1. Institute of Inorganic Chemistry, Goethe University Frankfurt, Max-von-Laue-Straße 7, 60438 Frankfurt am Main, Germany
2. Physics Department, University Kaiserslautern, Erwin-Schrödinger-Straße 56, 67663 Kaiserslautern, Germany
3. Department of Inorganic Chemistry, Faculty of Natural Sciences, Comenius University, Ilkovicova 6, 84215 Bratislava, Slovakia