Femtosecond X-ray Source Research Articles

Set-up for ultrafast time-resolved X-ray diffraction using a femtosecond laser-plasma keV X-ray source

A short-pulse 4.51 keV Ti K o femtosecond laser-plasma driven hard x-ray source has been built and characterized. This source is incorporated into a set-up for ultrafast time-resolved x-ray diffraction experiments, to study ultrafast lattice dynamics in laser-excited materials.

Tunable coherent femtosecond X-ray source driven by an intense femtosecond laser

The wavelength tunability of high harmonic generation is presented. By applying intense femtosecond laser pulse to gaseous medium, the wavelengths of high-order harmonics could be tuned. The wavelength shift large enough to cover the interval between adjacent orders was obtained in harmonics from Ar and Ne atoms driven by 25 fs pulses, opening a way to realize a tunable coherent x-ray source.

Image quality analysis for dual energy subtraction imaging with a femtosecond laser-based hard X-ray source

We present a study of image quality for dual energy subtraction imaging using an iodinated contrast agent and a femtosecond laser-based hard X-ray source. The INRS CPA laser (400 fs pulse focused on solid targets in a 3 /spl mu/m spot at 4 /spl times/ 10/sup 18/ W cm/sup -2/) was used to create a bright hard X-ray source (conversion efficiency of 10/sup -5/ in the characteristic K/sub /spl prop// line emission, 12 /spl mu/m X-ray source diameter). A model of image quality has been developed and been benchmarked with specific experiments using specially made angiography phantoms.

Generation of femtosecond pulses of synchrotron radiation

Femtosecond synchrotron pulses were generated directly from an electron storage ring. An ultrashort laser pulse was used to modulate the energy of electrons within a 100-femtosecond slice of the stored 30-picosecond electron bunch. The energy-modulated electrons were spatially separated from the long bunch and used to generate approximately 300-femtosecond synchrotron pulses at a bend-magnet beamline, with a spectral range from infrared to x-ray wavelengths. The same technique can be used to generate approximately 100-femtosecond x-ray pulses of substantially higher flux and brightness with an undulator. Such synchrotron-based femtosecond x-ray sources offer the possibility of applying x-ray techniques on an ultrafast time scale to investigate structural dynamics in condensed matter.

Ultrafast Structural Dynamics in InSb Probed by Time-Resolved X-Ray Diffraction

Ultrafast structural dynamics in laser-perturbed InSb are studied using time-resolved x-ray diffraction with a novel femtosecond x-ray source. We report the first observation of a delay in the onset of lattice expansion, which we attribute to energy relaxation processes and lattice strain propagation. In addition, we observe direct indications of ultrafast disordering on a subpicosecond time scale.