ESR study of the Mn²⁺ center in LiNbO₃

Fine structure and hyperfine structure of Mn²⁺ in LiNb0₃ are analyzed with electron spin resonance (ESR) at room temperature. It is concluded that the zero-field splitting of energy levels of electron spin angular moment between |±1/2> and |±3/2> is Δε₁ = - 587 × 10^-4 cm^-1, and that between |±3/2> and |±5/2> is Δε₂ = - 2633 × 10^-4 cm^-1. The anisotropic Lande factors are g∥ = 2.1810, and g⊥ = 2.0937. The fine structure constant is D = -536 × 10^-4 cm^-1, and hyperfine structure constants are A∥ = 88.36 cm^-1 and A⊥ = 81.20 × 10^-4 cm^-1. The interaction action of the fine structure is larger than that of the hyperfine structure. In addition, it is worth paying special attention to the fact that two forbidden transitions |-3/2>↔|1/2> and |-1/2>↔|5/2> are found.