Towards the analysis of attosecond dynamics in complex systems.

Area of Science:

• Quantum mechanics
• Atomic and molecular physics
• Laser physics

Background:

• Investigating molecular ionization dynamics is crucial for understanding light-matter interactions.
• Attosecond laser pulses enable probing ultrafast electronic processes.
• Combined XUV and IR laser fields offer unique control over ionization.

Purpose of the Study:

• To theoretically study the ionization of molecules and clusters driven by combined attosecond XUV and IR laser fields.
• To compare the accuracy and applicability of time-dependent density-functional theory (TDDFT) with the time-dependent Schrödinger equation (TDSE).
• To analyze the influence of system complexity on ionization dynamics and resonance phenomena.

Main Methods:

• Utilizing real-time, real-space time-dependent density-functional theory (TDDFT).
• Comparing TDDFT results with time-dependent Schrödinger equation (TDSE) calculations.
• Analyzing ionization yields as a function of the delay time between XUV and IR pulses.

Main Results:

• TDDFT and TDSE successfully reproduced the regular modulation observed in simple atomic systems (He, Ar).
• For complex systems (C3 chain, Na clusters), TDDFT revealed more intricate ionization patterns than TDSE.
• Discrepancies between TDDFT and TDSE in complex systems suggest the influence of strong resonance modes.

Conclusions:

• TDDFT is a viable tool for studying ionization dynamics in complex molecules and clusters.
• The complexity of ionization patterns increases with system complexity, potentially due to resonance effects.
• Further investigation is needed to fully elucidate the role of resonance modes in complex system ionization.