Reaction microscope for investigating ionization dynamics of weakly bound alkali dimers

Area of Science:

• Atomic, Molecular, and Optical (AMO) Physics
• Quantum Chemistry
• Laser Spectroscopy

Background:

• Magneto-optical traps (MOTs) are standard tools for cooling and trapping neutral atoms.
• Optical dipole traps (ODTs) offer advantages for trapping weakly bound molecules and enabling specific experimental conditions.
• Reaction microscopy provides kinematically complete measurements of atomic and molecular reactions.

Purpose of the Study:

• To implement a combined magneto-optical and optical dipole trap system for ultracold atoms and molecules.
• To investigate multi-photon ionization mechanisms of ⁶Li atoms and ⁶Li₂ molecules in strong laser fields.
• To demonstrate the capability of distinguishing ionization pathways influenced by the ODT's infrared field.

Main Methods:

• Utilizing a far-off-resonant optical dipole force trap integrated with a magneto-optical trap.
• Performing kinematically complete multi-photon ionization experiments on trapped ⁶Li atoms and ⁶Li₂ molecules.
• Employing femtosecond laser pulses (30 fs) at 780 nm for three-photon ionization of weakly bound dimers.
• Measuring photoelectron and recoil ion momenta in coincidence.

Main Results:

• Successful implementation of a hybrid trapping system for ultracold ⁶Li and ⁶Li₂.
• Distinction of ionization mechanisms occurring in the presence of the ODT's IR field.
• Detection of weakly bound ⁶Li₂ molecules via three-photon ionization.
• Direct measurement of photofragment momenta.

Conclusions:

• The combined MOT-ODT system is effective for studying ultracold species.
• The reaction microscope coupled with ODT allows detailed investigation of strong-field ionization dynamics.
• This approach provides new insights into the interaction of light with ultracold matter.