The allowed and forbidden transitions in the paramagnetic resonance of the manganese ion in cubic zinc selenide

The allowed and forbidden paramagnetic resonance transitions of Mn 2+ ions in single crystals of cubic ZnSe have been investigated. The parameters describing the spectrum observed at 77 °K have the values g = 2.0069 ± 0.0002, A = -61.8 ± 0.1 × 10 -4 cm -1 and a = 19.3 ± 0.1 × 10 -4 cm -1 and the quadrupole constant P is zero within the experimental error of +0.03 × 10 -4 cm -1 . These parameters were found from a third-order calculation of the eigenvalues and they are discussed with reference to the nature of the bonding. The forbidden transition absorption line positions were found experimentally to be independent of the crystal orientation and this is explained by considering only the nuclear spin-electronic spin interaction term A S. I. However, in order to explain the experimentally observed intensity variation with crystal orientation for the forbidden transitions an interaction between the cubic crystal-line electric field and the term A S. I must be considered. An expression is obtained for the intensity of the forbidden transitions of an ion with electron spin S and nuclear spin I in a cubic field.