ESR Spectra Of Mn2 Research Articles

The ESR spectra of Mn2+ ions and the low-temperature NQR spectra of 175Lu in LuNbO4 crystals

The electron-spin resonance spectra of Mn2+ ions and nuclear-quadrupole resonance spectra of 175Lu are investigated to find out the possibility of implementing the technique of dynamic alignment of nuclei using LuNbO4 single crystals doped with Mn2+. An estimate for the electron-spin resonance frequency of Mn2+ ions is obtained, and the temperature dependences of the quadrupole coupling constant eQq and the anisotropy parameter that characterizes the asymmetry of the electric field gradient at 175Lu nuclei are studied. It is demonstrated that LuNbO4 single crystals doped with Mn2+ ions can be used as working media in experiments on dynamic alignment of nuclei.

Influence of manganese concentration on the ESR spectrum of Mn2+ in SrO

Electron spin resonance spectra of manganese-doped strontium oxide have been studied at room temperature for Mn concentrations between 0.10 and 0.40 mol.%. The results suggest that the range of the exchange interaction between Mn2+ ions is about 0.63 nm.

ESR Spectra of Mn2+ Ions in Polycrystalline ZnS Films

ESR Spectra of Mn2+ Ions in Polycrystalline ZnS Films

PtP242. Fluctuations of incommensurate wave near faraelectric-modulated phase transition in Rb2ZnCl4

Abstract The ESR spectra of Mn2+ probe have been investigated in the temperature interval including paraelectric-incommensurate phase transition point Ti of Rb2ZnCl4. Near below Ti we have measured the temperature dependence of position of the inhomogeneously broaden ESR line. On the basis of the simple model - it is shown that ESR spectrum is influenced by phase and amplitude fluctuations of modulation wave.

Electron Spin Resonance and Optical Absorption Spectra of Mn2+ Ions in K2SO4ZnSO4 Glasses

AbstractElectron spin resonance and optical absorption measurements are performed on K2SO4ZnSO4 glasses containing 1 to 5 mol% of MnSO4 · H2O. The ESR spectra of Mn2+ doped samples exhibit a sextet centered at g = 2.02. The optical absorption spectrum at room temperature shows six bands characteristic of Mn2+ ions in octahedral symmetry. The crystal field (Dq) and Racah interelectronic repulsion parameters (B and C) are evaluated. ESR and optical absorption studies reveal that the Mn2+ ions go substitutionally to zinc ion sites and the site symmetry around the transition metal ion is octahedral.

ESR Analysis of Tetrahedral AB2C4 Defect Compounds with Mn2+ Ions as Spin Probes

AbstractThe ESR spectra of Mn2+ in eight defect tetrahedral structures have been analysed. The values for g and the hyperfine constant A turn out to be very close to those in the binary analogs with the same anion. As for the sulfides there is poor agreement between the measured and calculated b02 values, if one evaluates these values according to the superposition model of Newman and Urban using the unperturbed positions of the ligands. For some selenides and the telluride linewidths greater than 2.2 mT in the central sextets were observed and assigned to different degrees of disorder in the cation sublattices in agreement with recent X‐ray investigations.

The ESR spectra of Mn2+ in powdered samples

The ESR spectra of Mn2+ in powdered samples, for which the Mn2+ ion is in a site of axial crystal field, for which the crystal field parameter D is relatively large, do not show the large splitting of the allowed transitions and/or large forbidden transitions predicted by present theory. An explanation of observed spectra is given.

Strain‐modulated electron spin resonance spectra of 3d5 ions in ZnSe

AbstractFlexural‐strain‐modulated ESR spectra of Mn2+ and Fe3+ in ZnSe are reported. A study of the relative phases of the fine structure lines and of the angular dependence of the SMESR amplitudes reveals that first‐harmonic SMESR signals arise mainly through modulation of the off‐diagonal elements (g̃xz + g̃zx) of the tensor g̃. A slight amount of A‐modulation is present in ZnSe:Mn2+. Weak quadrature signals are observed in ZnSe:Fe3+; they are attributed to anelastic losses. A second‐harmonic SMESR signal is also present. It arises from second‐order line shifts. The angular dependence of the second‐harmonic signal reveals that, apart from (g̃xz + g̃zx), g̃zz‐modulation also plays some part in producing these signals. The component g̃xx normal to the bending plane, however, is not modulated.

Note on the ESR Spectrum of Mn2+ in α-Lead Azide

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ESR and NMR of Mn(II) Complexes in Methanol

ESR spectra of Mn2+ in methanol solutions of Mn(ClO4)2 containing various amounts of LiCl, NaNCS, LiBr, LiNO3, and LiClO4 were studied. In all solutions, variations in the integrated intensity of the ESR signal upon addition of the electrolyte were observed. This effect was interpreted in terms of the formation of asymmetrically substituted octahedral Mn2+ complexes, in many of which the zero-field splitting interaction causes fast electronic relaxation and therefore an ESR signal too broad to observe. Some of the mixed solvent-anion complexes do however yield resolved ESR signals; in particular, a well-defined spectrum due to [Mn(MeOH)4(NCS)2] could be characterized. From the decrease of the ESR signal the equilibrium constants for the formation of monosubstituted octahedral complexes, [Mn(MeOH)5X]+, were estimated. The equilibrium constants for Cl−, NCS−, Br−, NO3−, and ClO4− are respectively >100, >100, 10, 5, and 1M−1. At high LiCl concentrations tetrahedral [MnCl4]2−, exhibiting resolved ESR lines, is formed. In the ESR spectrum of the system Mn(ClO4)2–LiCl–methanol there is, in addition to the intense sextuplet, also a very broad background signal which is attributed to the monochloro complex. From the over-all width of this signal an estimate of the zero-field splitting energy in this complex was made. Proton magnetic resonance measurements were made in methanol solutions of Mn(ClO4)2 containing various amounts of LiCl. There is a strong dependence of the proton linewidth on temperature and on LiCl concentration. The results were interpreted in terms of exchange of methanol molecules in and out of the solvation shells of [Mn(MeOH)6]2+ and the various mixed chloro complexes, but only for [Mn(MeOH)6]2+could a quantitative analysis be made. The kinetic parameters for the exchange reaction of this complex are 1 / τM(25°C) = 9.5 × 105sec−1 and ΔE‡ = 7.4 kcal mole−1. In the monochloro complex the exchange rate is about twice as high.

The Electron Spin Resonance of Mn2+ Ion in Polyphosphate

Abstract A part of cation in polyphosphate was replaced with Mn2+ ion. Zero-field splitting parameter D due to the crystal field with axial symmetry was estimated according to Allen’s method from the ESR spectrum of Mn2+ ion. The value of D changes with the change in the state of polyphosphate, crystalline or glassy. As the degree of polymerization of sodium polyphosphate glass decreases, the value of D increases and approaches to the value corresponding to the crystalline state. These phenomena were interpreted as due to the disorderness of glassy state. The value of D was found to change with the variation of the kind of cation in polyphosphate. This was explained in terms of the effective cationic field.

Electron Spin Resonance of Manganese in Borate Glasses

The ESR spectra of Mn2+ ions have been observed in borate glasses of the composition (MnO)x(B2O3+0.04 K2O)1−x with x from 0.001 up to 0.030. For small concentrations of Mn2+ the central fine-structure transitions (M = +½↔—½), although broadened by the random orientation of small noncubic crystalline fields, show a well-resolved hyperfine structure. In addition to the Δm=0 transitions, ``forbidden'' Δm=±1 have been observed. The spectra prove that the coordination of the O2− ions around the Mn2+ ions is mainly cubic, but that small deformations of the cubic symmetry exist. The deformations vary from ion to ion, and range up to average values of the order of 5% in the interionic distances and 10 deg in the angles. The discussion has been based on a spin Hamiltonian involving an isotropic g factor, fine structure term D, and hyperfine structure term A. The line positions have been calculated up to the third order in D and A. The numerical results are: g=2.002±0.002, | A | /hc= (87–2)×10−4 cm−1, and DAv/hc= (89±10)×10−4 cm−1, the latter value representing an average over all deviations from cubic symmetry.