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Articles 931 - 960 of 967
Full-Text Articles in Physics
Synthetic Analogs Of The Active Sites Of Iron-Sulfur Proteins. Structure And Properties Of Bis[O-Xylyldithiolato-Μ2-Sulfidoferrate(Iii)], An Analog Of The 2fe-2s Proteins, J. J. Mayerle, Richard B. Frankel, R. H. Holm, James A. Ibers, W. D. Phillips, J. F. Weiher
Synthetic Analogs Of The Active Sites Of Iron-Sulfur Proteins. Structure And Properties Of Bis[O-Xylyldithiolato-Μ2-Sulfidoferrate(Iii)], An Analog Of The 2fe-2s Proteins, J. J. Mayerle, Richard B. Frankel, R. H. Holm, James A. Ibers, W. D. Phillips, J. F. Weiher
Physics
The synthetic analog approach has been applied to a clarification of the active sites of 2Fe-2S* proteins. The compound (Et4N)2[FeS(SCH2)2C6H4]2, derived from o-xylyl-α,α′-dithiol, has been prepared and its structure has been determined by x-ray diffraction. The centrosymmetric anion contains two tetrahedrally coordinated ferric ions bridged by two sulfide ions and separated by 2.70 Å. Comparison of electronic, Mössbauer, and proton magnetic resonance spectra and magnetic susceptibility of the anion with the corresponding properties of the oxidized forms of the proteins reveals …
Far Infrared Absportion Of Fe(2+) In Kmgf3, R. B. Frankel, C. R. Abeledo, A. Misetich
Far Infrared Absportion Of Fe(2+) In Kmgf3, R. B. Frankel, C. R. Abeledo, A. Misetich
Physics
Far infrared absorption in cubic KMgF3 doped with Fe2+ is reported . A line is observed at 87cm−1, which is assigned to the (Γ5g → Γ3g, Γ4g) transition in the Fe2+. The reduction in the spin-orbit coupling from the free ion value has been predicted by Ham, Schwarz and O'Brien.
Antiferromagnetic To Paramagnetic Transition In Fe2+: Mnf2 In External Magnetic Fields, C. R. Abeledo, Richard B. Frankel, M. A. Weber, A. Misetich
Antiferromagnetic To Paramagnetic Transition In Fe2+: Mnf2 In External Magnetic Fields, C. R. Abeledo, Richard B. Frankel, M. A. Weber, A. Misetich
Physics
Mössbauer effect measurements across the antiferromagnetic to paramagnetic phase boundary in Fe2+ : MnF2 in external magnetic fields are reported. From the data, J(Mn-Fe)= -1.7 cm-1. The phase boundary is found to vary as Ho2, as in pure MnF2.
Analysis Of Hyperfine Interactions Of Fe2+ In Fef2, Mnf2 And Znf2, C. R. Abeledo, Richard B. Frankel, A. Misetich
Analysis Of Hyperfine Interactions Of Fe2+ In Fef2, Mnf2 And Znf2, C. R. Abeledo, Richard B. Frankel, A. Misetich
Physics
Analysis of magnetic hyperfine interactions of Fe2+ in FeF2, Fe2+:MnF2 and Fe2+:ZnF2 yields a core polarization hyperfine field Hc = −514 ± 30 kOe and a value of (r−3)eff = 3.9 ± 0.04 au.
Electronic Properties Of Fe2+ In Cubic Kmgf3 From Mössbauer Spectroscopy, Richard B. Frankel, J. Chappert, J. R. Regnard, A. Misetich, C. R. Abeledo
Electronic Properties Of Fe2+ In Cubic Kmgf3 From Mössbauer Spectroscopy, Richard B. Frankel, J. Chappert, J. R. Regnard, A. Misetich, C. R. Abeledo
Physics
Iron-doped KMgF3 single crystals have been studied by Mössbauer spectroscopy of Fe57. Single lines due to Fe2+ and Fe3+ are observed at room temperature. For TK, the Fe2+ line splits into a quadrupole doublet with a splitting ΔEQ=0.44±0.02 mm/sec. Comparison with a random-strain model due to Ham yields a value of 120 cm-1 for the position of the first excited spin-orbit split level. Magnetic hyperfine structure in external magnetic fields at low temperature is observed and analysis yields a value of -495 ±30 kOe for the corepolarization hyperfine field …
Mössbauer Spectroscopy Study Of The Spin‐Flop Transition In Fe‐Doped Mnf2, C. R. Abeledo, Richard B. Frankel, A. Misetich, N. A. Blum
Mössbauer Spectroscopy Study Of The Spin‐Flop Transition In Fe‐Doped Mnf2, C. R. Abeledo, Richard B. Frankel, A. Misetich, N. A. Blum
Physics
Measurements of the hyperfine interaction in Fe+ + in MnF2 in external fields above the spin‐flop field at 4.2 K are reported and a value of g⊥ = 2.13 is derived, in good agreement with theory.
Mössbauer Effect In Fe-Doped Kmgf3, J. Chappert, J. R. Regnard, Richard B. Frankel, A. Misetich, N. A. Blum
Mössbauer Effect In Fe-Doped Kmgf3, J. Chappert, J. R. Regnard, Richard B. Frankel, A. Misetich, N. A. Blum
Physics
An iron-doped KMgF3 single crystal has been studied with the Mössbauer technique. The two charge states, Fe2+ and Fe3+, are observed. Below 12 °K an Fe2+ quadrupole doublet appears. Using Ham strain model we calculate that the first excited spin-orbit level lies ~ 120 cm-1 above the Γ5g ground state.
Isomeric Shift Of The 83 Kev Transition In 153Eu, E. Ansaldo, L. Grodzins, Richard B. Frankel
Isomeric Shift Of The 83 Kev Transition In 153Eu, E. Ansaldo, L. Grodzins, Richard B. Frankel
Physics
No abstract provided.
Local Magnetic Moments And The Mossbauer Effect, Richard B. Frankel, Brian B. Schwartz
Local Magnetic Moments And The Mossbauer Effect, Richard B. Frankel, Brian B. Schwartz
Physics
No abstract provided.
Mossbauer Study Of An Intramolecular Antiferromagnet, R. Lechan, C. R. Abeledo, R. B. Frankel
Mossbauer Study Of An Intramolecular Antiferromagnet, R. Lechan, C. R. Abeledo, R. B. Frankel
Physics
Mossbauer measurements at 4.2 ≤T ≤ 22 K and OsHosBO kOe are + reported in (Fe Salen Cl)2, a molecular complex containing two coupled Fe3+ ions bridged by oxygen atoms. At 4.2 K only the ground state with effective spin S = 0 is appreciably populated. Analysis of the magnetic field and temperature dependence of the magnetic hyperfine field yields an exchange constant J= -6.7 cm>sup>-1 and a hyperfine field of -192 kOe per unit spin at each Fe3+ nucleus.
Nuclear Orientation Of 253Es In Neodymium Ethylsulfate, A. J. Soinski, Richard B. Frankel, Q. O. Navarro, D. A. Shirley
Nuclear Orientation Of 253Es In Neodymium Ethylsulfate, A. J. Soinski, Richard B. Frankel, Q. O. Navarro, D. A. Shirley
Physics
Einsteinium-253 nuclei were oriented at low temperatures in a neodymium ethylsulfate lattice. From the temperature-dependent α-particle angular distribution a nuclear magnetic moment |μ|=(2.7±1.3)μN was deduced. From the values for the angular distribution function at the lowest temperatures it was possible to test the predictions of the Mang shell-model theory for the relative phases and amplitudes of the α-partial waves. As predicted, the waves of angular momentum L=0 and 2 are in phase, and the L=0 and 4 waves are out of phase. The predicted wave amplitudes are in error, especially that of the L …
Are There Magnetic Moments At The Transition Metal Sites In Feal, Coal, And Nial?, Richard B. Frankel, D. J. Sellmeyer, N. A. Blum
Are There Magnetic Moments At The Transition Metal Sites In Feal, Coal, And Nial?, Richard B. Frankel, D. J. Sellmeyer, N. A. Blum
Physics
Measurements of the hyperfine interactions in 57Fe in the CsCl structure intermetallic compounds FeAl, CoAl and NiAl are reported.
Stress-Induced Angular Momentum Quenching In Mgo: Fe2+ As Observed By Mössbauer Spectroscopy, J. Chappert, A. Misetich, Richard B. Frankel, N. A. Blum
Stress-Induced Angular Momentum Quenching In Mgo: Fe2+ As Observed By Mössbauer Spectroscopy, J. Chappert, A. Misetich, Richard B. Frankel, N. A. Blum
Physics
Under the influence of a suitable uniaxial stress, the quenching of the electronic angular momentum of the low-lying threefold degenerate Γ5g level of Fe2+ in cubic MgO has been observed by Mössbauer spectroscopy. The result is consistent with Ham's model for the appearance of a quadrupole doublet at low temperatures. A value for the strain coefficient of Fe2+ in MgO has been obtained: G11=585 cm-1.
Hyperfine Interaction In Gd In Diamagnetic, Metallic Hosts, Richard B. Frankel
Hyperfine Interaction In Gd In Diamagnetic, Metallic Hosts, Richard B. Frankel
Physics
Mössbauer effect data for dilute, paramagnetic Gd in the diamagnetic, metallic hosts YAl2, YbAl2 and Al are analyzed and yield a local conduction electron polarization contribution to the Gd hyperfine field of +140 kOe.
Nuclear Zeeman Effect In W182 In Iron, Richard B. Frankel, Y. Chow, L. Grodzins, J. Wulff
Nuclear Zeeman Effect In W182 In Iron, Richard B. Frankel, Y. Chow, L. Grodzins, J. Wulff
Physics
The Mössbauer effect in the 100-keV 2+→0+ transition in W182 was observed with dilute tungsten in iron alloy absorbers with concentrations from 0.5-5.0 at.%W at 4.2°K. From the Zeeman spectra in external longitudinal magnetic fields, the g factor of the first excited 2+ state was found to be 0.22±0.02, and the hyperfine field at tungsten nuclei in iron was found to be -708±25 kOe. The hyperfine interaction for Fe57 in these alloys was also measured, and the results are compared with measurements on alloys of Fe with other 5d impurities and with neutron diffraction measurements.
High-Field Studies Of Band Ferromagnetism In Fe And Ni By Mössbauer And Magnetic Moment Measurements, S. Foner, A. J. Freeman, N. A. Blum, Richard B. Frankel, E. J. Mcniff, Jr., H. C. Praddaude
High-Field Studies Of Band Ferromagnetism In Fe And Ni By Mössbauer And Magnetic Moment Measurements, S. Foner, A. J. Freeman, N. A. Blum, Richard B. Frankel, E. J. Mcniff, Jr., H. C. Praddaude
Physics
High-field susceptibility χHF in Fe and Ni (at 4.2, 77, and 300°K) and high-field Mössbauer studies in Fe at 4.2°K are reported and related to the band structure of Fe and Ni and to band models of ferromagnetism. The Mössbauer effect was employed to measure the change in the hyperfine field Hn at the 57Fe nucleus with application of an external field. Assuming Hn to be proportional to the bulk magnetization, a microscopic equivalent to χHF is obtained. We also show how the high-field data may be used alternatively to determine the nuclear g factor. …
Multiple Charge States, Hyperfine Interactions, And Relaxation Processes Of Fe In 57Co-Doped Mgo, J. Chappert, Richard B. Frankel, A. Misetich, N. A. Blum
Multiple Charge States, Hyperfine Interactions, And Relaxation Processes Of Fe In 57Co-Doped Mgo, J. Chappert, Richard B. Frankel, A. Misetich, N. A. Blum
Physics
The Mössbauer spectra of cobalt-57-doped magnesium oxide have been studied between 1.3 and 550°K in external magnetic fields of up to 135 kOe for both single-crystal and polycrystalline samples. At room temperature and zero external magnetic field, the velocity spectrum is composed of three single lines, attributed to monovalent, divalent, and trivalent iron. In certain samples, for T2+ line undergoes a transition to a quadrupole doublet with a splitting ΔEQ=0.30±0.02 mm/sec, while in certain other samples, annealed differently, no doublet is observed down to 1.5°K. The first case is in quantitative agreement with a random-strain model …
Absence Of Induced Magnetic Fields At Gd Nuclei In Gdfe2, H. Maletta, Richard B. Frankel, W. Henning, R. L. Mössbauer
Absence Of Induced Magnetic Fields At Gd Nuclei In Gdfe2, H. Maletta, Richard B. Frankel, W. Henning, R. L. Mössbauer
Physics
Measurements of the magnetic hyperfine field at 115Gd in GdFe2 in external magnetic fields reveal the absence of induced magnetic fields, in disagreement with other reported data.
Quadrupole Moment Of 57FeM, J. Chappert, Richard B. Frankel, A. Misetich, N. A. Blum
Quadrupole Moment Of 57FeM, J. Chappert, Richard B. Frankel, A. Misetich, N. A. Blum
Physics
The quadrupole splitting induced by a magnetic field at low temperatures has been measured by Mössbauer spectroscopy for Fe2+ in MgO; a value of +0.21 ± 0.03 barn for the quadrupole moment of 57Fem is obtained.
Three-Quasiparticle Intruder State In Te125 And The Magnetic Moment Of Sb125, N. J. Stone, Richard B. Frankel, D. A. Shirley
Three-Quasiparticle Intruder State In Te125 And The Magnetic Moment Of Sb125, N. J. Stone, Richard B. Frankel, D. A. Shirley
Physics
The levels of Te125 have been studied using Sb125 nuclei, polarized at T=0.014°K in an iron lattice, and Ge(Li) detectors. The magnetic moment of Sb125 was determined as (2.59±0.03) μN. Levels (spins) were assigned at 35.9(3/2+), 145.4(11/2-), 322.2(9/2-), 443.7(probably 3/2+), 462.5(5/2+), 525.4(probably 9/2-), 636.1(7/2+), 642.3(7/2+), 671.6(5/2+) (energies in keV). The even-parity levels could be identified with levels calculated by Kisslinger and Sorensen. Using their wave functions, we calculated E2/M1 mixing ratios and branching ratios, finding quite good agreement. The odd-parity states are of special interest. The 11/2-145.4-keV state and 9/2-525.4-keV state …
Magnetic Hyperfine Structure In 125Te, Richard B. Frankel, J. J. Huntzicker, D. A. Shirley, N. J. Stone
Magnetic Hyperfine Structure In 125Te, Richard B. Frankel, J. J. Huntzicker, D. A. Shirley, N. J. Stone
Physics
Mössbauer spectra of 125TeFe with improved resolution yield μ(35.5 keV) = +0.60 ± 0.02 nm. The effect of this value on hyperfine spectra of 125Te are discussed.
Magnetic‐Field Dependence Of The Hyperfine Field At Fe In Dilute Fe-Pd Alloys, N. A. Blum, Richard B. Frankel
Magnetic‐Field Dependence Of The Hyperfine Field At Fe In Dilute Fe-Pd Alloys, N. A. Blum, Richard B. Frankel
Physics
No abstract provided.
Mössbauer Effect In 57Fe In Copper And The Spin‐Compensated State, B. B. Schwartz, D. J. Kim, Richard B. Frankel, N. A. Blum
Mössbauer Effect In 57Fe In Copper And The Spin‐Compensated State, B. B. Schwartz, D. J. Kim, Richard B. Frankel, N. A. Blum
Physics
The results of Mössbauer experiments on dilute Fe in Cu in high external magnetic fields (42–146 kOe) are presented here as evidence for significant destruction of the spin‐compensated state by a magnetic field for which μH0∼kTK, where kTK is on the order of the energy change associated with the formation of the spin‐compensated state.
Mössbauer Study Of Ferrimagnetic Ordering In Nickel Ferrite And Chromium-Substituted Nickel Ferrite, J. Chappert, Richard B. Frankel
Mössbauer Study Of Ferrimagnetic Ordering In Nickel Ferrite And Chromium-Substituted Nickel Ferrite, J. Chappert, Richard B. Frankel
Physics
Mössbauer-effect measurements in external magnetic fields show that the magnetic structure of ferrimagnetic NiFe2O4 is the collinear Néel type. NiFe0.3Cr1.7O4 is shown to have a triangular structure with θA=20±10° and θB=50±4°.
Fe1+ And Fe2+ Hyperfine Fields In Mgo And Cao, J. Chappert, Richard B. Frankel, N. A. Blum
Fe1+ And Fe2+ Hyperfine Fields In Mgo And Cao, J. Chappert, Richard B. Frankel, N. A. Blum
Physics
Hyperfine interactions have been measured for Fe1+ and Fe2+ in MgO and CaO. The core polarization fields per spin moment are −127 kOeμB for both Fe1+ and Fe2+.
Mössbauer Evidence For A Spin-Compensated State In Dilute Fe-Cu Alloys, Richard B. Frankel, N. A. Blum, Brian B. Schwartz, Duk Joo Kim
Mössbauer Evidence For A Spin-Compensated State In Dilute Fe-Cu Alloys, Richard B. Frankel, N. A. Blum, Brian B. Schwartz, Duk Joo Kim
Physics
No abstract provided.
Observation Of Centrifugal Stretching In Sm152, D. Yeboah-Amankwah, L. Grodzins, Richard B. Frankel
Observation Of Centrifugal Stretching In Sm152, D. Yeboah-Amankwah, L. Grodzins, Richard B. Frankel
Physics
An isomer shift has been observed in the Mössbauer study of the 121.8-keV (2+→0+) transition in Sm152. A value of (Δ〈R2〉/〈R2〉)2-0=(10±3)×10-4 is deduced, based on isotope shift data for Sm152 and Sm154. This value disagrees with present theoretical prediction. In particular, the influence of the β band in Sm152 can only account for about 20% of the observed stretching.
High‐Magnetic‐Field Studies Of Orthorhombic And Rhombohedral Al2−XFeXO3 Compounds, M. Schieber, Richard B. Frankel, N. A. Blum, S. Foner
High‐Magnetic‐Field Studies Of Orthorhombic And Rhombohedral Al2−XFeXO3 Compounds, M. Schieber, Richard B. Frankel, N. A. Blum, S. Foner
Physics
Mössbauer and magnetic susceptibility experiments at temperatures down to 4.2°K and in external fields up to 140 kOe show orthorhombic Al2−xFexO3 (0.61.6Fe0.4O3 is paramagnetic above 80°K, and at 4.2°K exhibits a Mössbauer spectrum characteristic of a nonunique hyperfine field; the application of an external magnetic field produces a spectrum with an enhanced Δm=0 line which suggests a canted spin structure similar to that in the high‐temperature phase (T>260°K) of αFe2O3.
Hyperfine Fields And Isomer Shifts In Magnetically Ordered Europium Compounds, H. H. Wickman, I. Nowik, J. H. Wernick, D. A. Shirley, Richard B. Frankel
Hyperfine Fields And Isomer Shifts In Magnetically Ordered Europium Compounds, H. H. Wickman, I. Nowik, J. H. Wernick, D. A. Shirley, Richard B. Frankel
Physics
The Mössbauer technique was employed to study hyperfine fields in several ordered divalent europium compounds at low temperatures. The intermetallics EuCu2, EuAl2, and EuAl4 were ordered at helium temperatures and the observed fields and isomer shifts were 189(8) kOe, −0.88 cm∕sec; 278(8) kOe, −0.97 cm∕sec; and 290(8) kOe, −1.14 cm∕sec, respectively. Comparison of these results and previous measurements with EuO, EuS, and Eu metal indicates a possible correlation between isomer shift and internal field. With the exception of EuCu2 the internal fields increase with increasing magnitude of isomer shift. Interpretation of this trend with a …
Ferromagnetic Metals In High Magnetic Fields, A. J. Freeman, N. A. Blum, S. Foner, Richard B. Frankel, E. J. Mcniff, Jr.
Ferromagnetic Metals In High Magnetic Fields, A. J. Freeman, N. A. Blum, S. Foner, Richard B. Frankel, E. J. Mcniff, Jr.
Physics
High‐field susceptibility results are presented for Mössbauer measurements on iron at low temperatures in fields up to 135 kOe and magnetization measurements on iron and nickel single crystals in fields up to 148 kOe with vibrating sample magnetometers. The Mössbauer measurements give the hyperfine field Hn= Hint− (H0−HDM)+ΔH, where Hint is the hyperfine field at zero applied field, H0 is the applied field, HDM is the demagnetizing field, and ΔH is a term which would reflect a change in the magnetization at high field, …