[1] Lund University, Department of Solid State Physics, Box 118, S-221 00 Lund, Sweden
[2] Gerhard-Mercator-University Duisburg, Chemical Engineering, Bismarckstr. 81, D-47048 Duisburg, Germany
[3] Gerhard-Mercator-University Duisburg, Process- and Aerosol Measurement, Bismarckstr. 81, D-47048 Duisburg, Germany