Gas phase photolysis of 1-butene at 147 nm (8.4 eV)

Abstract

The photolysis of 1-butene was carried out in a static system using the xenon resonance line at 147 nm (8.4 eV) at pressures in the range 15 – 500 Torr (2 – 66.5 kPa). The major products observed were acetylene, ethane, ethylene, allene, propyne, 1,3-butadiene and isopentane. The radical species were identified by using scavengers such as oxygen and H 2S. Evidence is presented for the occurrence of ten primary processes to which quantum yields have been ascribed. The main process is a β cleavage of the C-C bond which occurs with a yield of φ = 0.51. A hydrogen atom mechanism involving the occurrence of hot hydrogen atoms (about 30% of them have an excess energy of about 0.26 eV) was proposed to account for the pressure dependence of propylene. Dissociation of excited radicals contributes to the formation of allene and propyne.