Mössbauer spectra on [Fe(H2O)6]K2(SO4)2 exhibit slow electronic relaxation

Mössbauer spectra on single crystals of Fe(H₂O)₆]K₂(SO₄)₂ in fields from 1.5 T to 5 T at temperatures from 4.2 K to 20 K show considerable line broadenings up to 0.95 mm/s. This broadening strongly depends on the specific line in the spectrum, the temperature, and the strength and direction of the external field. It is shown that these phenomena are due to electronic relaxation rates that are some-what slower (≈10^?8 s) than the fast relaxation limit.