Multiphoton IR laser-induced unimolecular decay of the (CF3)3 CBr molecule

Abstract

The unimolecular decay of IR multiple-photon excited (MPE)(CF₃)₃ CBr has been studied in a pulsed molecular beam. The highly sensitive (ca. 80 atoms in the probing volume) time-resolved [2 + 1] resonance-enhanced multiphoton ionization (REMPI) technique was developed to detect Br atoms, and was used to study the kinetics of (CF₃)₃CBr dissociation as well as the energy distribution in the products. IR multiphoton dissociation (MPD) of the above molecules results in the formation of Br atoms mainly in the ground state. The time evolution of the Br concentration was measured for a number of excitation energy fluences in the interval 0.1–40 µs. Dissociation rate constants as well as the translational energies of decay products were determined. The comparison with RRKM theory predictions is discussed.