1. Faculty
of Physics, Vilnius University, Sauletekio 9, LT-10222 Vilnius, Lithuania
2. Faculty
of Chemistry and Mineralogy, Universität Leipzig, Johannisallee
29, D-04103 Leipzig, Germany
3. Faculty
of Physics and Earth Sciences, Universität Leipzig, Linnestrasse
5, D-04103 Leipzig, Germany
4. Institute
of Inorganic Chemistry, University of Stuttgart, Pfaffenwaldring 55, D-70569 Stuttgart, Germany