Spectroscopic Splitting Factor Research Articles

EPR Analysis of Cu2+ ion Doped Potassium borodicitrate Single Crystal

In our present investigation single crystals of Potassium borodicitrate (KBDC) (for a fixed content- host lattice) with Cu2+, a guest species, as a dopant (at four 0.2, 0.5, 1 and 2 g) in weight ratio have been synthesized at room temperature by using slow evaporation method. These as-synthesized 4 crystals have been subjected to Electron Paramagnetic Resonance (EPR) studies. The EPR spectrum shows that 0.5 g dopant KBDC give a 4 equidistant hyperfine lines with the perfect symmetry confirms that the localization of Cu2+, a paramagnetic impurity, within it reveals that the maximum absorption of EPR signals happens at 0.5 g Cu2+ than any other concentrations with reference to 20° in horizontal plane than the normal and vertical recording in the same angular projection. The Spin Hamiltonian calculations are used to obtain spectroscopic field splitting factor g-tensor values, gxx = 2.0421, gyy = 2.1962, gzz = 2.2827 and hyperfine splitting factor A-tensor values Axx = 150, Ayy = 112 and Azz = 134. The K–O bond length associated with directional cosines of gzz tensor reveal that the Cu2+ is located interstitially. This optimized single crystal has furtherance been subjected to Single cystal X-ray diffraction (SXRD), Fourier transform infrared Spectrascopy (FTIR). Scanning electron microscope (SEM) Energy dispersive X-ray analysis (EDAX) and compared with pure KBDC single crystal. The XRD unit cell crystalline parameter variations reveal that there is doping effect of Cu2+ into the host lattice brings forth structural coordination of Cu2+ with KBDC. The FTIR confirms that complexation of host and guest through molecular interactions in the finger print region. The EDAX mapping shows Cu2+ presence in the crystal. HIGHLIGHTS SXRD are taken to confirm that structure of pure KBDC and Cu2+ doped KBDC are same The spin Hamiltonian parameters of KBDC-Cu2+ single crystal are calculated through EPR spectra On analyzing the spectra, it is found that the doped ion site location symmetry is identified as interstitial and experience orthorhombic local field symmetry In addition to the above studies FTIR and EDX confirms the presence of Cu2+ ion GRAPHICAL ABSTRACT

The effect of a polarizing magnetic field on the dynamic properties and the specific absorption rate of a ferrofluid in the microwave range

ABSTRACT Measurements are presented of the frequency and field dependent, complex magnetic permeability, μ(f, H) = μ′(f, H)-i μ″(f, H), of a kerosene-based ferrofluid sample with magnetite particles, over the frequency range, f, of 0.4–6 GHz, and polarizing field, H, range of 0–102 kA/m. In this frequency range, both the ferromagnetic resonance at a frequency, f res , and the corresponding maximum absorption at a frequency, f max , were determined. From the H dependence of both f res and the ratio of f max /f res , we determined the anisotropy field, H A , the anisotropy constant K eff , the gyromagnetic ratio, , the damping parameter, , the spectroscopic splitting factor, g, and the internal magnetic viscosity, . Also, the theoretical Néel relaxation time, , was evaluated. Furthermore, the measurements of, μ(f), enabled one to study the effect of, H, on the the specific absorption rate, SAR, and the time dependence of the variation in temperature, ΔT, of the investigated ferrofluid sample. The SAR was calculated, using a new equation for the calculation of the SAR of ferrofluids. This equation offers a more precise computation of the SAR in that it takes into account the density of the ferrofluid ρ F , as opposed to using just the density of the dispersed solid particles, ρ S . These results illustrate how control of the SAR and the variation in ΔT, of the ferrofluid sample, through the variation of H, and has applications in the treatment of cancer by magnetic hyperthermia, for modeling bio-heat transfer phenomena, microwave heating or the possibility of use of the ferrofluid as a shield material against microwave electromagnetic radiation. Also, knowledge of the magnetic parameters of ferrofluids, is useful in the design and manufacture of some microwave devices.

Broadband Electron Spin Resonance Study in a Sr2FeMoO6 Double Perovskite.

We report broadband magnetic resonance in polycrystalline Sr2FeMoO6 measured over the wide temperature (T = 10–370 K) and frequency (f = 2–18 GHz) ranges. Sr2FeMoO6 was synthesized by the sol–gel method and found to be ferromagnetic below TC = 325 K. A coplanar waveguide-based broadband spectrometer was used to record the broadband electron spin resonance (ESR) both in frequency sweep and field sweep modes. From the frequency sweep mode at fixed dc magnetic fields, we obtain the spectroscopic splitting factor g ∼ 2.02 for T ≥ TC K, which confirms the 3+ ionic state of Fe in the material. The effective g value was found to decrease monotonically with decreasing temperature in the ferromagnetic regime. Resonance frequency decreases and the line width of the spectra increases as the temperature decreases below TC. At room temperature (RT) and above, the line width (ΔH) of the ESR signal increases linearly with frequency, giving Gilbert damping constant α ∼0.032 ± 0.005 at RT. However, at lower temperatures, a minimum emerges in the ΔH vs frequency curve, and the minimum shifts to a higher frequency with decreasing temperature, confining the linear frequency regime to a narrow-frequency regime. Additional inhomogeneous broadening and low-field-loss terms are needed to describe the line width in the entire frequency range.

Correlation between Dzyaloshinskii-Moriya interaction and orbital angular momentum at an oxide-ferromagnet interface

We report on the Dzyaloshinskii-Moriya (DMI) interaction at the interface between a ferromagnet and an oxide. We demonstrate experimentally that oxides can give rise to DMI. By comparison of systems comprised of Pt/Co90Fe10/Oxide and Cu/Co90Fe10/Oxide, we also show how oxidation of one interface can enhance and add to the total DMI of that generated by the Pt interface. This is due to the fact that the DMI on both interfaces promotes left-handed chirality. Finally, by use of ferromagnetic resonance spectroscopy, we show that the DMI and the spectroscopic splitting factor, which is a measure of the orbital momentum, are correlated. This indicates the importance of hybridization and charge transfer at the oxide interface for the DMI.

Characterization of Cu2+ Impurity Ion in K₂SnCl6:Cu Single Crystal

K₂SnClSUB6/SUB single crystals doped with Cu were grown by the evaporation of saturated solution. The electron magnetic resonance (EMR) of the CuSUP2+/SUP ion in the crystal has been investigated by using an X-band spectrometer. The rotation pattern in the crystallographic plane together with spin Hamiltonian parameters of CuSUP2+/SUP ion in K₂SnClSUB6/SUB:Cu single crystal shows that the local site symmetry of the CuSUP2+/SUP ion is cubic at room temperature. The calculated spectroscopic splitting factor g of CuSUP2+/SUP impurity ion is 2.1908(±0.0007). The hyperfine constants of CuSUP2+/SUP impurity ion due to the SUP63/SUPCu and 65Cu isotopes in K₂SnClSUB6/SUB:Cu crystal are 0.83(±0.01)×10SUP−4/SUP cmSUP−1/SUP and 0.89(±0.01)×10SUP−4/SUP cmd, respectively. It turns out that the CuSUP2+/SUP ion substitutes for the KSUP+/SUP ion without any nearby charge compensation.

Shape effect in FMR of Ni-Co-Mn-In layers obtained by pulsed laser deposition

We have studied thin layers of Ni50-x Cox Mn50-y Iny alloys on (001) Si substrate obtained by pulsed laser deposition method (PLD) using YAG Nd3+ laser operating at second harmonic. The target was bulk Ni50-x Cox Mn50-y Iny (x = 5, y = 14.5) alloy prepared by induction melting of pure elements under argon atmosphere. Magnetic properties were investigated on Bruker X band EPR spectrometer (9.36 GHz) at room temperature. The magnetic resonance spectrum consists of non-symmetric lines with resonance field within wide field range (2500-4800 Gs) depending on the orientation of the static field in the plane perpendicular to the layer. Calculated spectroscopic splitting factor g = 2.09.

Strong magnetic correlations to 900 K in single crystals of the trigonal antiferromagnetic insulatorsSrMn2As2andCaMn2As2

Crystallographic, electronic transport, thermal and magnetic properties are reported for SrMn2As2 and CaMn2As2 single crystals grown using Sn flux. Rietveld refinements of powder x-ray diffraction data show that the two compounds are isostructural and crystallize in the trigonal CaAl2Si2-type structure (space group P-3m1), in agreement with the literature. Electrical resistivity rho versus temperature T measurements demonstrate insulating ground states for both compounds with activation energies of 85 meV for SrMn2As2 and 61 meV for CaMn2As2. In a local-moment picture, the Mn^{+2} 3d^5 ions are expected to have high-spin S = 5/2 with spectroscopic splitting factor g = 2. Magnetic susceptibility chi and heat capacity measurements versus T reveal antiferromagnetic (AFM) transitions at TN = 120(2) K and 62(3) K for SrMn2As2 and CaMn2As2, respectively. The anisotropic chi(T < TN) data indicate that the hexagonal c axis is the hard axis and hence that the ordered Mn moments are aligned in the ab plane. The chi(T) for both compounds and Cp(T) data for SrMn2As2 show strong dynamic short-range AFM correlations from TN up to at least 900 K, likely associated with quasi-two-dimensional connectivity of strong AFM exchange interactions between the Mn spins within the corrugated honeycomb Mn layers parallel to the ab plane.

The magnetic structure of EuCu2Sb2

Antiferromagnetic ordering of EuCu2Sb2 which forms in the tetragonal CaBe2Ge2-type structure (space group P4/nmm #129) has been studied using neutron powder diffraction and 151Eu Mössbauer spectroscopy. The room temperature 151Eu isomer shift of −12.8(1) mm s−1 shows the Eu to be divalent, while the 151Eu hyperfine magnetic field (Bhf) reaches 28.7(2) T at 2.1 K, indicating a full Eu2+ magnetic moment. Bhf(T) follows a smooth Brillouin function and yields an ordering temperature of 5.1(1) K. Refinement of the neutron diffraction data reveals a collinear A-type antiferromagnetic arrangement with the Eu moments perpendicular to the tetragonal c-axis. The refined Eu magnetic moment at 0.4 K is 7.08(15) μB which is the full free-ion moment expected for the Eu2+ ion with and a spectroscopic splitting factor of g = 2.

EPR dosimetric properties of nano-barium sulfate

Nano/micro BaSO4 were prepared through the co-precipitation method to measure ionizing radiation doses using electron paramagnetic resonance (EPR). The nano-BaSO4 sample was characterized using X-ray diffraction (XRD), and transmission electron microscopy (TEM) techniques. The dose response and fading properties of nano- and micro-phase BaSO4 were compared in EPR spectra. The prepared nano- and micro-BaSO4 samples have the same hole and electron centers, which may be attributed to SO4− and SO3−, respectively. The dosimetric signals for prepared nano- and micro-BaSO4 have spectroscopic splitting factor (g) with values 2.0025±0.0006 and 2.0027±0.0006, respectively. The nanocrystalline sample has a linear γ-ray dose response over the range 0.4Gy–1kGy. The performance parameters which including detection limit and critical level calculated from weighted and unweighted least-squares fitting. The sensitivity of nano-BaSO4 to γ-ray is one and a half times more than alanine. The lifetime and activation energy for nano-BaSO4 were estimated by conducting a thermal stability study, and were 5.7±1.1×104 years and 0.73±0.14eV, respectively. The combined and expanded uncertainties accompanying measurements were ±3.89% and ±7.78%, respectively.

EPR study of γ-irradiated cholesteryl methyl carbonate

The electron paramagnetic resonance (EPR) of γ-irradiated single crystals of cholesteryl methyl carbonate (C29H48O3) has been studied for different orientations of the crystals in a magnetic field. EPR spectra of cholesteryl methyl carbonate (C29H48O3irradiated by 60Co-γ were recorded between 125K and 300K for different orientations of the crystal in the magnetic field. The spectra were found to be temperature independent. In C29H48O3 single crystal, the radiation damage centers caused by a 60Co-γ source were determined as CḢ3CH2CH radical. For CḢ3CH2CH radical, a value of spectroscopic splitting factor g was calculated and experimentally results were supported by simulation program (WinEPR).

Strontium sulfate as an EPR dosimeter for radiation technology application

The dosimetric characteristics of γ-radiation induced defects in strontium sulfate rod dosimeter are investigated using electron paramagnetic resonance (EPR) technique focusing on the low dose range of 1–100Gy. Significant EPR signals of spectroscopic splitting factor (g) 2.01075, 2.04225, 2.03166, 2.00774 and 1.9219086 are observed in the rod upon γ-irradiation. The intensity of the signals increases linearly with increasing absorbed doses up to 100Gy. The EPR response of irradiated dosimeter exhibits good stability over three months of storage. In addition, the response during irradiation is independent on both relative humidity (from 0% to 65%) and temperature (from 10°C to 35°C). The prepared rods are nearly water equivalent in the range of 0.4–5MeV and the overall uncertainty (2σ) of dose monitoring is approximately 4.26%.

A comparative study of nanosized iron oxide particles; magnetite (Fe3O4), maghemite (γ-Fe2O3) and hematite (α-Fe2O3), using ferromagnetic resonance

We investigated intra/inter particle interactions in single domain size magnetite (Fe3O4), maghemite (γ-Fe2O3) and hematite (α-Fe2O3) iron oxide particles. The magnetic analyses were done using vibrating sample magnetometer and magnetic resonance measurements that were taken from 5 to 300K and from 120 to 300K, respectively. The magnetic resonance analyses were done for the iron oxides, frozen under 5000G fields in glycerol matrix. By changing the temperature, a change in resonance field lines was observed at each Fe3O4, γ-Fe2O3 and α-Fe2O3 nanoparticles. However, the fits in resonant lines showed that Landég values (spectroscopic splitting factor) stayed stable with temperature decrease. The thermal sensitivities that were determined from Landég factors, revealed three dominant interactions on resonant lines namely; the exchange coupling in between Fe2+, Fe3+ and O− (g1=3.01±0.08), Fe3+ centers (1.88±0.03⩽g2⩽2.02±0.03, depending on iron oxide states) and flip flop of O− ions in between ionic states of Fe2+–O−1 and Fe3+–O−2 (2.35±0.06⩽g3⩽2.44±0.06, depending on iron oxide states).

EPR and photoluminescence properties of Mn2+ doped CdS nanoparticles synthesized via co-precipitation method

The structural properties of Mn doped CdS (Mn:CdS) nanoparticles (NPs) are studied using X-ray diffraction (XRD), Transmission electron microscopy (TEM), Ultraviolet–visible (UV–vis), Photoluminescence (PL), Raman and Electron paramagnetic resonance (EPR) spectroscopy. XRD analysis shows the nanostructure with 2–4nm of average crystallite size. The planes (110), (103) and (112) in XRD pattern distinguish the wurtzite structure of the Mn:CdS NPs. The intensity of the plane (102) increases as the doping concentration of Mn2+ increases. UV–vis absorption spectra show blue shift as compared to bulk CdS. The optical band gap energy of Mn2+ (0, 0.35, 0.70 and 1.35at.%) doped CdS NPs corresponding to absorption edge are found to be 5.29, 5.28, 5.25 and 5.21eV, respectively. The intensity of luminescence is changing with the concentration of Mn2+ doped in CdS NPs. Raman spectra show blue shift in fundamental optical phonon mode (1LO) as well as second optical phonon mode (2LO) as compared to bulk CdS. The intensity ratio of the 2LO to 1LO modes slightly decreases as Mn2+ concentration increases. EPR shows the existence of Mn2+ with different local structures in CdS nanoparticles. The values of spectroscopic splitting factor (g) and hyperfine interaction constant (A) decrease as Mn2+ concentration increases in CdS NPs.

Electronic structures of organometallic complexes of f elements LXXIX: Truncated crystal field splitting patterns of monomeric pseudo trigonal planar Yb(η5-C5H4R)3 (R = Me, Et, tBu, SiMe3) complexes and polymeric [(η5-C5H5)2Yb(μ-η5:η1-C5H5)] as well as selected mono adducts

The absorption spectra of pseudo (ψ) trigonal planar tris(methylcyclopentadienyl)ytterbium(III) (Yb(C5H4Me)3) have been recorded at room temperature and circa 77 K. The vibronic transitions were separated from the expected three purely electronic ones by correlating the transition energies with observed and assigned vibrational transition frequencies in the infrared spectrum. With this knowledge, the zero-phonon transitions in the absorption spectra of Yb(C5H4R)3 (R = Et, tBu, SiMe3) and [(η5-C5H5)2Yb(μ-η5:η1-C5H5)] (YbCp3), the latter being known since 1967, could be separated from phonon-assisted ones. The first low temperature luminescence measurements of an organometallic YbIII compound were performed by means of powdered YbCp3•THF and YbCp3•CNC6H11, respectively, and in both cases purely electronic and vibronic transitions were separated. The wavefunctions resulting from a fit of the truncated crystal field splitting pattern of YbCp3•THF allowed interpretation of the spectroscopic splitting factors g||/g⊥ and the temperature dependence of the paramagnetic susceptibility of this compound as well as the susceptibility anisotropy χ|| − χ⊥ of YbCp3•B (B = CNnBu, γ-picoline) and Yb(C5H4Me)3•B (B = CNtBu).

Electron paramagnetic resonance of gamma-irradiated single crystals of ethan-1,2 disulfonic acid disodium

ESR spectra of ethan-1,2 disulfonic acid disodium (C2H4Na2O6S2) irradiated by 60Co-γ were recorded between 125K and 300K and for different orientations of the crystal in the magnetic field. The spectra were found to be temperature independent. In C2H4Na2O6S2 single crystal, the radiation damage centers caused by a 60Co-γ source were determined as SO2 radical. For SO2 radical, a value of spectroscopic splitting factor g was calculated.

The Raman scattering investigation of the features of low-energy electronic excitations of the terbium ion in the KTb(WO4)2 crystal

Raman scattering of light in the KTb(WO4)2 single crystal is investigated in the frequency range of 3–950 cm−1 at 5 K. The ground multiplet 7F6 of Tb3+ ion is split by the crystal field with symmetry C2, and all the multiplet components are detected. It is found that the first excited electronic quasidoublet consists of two singlet levels of different symmetry and is separated from the ground quasidoublet by ∼75 cm−1. Behavior of all the detected levels is investigated in external magnetic fields H ⊥ C2 and H || C2. Spectroscopic splitting factors are determined for the ground and excited levels of the Tb3+ ion in the KTb(WO4)2 crystal. Experimental data support the view that at low temperatures the case of Ising anisotropy is realized, and the crystal under study should be considered as a system of two-level magnetic ions.

Influence of heating time and pressure treatment of potato starch on the generation of radicals: EPR studies

The influence of heating time and pressurizing time under pressure of 1GPa on radicals generation in potato starch polymer was investigated by EPR. Potato starch was heated at two temperatures: 413±2K (140°C) and 473±2K (200°C) for 15, 30, 60, 120, 180, 240, 270 and 300min and subdued to pressurizing under pressure of 1±0.002GPa for 6, 60, 300 and 1440min. In starch heated at 413K (140°C) a decrease in the relative intensity of the EPR signal as a function of the pressurizing time can be observed, whereas in starch heated at 473K (200°C) such a decrease is not observed. The EPR spectra analysis indicates that they are powder spectra due to the paramagnetic centers leading to Lorentzian line shapes with weak spectroscopic splitting factor g anisotropies and linewidth anisotropies. We have shown that pressurization of starch causes a decrease in the number of radicals in a temperature range in which the polymer is not yet disintegrated. The results of the EPR investigations indicate the existence of a carbon radical center situated at the carbon C1 of the glucose ring. In the EPR spectra of the samples heated with no oxygen access, the hyperfine structure is poorly visible. In the registered EPR spectra of the samples heated with oxygen access, the hyperfine structure is not observed.

Electron Paramagnetic Resonance of Mn2+-Doped Cadmium Formate Dihydrate Single Crystals

An electron paramagnetic resonance (EPR) study on Mn2+ doped Cadmium formate dihydrate single crystals is carried out. The EPR spectrum at room temperature exhibits only one out of five fine structural transitions which split into six hyperfine lines in all directions. The spectrum is simulated using the EasySpin program and evaluated spin Hamiltonian parameters. The simulated EPR spectrum is in good agreement with the experiment. By comparing direction cosines of spectroscopic splitting factor g and the direction cosines of different bonds determined by the crystal structure data it is found that Mn2+ enters the lattice substitutionally and only one Mn2+ site is identified. The obtained g and the hyperfine interaction constant A achieved are g = 2.006 ± 0.002, A = (98 ± 2) × 10−4 cm−1 and the second-order axial zero-field splitting parameter D = (60 ± 2) × 10−4 cm−1.

Effects of gamma irradiation on the single crystal ergosterol: An EPR study

► The irradiation effect on single crystal of ergosterol was determined firstly. ► Ergosterol, provitamin D 2 , have also antitumor properties is an important molecule. ► Two type of radical were produced in the host crystal by gamma irradiation. ► The EPR parameters of radicals slightly dependent on temperature. ► The EPR parameters of produced radicals were determined. Single crystals of ergosterol were investigated by Electron Paramagnetic Resonance (EPR) technique, with γ irradiation of the crystals at different orientations in the magnetic field between temperatures of 120 and 380 K, and the spectra were found to be slightly dependent on temperature. Because of the importance of ergosterol it is important to determine the irradiation effects on this molecule. Taking into consideration the chemical structure and the experimental spectra of the irradiated single crystal ergosterol, we found that two paramagnetic species which were labeled as radical A, CH 2α H β , and radical B, CH α H β H γ H σ , were produced in the host crystal. The EPR parameters; spectroscopic splitting factor, g , and hyperfine coupling constant, a, were determined for each radical.

Precessional dynamics of Ni45Fe55 thin films for ultrahigh frequency integrated magnetics

Future monolithic point of load switched mode power supplies will be expected to meet the energy requirements of miniaturized, high functionality electronic devices. Recently, Ni45Fe55 has emerged as a potentially important material choice for use as a soft magnetic core material within high frequency integrated passive magnetic components. The operating frequency range of the integrated passives which form a key part of the point of load power supply must increase to allow for inductor/transformer miniaturization to become monolithic with power integrated circuits. In this work, an analysis of the high frequency permeability spectra of an electroplated Ni45Fe55 thin film has been carried out to quantitatively analyze the material’s high frequency performance. Complex permeability spectra of the film have been investigated at frequencies up to 9 GHz to identify both the film’s spectroscopic splitting factor (g) and its effective dimensionless damping parameter (α). The Kittel equation is utilized to identify g as 2.128, while α is determined to be approximately 0.045. The critically damped condition for the film is also examined to extract α in the critically damped case under a range of externally applied bias fields. It is concluded that for monolithic power inductors, improved device performance can be achieved when the ferromagnetic core is in an underdamped state up to a critical frequency.