| Popis: |
In previous papers of this series, a study has been made of the theory of magnetic resonance in a Ґ 3 doublet (paper I), together with experimental studies of Cs 2 NaHoCl 6 by n. m. r. (paper II) and by e. s. r. (paper III). In this substance the Ho 3+ ion, 4f 10 , 5 I 8 , is in an octahedral crystal field which gives a Ґ 3 doublet as the ground electronic state. The results, both from enhanced n. m. r. of the 165 Ho nucleus ( I = 7/2) and from e. s. r., provide evidence of fast motional averaging, ascribed to interactions between the ions. The measurements are in substantial agreement with the theory of I; however, though the theory is correct for the electronic levels and transitions, and for the nuclear electric quadrupole interaction in zero magnetic field, it needs improvement in the treatment of the nuclear terms when a field B is applied. In this paper a general theory is developed for the case when B is in an arbitrary direction, together with some special cases that are analytically simpler. These include B along [111], the spectrum of an isolated ion, and the spectrum of a concentrated compound where there are fast flip-flops between the electronic states. |
