1. Institute of Physics
2. University of Tartu
3. 50411 Tartu
4. Estonia
5. Institute of Silicate Materials
6. RMS Foundation
7. 2544 Bettlach
8. Switzerland
9. Institute of Solid State Physics
10. University of Latvia
11. 1063 Riga
12. Latvia
13. Riga Technical University
14. Riga LV-1048