Probing proton dynamics in molecules on an attosecond time scale

Area of Science:

• Physical Chemistry
• Quantum Dynamics
• Molecular Spectroscopy

Background:

• Observing ultrafast molecular dynamics requires high temporal resolution.
• Current methods face limitations in probing subfemtosecond processes.
• Understanding nuclear rearrangement is crucial for chemical reactions.

Purpose of the Study:

• To develop and demonstrate a technique for probing nuclear dynamics on a subfemtosecond timescale.
• To achieve 100-attosecond temporal resolution in observing molecular structural changes.
• To validate the method by comparing experimental results with theoretical calculations.

Main Methods:

• Utilizing high-order harmonic generation (HHG) in molecules.
• Exploiting the chirp in the electron wavepacket and emitted photons.
• Employing strong-field laser ionization and electron-ion recombination.
• Analyzing harmonic spectra from molecular hydrogen, deuterium, methane, and deuterated methane.

Main Results:

• Demonstrated subfemtosecond temporal resolution for probing nuclear dynamics.
• Achieved 100-attosecond resolution in observing molecular structural rearrangement.
• Experimental measurements on H2 and D2 agreed with theoretical calculations for H2+ dynamics.
• Observed a few-femtosecond timescale for proton rearrangement in ionized methane (CH4 and CD4).

Conclusions:

• The high-order harmonic generation technique provides unprecedented temporal resolution for studying molecular dynamics.
• The method is validated for probing ultrafast nuclear motion and structural changes.
• This technique opens new avenues for investigating fundamental processes in chemistry and physics.