Laser-Photolysis of Organic Esters at 193 nm and 248 nm: Products and Quantum Yields

Abstract

Acetates, the esters of acetic acid, are excellent solvents of great technical importance. Due to their high vapour pressure, they are also atmospheric pollutants, which makes it necessary to develop ways for their destruction in the gaseous state. Efficient photochemical purification processes of gas mixtures represent an environmentally compatible alternative to thermal and plasmachemical degradation processes. Due to the precise control of the radiation parameters lasers can be readily adapted to specific problems. UV-photolysis is used to examine some general and specific aspects of excimer laser induced chemical reactions in the gas phase. The photolysis of different acetates with laser radiation at 193nm and 248nm is studied using FTIR-spectroscopy and photoionisation mass spectroscopy. In first experiments the formation of stable end products and the decomposition of parent molecules were analysed. From literature only laser photolysis experiments of acetates with IR multiphoton dissociation are known so far (HINTSA). The aim of this work is to give results of the UV-photodecomposition of methyl-, ethyl- and butyl acetate in dependence on laser wavelength, laser fluence, reactant pressure and buffer gas pressure.