1. Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
2. Department of Chemistry, University of Virginia, Charlottesville, Virginia 22901, USA
3. Institut für Physik, Johannes Gutenberg Universität Mainz, 55099 Mainz, Germany and Leibniz-Institut für Polymerforschung, Institut Theorie der Polymere, Hohe Str. 6, 01069 Dresden, Germany
4. Bulgarian Academy of Sciences, Institute of Physical Chemistry, 1113 Sofia, Bulgaria