Effect of added gases on the photolysis of biacetyl

Abstract

Measurements of the intensity of the gas-phase phosphorescence of biacetyl when irradiated with light of 4350 Å in the presence of several added gases, show that molecules without low-lying triplets are very inefficient quenchers unless they are very reactive toward free radicals.

Comparison between biacetyl phosphorescence yield in the presence of triethylborane and the rate of production of ethyl radicals shows that the triplet quenching by triethylborane involves a chemical reaction that produces ethyl radicals.

From the relationship between the phosphorescence yield at 3660 Å and the pressure of added gas, relative efficiencies for deactivation of vibrationally excited biacetyl molecules have been obtained.