1. Experimental Physics VI; Julius Maximilian University of Würzburg; Am Hubland 97074 Würzburg Germany
2. Department of Polymer Chemistry and Technology; Kaunas University of Technology; Radvilenu pl. 19 LT-50254 Kaunas Lithuania
3. Lviv Polytechnic National University; S. Bandera 12 79013 Lviv Ukraine
4. Bavarian Centre for Applied Energy Research (ZAE Bayern); 97074 Würzburg Germany