1. Institute of Coal Chemistry, Polish Academy of Sciences, Sowińskiego 5, 44-121 Gliwice, Poland, Institute of Physics, Academy of Jan Dlugosz, Armii Krajowej 13/15, 42-200 Czȩstochowa, Poland, and Department of Chemical Technology of Coal and Petroleum, Silesian Technical University, Krzywoustego 3, 44-100 Gliwice, Poland