SUB-PICOSECOND RESOLUTION AT SYNCHROTRON SOURCES: HOW AND WHY?

Richard Neutze

Department of Biochemistry, Biomedical Centre, Uppsala University, Box 576, S-75123 Uppsala, Sweden

100 picosecond X-ray snapshots of the dynamics of macromolecular systems are now (somewhat) routinely available at synchrotron sources. Standard experimental protocols cannot achieve faster temporal resolution as they are limited by the duration of the electron bunch within the synchrotron ring. Momentum towards sub-picosecond structural studies has been provided by laser plasma sources [1], pulsed electron diffraction [2], 90o Thompson scattering [3], and through the heating of X-ray mirrors [4].

With the commissioning of on-line femtosecond laser facilities at dedicated beamlines, the challenge which presents itself to synchrotron radiation is: How can we extend the temporal resolution below that of a single X-ray pulse? Two experimental protocols promising this goal [5,6] are presented. With novel experimental and analysis strategies, intense monochromatic synchrotron generated X-rays should become the light-source of choice for structural studies on ultra-fast systems. Examples within photo-chemistry and condensed matter physics are chosen, illustrating the exciting scientific opportunities arising from the opening of new structural windows on the sub-picosecond domain.

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  4. J. Larsson et al., Applied Physics A, 66, 587 (1998).
  5. R. Neutze, J. Hajdu, Proc. Natl. Acad. Sci. USA, 94, 5651 (1997).
  6. R. Neutze, Deconvoluting ultrafast dynamics: picosecond time-resolution with synchrotron radiation}, submitted.