The Detection of Ethyl Chloride Using Photofragmentation

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Abstract
We propose measuring chlorinated hydrocarbon emissions from hazardous waste incinerators by fragmenting molecules in the exhaust stream with high powered UV laser light, then measuring the subsequent concentration of the CCl fragment via laser induced fluorescence. We have shown that one of the chlorinated hydrocarbons, C2H5Cl, can be efficiently fragmented by 193nm ArF excimer laser under the necessary conditions of atmospheric pressure and elevated temperatures, and in mixtures with air, H2O, and CO2. When a delayed pulse of light at 271.4nm is added to the 193 nm pulse, fluorescence from CCl generated by the fragmentation process can be detected. The CCl fluorescence can be easily distinguished from O2 emission excited by the 193 nm laser due to the time interval between the different colored laser pulses. The level of CCl fluorescence is strongly dependent on the C2H5Cl concentration for the range of concentrations measured, 3 to 300 ppm. Conversely, CCl fluorescence could not be detected following the fragmentation of mixtures containing 015% HCI and 0-2% C2H4.