The ESR spectra of Ni2+ ions in single crystals of CdCl2 were studied at 9 as well as 35 GHz. A single line was observed at 9 GHz, which was assigned to a forbidden transition between two spin levels Ms=±1. The constants in the spin-Hamiltonian were determined as g⁄⁄=2.25±0.02, g⊥=2.22±0.02, |D|=1.35±0.02 cm−1.
