Dynamics of three-body half collisions. II. Instantaneous three-body decomposition in the photodissociation of trifluoroacetyl iodidea)

Abstract

Photofragment spectroscopy of trifluoroacetyl iodide (CF₃COI) at 266 nm shows evidence of an instantaneous decomposition to I, CO, and CF₃ fragments. The transition dipole moment for photon absorption lies in the C–C–O plane within 20° of the C–I bond axis, and decomposition of the photoexcited CF₃COI molecule is rapid (∼10⁻¹³ sec). A two‐step dissociation model developed to explain acetyl iodide photodissociation does not apply to trifluoroacetyl iodide, indicating fluorine substitution has a dramatic effect on photodissociation dynamics. Monte Carlo trajectory calculations using a very simple potential energy surface are surprisingly successful in predicting the observed dissociation behavior.