Molecular alignment effect on the photoassociation process via a pump-dump scheme.

Area of Science:

• Quantum Chemistry
• Molecular Physics
• Spectroscopy

Background:

• Photoassociation is a key process for creating molecules from free atoms.
• The pump-dump scheme offers precise control over molecular state preparation and transfer.
• Understanding molecular dynamics in excited states is crucial for chemical synthesis and control.

Purpose of the Study:

• To investigate photoassociation dynamics in heteronuclear (NaH) and homonuclear (Na2) systems.
• To analyze the role of molecular alignment in the pump-dump process.
• To determine the influence of alignment on population transfer to the ground electronic state.

Main Methods:

• Time-dependent quantum wavepacket method.
• Simulation of pump-pulse excitation from atomic continuum to excited molecular states.
• Simulation of dump-pulse transfer from excited to ground molecular states.

Main Results:

• Pump pulse creates a superposition of rovibrational levels in the excited state, leading to field-free molecular alignment.
• Molecular alignment modulates the effective coupling and population transfer pathways during the dump pulse.
• Final population transfer to the ground state exhibits periodic dependence on the dump pulse delay time.

Conclusions:

• Molecular alignment is a critical factor influencing photoassociation efficiency in the pump-dump scheme.
• The observed periodicity offers a pathway for controlling molecular population transfer.
• This work provides insights into laser-controlled chemical reactions and molecular state preparation.