Rapid proton transfer mediated by a strong laser field

Area of Science:

• Physical Chemistry
• Molecular Dynamics
• Laser Physics

Background:

• Polyatomic molecules interacting with intense laser fields can undergo complex dynamics.
• Understanding fragmentation pathways like Coulomb explosion is crucial for molecular control.

Purpose of the Study:

• To investigate the ultrafast dynamics of anthraquinone under intense laser irradiation.
• To elucidate the role of intramolecular processes preceding Coulomb explosion.

Main Methods:

• Experimental measurement of kinetic energy distributions of ejected particles.
• Theoretical calculations of potential energy surfaces and molecular dynamics simulations.
• Utilizing 60 fs, 800 nm laser pulses with intensities ranging from 0.2 to 4.0 x 10^14 W/cm^2.

Main Results:

• Observed kinetic energy distributions indicate field-driven molecular restructuring before Coulomb explosion.
• Calculations reveal fast intramolecular proton migration perpendicular to the laser polarization.
• Identified a field-dressed metastable potential energy minimum facilitating proton migration.

Conclusions:

• Field-driven isomerization is a significant phenomenon in the interaction of polyatomic molecules with intense lasers.
• Intramolecular proton migration plays a key role in the pathway to Coulomb explosion.
• This study reveals a new mechanism for controlling molecular fragmentation with lasers.