Investigating the Collision Dynamics of CO Super Rotors in the Single-Collision Regime*

The dynamics of optically centrifuged CO molecules is investigated for the J = 29 – 68 rotational levels. An optical centrifuge is used to prepare an ensemble of CO molecules with oriented angular momentum in extremely high rotational states. High resolution transient IR absorption spectroscopy measures the state-resolved collision dynamics as the ensemble rotationally relaxes to thermal equilibrium. Implementation of a new multi-pass IR configuration in the experimental set-up has substantially increased signal-to-noise levels relative to previous single-pass measurements. It is now possible to observe population in rotational states associated with the nascent centrifuged distribution. Here we report the initial distribution of centrifuged CO molecules and investigate the collision dynamics in the single-collision regime. The mechanism of super rotor energy transfer is revealed through polarization-sensitive spectroscopy and time dependent orientational anisotropy measurements.