1. Institute of Materials Chemistry, Vienna University of Technology, Getreidemarkt 9/165-TC, A-1060 Vienna, Austria
2. Institut für Festkörpertheorie und -optik, Friedrich-Schiller-Universität Jena and European Theoretical Spectroscopy Facility, Max-Wien-Platz 1, 07743 Jena, Germany
3. Institut für Physik, Martin-Luther-Universität Halle-Wittenberg, D-06099 Halle, Germany
4. School of Physical Sciences, National Institute of Science Education and Research, HBNI, Bhubaneswar 752050, India