Charge migration in photo-ionized aromatic amino acids

Area of Science:

• Physical Chemistry
• Quantum Dynamics
• Molecular Spectroscopy

Background:

• Attosecond pump-probe spectroscopy directly observes light-activated electronic motion in molecules.
• Recent advances enable studying charge migration in biochemically relevant molecules.
• The impact of ultrafast charge flow on molecular reactivity remains an active research area.

Purpose of the Study:

• To investigate light-induced charge migration in phenylalanine and tryptophan using attosecond pulses.
• To understand the influence of nuclear dynamics on quantum coherences during charge migration.
• To compare how functional groups affect fragmentation and charge rearrangement in these amino acids.

Main Methods:

• Utilizing extreme ultraviolet attosecond pulses to initiate charge migration.
• Performing advanced numerical calculations to interpret experimental data.
• Comparing experimental results between phenylalanine and tryptophan.

Main Results:

• Observed distinct charge dynamics, including periodicities and decoherence times, in phenylalanine and tryptophan.
• Demonstrated that functional groups significantly alter fragmentation pathways and charge rearrangement.
• Numerical calculations showed quantum coherences persisting for several femtoseconds even in large molecules like tryptophan.

Conclusions:

• Charge migration dynamics are molecule-specific and influenced by functional groups.
• Ultrafast charge flow plays a crucial role in molecular reactivity and fragmentation.
• Attosecond spectroscopy provides a powerful tool for understanding and potentially controlling photo-induced dynamics in bio-relevant molecules.