1. Solid State
Physics, University of Siegen, Walter Flex
Strasse-3, D-57068 Siegen, Germany
2. Macromolecular Chemistry, University of Wuppertal, D-42097, Gauss-Str. 20, Wuppertal, Germany
3. Institut Charles Sadron, CNRS - Université de Strasbourg, 23 rue du loess, 67034 Strasbourg, France