Author Affiliations

A. Rousse,¹ S. Fourmaux,¹ S. Sebban,¹ G. Grillon,¹ Ph. Balcou,¹ D. Hulin,¹ C. Rischel,² I. Uschmann,³ E. Förster,³ J.P. Geindre,⁴ P. Audebert,⁴ and J.C. Gauthier⁴

¹Labaratoire d'Optique Appliquée - ENSTA. CNRS UMR7639, Ecole Polytechnique, Cheminde la Hunière.91761 Palaiseau, France

²Niels Bohr Institute, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark and Department of Mathematics and Physics, The Royal Veterinary and Agricultural University, Thorvaldsensvej 40, DK-1871 Frederiksberg C, Denmark

³X-ray Optics Group, Institute of Optics and Quantum Electronics, Friedrich Schiller University Jena, Max-Wien-Platz 1, 07743 Jena, Germany

⁴Laboratoire pour I'Utilisation des Lasers Intenses, UMR7605, CNRS - Ecole Polytechnique - CEA-Université Paris VI. Ecole, Polytechnique 91128 Palaiseau. France

Phone: +33 (0)1 69 31 99 01 FAX: +33 (0)1 69 31 99 96, Tel: +45 352R 2311 (KVL) Fax: +45 3532 5016, Tel. / Fax.: (49) 3641 94 72 64 / (49) 3641 94 72 62, phone: +23 (0)1 69 33 46 46 FAX +33 (0)1 69 33 30 09