A supersonic laser ablation beam source with narrow velocity spreads

Area of Science:

• Physical Chemistry
• Molecular Beam Spectroscopy
• Laser Cooling

Background:

• Precise control over molecular beam properties is crucial for advanced spectroscopic studies and quantum manipulation.
• Existing supersonic laser ablation sources for metal fluorides often yield beams with broader velocity distributions.
• Low rotational temperatures are desirable for efficient laser cooling and state preparation of molecules.

Purpose of the Study:

• To construct and characterize a new supersonic beam source for SrF and BaF molecules.
• To achieve narrow translational velocity spreads in the generated molecular beams.
• To assess the suitability of the source for subsequent laser cooling and Stark deceleration experiments.

Main Methods:

• A supersonic expansion of argon seeded with sulfur hexafluoride (SF₆) was employed.
• Laser ablation of barium/strontium metal targets was used to generate the metal fluoride species.
• An Even-Lavie valve was utilized for gas expansion at a 10 Hz repetition rate.

Main Results:

• Molecular beams of SrF and BaF were successfully produced with narrow translational velocity spreads (Δv/v ≈ 0.054).
• The measured velocity spread is significantly narrower than those reported for similar sources.
• A low rotational temperature of 3.5 K was determined for BaF molecules.
• High molecular yields (6 × 10⁸ sr^-1 pulse^-1 for BaF, 10⁷ sr^-1 pulse^-1 for SrF) were achieved in the X²Σ⁺ (ν = 0, N = 1) state.

Conclusions:

• The developed supersonic beam source offers superior performance in terms of velocity spread for SrF and BaF.
• The narrow velocity spread and high yields make the source highly suitable for Stark deceleration and laser cooling.
• This advancement facilitates future research in precision measurements and quantum control of these molecules.