ULTRAVIOLET-ABSORPTION SPECTRA AND KINETICS OF ACETONYL AND ACETONYLPEROXY RADICALS

Acetonyl radicals and acetonylperoxy radicals were produced by pulse radiolysis of gas mixtures with varying concentrations of CH3COCH3 and O2 in 1 atm of SF6 to initiate the reactions (1) F+CH3COCH3→HF+CH3COCH2, (2) 2CH3COCH2 → products, (3) CH3COCH2+O2(+M) → CH3COCH2O2(+M) and (4) 2CH3COCH2O2 → products. The ultraviolet absorption spectrum of the acetonyl radical is composed of a fairly weak band centered at 315 nm and a stronger band in the range of 200-250 nm. The absorption cross section has been determined, σ(310 nm) = (8.73 ± 0.50) × 10-19 cm2 molecule-1. The values k2=(4.8 ± 0.4) × 10-11, k3=(1.5 ± 0.3) × 10-12 and k4=(8.3 ± 1.6) × 10-12 cm3 molecule-1 s-1 at 298 K were derived by computer modelling of the observed kinetic features. © 1990.