Femtosecond time resolution in x-ray diffraction experiments.
This paper presents the theoretical background for a synthesis of femtosecond spectroscopy and x-ray diffraction. When a diffraction quality crystal with 0.1-0.3 mm overall dimensions is photoactivated by a femtosecond laser pulse (physical length = 0.3 microm), the evolution of molecules at separated points in the crystal will not be simultaneous because a finite time is required for the laser pulse to propagate through the body of the crystal. Utilizing this lack of global crystal synchronization, topographic x-ray diffraction may enable femtosecond temporal resolution to be achieved from reflection profiles in the diffraction pattern with x-ray exposures of picosecond or longer duration. Such x-ray pulses are currently available, and could be used to study femtosecond reaction dynamics at atomic resolution on crystals of both small- and macromolecules. A general treatment of excitation and diffraction geometries in relation to spatial and temporal resolution is presented.
Neutze
R
R
Department of Biochemistry, Biomedical Centre, Uppsala University, Box 576, S-75123 Uppsala, Sweden. neutze@xray.bmc.uu.se
Hajdu
J
J
D018360:Crystallography, X-Ray / Q000295:instrumentation / Q000379:methods*; D007700:Kinetics; D007834:Lasers; D008962:Models, Theoretical; D012680:Sensitivity and Specificity; D013997:Time Factors