We present results of EPR and near-infrared fluorescence-line-narrowing experiments performed on Cr-doped forsterite. The optical measurements permit identification of the signals in the complex EPR spectrum due to the near-infrared lasing center. The site symmetry of the lasing center is shown to be ${\mathit{c}}_{\mathit{s}}$, with the mirror plane being in the crystallographic a-b plane. The magnetic z axes of the two magnetically inequivalent sites are in the mirror plane at an angle of ±43° to the b axis. In addition, the relative energies of the ground-state triplet have also been measured and can be written in terms of spin Hamiltonian energy parameters: D=+2.20 and E=-0.149 ${\mathrm{cm}}^{\mathrm{-}1}$.

• Received 2 August 1991

DOI:https://doi.org/10.1103/PhysRevB.44.12589