Rotational energy transfer in the Na2b3Π u state: Propensity rules for rotation, spin-orbit component, and e/f-parity changing collisions

Li Li, Qingshi Zhu, A. M. Lyyra, Thou Jen Whang, W. C. Stwalley, R. W. Field, M. H. Alexander

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State-to-state collision-induced transitions within the Na2 b 3Πn state have been studied by a sub-Doppler optical-optical double resonance (OODR) technique employing cw, single mode dye lasers for the PUMP and PROBE steps. The main experimental results are (1) strong Φ-conservation is observed when a low-J 3Π0 or 3Π1 parent level is initially prepared (we are unable to prepare low-J 3Π2 levels). This Ω-conservation relaxes as J increases. (2) e/f parity conservation (i.e., propensity for even ΔJ changes in homonuclear molecules) is observed at low-J within the 3Π0 manifold. This propensity for e/f-conservation relaxes rapidly as J increases. (3) The e/f parity conservation rule observed within the 3Π0 manifold is observed not to apply to the collision-induced transitions within the 3Π 1 manifold. At low-J, ΔJ= ±1, e→f transitions are even stronger than ΔJ= ±2, e→e transitions. (4) At higher-J, for example J=16, neither Ω-conservation nor e/f-conservation within the 3Π0 manifold are observed. These results are compared with theoretical predictions for a case (a) 3Π state [Alexander and Pouilly, J. Chem. Phys. 79, 1545 (1983)] and with experimental observations on another homonuclear molecule, N2 in the B 3Π g state, which also exhibits intermediate coupling between cases (a) and (b) [Ali and Dagdigian, J. Chem. Phys. 87, 6915 (1987)].

Original languageEnglish
Pages (from-to)8406-8412
Number of pages7
JournalThe Journal of Chemical Physics
Issue number11
Publication statusPublished - 1993 Jan 1

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)
  • Physical and Theoretical Chemistry

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