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Quantum Dynamics of Ultracold N a + N a 2 Collisions

2002; American Physical Society; Volume: 89; Issue: 15 Linguagem: Inglês

10.1103/physrevlett.89.153201

1092-0145

Pavel Soldán, Marko T. Cvitaš, Jeremy M. Hutson, Pascal Honvault, Jean–Michel Launay,

Spectroscopy and Laser Applications

Ultracold collisions between spin-polarized Na atoms and vibrationally excited Na2 molecules are investigated theoretically, using a reactive scattering formalism (including atom exchange). Calculations are carried out on both pairwise additive and nonadditive potential energy surfaces for the quartet electronic state. The Wigner threshold laws are followed for energies below 10(-5) K. Vibrational relaxation processes dominate elastic processes for temperatures below 10(-3)-10(-4) K. For temperatures below 10(-5) K, the rate coefficients for vibrational relaxation (v=1-->0) are 4.8x10(-11) and 5.2x10(-10) cm(3) s(-1) for the additive and nonadditive potentials, respectively. The large difference emphasizes the importance of using accurate potential energy surfaces for such calculations.