Time-resolved k(E*) measurements for dissociation of allyl iodide vibrationally excited via C-H overtones (v=6)

The direct time-resolved measurements of the energy dependent rate constant k(E*) have been carried out for dissociation of allyl iodide (AI) vibrationally excited via C-H overtones (v=6). Resonant two-photon ionization (R2PI) technique has been used for the detection of atomic iodine I(P-2(3/2)) arising from the dissociation of photoexcited AI molecules. For R2PI detection a method with narrow-band vacuum ultraviolet radiation (VUV) was used. VUV radiation was generated by means of nonresonant frequency tripling of visible dye-laser radiation in gaseous xenon. Measured k(E-*) values were found to be in excellent agreement with those calculated within the microcanonical version of the statistical Rice-Ramsperger-Kassel-Marcus theory in its "phase space" or "loose" transition state limit. The canonical version of the same model is also in good agreement with experimental data from the literature on the dissociation of allyl iodide under thermal heating conditions where collisional excitation takes place. (C) 2000 American Institute of Physics. [S0021-9606(00)01714-1].