Nonlinear instabilities in photochemical reactions

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This program aims to explore nonlinear behavior in photochemical reactions and to subsequently utilize nonlinear dynamics as a tool to gain insights into fundamental processes occurring in these complicated photochemical reactions. Photochemical reactions are ubiquitous in nature, ranging from the action of sunlight on car exhaust fumes to photosynthesis by plants. Many photochemical processes involve chain reactions, which can potentially result in the occurrence of nonlinear instabilities such as chemical oscillations and propagating waves. This exploratory research is expected to discover a series of new photo-mediated chemical oscillators, in which light plays a more critical role to exclusively control the production of key intermediate reagents. This program will significantly advance our understanding of perturbed nonlinear dynamics. In addition, methods of using nonlinear theory to gain insight into photochemical reactions of cyclic compounds such as 1,4-benzoquinone and dopamine will be developed here. These methods shall be applicable to other photochemical processes as well. Our exploration on light-controlled nonlinear behavior in the 1,4-benzoquinone-bromate reaction will be conducted in a batch reactor and in a continuously flow stirred tank reactor. Reactions will be followed simultaneously by a Pt and a bromide ion selective electrode, coupled with a Hg|Hg2SO4|K2SO4 reference electrode. Irradiation will be implemented with a halogen light source, equipped with two bifurcated optic fibers. UV/Vis spectroscopic method will be employed to analyze the evolution of intermediate species. To decipher the underlying reaction mechanisms, the reaction mixture will be further analyzed by Infrared Spectroscopy, NMR, and Mass Spectrometry.