Crystal Field Theory on the 3d Electronic States

Crystal field theory provides a simple picture on understanding the electronic structures of the 3d electrons in iron including the split energy levels of the 3d electrons and their associated spin states in the mantle minerals [28], In the simple case of the sixfold, octahedrally coordinated Fe in ferropericlase, the 3d electrons of iron can occupy different degenerate sets of 3d orbitals, namely the triplet t2g-like and doublet eg-like orbitals (Fig. 2.4) [28]. The occupation of the 

The QS arises from the interaction between the nuclear quadrupole moment and the nonspherical component of the electronic charge distribution described by its effective electric field gradient (EFG) in a simplified model [19,28]. The effective electric field gradient is dramatically reduced due to the spin-pairing transition. The electron shell of the high-spin Fe ions in the octahedral coordination is spherically asymmetric with S = 2 and t e t, whereas Fe ions in the low-spin state are more spherically symmetric with S = 0 and (the arrows indicate spin up or spin down whereas 

2 MOSSBAUER SPECTROSCOPY IN STUDYING ELECTRONIC SPIN AND VALENCE STATES OF IRON 

---