1. Regional Centre of Advanced Technologies and Materials; Department of Physical Chemistry, Faculty of Science; Palacky University; Slechtitelu 11 783 71 Olomouc Czech Republic
2. Physics Department; University of Ioannina; Ioannina 45110 Greece
3. School of Physical and Mathematical Science; Division of Chemistry and Biological Chemistry; Nanyang Technological University; 21 Nanyang Link Singapore