1. Instituto
de Física Gleb Wataghin, Universidade Estadual de Campinas, SP 13083-859, Brazil
2. Max Planck Institute for the Structure and Dynamics of Matter, Luruper Chaussee 149, 22761 Hamburg, Germany
3. Dipartimento
di Fisica e Chimica, Università degli Studi di Palermo, Via
Archirafi 36, I-90123 Palermo, Italy
4. Center for Free-Electron Laser Science and Department
of Physics, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
5. Nano-Bio
Spectroscopy Group and ETSF, Dpto. Física de Materiales, Universidad del País Vasco UPV/EHU, 20018 San Sebastián, Spain