Advances in femtosecond laser technology make feasible the generation
of femtosecond x-ray pulses. An analysis of Bragg diffraction of subpi
cosecond x-ray pulses is presented. It is shown that the three-dimensi
onal nature of the diffracting crystal grating and the finite size of
the x-ray beam will lead to a considerable broadening of the diffracte
d femtosecond x-ray pulse. (C) 1998 American Institute of Physics.