Electronic Structure of Ferrous Iron in Hemoglobin Inferred from Mössbauer Measurements

The effect of rhombic perturbation on the low‐lying energy levels (calculated for tetragonal point symmetry) of ferrous iron in deoxyhemoglobin Hb(rat, $p\mathrm{H}\text{\hspace{0.17em}=\hspace{0.17em}10}$ ) is investigated. The resulting temperature dependent electric‐field gradient is compared with experimental values in order to get information about the energy‐term scheme. The rhombic perturbation is shown to be small, leading to the splitting of the orbital doublet ${}^{5}E$ by less than 400 cm⁻¹. Application is made to the magnetic susceptibility which is calculated by means of the electronic structure inferred from the quadrupole splitting data.