Interpretation of Quadrupole Splittings and Isomer Shifts in Hemoglobin

It is shown that the major features of the quadrupole splitting observed in the Mössbauer spectra of several derivatives of hemoglobin are explainable on the basis of the molecular orbital calculations of Zerner, Gouterman, and Kobayashi [Theoret. Chim. Acta 6, 363 (1966)] on iron porphin complexes while attempts to use ligand-field theory for the same purpose have been unsuccessful. Difficulties in the interpretation of isomer shifts are discussed.