ESR of spin 5/2 systems with axial symmetry and moderately large zero‐field splittings. Application of line‐shape calculations to the interpretation of randomly oriented microcrystallite spectra
| Autor: | R. E. Coffman, Dimitri Coucouvanis, W. V. Sweeney |
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| Rok vydání: | 1973 |
| Předmět: | |
| Zdroj: | The Journal of Chemical Physics. 59:369-379 |
| ISSN: | 1089-7690 0021-9606 |
| DOI: | 10.1063/1.1679814 |
| Popis: | Magnetic resonance line positions and intensities are calculated for the simplified spin‐Hamiltonian H=D[Sz2−S(S+1)/3]+g μBH·Swith S=5/2. The resonance line positions and intensities are found by direct diagonalization of the matrix of ℋ and are plotted versus the axial angle θ and the magnetic field H. The region 1/2≲|D|/h ν ≲ 2 is explored, where v=the microwave frequency, and line shapes integrated over all orientations are calculated using a Gaussian line shape with isotropic linewidth. The results are compared with the experimental EPR spectra of two crystallographically isomorphic high‐spin trisdithio‐oxalato‐Fe(III) salts, one having |D|=0.26 GHz (treated by perturbation theory, including quartic spin operators), and the other |D|=6.8 GHz. Single crystal measurements were made for the former case, but only powder measurements of the latter system were possible. Calculation of the powder line shape for the |D|=6.8 GHz spectrum for both X‐band and Ka‐band EPR spectra gives good agreement with experi... |
| Databáze: | OpenAIRE |
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