Infrared free-electron-laser photolysis of CFCl3 and CF2Cl2

A tunable infrared free-electron laser comprised of a train of picosecond pulses was utilized to destroy the Freons CFCl3 and CF2Cl2 by multiple-photon dissociation. The experiments explored the effects of laser frequency, laser fluence, spectral bandwidth, frequency chirping, reactant partial pressure, and oxygen (or air) partial pressure. We determined the optimum laser frequencies for dissociation of both of the Freons and also showed that a broader spectral bandwidth laser enhances reaction. A strong reduction of dissociation fraction with increasing pressure made infrared photodissociation of Freons at near atmospheric pressure difficult. Improvement of the high-pressure photolysis would require a laser macropulse much shorter than the 2 mu s used in these experiments.