The Infrared Multiphoton Dissociation of Hexafluoroethane

Abstract

<p>The infrared multiphoton dissociation (IRMPD) of "neat" hexafluoroethane has been investigated for the first time. The stable products of photolysis are CF₄, C₂F₄, C₃F₈ and C₄F₁₀. Product analysis involved tunable diode laser (TDL) and fourier transform infrared spectroscopy, as well as gas chromatography where applicable. The high sensitivity and resolution of the TDL allows for the measurement of the stable products CF₄ and C₂F₄ after irradiation by a single infrared laser pulse.</p> <p>A high frequency modulation TDL technique has been developed to monitor the transient infrared absorptions produced by the IRMPD of various fluorocarbons. The technique was applied to the detection of CF₂ and CF₃ radicals produced by the IRMPD of known precursors. In the case of hexafluoroethane the TDL modulation technique was used to confirm that the primary dissociation pathway involves c-c bond session.</p> <p>The role of added H₂, leading to elimination of CF₄ and increase of C₂F₄ as products, is clarified. Evidence for a second dissociation pathway producing C₂F₅ and a F atom is also presented. The understanding of the overall chemical mechanism of IRMPD of C₂F₆ and reaction of the intermediates formed has been considerably extended.</p>