[1] Aristotle Univ Thessaloniki, Sch Technol, Div Phys, GR-54121 Thessaloniki, Greece
[2] FORTH, Inst Chem Engn & High Temp Chem Proc, GR-26504 Patras, Greece
[3] Univ Montpellier 2, Lab Physicochim Mat Condensee, CNRS, UMR 5617, F-34095 Montpellier 5, France
[4] Natl Inst Adv Ind Sci & Technol, Ctr Appl Near Field Opt Res, Tsukuba, Ibaraki 3058562, Japan