Generation of Femtosecond Synchrotron Pulses: Performance and Characterization

Abstract. Femtosecond synchrotron pulses of <200 fs duration are generated at the Advanced Light Source beamline 5.3.1 via laser manipulation of the stored electron beam. We demonstrate a peak laser acceleration of >13 MeV relative to the nominal 1.9 GeV beam energy. Femtosecond pulses are effectively isolated from the long-pulse background using the transverse dispersion of the storage ring in combination with an x-ray imaging optic and a pair of slits to achieve a signal/background ratio of ~1

Femtosecond X-ray Pulses from a Synchrotron

An important frontier in ultrafast science is the application of femtosecond x-ray pulses to the study of structural dynamics in condensed matter. We show that femtosecond laser pulses can be used to generate high-brightness, tunable, femtosecond x-ray pulses from a synchrotron. Performance of existing and proposed femtosecond x-ray beamlines at the Advanced Light Source synchrotron are discussed

Coherent infrared radiation from the ALS generated via femtosecond laser modulation of the electron beam

Interaction of an electron beam with a femtosecond laser pulse co-propagating through a wiggler at the ALS produces large modulation of the electron energies within a short {approx}100 fs slice of the electron bunch. Propagating around the storage ring, this bunch develops a longitudinal density perturbation due to the dispersion of electron trajectories. The length of the perturbation evolves with a distance from the wiggler but is much shorter than the electron bunch length. This perturbation causes the electron bunch to emit short pulses of temporally and spatially coherent infrared light which are automatically synchronized to the modulating laser. The intensity and spectra of the infrared light were measured in two storage ring locations for a nominal ALS lattice and for an experimental lattice with the higher momentum compaction factor. The onset of instability stimulated by laser e-beam interaction had been discovered. The infrared signal is now routinely used as a sensitive monitor for a fine tuning of the laser beam alignment during data accumulation in the experiments with femtosecond x-ray pulses

Ultrafast x-ray science at the Advanced Light Source

Our scientific understanding of the static or time-averaged structure of condensed matter on the atomic scale has been dramatically advanced by direct structural measurements using x-ray techniques and modern synchrotron sources. Of course the structure of condensed matter is not static, and to understanding the behavior of condensed matter at the most fundamental level requires structural measurements on the time scale on which atoms move. The evolution of condensed-matter structure, via the making and breaking of chemical bonds and the rearrangement of atoms, occurs on the fundamental time scale of a vibrational period, ~;100 fs. Atomic motion and structural dynamics on this time scale ultimately determine the course of phase transitions in solids, the kinetic pathways of chemical reactions, and even the efficiency and function of biological processes. The integration of x-ray measurement techniques, a high-brightness femtosecond x-ray source, femtosecond lasers, and stroboscopic pump-probe techniques will provide the unique capability to address fundamental scientific questions in solid-state physics, chemistry, AMO physics, and biology involving structural dynamics. In this paper, we review recent work in ultrafast x-ray science at the ALS including time-resolved diffraction measurements and efforts to develop dedicated beamlines for femtosecond x-ray experiments