Paramagnetic Resonance of Divalent Iron in Calcium Oxide

Abstract

Paramagnetic resonance of divalent iron in single crystals of CaO has been observed at 4.2° and 2°K. The features of the resonance spectrum are: (1) a broad line at g≃3.30; (2) a narrow resonance superimposed upon the broad line at g=3.298±0.002; (3) an asymmetric line at half field with a high‐field cutoff at g≃6.58. At 4.2°K the double quantum transition exhibits an anisotropic behavior with microwave power and orientation. There is evidence of tetragonal distortions about the Fe²⁺ ion which coincide with the cubic crystal axes. These distortions cannot be ascribed with any degree of certainty to Jahn—Teller splitting.