Hyperfine Interact DOI 10.1007/s10751-010-0184-5 Mössbauer spectroscopy of 57 Fe in α-Al 2 O 3 following implantation of 57 Mn ∗ H. P. Gunnlaugsson · R. Mantovan · T. E. Mølholt · D. Naidoo · K. Johnston · H. Masenda · K. Bharuth-Ram · G. Langouche · S. Ólafsson · R. Sielemann · G. Weyer · Y. Kobayashi · the ISOLDE collaboration © Springer Science+Business Media B.V. 2010 Abstract The valence state and annealing reactions of Mn/Fe in single crystalline α-Al 2 O 3 have been determined following low fluence (<10 12 cm −2 ) 60 keV im- plantations of 57 Mn + (T 1/2 = 1.5 min) and emission Mössbauer spectroscopy on the 57m Fe daughter nuclei in the temperature range from 110–700 K. At 110 K, most probe atoms are found in the Fe 2+ state in amorphous surroundings due to the implantation damage. A fraction of the Fe is found in cubic environment, possibly nano-precipitates of η-Al 2 O 3 . This site is found to disappear from the H. P. Gunnlaugsson (B ) · G. Weyer Department of Physics and Astronomy, Aarhus University, 8000 Århus C, Denmark e-mail: hpg@phys.au.dk R. Mantovan Laboratorio MDM, IMM-CNR, Via Olivetti 2, 20041 Agrate Brianza (MB), Italy T. E. Mølholt · S. Ólafsson Science Institute, University of Iceland, Dunhaga 3, 107 Reykjavík, Iceland D. Naidoo · H. Masenda School of Physics, University of the Witwatersrand, Private Bag 3, WITS 2050, South Africa K. Johnston · the ISOLDE collaboration PH Dept, ISOLDE/CERN, 1211 Geneva 23, Switzerland K. Bharuth-Ram School of Physics, University of KwaZulu-Natal, Durban 4001, South Africa G. Langouche Instituut voor Kern- en Stralingsfysica, University of Leuven, 3001 Leuven, Belgium R. Sielemann Helmholtz-Zentrum Berlin für Materialien und Energie, 14109 Berlin, Germany Y. Kobayashi The Institute of Physical and Chemical Research (RIKEN), Wako, Saitama 351-0198, Japan