Probing laser-driven surface and subsurface dynamics via grazing-incidence XFEL scattering and diffraction

Area of Science:

• Materials Science
• Surface Science
• Condensed Matter Physics

Background:

• Understanding ultrafast laser-matter interactions is crucial for materials processing and inertial confinement fusion.
• Existing methods lack the depth-selective and time-resolved capabilities needed to probe near-surface dynamics.
• Characterizing transient states like melting and recrystallization requires advanced diagnostic tools.

Purpose of the Study:

• To develop and demonstrate a novel grazing-incidence X-ray platform for simultaneous time-resolved GISAXS and GID.
• To achieve picosecond resolution and depth-selective sensitivity for studying laser-induced dynamics in gold films.
• To provide experimental benchmarks for theoretical models of ultrafast laser-matter interactions.

Main Methods:

• Utilizing an X-ray free-electron laser (XFEL) for high-intensity, short-pulse X-ray generation.
• Employing grazing-incidence small-angle X-ray scattering (GISAXS) to probe surface nanomorphology.
• Using grazing-incidence X-ray diffraction (GID) to analyze subsurface lattice dynamics and phase transitions.

Main Results:

• Simultaneous GISAXS and GID measurements with picosecond resolution were achieved.
• Depth-selective sensitivity to near-surface dynamics was demonstrated by tuning the X-ray incidence angle.
• Ultrafast changes in surface nanomorphology, lattice compression, melting, and recrystallization were quantified.

Conclusions:

• The developed X-ray platform overcomes limitations of synchrotron-based methods, offering superior photon flux and time resolution.
• This technique provides critical, time-resolved data for validating theoretical models of laser-matter interactions and warm dense matter.
• The depth-selective methodology shows promise for applications in inertial confinement fusion, enabling visualization of buried-interface dynamics.