EPR Observations of Temperature Dependent Level Crossing for Gd3+ in LaCl3

Observations by electron paramagnetic resonance of LaCl₃ single crystals containing very small concentrations of Gd³⁺ have revealed previously unresolved structure in the Gd³⁺ spectrum at temperatures between 150 and 294°K. A multiple crossing of the ${}^8{S}_{\text{7/2}}$ ground doublets occurs in this temperature range, and the ability to make correct $M_8$ assignments to the EPR transitions results in values for the spin‐Hamiltonian parameters which differ from those reported previously.