In the first reporting period, we accomplished near-complete chiral selection in rotational states. Before the research in COCOCIMO, enantiomer-specific state transfer was facing two fundamental limitations. First, for all currently experimentally accessible internal temperatures of chiral molecules (at lowest a fraction of a Kelvin) all rotational states of a triad of rotational states are populated. Second, for all triads of rotational states apart for the ones only involving J=0 and J=1, multiple Rabi frequencies per transition limit the achievable efficiency of ESST. This is due to the orientational degeneracy of rotational quantum states.
We have recently realized near-ideal experimental conditions for enantiomer-specific state transfer by combining optical and microwave methods. In our experiments, we overcome the previous limitation due to thermal population in all participating rotational states. In our study, we circumvent the limitation of ESST due to orientational degeneracy by targeting a triad of rotational states connected to the absolute ground state. We have shown that 96% state-specific enantiomeric purity can be obtained from a racemic mixture. This work has been published in Nature Communications 15, 7441 (2024).
For future experiments targeted at quantum-state selective matter-wave diffraction, we characterized a promising target molecule, 1-phenylethanol. We performed an extensive high-resolution spectroscopy study to determine the rotational energy level structure in the electronic ground and S1 electronically excited state. This work has been published in Physical Chemistry Chemical Physics 27, 22906-22910 (2025). In addition, we have made important steps forward to setting up from scratch the novel matter-wave diffraction experiment.
