EPR Study of Fe$\text{}^{3+}$ Paramagnetic Centers in Doped Triglycine Sulphate Crystals

This paper presents EPR study of Fe$\text{}^{3+}$ in triglycine sulphate doped with Fe$\text{}^{3+}$ crystal. Fe$\text{}^{3 +}$ ion is in a high spin state S=5/2. EPR signal can be detected only below 200 K. At 4.2 K the EPR spectrum results from three non-equivalent sites of Fe$\text{}^{3+}$ ions. The spin Hamiltonian: H=β BĝS+D[S$\text{}_{z}^{2}$-(1/3)S(S+1)]+E(S$\text{}_{x}^{2}$-S$\text{}_{y}^{2}$) has been applied to describe the spectrum. The zero field splitting parameter in this case fulfills the condition: D≫hν. An experimental spectrum reflects clearly only two resonance transitions: |±1/2ã (the lowest Kramers doublet) and |±3/2〉 (the middle Kramers doublet). The iron complexes occupy interstitial positions in the crystal with distorted octahedral or tetrahedral co-ordination.