title: Impulsive Collision Dynamics of CO Super Rotors from an Optical Centrifuge.
abstract: We report state-resolved collision dynamics for CO molecules prepared in an optical centrifuge and measured with high-resolution transient IR absorption spectroscopy. Time-resolved polarization-sensitive measurements of excited CO molecules in the J=29 rotational state reveal that the oriented angular momentum of CO rotors is relaxed by impulsive collisions. The translational energy gains for molecules in the initial plane of rotation are threefold larger than for randomized angular momentum orientations, indicating the presence of anisotropic kinetic energy. The transient data show enhanced population for CO molecules in the initial plane of rotation immediately following the optical centrifuge pulse. A comparison with previous CO2super rotor studies illustrates the behavior of molecular gyroscopes; spatial reorientation of CO2J=76 rotors takes substantially longer than that for CO J=29 rotors, despite similarities in classical rotational period and rotational energy gap. High-resolution transient IR absorption measurements of the CO J=29-39 rotational states show that the collisional depopulation rates increase with J quantum number.
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA.
authors.forename: Matthew J
authors.initials: MJ
authors.lastname: Murray
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA.
authors.forename: Hannah M
authors.initials: HM
authors.lastname: Ogden
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA.
authors.forename: Carlos
authors.initials: C
authors.lastname: Toro
authors.affiliation: National Institute of Standards and Technology, 100 Bureau Drive, Stop 8320, Gaithersburg, MD, 20899, USA.
authors.forename: Qingnan
authors.initials: Q
authors.lastname: Liu
authors.affiliation: Department of Chemistry and Biochemistry, University of Maryland, College Park, MD, USA.
authors.forename: Amy S
authors.initials: AS
authors.lastname: Mullin
keywords: collision dynamics; energy transfer; molecular dynamics; super rotors; time-resolved spectroscopy