In-beam Mossbauer spectra of Mn-57 implanted into a low-temperature Ar solid were measured. Only Fe-57(+) with the 3d(7) electronic configuration was observed. The production mechanism of Fe-57(+) (3d(7)) 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 beta-decay of Mn-57(2+) produced Fe-57(3+) followed by the formation of Fe-57(+) (3d(7)) without disturbing the symmetric surrounding of the Ar lattice. The temperature dependence of the recoil free fraction was well described using the Debye temperature Theta(D) = 61.3 K. (C) 2013 Elsevier B. V. All rights reserved.