Fe multilayers. This paper presents the first results of an ab-initio electronic structure calculations, performed for Fe-N and Fe-O multilayers. Firstly, the formation energy and the cohesive energy of the multilayers are discussed. For optimised values, the cohesive energy of the multilayers to obtain the lattice parameters at the equilibrium ground state was used, i.e. a new methodology for this calculus was applied. Secondly, the magnetic properties and hyperfine interactions (magnetic field, electric field gradient and the isomer shift) of the iron atoms of the multilayers are discussed.

Combined effect of high curing temperature and crack width on chloride migration in reinforced concrete beams

NASA Astrophysics Data System (ADS)

Elkedrouci, L.; Diao, B.; Pang, S.; Li, Y.

2018-03-01

Deterioration of reinforced concrete structures is a serious concern in the construction engineering, largely due to chloride induced corrosion of reinforcement. Chloride penetration is markedly influenced by one or several major factors at the same time such as cuing in combination with different crack widths which have spectacular effect on reinforced concrete structures. This research presents the results of an experimental investigation involving reinforced concrete beams with three different crack widths ranging from 0 to 0.2mm, curing temperatures of 20°C or 40°C and water-to-cement of 0.5. Chloride content profiles were determined under non-steady state diffusion at 20°C. Based on the obtained results, higher chloride content was obtained under condition of high curing temperature in combination with large crack more than 0.1mm and there are no significant differences between narrow crack width (less than 0.1 mm) and beams without crack (0 mm).

Coma measurement by use of an alternating phase-shifting mask mark with a specific phase width

DOE Office of Scientific and Technical Information (OSTI.GOV)

Qiu Zicheng; Wang Xiangzhao; Yuan Qiongyan

2009-01-10

The correlation between the coma sensitivity of the alternating phase-shifting mask (Alt-PSM) mark and the mark's structure is studied based on the Hopkins theory of partially coherent imaging and positive resist optical lithography (PROLITH) simulation. It is found that an optimized Alt-PSM mark with its phase width being two-thirds its pitch has a higher sensitivity to coma than Alt-PSM marks with the same pitch and the different phase widths. The pitch of the Alt-PSM mark is also optimized by PROLITH simulation, and the structure of p=1.92{lambda}/NA and pw=2p/3 proves to be with the highest sensitivity. The optimized Alt-PSM mark ismore » used as a measurement mark to retrieve coma aberration from the projection optics in lithographic tools. In comparison with an ordinary Alt-PSM mark with its phase width being a half its pitch, the measurement accuracies of Z7 and Z14 apparently increase.« less