A versatile molecular beam apparatus for cold/ultracold collisions.

Area of Science:

• Physical Chemistry
• Molecular Collisions
• Quantum Phenomena

Background:

• Observing quantum phenomena requires experiments at very low collision energies.
• Existing apparatuses may have limitations in achieving millikelvin collision energies and precise control.

Purpose of the Study:

• To develop and describe a novel apparatus for intrabeam and near-copropagating beam scattering experiments.
• To enable studies of quantum phenomena at collision energies from room temperature down to below 1 K.
• To demonstrate the instrument's versatility in measuring state-to-state differential cross sections.

Main Methods:

• Detailed description of apparatus components: single/dual molecular beam valves, high-speed chopper, discharge source.
• Intrabeam scattering setup utilizing a novel dual-slit chopper for millikelvin collision energies (20% energy spread).
• Near-copropagating beam configuration for measuring state-to-state differential cross sections of NO-Ar collisions.

Main Results:

• The apparatus successfully achieves collision energies down to millikelvins.
• State-to-state differential cross sections for rotationally inelastic collisions of highly vibrationally excited NO with Ar were measured.
• The instrument demonstrates versatility across broadly tunable energies.

Conclusions:

• The developed apparatus is capable of performing advanced molecular scattering experiments at ultra-low temperatures.
• The instrument facilitates the study of quantum phenomena and provides detailed collision dynamics.
• Future applications include stereodynamics and cold state-to-state collisions of polyatomic molecules.