The hyperfine interactions of fluorine ions in the vicinity of Cr3+and Cr+in KMgF3. I.19F and53Cr ENDOR measurements

Abstract

ENDOR measurements on the nuclei of the first, second and third nearest sets of fluorine ions to Cr³⁺ and Cr⁺ in KMgF₃ are reported. The main results concern the second nearest, whose hyperfine tensors are found in both cases to show significant departures from the values expected on a purely dipolar basis. The axial third nearest fluorines for Cr⁺ also show small departures from the predicted dipolar interaction, but those for Cr³⁺ do not. For Cr³⁺ a term in the spin Hamiltonian cubic in the electronic spin and linear in the first nearest fluorine nuclear spin was detected. ⁵³Cr ENDOR was observed for Cr³⁺, and the hyperfine constant determined to be (17.887+or-0.005)*10^-4 cm^-1.