Allan H. Laufer

Quantum yield of vinylidene (3B) from the vacuum UV photolysis of acetylene and ethylene

Abstract The primary processes in the photodecomposition in the vacuum UV of the unsaturated hydrocarbons acetylene and ethylene have been investigated. The formation of electronically excited triplet vinylidene (H2CC) radicals is shown to be a major process. The quantum yields of vinylidene production are equal to 0.4 and 0.75 from acetylene and ethylene respectively. Vinyl radical formation in the ethylene photolysis is discussed.

Vinylidene (3B2): an active intermediate in the photolysis of ethylene

Abstract Triplet vinylidene has been observed, by time-resolved absorption spectroscopy, as an intermediate in the vacuum UV flash photolysis of ethylene. The several primary photochemical processes are discussed. Rate constants for the interaction of both protonated and deuterated vinylidene species with C 2 H 4 and C 2 D 4 have been obtained. They are 1.4 × 10 −11 cm 3 molecule −1 s −1 and 1.4 × 10 −12 cm 3 molecule −1 s −1 respectively. The nature of the interaction between triplet vinylidene and ethylene is discussed.

Extinction coefficient of H2CC(3B2) at 137 nm

The extinction coefficient of H2CC(3B2) was obtained at 137 nm. The vinylidene radicals were produced from the flash photolysis of C2H3Cl and their concentration derived from the quantity of HCl produced in the photolysis. The measured extinction coefficient is 694±218 atm−1 cm−1.