Quantum yields for the collisionally induced dissociation of excited I2B3Π0+u to I(52P½)+ I(52P); non-equilibrium effects in the combination of atoms

Abstract

Highly vibrationally excited I₂B³Π₀ ⁺ _u was produced by irradiation of iodine vapour, through interference filters, to the long wavelength of the 4985 Å convergence limit. Relative quantum yields were measured for the endothermic dissociation, I₂B³Π₀ ⁺ _u+ M → I(5²P_½)+ I(5²P)+ M, where M = He or Xe. Quantum yields of I(5²P_½) formation were indistinguishable in the two inert gases at all wavelengths. The yields of the excited atoms are surprisingly large; for example, molecules excited 3 kT below the limit undergo the endothermic dissociation with 0.5 probability. The results are discussed in relation to fluorescence quenching measurements and non-equilibrium effects in the combination of atoms.