EPR of Mn²⁺ in Na₂ZnCl₄ · 3 H₂O

Abstract

The EPR spectrum of Mn 2+ in Na,ZnCl 4 ·3 H 2 O was investigated in the range 100 K ≦T≦300 K. The spectrum can be described by a Spin Hamiltonian with axial symmetry. The g factor is anisotropic, g ∥ = 2.0007 ±0.0005; g ⊥ = 2.0030 ± 0.0005. The axial crystal field splitting constants are D = (-901.0 ±2.0) -10 -4 cm -1 , B = (-5.7 ± 2.0) · 10 -4 cm -1 . The hyperfine splitting constants A = (-74.9 ±0.2)-10 -4 cm -1 and A ⊥ = (-74.2 ± 0.2) · 10 -4 cm -1 have been determined. This corresponds to a Mn 2+ ion bond to four Cl - ions within a tetrahedron. Since a large crystal field splitting constant D is observed, a strong axial crystal field at the site of the Mn 2+ ion is assumed. From the temperature dependence of the crystal field splitting constant D a dominant phonon frequency of (117 ± 10) · 10 11 sec -1 is deduced.