Mössbauer studies of elant materials. II. Spectra of ⁵⁷fe‐enriched duckweed at low temperatures

Abstract

Samples of ⁵⁷Fe‐enriched duckweed have been studied by Mössbauer spectroscopy at 4.2 and 1.3K and at 4.2K in the presence of both snail and large external magnetic fields. All spectra support the results previously obtained at higher temperatures which suggested that the iron was present exclusively in the ferric form. The present results show that most, if not all, of the iron is antiferromagnetic‐ally‐coupled at low temperatures, although the presence of a small fraction (< 15%) of paramagnetic material, arising from isolated ferric ions in complexes, could not be discounted. The most common antiferromagnetic material found in plants is ferritin, an iron‐storage protein, but a comparison of the present results with those in the literature for ferritin, shows that, if it is responsible for the Mössbauer spectra, its core must be < 15Å diameter, much smaller than the maximum value of 60–70Å.

Key words:

• Mössbauer spectroscopy
• iron
• plant leaves