Cold collisions of highly rotationally excited CO2with He: The prospects for cold chemistry with super-rotors

Abstract

Building on recent advances in ultrafast lasers and methods to slow molecules, an experiment is proposed to produce translationally cold CO${}_{2}$ super-rotors ($j\ensuremath{\sim}200$) by combining an optical centrifuge with helium-buffer-gas cooling. Quantum mechanical calculations of the complex scattering length for He-CO${}_{2}$ collisions demonstrate that the efficiency of rotational quenching decreases rapidly with increasing rotational excitation $j$ in the ultracold regime. Extrapolating to helium cryogenic temperatures, rotational quenching is predicted to remain inefficient up to $\ensuremath{\sim}$1 K, allowing for the possible creation of a beam of translationally cold, rotationally hot molecules.