1. Department of Physics, AlbaNova University Center, Stockholm University, S-106 91 Stockholm, Sweden
2. Max Plank Institute for Polymer Research, Ackermannweg 10, 55128 Mainz, Germany
3. Department of Physics, Universität Siegen, Walter-Flex-Strasse 3, 57072 Siegen, Germany
4. Deutsches Elektronen-Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg, Germany
5. Institute of Physics, Johannes Gutenberg University, 55128 Mainz, Germany