Noble-gas broadening of an optical transition of I2 measured by coherent transients. IV. Three-dimensional calculations of quantum mechanical elastic collision rates for small velocity changes of I2 molecules (in a coherent superposition of two electronic states) interacting with noble gases (He, Ne, Ar, Kr, Xe)

Abstract

Abstract In preceding papers collision rates for velocity changes within the bandwidth of the excited molecules have been obtained for iodine molecules colliding with noble-gas atoms (He, Ne, At, Kr, Xe). Three types of these collision rates should be discerned: the iodine molecule can be in its electronic ground state (X 12′ , v″ = 2, J″ = 59) or in an excited electronic state (B 3 Π + o,u , ν ′= 15, J ′ = 60) or in a coherent superposition of these two states. The collision rate associated with the coherent superposition has been shown to be less than half the sum of the other two, the reason being destructive interference of the quantum mechanical scattering amplitudes associated with the two states. In the present paper we concentrate on the quantum mechanical calculation of these velocity changing collision rates for the different noble-gas partners, treating the I 2 molecules as rigid rotors.