Femtosecond Reduction of Atomic Scattering Factors Triggered by Intense X-Ray Pulse

Area of Science:

• Materials Science
• Condensed Matter Physics
• Ultrafast Science

Background:

• X-ray diffraction is a fundamental tool for probing atomic structure.
• Understanding material response to intense ultrashort laser pulses is crucial for developing new technologies.

Purpose of the Study:

• To investigate the effect of high-intensity femtosecond X-ray pulses on silicon's X-ray diffraction.
• To elucidate the physical mechanisms behind observed changes in diffraction intensity.

Main Methods:

• Experimental measurement of X-ray diffraction from silicon irradiated with 6 fs X-ray pulses (11.5 keV) at intensities up to 4.6×10^19 W/cm².
• Computational simulation to model the ultrafast ionization dynamics and their effect on atomic scattering factors.

Main Results:

• Significant suppression of X-ray diffraction intensity observed at X-ray intensities around 10^19 W/cm².
• Simulations confirm that ultrafast ionization (photoionization, Auger decay, collisional ionization) drastically alters atomic scattering factors, causing the diffraction reduction.

Conclusions:

• Ultrafast ionization dynamics induced by intense femtosecond X-rays profoundly impact X-ray diffraction from silicon.
• The observed ultrafast reduction in atomic scattering factor opens avenues for novel nonlinear X-ray techniques, including pulse shortening and contrast variation X-ray scattering.