Ultrafast energy-dispersive soft-x-ray diffraction in the water window with a laser-driven source

Area of Science:

• Solid-state physics
• Materials science
• Ultrafast spectroscopy

Background:

• Time-resolved soft-X-ray diffraction probes ultrafast dynamics in materials.
• Laboratory-based high-harmonic generation (HHG) sources offer necessary photon energies but have limited flux and broad spectra.
• Monochromatic diffraction schemes are challenging with broadband HHG sources.

Purpose of the Study:

• To present a novel energy-dispersive soft-X-ray diffraction scheme.
• To achieve femtosecond temporal resolution for probing ordering phenomena.
• To utilize broadband HHG emission for efficient reciprocal space probing.

Main Methods:

• Developed an energy-dispersive soft-X-ray diffraction setup.
• Utilized broadband high-harmonic generation (HHG) light sources (200-600 eV).
• Studied laser-induced structural dynamics of a Mo/Si superlattice via ultrafast, non-resonant soft-X-ray diffraction.

Main Results:

• Successfully probed large slices in reciprocal space using broadband HHG.
• Measured the shift of the first-order superlattice Bragg peak in a Mo/Si superlattice.
• Extracted ultrafast strain dynamics from diffraction peak shifts using simulations.

Conclusions:

• The developed energy-dispersive method enables efficient probing of ultrafast dynamics.
• This technique is applicable to various solid-state materials across the water window.
• Strain dynamics in Mo/Si superlattices were successfully resolved at femtosecond timescales.