Spin-lattice relaxation in Mössbauer spectra of Fe(III) high-spin complexes in an orthorhombic crystal field

1994 ◽  
Vol 91 (1) ◽  
pp. 879-883 ◽  
Author(s):  
O. Yakovleva ◽  
T. Rimke ◽  
B. Meier ◽  
F. Parak
1980 ◽  
Vol 33 (4) ◽  
pp. 733 ◽  
Author(s):  
DJ Newman

An analysis of dynamic crystal field data for cubic systems is carried out in order to assess the possible usefulness of the superposition model in understanding the results of lattice strain and spin-lattice relaxation experiments. The data used in this work are the electron paramagnetic resonance (EPR) results for strained cubic crystals obtained by Buisson, Baker and their coworkers, and the spinlattice relaxation results obtained by Buisson, Stapleton and their coworkers. A method of generalizing the superposition model to take into account long range electrostatic contributions without introducing additional unknown parameters is proposed, and shown to give consistent results. It is concluded that differences between bulk and local strains must be taken into account in any model of the dynamic crystal field, if it is to achieve success.


Measurements of the magnetic susceptibility at low temperatures have been made on single crystals of cerous magnesium nitrate, with a view to determining the energies of the low-lying states and the coefficients of the crystalline potential. The analysis, in terms of a crystal field of C 3v symmetry acting on one 4 f electron, gives results which are qualitatively similar to those of Judd’s earlier work, but the relative magnitudes of the six coefficients which fit the data suggest that a simple ionic crystal field model does not in fact describe the properties completely. A similar analysis of susceptibility measurements over a wider temperature range, recently reported by Hellwege, indicates substantially the same conclusion. A number of factors generally omitted from the theory of rare-earth salts are considered, but more detailed calculations are required to decide which, if any, are important here. In spite of the uncertainties, the analysis gives quite a good estimate of the energy of the first excited doublet, (38 + 3)°, in reasonable agreement with the results of measurements of the spin-lattice relaxation time.


2016 ◽  
Vol 52 (66) ◽  
pp. 10175-10178 ◽  
Author(s):  
Joseph M. Zadrozny ◽  
Michael J. Graham ◽  
Matthew D. Krzyaniak ◽  
Michael R. Wasielewski ◽  
Danna E. Freedman

The high-spin molecule [Fe(C5O5)3]3− displays a remarkable slowing of spin lattice relaxation upon application of a high magnetic field.


In thulium phosphate, TmPO 4 , the lowest levels of the manifold 3 H 6 , split by the crystal field, are a singlet, and a doublet, followed by another singlet. Measurements by Bleaney et al . ( Proc. R. Soc. Lond. A 387, 75(1983)) of enhanced nuclear magnetic resonance were fitted to these levels by using a set of crystal-field parameters and wave functions based on optical absorption measurements of Brecher et al . ( J. chem. Phys. 49, 3303 (1968)) on Eu 3+ in YPO 4 . Two other sets of parameters (Hodges: J. Phys. 44, 833 (1983); Becker et al.: J. chem. Phys. 81, 2872 (1984)) give similar levels, except that the two lowest singlets are interchanged. A fresh set of parameters (adjusted from those of Hodges) is shown to give the correct Zeeman splitting for the doublet, and to fit the enhanced nuclear resonance measurements. Measurements of phonon velocities and of acoustic magnetic resonance at 0.7 GHz are also reported at field strengths up to 3 T. Values of the direct spin-lattice relaxation rates derived from these measurements are compared with results from other methods. The Orbach-Aminov relaxation rate is discussed, together with that in some other enhanced nuclear paramagnets.


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