Physical Sciences and Mathematics Commons^™

Hyperfine Interactions In Antiferromagnetic Eute Using The Te-125 Mossbauer Resonance, N. A. Blum, Richard B. Frankel

Physics

Europium telluride crystallizes in the NaCl structure and is antiferromagnetic with a Néel temperature TN of 9.6 K. We have used the 35.5 keV Møssbauer transition in Te-125 to examine the nature of the spontaneous magnetic moment which has been observed in conducting samples below TN. At 80 K the Mössbauer resonance spectrum consisted of a single absorption line comparable in width with the spectrum of nonmagnetic cubic ZnTe, indicating the absence of a significant quadrupole splitting at this temperature. At 4.2 K the line-width increased by a factor of 1.5, which is equivalent to a single magnetic hyperfine field …

Asymptotic Numbers: Algebraic Operations With Them, Christo Ya. Christov, Todor D. Todorov

Mathematics

The main subject of the present paper is to define the four algebraic operations - additions, subtraction, multiplication and division in the set of the asymptotic numbers A [7] and to deduce the corresponding formulas for the components of the asymptotic number, representing the result as functions of the components of the arguments. The definitions of the operations, in fact, are introduced as a special case of the more general notion of a quasiclassical function - one special class of functions defined on A. The discussion of the algebraic and some other properties of the asymptotic numbers is put …

Model System Studies Of Axial Ligation In The Oxidized Reaction States Of Cytochrome P-450 Enzymes, R. H. Holm, S. C. Tang, S. Koch, G. C. Papaethymiou, S. Foner, R. B. Frankel, J. A. Ibers

Physics

No abstract provided.

Synthetic Analogs Of Active Sites Of Iron-Sulfur Proteins: Bis (O-Xylyldithiolato) Ferrate (Iii) Monoanion, A Structurally Unconstrained Model For The Rubredoxin Fe-S4 Unit, R. W. Lane, James A. Ibers, Richard B. Frankel, R. H. Holm

Physics

To complete the set of synthetic analogs of the three recognized types of active sites in iron-sulfur redox proteins, the compound (Et₄N)[Fe((SCH₂)₂C₆H₄)₂], derived from o-xylyl-α,α'-dithiol, has been prepared and its structure has been determined by x-ray diffraction. The bischelate anion contains a near-tetrahedral Fe(III)-S₄ coordination unit with small rhombic distortions and all Fe-S bond distances in the range 2.252-2.279 Å. Its electronic properties have been partially characterized by measurement of electronic absorption, paramagnetic resonance, Mössbauer spectra, and magnetic susceptibility. The analog, as …

Linear Chain Compounds: Metamagnetism In Co(Pyr)2Cl2, Fe(Pyr)2Cl2, Fe(Pyr)2(Ncs)2 And Ni(Pyr)2Cl2, S. Foner, Richard B. Frankel, E. J. Mcniff, Jr., W. M. Reiff, B. F. Little, Gary J. Long

Physics

We report the observation of low field metamagnetic behavior in powder samples of Co(pyr)₂Cl₂, Fe(pyr)₂Cl₂, Fe(pyr)₂(NCS)₂ and Ni(pyr)₂Cl₂ where pyr=pyridine. These materials have linear chain structures with strong ferromagnetic interactions along the chains, and relatively weak antiferromagnetic interactions between chains. In all four compounds the transitions were observed as a rapid increase in the magnetic moment with increasing magnetic field. In Fe(pyr)₂Cl₂, Fe(pyr)₂(NCS)₂, and Ni(pyr)₂Cl₂, the transitions at 4.2 K were observed at 0.7 …

Hyperfine Interactions In Mgf2:Fe2+ And Znf2:Fe2+ By Mössbauer Spectroscopy, C. R. Abeledo, Richard B. Frankel, A. Misetich

Physics

Measurement of the magnetic hyperfine interaction in paramagnetic Fe²⁺ in ZnF₂ and MgF₂ by Mössbauer spectroscopy is reported. The results, −275 ± 3 kOe and −270 ± 3 kOe for ZnF₂:Fe²⁺ and MgF₂:Fe²⁺ respectively are compared with a previous analysis of hyperfine interactions in the rutile fluorides.

Metamagnetic Behavior Of Linear Chain Pyridine Compounds: Co(Pyridine)2Cl2, Fe(Pyridine)2Cl2, Fe(Pyridine)2(Ncs)2 And Ni(Pyridine)2Cl2, S. Foner, R. B. Frankel, W. M. Reiff, B. F. Little, G. J. Long

Physics

Magnetic phase transitions in the pyridine (pyr) compounds Co(pyr)₂Cl₂, Fe(pyr)₂Cl₂, Fe(pyr)₂(NCS)₂ and Ni(pyr)₂Cl₂ have been observed at applied magnetic fields of not, vert, similar0.7, 0.7, 1.1 and 2.7 kG respectively. These low field phase transitions are observed in the Fe and Ni compounds at T = 4.2 K, and in the Co compound at T < 3K, and are consistent with metamagnetic behavior. Magnetic saturation is not achieved in any of these compounds for fields of 60 kG, reflecting high anisotropy.

Mössbauer Properties Of Synthetic Analogs Of Active Sites Of The Iron-Sulfur Proteins, Richard B. Frankel, B. A. Averill, R. H. Holm

Physics

Mössbauer spectroscopy of the synthetic tetramers [Fe₄S₄(SR)₄]^2- (R = alkyl, aryl) and the corresponding trianions obtained by one-electron reduction, when compared with available data for 4-Fe and 8-Fe iron-sulfur proteins, shows that these tetramers are electronic analogs of the active sites of the proteins.

Kinectics Of The Ground State Transformation In Fe(Ii) (N, N -Dicyclohexylthiourea)6(Cio4)2, R. Latorre, J. A. Costamagna, E. Frank, C. R. Abeledo, Richard B. Frankel

Physics

The high spin complex Fe(II) (N, N'-dicyclohexylthiourea)₆(ClO₄)₆ exists in two forms which only differ in the distortion from octahedral symmetry of the environment of the Fe ion. Thermodynamic data for the transformation from one form to the other as obtained from Mössbauer spectroscopy are presented and a method to derive kinetic parameters is described.

Sign Of The Electric Field Gradient Tensor And The Nature Of The Low Temperature Phase Transition In Fe(Pyridine)2Cl2, W. M. Reiff, Richard B. Frankel, B. F. Little, Gary J. Long

Physics

Mossbauer spectra of Fe(pyridine)₂Cl₂ have been determined in large external magnetic fields at room temperature and 78 K. The principal component of the electric field gradient tensor is positive and consistent with an electron in the d_xy orbital. The results indicate no change in orbital ground state for the low temperature phase transition of this material.

A Prior Distribution For Smooth Regression, Leonard W. Deaton

Statistics

No abstract provided.

Synthetic Analogs Of The Active Sites Of Iron-Sulfur Proteins. Viii. Some Electronic Properties Of [Fe4S4(Sr)4]3; Analogs Of Reduced Bacterial Ferredoxins, R. B. Frankel, T. Herskovitz, B. A. Averill, R. H. Holm, P. J. Krusic, W. D. Phillips

Physics

One-electron reduction of the synthetic tetramers [Fe₄S₄(SR)₄]^2- (R = CH₂Ph, Ph), by chemical and electrochemical methods affords the corresponding trianions. The collective results from optical, electron paramagnetic resonance, and Mössbauer spectroscopy, when compared to available data for reduced 4-Fe and 8-Fe ferredoxin proteins and super-reduced Chromatium high-potential protein, reveal that [Fe₄S₄(SR)₄]^3- are electronic analogs of the [Fe₄S₄(S-Cys)₄] active sites of these proteins.

Fomes Annosus In Giant Sequoia, Douglas D. Piirto, John R. Parmeter Jr., F. W. Cobb Jr.

Natural Resources Management and Environmental Sciences

No abstract provided.

The Effects Of Dwarf Mistletoe On The Wood Properties Of Lodgepole Pine, Douglas D. Piirto, Donald L. Crews, Harry E. Troxell

Natural Resources Management and Environmental Sciences

The effects of dwarf mistletoe (Arceuthobium americanum Nutt. ex. Engelm.) on the wood properties of lodgepole pine (Pinus contorta Dougl.) were studied. The results indicate: a decline in modulus of elasticity, modulus of rupture, and work to proportional limit in both infected and noninfected wood from the infected trees; a higher specific gravity of the infected wood; a higher percentage of alcohol-benzene extractives in the infected wood; an increase in longitudinal shrinkage in both infected and noninfected wood from the same tree; a lower percentage of latewood in wood from infected trees; no significant difference in growth ring …

Abstract: Phase Transitions In Fecl2·2h2O In External Magnetic Fields: Mössbauer Spectroscopy, L. D. Kandel, M. A. Weber, Richard B. Frankel, C. R. Abeledo

Physics

Monoclinic FeCl₂·2H₂O orders antiferromagnetically at T_N = 23 K, and the magnetic structure consists of two sublattices of -FeCl₂-chains lying along the c-axis. The coupling along the chains is ferromagnetic with weak antiferromagnetic coupling between chains. Application of an external magnetic field along the easy axis (a) induces phase transitions at H₁ = 39 kOe and at H₂ = 46 kOe.

We report the observation of the three phases using the Mössbauer effect in a single crystal of FeCl₂·2H₂O cut parallel to the c-axis and placed at …

Mössbauer Spectroscopy Of Magnetic Phases In Fecl2 · 2h2O, L. Kandel, M. A. Weber, Richard B. Frankel, C. R. Abeledo

Physics

Mössbauer spectroscopy of the three magnetic phases of single crystal FeCl₂ · 2H₂ in external magnetic fields at 4.2 K is reported.

Lipschitz Spaces On The Surface Of Unit Sphere In Euclidean N-Space, Harvey Greenwald

Mathematics

This paper is concerned with defining Lipschitz spaces on Σn-1 the surface of the unit sphere in Rn. The importance of this example is that Σn-1 is not a group but a symmetric space. One begins with functions in Lp(Σn-1),1≤p≤∞. Σn-1 is a symmetric space and is related in a natural way to the rotation group SO(n). One can then use the group SO(n) to define first and second differences for functions in Lp(Σn-1). Such a function is the boundary value of its Poisson integral. This enables one to work with functions which are harmonic. Differences can then be replaced …

Phase Transitions In Antiferromagnets In External Magnetic Fields: Mossbauer Spectroscopy, Richard B. Frankel

Physics

No abstract provided.

The Construction Of Two Prototype Multi-Storey Air-Supported Buildings, Jens G. Pohl, James Montero

Collaborative Agent Design (CAD) Research Center

To treat a multi-storey building as a large, inflatable container forces the architect to consider design and construction criteria foreign to the building industry at large. While satisfactory progress has been made in the development of theoretical solutions for problems dealing with the structural and planning implications of a hyperbaric building environment, the time has come to consider practical issues.

This paper discusses the design, construction and operation of two prototype, multi-storey, air-supported buildings. The first building was completed in November, 1972 at the School of Building, University of New South Wales, Australia, and the second building was completed in …

Hyperfine Interactions In The Intramolecular Antiferromagnet (Fe Salen C1)2, R. Lechan, C. Nicolini, C. R. Abeledo, Richard B. Frankel

Physics

Magnetic hyperfine interactions in (Fe salen C1)₂ have been studied using the Mössbauer effect in external magnetic fields up to 80 kOe and for 4.2 ≤ T ≤ 80 °K. The low‐temperature results are adequately described by a simple intramolecular exchange model with J = 7.0 cm⁻¹ and a hyperfine interaction constant of −180 kOe per unit spin. At higher temperature the effective field approximation breaks down. Data for (Fe salen)₂O are also briefly reported.

Orbital Ground State Inversion In [Fe(H2O)6](Clo4)2, W. M. Reiff, Richard B. Frankel, C. R. Abeledo

Physics

Mössbauer spectroscopy in external magnetic fields has been used to measure the signs of the principal components of the electric field gradient V_zz in the two forms of [Fe(H₂O)₆)(Cl0₄)₂. The signs are V_zznegative for low temperature form (A) with quadrupole splitting ΔE_A = 3.4 mm/sec, and V_zz positive for high temperature form (B) with ΔE_B = 1.4 mm/sec. This implies a trigonally distorted ligand field and the transition (A) → (B) corresponds to compression → elongation with respect to the trigonal axis.

Orbital Ground State Reversal In The High‐Spin Complex Fe(Ii) (N, N′‐Dicyclohexylthiourea)6(Clo4)2, R. Latorre, C. R. Abeledo, Richard B. Frankel, J. A. Costamagna, W. M. Reiff, E. Frank

Physics

Mössbauer spectroscopy of iron (II)(N, N′‐Dicyclohexylthiourea)₆ (ClO₄)₂ shows the existence of two isomers. At low temperatures (T < 200°K) a form A with quadrupole splitting ΔE = 3.31 mm∕sec is stable. At and above room temperature a form B with ΔE = 1.32 mm∕sec is stable. For 200 °K < T < 300°K both forms are observed with the B∕A ratio increasing with increasing temperature. The values of ΔE are typical of Fe²⁺ with an orbital singlet and an orbital doublet ground state for A and B, respectively. The isomer shift and magnetic susceptibility results indicate that both …

High Magnetic Field Behavior Of Iron Impurities In Chromium, Richard B. Frankel, N. A. Blum

Physics

Mössbauer measurements in ⁵⁷Fe in dilute FeCr alloys in external magnetic fields up to 140 kOe are presented. The magnetic hyperfine interactions are compared with results obtained by Herbert, Clark and Wilson and are discussed in terms of a model due to Housley and Dash.

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 …

The Photolysis Of Propane At 123.6 Nm, James H. Vorachek, Robert D. Koob

Office of the Provost Scholarship

Propane has been photolyzed at 123.6 nm, in the presence and absence of O₂, at pressures from 2–380 Torr. All products except ethane exhibit a pressure dependence which is attributed to secondary dissociation of the primary fragments, H₂, CH₄, C₂H₄, and C₃H₆. It is assumed that the range of energies carried by these fragments is broad enough that some will not dissociate even at low pressures while others of the same species cannot be stabilized even at high pressures. An internally consistent analysis rationalizes the entire …

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.

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.

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 H_c = −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

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 ΔE_Q=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

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.