Rotational Cooling in a Time-Reversal Symmetry Violation Molecular Beam Experiment

Our experiment is designed to search for time-reversal symmetry violation in a thallium nucleus by measuring its Schiff moment (SM) in thallium fluoride (TlF) molecules. Interrogating a cold molecular beam and manipulating quantum states of the molecule using optical and microwave transitions are the first steps that have to be undertaken in the experiment. A cold beam of TlF is acquired through a cryogenic buffer gas beam source where we ablate a solid TlF target in a neon-filled chamber and obtain molecules with a rotational temperature of 7K. In order to measure SM with high precision, we need to first bring as many molecules as possible to a single quantum state. After assembling the first portion of the setup, we characterized the molecular beam and performed spectroscopic measurements of TlF using a frequency-stabilized ultraviolet laser. Here, we present results of the first major part of the experiment - rotational cooling. This procedure allows us to bring the majority of molecules to a single hyperfine Zeeman sublevel in the ground rotational state manifold with the use of a single laser and a pair of microwave beams.