In this project, funded by the Experimental Physical Chemistry Program of the Chemistry Division, Professor Jingsong Zhang of the University of California at Riverside will investigate the properties of free radicals in molecular beams. Laser spectroscopy, as well as time-resolved and state-to-state photodissociation dynamics will be applied to prototypical reactive intermediates of relevance to combustion, atmospheric chemistry, chemical vapor deposition, and to organic and polymer chemistry. The systems to be studied include diatomic hydride-, small alkyl-, and unsaturated aliphatic radicals. Specific attention will be given to: a) detailed mechanisms involving dissociation and complex nuclear rearrangements; b) open-shell electronic states, structures and multiple potential energy surfaces and their influences on photodissociation/unimolecular reactions; c) competitive dissociation pathways and decomposition mechanisms, and product energy disposal; and d) free-radical electronic states, thermodynamics, and energetics. This research aims to achieve an understanding of free-radical photochemistry at the same level as that for closed-shell molecules. Graduate and undergraduate students will participate in this research. They will acquire knowledge and skills in preparation for advanced studies or employment in industry, academia, or government laboratories.