Reprint Series 11 October 1996, Volume 274, pp. 236-238 SCiENCE o Femtosecond X-rayPulsesat 0.4 A Generated by 90°ThomsonScattering:A Tool for Probingthe StructuralDynamicsof Materials R. W. Schoenlein,* W. P. Leemans, A. H. Chin, P. Volfbeyn, T. E. Glover, P. Balling, M. Zolotorev, K.-J. Kim, S. Chattopadhyay, and C. V. Shank Copyright @ 1996 by the American Association for the Advancement of Science