The optical phonon spectrum of SmFeAsO C. Marini, C. Mirri, G. Profeta, S. Lupi, D. Di Castro, R. Sopracase, P. Postorino, P. Calvani, A. Perucchi, S. Massidda et al. (5 more) EPL, 84 6 (2008) 67013 Published online: 12 January 2009 DOI: 10.1209/0295-5075/84/67013