1. Dipartimento
di Chimica, Materiali e Ingegneria Chimica “G. Natta”, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133 Milano Italy
2. Nanobiophotonics
and Laser Microspectroscopy Center, Faculty of Physics and Interdisciplinary
Research Institute in Bio-Nano-Sciences, Babes-Bolyai University, Treboniu Laurian Street 42, Cluj Napoca 400271, Romania
3. Department
of Materials, Imperial College London, Exhibition Road, London, SW7 2AZ, U.K.
4. DWI-Leibniz
Institute for Interactive Materials, RWTH Aachen University, 52074 Aachen, Germany
5. Institute
of Physics, University of Freiburg, Hermann-Herder Strasse 3, Freiburg 79104, Germany