1. Université Libre de Bruxelles, École Polytechnique de Bruxelles; Service 4MAT, av. F.D. Roosevelt 50-CP 165/63, 1050; Brussels Belgium
2. Department of Chemistry, Research Group PLASMANT; University of Antwerp, Universiteitsplein 1, B-2610; Wilrijk-Antwerp Belgium
3. Université de Mons, ChIPS, av. Nicolas Copernic 1, 7000; Mons Belgium
4. Faculty of Physics, Sofia University; Blvd “James Bourchier” 5, 1164; Sofia Bulgaria
5. Department of Applied Physics, Research Group EPG; Eindhoven University of Technology, P.O. Box 513, 5600 MB; Eindhoven the Netherlands
6. Materia Nova Research Center; av. Nicolas Copernic 1, 7000; Mons Belgium