In-beam Mِssbauer spectra of 57Mn implanted into low-temperature solid Ar

In-beam Mössbauer spectra of 57Mn implanted into a low-temperature Ar solid were measured. Only 57Fe+ with the 3d7 electronic configuration was observed. The production mechanism of 57Fe+ (3d7) is discussed in terms of a charge transfer process between charged species and the surrounding Ar atoms; Mn2+ was trapped in a substitutional position in the fcc Ar lattice, and β-decay of 57Mn2+ produced 57Fe3+ followed by the formation of 57Fe+ (3d7) without disturbing the symmetric surrounding of the Ar lattice. The temperature dependence of the recoil free fraction was well described using the Debye temperature ΘD = 61.3 K.