Wave packet study of the methyl iodide photodissociation dynamics in the 266-333 nm wavelength range

摘要

Photolysis of CH3I is studied in the range of excitation wavelengths λ = 266-333 nm using a three-dimensional wave packet method. The aim is to try to clarify some discrepancies arisen in different experiments for the vibrational distributions of the CH_3 (ν_2) fragment (being ν2 the umbrella bend mode or the symmetric deformation mode of the CH_3 group) produced through the channel CH_3 (ν_2)+I(~2P_(3/2)). The simulations predict non-statistical vibrational distributions peaking at ν_2 = 1 in the range λ = 266-315 nm, and a change to statistical behavior with a maximum at ν_2 = 0 for longer wavelengths. The calculations agree qualitatively with all the available experiments for λ = 266-280 nm. For λ ≥ 298 nm theory is consistent with one of the experiments and disagrees with the other two.