Electronic spectrum of chromate(V) ion in Sr5(PO4)3Cl host lattice

Abstract

The polarized electronic spectrum of CrO^3– ₄ doped in crystals of Sr₅(PO₄)₃Cl has been measured at 4.2 K in the range 8000–45 000 cm^–1. On the basis of the lattice site-symmetry perturbation, of a careful analysis of the possible excited states and of the expected polarizations of the corresponding transitions, it is concluded that the ground state is ²E_z ², the system of bands in the region 10 000–17 000 cm^–1 correspond to ligand field transitions, and that all the observed bands except that at 41 500 cm^–1 are assigned to ²T₂ excited states in T_d symmetry. The splitting of the ligand field band is interpreted by introducing two perturbations due to the site-symmetry, T_d→C_3v and C_3v→C_s, and the spin–orbit coupling. The T_d ligand field parameter Δ is 13 500 cm^–1 and the splitting of the ligand-field band due to the perturbation T_d→C_3v is 3ε∼ 2890 cm^–1.