Competitive Processes in the Multiphoton Activation of 1,1,2,2-Tetrafluorocyclobutane: Affirmation of RRKM Behavior

Article abstract of DOI:10.1021/j150625a006

The irradiation of 1,1,2,2-tetrafluorocyclobutane with a pulsed CO2 TEA leser involves at least four competitive processes: activation via photon absorption, collisional deactivation, and two decomposition channels producing 2 C2H2F2 or C2H4 and C2F4.These products are also observed in conventional thermal activation experiments.Photon pulse energy and background gas pressure were varied to obtain information on the magnitude of the decomposition rate constants.Both absolute and relative product yields were used to demonstrate that the results are consistent with the RRKM model for unimolecular reactions.For a fluence of 4.0 J/cm² the average excess energy is ca. 41 kcal/mol with a rate constant of 2.4E7 s^-1.By changing pressure and laser intensity the excitation energy can be scanned over a range of 17 kcal/mol.The various competitions can be used independently to delineate information on activation and intermolecular energy transfer rates as a function of excitation level.