In-beam Mössbauer spectra of 57Mn implanted into ice

Abstract

In-beam Mossbauer spectra of 57Mn implanted into ice were measured at 13, 77, and 150 K to investigate the interaction of Fe atoms with water molecules having a lattice structure of ice. Three types of 57Fe species, which were high-spin divalent Fe2+ species, were evident in the ice. Although a divalent Fe2+ ion in water is stabilized in the form of hexaquo ferrous ions, Fe(H2O)\(_{\mathrm {6}}^{\mathrm {2+}}\), the 57Fe atom implanted into low-temperature ice had a different chemical form. Density functional theory calculations were performed to make assignments of the species identified from the Mossbauer spectra. The major species was assigned to Fe2+ bonded to four H2O molecules of the ice, Fe(H2O)\(_{\mathrm {4}}^{\mathrm {2+}}\), which is located inside of cubic form ice (ice Ic). Other minor species that appeared at 13 K was assigned to Fe2+ bonded to OH− and three H2O molecules, FeOH(H2O)\(_{\mathrm {3}}^{\mathrm {+}}\), trapped in the ice. Another species that appeared at higher temperatures of 77 and 130 K was assigned to Fe(OH)2(H2O)2 trapped in ice Ic.