PHOTOCHEMISTRY OF THE PHOTOINITIATOR 4-[2'-N,N-(DIETHYLAMINO)ETHOXY]-BENZOPHENONE - SPECTROSCOPY, RADICAL GENERATION AND QUENCHING

The photochemistry at 308 nm of the photoinitiator 4-[2'-N,N-(diethyla mino)ethoxy] - benzophenone was studied. The phosphorescence emission and lifetime of the lowest triplet state were characterized. The 4-alk ylaminoketyl radical was generated in the ground state through hydroge n atom abstraction by the lowest triplet state of the initiator. The i ntermolecular vs. intramolecular character of this process was analyse d. The radical was excited to the first doublet excited slate using 34 0 nm pulses from a dye laser. The temporal evolution of the radical co ncentration in the ground and excited states was followed by laser-ind uced fluorescence (LIF) and fluorescence intensity measurements respec tively, The quenching of the ketyl radical in the ground and excited s tates by its precursor, O-2, methyl methacrylate and styrene was deter mined, The effect of the solvent on the quenching of the ketyl radical was studied, Detailed studies on the radical fluorescence were also p erformed.