CO2 laser induced decomposition of freon 113

Irradiations were made on CCl2FCClF2, Freon 113, to see if the resulting decomposition was photochemical in nature. The irradiation source was Molectron 250, continuous wave, infrared laser operating in the single line mode. The wavelength of irradiation was varied over the range 9.473 µ to 9.734 µ. The pressure except one (in which the cell window broke). Relative rates of reaction were calculated for a constant power absorbed by the sample of 7.8 ± 4W. These relative rates were plotted against the irradiation wavelength. This was superimposed on a plot of the IR band for Freon 113 which was irradiated in this project. A difference in wavelength of 0.11 µ in the maximum of absorption of the IR band for Freon 113 and the maximum relative rate of reaction was found. This indicated that the fastest reaction occurs when the laser is tuned to a vibrational level transition other than the v = 0 to v = 1 transition. Thermal and photochemical models are discussed, but are rejected as possible mechanisms for the reaction observed in this project. A model combining thermal excitation and photochemical reaction is discussed. Despite some assumptions made, it is shown that this model explains the data well