1. Central Laboratory of Photoprocesses, Bulgarian Academy of Sciences, G. Bonchev Str., bl. 109, 1040 Sofia, Bulgaria
2. Institute of Macromolecul ar Chemistry, Academy of Sciences of the Czech Republic, Heyrovský Sq. 2, 162 06 Prague 6, Czech Republic
3. Faculty of Chemistry, Technical University of Brno, Purkyňova 118, 612 00 Brno, Czech Republic
4. Institute of Physical and Theoretical Chemistry, Technical University of Wrocław, Wyb. Wyspiańskiego 27, 50-370 Wrocław, Poland