1. Institute of Catalysis, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.11, 1113 Sofia, Bulgaria
2. Georgi Nadjakov Institute of Solid State Physics, Bulgarian Academy of Sciences, 72 Tzarigradsko Chaussee Blvd., BG-1784 Sofia, Bulgaria
3. Institute of Physical Chemistry “Ilie Murgulescu”, Romanian Academy, Spl. Independentei 202, Bucharest 060021, Romania
4. A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences, Vavilova str., 28, Moscow 119991, Russia