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  • 1
    Electronic Resource
    Electronic Resource
    Electron paramagnetic resonance of Mn2+ in FeSiF6⋅6H2O and FeSiF6⋅6D2O above 100 K (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 92-94 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: In electron paramagnetic resonance measurements on Mn2+ in single crystals of FeSiF6⋅6H2O and FeSiF6⋅6D2O at 9.3 GHz, changes in the resolution of the outer sets of hyperfine lines were used to observe the trigonal to monoclinic structural phase transition, which occurred over the range 223–227 K in both crystals. The magnitude of the axial spin-Hamiltonian parameter D for FeSiF6⋅6D2O was (273±1)×10−4 cm−1 at 300 K and decreased slightly with decreasing temperature in the trigonal phase. In the monoclinic phase ||D|| was (263±1)×10−4 cm−1 at 220 K and increased slightly with decreasing temperature. Similar values were obtained for FeSiF6⋅6H2O. An abrupt linewidth increase on warming through the transition is postulated to result from a decrease in the effective Mn2+–Fe2+ exchange interaction due to SiF2−6 reorientation. A gradual decrease in linewidth with temperature at higher temperatures is ascribed to a reduction of the second moment of the Mn2+–Fe2+ dipolar interaction.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454489
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  • 2
    Electronic Resource
    Electronic Resource
    Temperature dependence of the EPR zero-field splitting of Mn2+ in ZnSiF6⋅6H2O (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 3801-3803 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The temperature dependence of the EPR spectrum of Mn2+ in ZnSiF6⋅6H2O was measured at 9.2 GHz between 15 and 297 K. Both the g and A tensors were found to be isotropic with values close to 2.000 and −90×10−4 cm−1, respectively. A slight decrease in the magnitude of A with increasing temperature was observed. The zero-field splitting parameters D and a–F were found to vary from −130.5×10−4 and 9.9×10−4 cm−1, respectively, at 15 K to −170.2×10−4 and 7.8×10−4 cm−1, respectively, at 297 K. The data for D below 100 K were fitted to the orbit–lattice interaction in the long-wavelength approximation with a Debye temperature of 138 K. An estimate of the low-temperature ratio of D for Ni2+ and Mn2+ in ZnSiF6⋅6H2O based on the long-wavelength fits was in good agreement with the measured ratio of 10 at 4 K.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451937
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  • 3
    Electronic Resource
    Electronic Resource
    Temperature dependence of the g value of Ni2+ in ZnSiF6⋅6H2O (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 705-706 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The measured increase in g(parallel) between 4 and 100 K for Ni2+ in ZnSiF6⋅H2O has been explained as a consequence of the dynamical phonon coupling between the spins and the lattice. The Debye temperature of θ=130 K previously determined from the zero-field splitting has been found to agree with that obtained from the temperature dependence of the g value. The zero-point vibrational correction to the g value has been deduced.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454148
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  • 4
    Electronic Resource
    Electronic Resource
    The temperature dependence of the EPR spectrum of Cu2+ in ZnTiF6⋅6H2O between 4 and 160 K (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 6660-6664 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The EPR spectrum of Cu2+ in the low temperature monoclinic phase of ZnTiF6⋅6H2O was studied at 9.24 GHz between 4 and 160 K. Assuming the Jahn–Teller spectra to have axial symmetry, g(parallel) was found to vary from 2.472±0.004 at 4 K to 2.331±0.004 at 158 K, while g⊥ varied from 2.097±0.004 to 2.173±0.004 over this range. From the temperature variations of the g values, the lowering of the energy Δ of one potential well associated with the Jahn–Teller distortion compared to the other two was found to be approximately 143 cm−1. It is shown that an apparent decrease in Δ with increasing temperature above 100 K could be due to the presence of an excited vibronic state about 170 cm−1 above the ground state. The variation of ||A(parallel)|| from (107±1)×10−4 cm−1 at 4 K to (53±3)×10−4 cm−1 at 158 K agreed with predictions based on the temperature variation of the g tensor.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.452413
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  • 5
    Electronic Resource
    Electronic Resource
    Phase transitions in ZnTiF6⋅6H2O observed by the electron paramagnetic resonance of Mn2+ (1989)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 91 (1989), S. 3614-3617 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The temperature dependence and hysteresis of the trigonal–monoclinic phase transition occurring near 180 K in ZnTiF6⋅6H2O were studied as functions of Mn concentration, and spin–Hamiltonian parameters were determined in both the trigonal and monoclinic phases. Changes in the 9 GHz electron paramagnetic resonance (EPR) spectrum between 30 and 10 K indicated a first order phase transition on cooling to a more disordered structure. Additional lines showing ligand hyperfine structure, with an even number of components, are attributed to paramagnetic impurities occupying Ti4+ sites with single F− vacancies.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.456893
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  • 6
    Electronic Resource
    Electronic Resource
    Measurement of Debye temperature from the zero-field splitting of Ni2+ in ZnSiF6⋅6H2O (1988)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 88 (1988), S. 634-636 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The variation of the zero-field splitting parameter D for Ni2+ in ZnSiF6⋅6H2O between 4 and 250 K has been used to calculate the temperature dependence of the Debye temperature θD(T) in ZnSiF6⋅6H2O. θD(T) was determined to be 143 K at a temperature of 30 K and 127 K at 250 K. There was a pronounced minimum of 105 K in θD(T) near 60 K. The behavior of θD(T) is qualitatively similar to that found for alkali halides from specific heat data.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.454190
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  • 7
    Electronic Resource
    Electronic Resource
    Zeeman, hyperfine, and magnetic dipolar effects on the EPR spectrum of a cubic copper tetramer (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 3770-3775 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The Zeeman interaction for an isolated multiplet of a cubic Cu2+ tetramer, characterized by the total spin quantum number S, is shown to be essentially isotropic, with g=(g(parallel)+2g⊥)/3, where g(parallel) and g⊥ are single Cu2+ ion components. Matrix elements are given for the off-diagonal part of the Zeeman interaction within the three S=1 multiplets. The hyperfine structure for each isotope in a [100] direction is shown to be a 13 line structure. The intracluster magnetic dipole–dipole (MDD) interaction has nonzero matrix elements within the three S=1 multiplets, which are degenerate for an isotropic exchange interaction with equal coupling constants. With the MDD interaction treated as a perturbation of the Zeeman interaction, it is found that the single line at g=2.10, expected on the basis of the Zeeman interaction alone, is split into four lines separated from the former line by ±h0 and ±2h0, where h0(approximately-equal-to)480 G. The MDD coupling constant, calculated assuming point dipoles, is an order of magnitude too small to explain the zero-field splitting of the S=2 multiplet measured by EPR in Cu4OCl6(TPPO)4.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.450897
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  • 8
    Electronic Resource
    Electronic Resource
    The temperature dependence of the EPR spectrum of Mn2+ in ZnSiF6 ⋅ 6D2O (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 1699-1700 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: The EPR spectrum of Mn2+ in ZnSiF6 ⋅ 6D2O was measured at 9.2 GHz between 25 and 300 K. The g tensor was essentially isotropic and temperature independent with all measured values in the range 2.000 to 2.001. The zero-field splitting parameters D and (a−F) were −(170.4±0.3)×10−4 and +(7.9±0.2)×10−4 cm−1, respectively, at 300 K and −(132.2±0.5)×10−4 cm−1 and +(9.3±0.3)×10−4 cm−1, respectively, at 50 K. The hyperfine tensor A, which was isotropic to within the experimental errors, varied from −(89.6±0.2)×10−4 cm−1 at 300 K to −(90.1±0.2)×10−4 cm−1 at 50 K. The temperature dependence of D was qualitatively similar to that measured for Ni2+ in the same crystal.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451163
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  • 9
    Electronic Resource
    Electronic Resource
    Ni2+–Fe2+ exchange in FeSiF6 ⋅ 6H2O (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 84 (1986), S. 4786-4788 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: An anomalously large D parameter determined previously for the Ni2+ EPR spectrum in FeSiF6 ⋅ 6H2O perpendicular to the crystal c axis at 4.2 K is reinterpreted as a reduction of the effective value of g⊥ through Ni2+–Fe2+ exchange. Assuming a superexchange interaction of the form J S ⋅ S' between a Ni2+ ion and each of its nearest neighbor Fe2+ ions, the resulting value J=+ (0.048±0.005) cm−1 is consistent with the values obtained for similar systems. Direct effects of the exchange interaction on the D and E parameters are shown to be negligible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.449964
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  • 10
    Electronic Resource
    Electronic Resource
    EPR measurement of Cu2+–Fe2+ exchange in FeSiF6 ⋅ 6H2O at 4.2 K (1985)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 83 (1985), S. 4400-4404 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Six inequivalent Cu2+ EPR spectra were observed at 4.2 K in single crystals of FeSiF6 ⋅ 6H20. The estimated parameters gz∼2.38 and θ∼40°, where θ is the angle between the ionic z axis and the c axis, differ from those measured in crystals of similar structure. These differences have been explained in terms of an isotropic Cu2+–Fe2+ exchange Hamiltonian JS1 ⋅ S2, with J=+(0.030±0.003) cm−1, which gives a contribution gex∼−5.05 J sin2 θ, where θ is the angle between the external magnetic field and the z axis. Perpendicular to the c axis, an independent estimate of +0.034 cm−1 for J was made from the low-field displacement of a satellite spectrum.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.449057
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