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California Polytechnic State University, San Luis Obispo

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Articles 601 - 625 of 625

Full-Text Articles in Physics

Stress-Induced Angular Momentum Quenching In Mgo: Fe2+ As Observed By Mössbauer Spectroscopy, J. Chappert, A. Misetich, Richard B. Frankel, N. A. Blum Mar 1970

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 Nov 1969

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 Oct 1969

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 5 ...


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 May 1969

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 ...


Multiple Charge States, Hyperfine Interactions, And Relaxation Processes Of Fe In 57Co-Doped Mgo, J. Chappert, Richard B. Frankel, A. Misetich, N. A. Blum Mar 1969

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 ...


Absence Of Induced Magnetic Fields At Gd Nuclei In Gdfe2, H. Maletta, Richard B. Frankel, W. Henning, R. L. Mössbauer Jan 1969

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 Jan 1969

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 Aug 1968

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 ...


Magnetic Hyperfine Structure In 125Te, Richard B. Frankel, J. J. Huntzicker, D. A. Shirley, N. J. Stone Apr 1968

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.


Mössbauer Effect In 57Fe In Copper And The Spin‐Compensated State, B. B. Schwartz, D. J. Kim, Richard B. Frankel, N. A. Blum Feb 1968

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.


Magnetic‐Field Dependence Of The Hyperfine Field At Fe In Dilute Fe-Pd Alloys, N. A. Blum, Richard B. Frankel Feb 1968

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 Study Of Ferrimagnetic Ordering In Nickel Ferrite And Chromium-Substituted Nickel Ferrite, J. Chappert, Richard B. Frankel Sep 1967

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 Jul 1967

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 Jun 1967

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 May 1967

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 Mar 1967

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.


Ferromagnetic Metals In High Magnetic Fields, A. J. Freeman, N. A. Blum, S. Foner, Richard B. Frankel, E. J. Mcniff, Jr. Mar 1966

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− (H0HDM)+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, i.e., ΔH ...


Hyperfine Fields And Isomer Shifts In Magnetically Ordered Europium Compounds, H. H. Wickman, I. Nowik, J. H. Wernick, D. A. Shirley, Richard B. Frankel Mar 1966

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 ...


Isomer-Shift Measurement In W182, S. G. Cohen, N. A. Blum, Y. W. Chow, Richard B. Frankel, L. Grodzins Feb 1966

Isomer-Shift Measurement In W182, S. G. Cohen, N. A. Blum, Y. W. Chow, Richard B. Frankel, L. Grodzins

Physics

No abstract provided.


Magnetic Structure Of Ga2−Xfexo3, R. B. Frankel, N. A. Blum, S. Foner, A. J. Freeman, M. Schieber Jan 1966

Magnetic Structure Of Ga2−Xfexo3, R. B. Frankel, N. A. Blum, S. Foner, A. J. Freeman, M. Schieber

Physics

High‐magnetic‐field‐Mössbauer and magnetic‐moment experiments have been performed with Ga2−xFexO3. This magnetic system is of considerable interest because it is piezoelectric, weakly magnetic,1 and magnetoelectric.2 The crystal structure has been determined3 and a magnetic ordering inferred.3 The magnetic‐moment measurements were made using a vibrating sample magnetometer in fields up to 75 kOe. The samples used for the Mössbauer absorption experiments consisted of 57Fe enriched powders, grown from a flux, embedded in lucite, and having x=0.8 and 1.2. A mosaic absorber made of small x‐ray oriented single crystals was ...


Ferrimagnetic Structure Of Magnetoelectric Ga2-XFeXO3, Richard B. Frankel, N. A. Blum, S. Foner, A. J. Freeman, M. Schieber Dec 1965

Ferrimagnetic Structure Of Magnetoelectric Ga2-XFeXO3, Richard B. Frankel, N. A. Blum, S. Foner, A. J. Freeman, M. Schieber

Physics

No abstract provided.


Cerium Magnesium Nitrate Temperature Scale From Nuclear Orientation, Richard B. Frankel, D. A. Shirley, N. J. Stone Nov 1965

Cerium Magnesium Nitrate Temperature Scale From Nuclear Orientation, Richard B. Frankel, D. A. Shirley, N. J. Stone

Physics

Systematic deviations were found below 0.003°K in the temperature dependence of nuclear orientation of Ce137m in cerous magnesium nitrate, using the temperature scale proposed by Daniels and Robinson. The temperature scale below 0.006°K was redetermined using a new method: nuclear orientation. This has the advantage over the 'Y-ray heating method of high sensitivity at the lowest temperature. The most striking result is hat a value of 1/T of 520, rather than the previously accepted 324, is obtained by demagnetization from initial condItions of 18.8 kG deg-1. The useful absolute temperature range ...


Sign Change Of Induced Hyperfine Fields In The 5p Shell, Richard B. Frankel, J. J. Huntzicker, E. Matthias, S. S. Rosenblum, N. J. Stone Mar 1965

Sign Change Of Induced Hyperfine Fields In The 5p Shell, Richard B. Frankel, J. J. Huntzicker, E. Matthias, S. S. Rosenblum, N. J. Stone

Physics

No abstract provided.


Angular Distributions Of Conversion Electrons From Oriented Ce137M Nuclei, Richard B. Frankel, D. A. Shirley, N. J. Stone Nov 1964

Angular Distributions Of Conversion Electrons From Oriented Ce137M Nuclei, Richard B. Frankel, D. A. Shirley, N. J. Stone

Physics

The angular distributions of K- and of (L+M)-conversion electrons from oriented Ce137m nuclei were observed. Precise simultaneous intensity measurements of conversion electrons and γ rays from the same sample provided an accurate, direct determination of the particle parameters b2 associated with the 255-keV isomeric transition in Ce137. The K-electron result, b2=1.061 (18), is in excellent agreement with a theoretical prediction based on a "point nucleus" model. Techniques and parameters in this experiment, the first of its kind, are discussed. A more careful determination of the temperature dependence of anisotropy of the ...


Resonant Absorption Studies With Eu151, D. A. Shirley, Richard B. Frankel, H. H. Wickman Jan 1964

Resonant Absorption Studies With Eu151, D. A. Shirley, Richard B. Frankel, H. H. Wickman

Physics

No abstract provided.