1. Department
of Forest Products Technology, School of Chemical Technology, Aalto University, P.O.
Box 16300, 00076 Aalto, Finland
2. VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, 02044 VTT, Finland
3. Department
of Applied Physics, School of Science, Aalto University, P.O. Box 11100, 00076 Aalto, Finland