Primary processes in the gas-phase photolysis of acetaldehyde

Abstract

The effect of cis-butene-2 on the photolysis of acetaldehyde vapour at 3130 Å and the simultaneous cis-trans isomerization has been used to examine the nature and extent of the primary processes. Excitation at this wavelength produces a triplet quantum yield of 0.4 at 48°C and a slightly lower value at 100°C. In distinction to other work it is concluded that dissociation occurs mainly from the triplet state at 48°C and also to some extent from the singlet state at 100°C. The mechanism of the photolysis is compared with that for acetone; the difference in the yields of the triplet states are attributed to vibrational energy interactions.