Reactive scattering of methyl radicals CH3+ ICl, IBr, I2

Abstract

Angular distribution measurements of methyl iodide reactive scattering from crossed beams of methyl radicals and halogen molecules, ICl, IBr, I₂ are reported. The methyl radical beam is generated by pyrolysis of azomethane flowing through a heated tantalum tube at ∼1600 K; the halogen molecule beam issues from a nozzle beam source at ∼380 K. Reactively scattered methyl iodide is detected by an electron bombardment mass spectrometer. The differential cross sections peak sideways in centre-of-mass coordinates, showing a marked similarity to the corresponding deuterium atom–halogen molecule reactions. Qualitative molecular orbital theory offers a comprehensive rationalisation of methyl radical, deuterium atom and halogen atom reaction dynamics with halogen molecules.