Experimental determination of the oscillator strength of the B( 2 B 1 )—X( 2 A 2 ) transition of the free allyl radical

The integrated absorption of the β1–X transition of the methyl radical (2160 Å) and the B–X transition of the allyl radical (2100–2400 Å) were compared, in the flash photolysis of butene-1. From the f-value of the CH3 band, the oscillator strength of the allyl transition was recorded as 0.140 (±0.028). The rate coefficient for recombination of allyl radicals was in the range 8.5(±3)× 1012 cm3 mol–1 s–1.