1. Institute of Applied Chemistry, Riga Technical University, 3/7 Paula Valdena Street, Riga LV-1048, Latvia
2. Latvian Institute of Organic Synthesis, 21 Aizkraukles Street, Riga LV-1006, Latvia
3. Institute of Solid State Physics, University of Latvia, 8 Kengaraga Street, Riga LV-1063, Latvia