Optical properties of BaFe2-xCoxAs2 E. van Heumen, Y. Huang, S. de Jong, A. B. Kuzmenko, M. S. Golden and D. van der Marel EPL, 90 3 (2010) 37005 Published online: 01 June 2010 DOI: 10.1209/0295-5075/90/37005