Simulations of Attosecond Metallization in Quartz and Diamond Probed with Inner-Shell Transient Absorption...

Area of Science:

• Condensed Matter Physics
• Quantum Optics
• Computational Materials Science

Background:

• Intense infrared laser pulses can induce transient metallization in dielectric materials.
• The underlying attosecond dynamics of this process are not fully understood.
• Experimental techniques like attosecond transient absorption (ATA) provide valuable data but require theoretical interpretation.

Purpose of the Study:

• To perform first-principles simulations of attosecond transient absorption (ATA) in dielectrics.
• To understand the initial attosecond dynamics of laser-induced transient metallization.
• To aid in the interpretation of experimental ATA spectra and guide future research.

Main Methods:

• Utilized real-time time-dependent density functional theory (RT-TDDFT).
• Employed bulk-mimicking clusters with Koopmans-tuned range-separated hybrid functionals and Gaussian basis sets.
• Simulated ATA spectra in the extreme ultraviolet and X-ray ranges.

Main Results:

• Achieved good agreement with experimental data for breakdown thresholds in silica and diamond.
• Identified the Keldysh parameter of approximately one at breakdown, indicating a transition to tunneling-driven dynamics.
• Observed a mixture of multiphoton and tunneling excitations below the breakdown threshold.
• Computed ATA spectra showed good agreement with experiments, revealing decreased optical density due to conduction band population.

Conclusions:

• First-principles simulations are valuable for interpreting complex spectral modulations in ATA experiments.
• The developed method accurately models laser-induced transient metallization dynamics in dielectrics.
• This approach provides crucial insights for guiding future attosecond spectroscopy experiments on solids.