Ultracold fluorine production via Doppler cooled BeF

Area of Science:

• Atomic and Molecular Physics
• Quantum Chemistry
• Laser Cooling Techniques

Background:

• Current laser-cooling methods are insufficient for many elements, limiting research in areas like ultracold atom applications.
• Beryllium fluoride (BeF) presents a potential candidate for laser cooling and subsequent fragmentation into ultracold atoms.
• Generating ultracold fluorine atoms is crucial for various scientific investigations.

Purpose of the Study:

• To investigate the feasibility of producing ultracold fluorine atoms via zero energy fragmentation of laser-cooled BeF molecules.
• To perform accurate theoretical calculations for the electronic states of BeF, including spin-orbit coupling.
• To propose viable laser-cooling schemes and fragmentation pathways for BeF.

Main Methods:

• Ab initio calculations were performed on the electronic states of the BeF diatomic molecule.
• Spin-orbit coupling effects were included in the calculations.
• Multi-Reference Configuration Interaction (MRCI) calculations were used to determine potential energy curves for Rydberg states.

Main Results:

• Calculated electronic state minima for BeF closely match experimental spectroscopic values (within 1 pm).
• A four-color laser cooling scheme targeting the A(2)Π← X(2)Σ(+) transition in BeF was demonstrated as feasible.
• MRCI potentials for low-lying Rydberg states of BeF were computed for the first time and show good agreement with experimental data.

Conclusions:

• Laser cooling of BeF molecules is achievable, paving the way for ultracold fluorine atom production.
• Proposed multi-pulse excitation schemes offer a route to generate cold fluorine atoms from cooled BeF molecules.
• This research opens new avenues for producing ultracold atoms of elements not amenable to direct laser cooling.