Determination of Rate Constants for Reactions of O Atoms with C2H2, C2D2, C2H4, and C3H6 Using a Pulsed Vacuum-uv Photolysis—Chemiluminescent Method

Abstract

Absolute rate constants for the primary reactions of O atoms with C₂H₂, C₂D₂, C₂H₄, and C₃H₆ were determined using vacuum‐uv flash photolysis of NO to produce the O atoms. Decays of O atoms were monitored by ${\mathrm{NO}}_2^{*}$ chemiluminescent emission with initial O‐atom concentrations in the range 1–5×10¹⁰ atoms cm⁻³. The rate constants obtained at 300°K are (in units of cubic centimeters molecule⁻¹· second⁻¹): ${\text{k=1.31×10}}^{\text{−13}}\text{\hspace{0.17em}(+5;\hspace{0.17em}−10\%)}$ , for $\mathrm{O}+{\mathrm{C}}_2{\mathrm{H}}_2$ and $\mathrm{O}+{\mathrm{C}}_2{\mathrm{D}}_2$ ; ${\text{k=6.3×10}}^{\text{−13}}\text{\hspace{0.17em}(+5;\hspace{0.17em}−15\%)}$ , for $\mathrm{O}+{\mathrm{C}}_2{\mathrm{H}}_4$ ; ${\text{k=3.6×10}}^{\text{−12}}\text{\hspace{0.17em}(+5;\hspace{0.17em}−10\%)}$ , for $\mathrm{O}+{\mathrm{C}}_3{\mathrm{H}}_6$ . The parameters involved in the assignment of the error limits are discussed in detail.