Electron localization following attosecond molecular photoionization.

Area of Science:

• Physical Chemistry
• Quantum Dynamics
• Molecular Physics

Background:

• Femtosecond laser pulses allow probing atomic motion in chemical transformations.
• Attosecond (10^-18 s) laser pulses now enable studies on the electronic timescale.
• Previous work monitored molecular dissociation on femtosecond timescales.

Purpose of the Study:

• To investigate electronic charge localization in molecules using attosecond pump-probe spectroscopy.
• To explore the dynamics of electron and nuclear motion beyond the Born-Oppenheimer approximation.
• To demonstrate attosecond resolution in observing molecular processes.

Main Methods:

• Utilized isolated attosecond ultraviolet pulses and intense few-cycle infrared pulses for molecular pump-probe experiments.
• Studied dissociative ionization of hydrogen (H2) and deuterium (D2) molecules.
• Measured electronic charge distribution localization with attosecond time resolution.

Main Results:

• Observed attosecond-time-resolved electronic charge localization in H2 and D2 molecules.
• Identified two mechanisms for charge localization influenced by the infrared laser: photoionization alteration and laser-driven population transfer.
• Demonstrated quantum mechanical interference and laser-driven state transfer as key processes.

Conclusions:

• Attosecond pump-probe spectroscopy is a powerful tool for studying ultrafast molecular dynamics.
• The research provides insights into the coupling of electronic and nuclear motions.
• This technique opens new avenues for understanding fundamental chemical processes at the electronic level.