Photodissociation of Acrylic Acid at 193 nm

This paper describes the photolysis of acrylic acid (H 2 C CHCOOH) monomers upon π → π* excitation at 193 nm. The photofragment velocity distribution measurements indicate that only primary C−C and C−O bond fissions are major photodissociation pathways; molecular decarboxylation and decarbonylation reactions do not occur to a significant extent. There are two different primary C−C bond fission channels resulting in the production of HOCO radicals in the ground and first electronically excited states. We also determine an upper limit on the C−C bond strength of about 100 kcal/mol; this agrees with the value we calculate from literature heats of formation but is considerably less than that assumed by previous workers.