Optical conductivity study of screening of many-body effects in graphene interfaces Pranjal Kumar Gogoi, Iman Santoso, Surajit Saha, Sihao Wang, Antonio H. Castro Neto, Kian Ping Loh, T. Venkatesan and Andrivo Rusydi EPL, 99 6 (2012) 67009 Published online: 05 October 2012 DOI: 10.1209/0295-5075/99/67009