[1] Univ Munster, NRW Grad Sch Chem, D-48149 Munster, Germany
[2] Univ Munster, Ctr Nanotechnol CeNTech, D-48149 Munster, Germany
[3] Univ Munster, Inst Phys, D-48149 Munster, Germany
[4] Munster Univ Appl Sci, Dept Chem Engn, D-48565 Steinfurt, Germany