Affiliation: | (1) European Synchrotron Radiation Facility, BP 220, F-38043 Grenoble, France;(2) Universitát Rostock, Fachbereich Physik, August-Bebel-Str. 55, 18055 Rostock, Germany;(3) Physik Department E13, Technische Universitát München, D-85747 Garching, Germany |