1. Physics and Chemistry of Nanostructures, Ghent University, Krijgslaan
281-S3, 9000 Ghent, Belgium
2. Center for Nano- and Biophotonics (NB-Photonics), Ghent University, Belgium
3. L3 − Luminescent Lanthanide Lab, f-Element Coordination
Chemistry, Ghent University, Krijgslaan 281-S3, 9000 Ghent, Belgium
4. OPERA Department, Université Libre de Bruxelles, Brussels 1050, Belgium
5. Institut für
Festkörperphysik, Technische Universität Berlin, Hardenbergstr.
36, 10623 Berlin, Germany