UV absorption spectrum and kinetics of the self-reaction of neopentyl radicals in the gas phase at 298 K

Neopentyl radicals were produced via the reaction F+(CH3)4C-->(CH3)3CCH2+HF, which was initiated by pulse radiolysis of neopentane/SF6 gas mixtures at 298 K. The ultraviolet absorption spectrum of neopentyl radicals has been recorded over the wavelength range 220-270 nm. An absorption cross section, sigma((CH3)3CCH2) (240 nm) = (4.88 +/- 0.42) x 10(-18) cm2 molecule-1, has been obtained based on absolute yields using CH3O2 as a reference. The decay of neopentyl radicals was found to follow second-order kinetics in accordance with the self-reaction 2(CH3)3CCH2--> products, with an absolute bimolecular rate constant of (2.1 +/- 0.2) x 10(-11) cm3 molecule-1 s-1 (+/- 2sigma).