1. Faculty of Chemistry, Pasteura 1, PL-02-093 Warsaw, Faculty of Biology, Warsaw University, Miecznikowa 1, PL-02-096 Warsaw, Poland, Department of Chemistry, University of Antwerp, Universiteitsplein 1, B-2610 Antwerp, Belgium, and HASYLAB at DESY, Notkestrasse 58, D-22603 Hamburg, Germany