EPR theoretical study of local lattice structure on Mn 2+ ion doped in calcite and differences between single crystal and fresh water snail, Pila globosa

Abstract

By diagonalizing the complete energy matrices for a d 5 configuration ion in a trigonal ligand-field and considering the second-order, fourth-order EPR parameters D and ( a − F) simultaneously, the substitution position of Mn 2+ ion in the CaCO 3:Mn 2+ system has been studied by analyzing the optical absorption and EPR spectra of single crystal and the ostracum layer of operculum of fresh water snail Pila globosa. The results show that in the single crystal there is an obvious compressed distortion Δ R = −0.158 Å and Δ θ = 0.70°, and the distortion in P. globosa is Δ R = −0.107 Å and Δ θ = −0.34° ∼ −0.23°. Meanwhile the EPR parameters 10 4( a − F) = 7.02–7.29 cm −1 and 10 4 a = 6.35 cm −1 are predicted in P. globosa.