Pulsed CO2 laser photolysis of CF2Cl2

The pulsed infrared laser photolysis of CF₂Cl₂ yields primarily (more than 85%) the CF₂Cl free radical and atomic chlorine. Somewhat smaller amounts (less than 15%) of CF₂ and molecular chlorine are produced in a competing primary process. Depending on experimental conditions, e.g. pressure and intensity, secondary processes can occur that can obscure the primary chemistry. For example, at low intensity the CF₂Cl radical can thermally dissociate to yield CF₂ plus chlorine atoms while at high intensity the CF₂Cl radical can undergo reaction with chlorine atoms to yield CF₂ and molecular chlorine. Quantitative measurements can be made of the relative importance of the primary atomic or molecular chlorine elimination channels under conditions where secondary removal of CF₂Cl is entirely eliminated. Under these conditions, the relative importance of these two channels does not depend on the intensity of the laser or on the laser wavelength.The overall chemistry occurring in this complex system is evaluated in the absence as well as in the presence of atomic and free-radical scavengers using conventional end-product analysis techniques.