On the interpretation of isotope effects in Moessbauer spectroscopy

The deuterium and 18O isotope effects observed in the quadrupole splitting of FeSO4x7H2O, FeCl2x4H2O hydrates and their frozen aqueous solutions are interpreted in terms of the displacement of water molecules surrounding the ions. The differences in the distances of the closest approach of the water oxygen atoms to the ion brought about by the isotope substitution account qualitatively for the observed experimental results. The effect of the solution (hydrate) structure and temperature is also discussed. (author)