1. Institute of Atomic Physics and Spectroscopy, University of Latvia, 19 Raina Blvd., LV-1586 Riga, Latvia
2. Center for Collective Use of Scientific Equipment, Sumy State University, 31, Sanatornaya St., 40018 Sumy, Ukraine
3. Faculty of Chemistry and Geosciences, Institute of Chemistry, Vilnius University, Naugarduko Str. 24, LT-03225 Vilnius, Lithuania
4. Medical Institute Sumy State University, Sanatorna Str. 1, 40007 Sumy, Ukraine