The photolysis of N 2 O at 2139 Å and 1849 Å

The method of chemical difference was utilized to accurately determine the relative importance of all the reaction steps in the direct photolysis of N 2 O at 2139 Å (25° and 250°C) and 1849 Å (25° C), as well as in the Hg6( 1 P 1 )‐sensitized photolysis of N 2 O at 1849 Å (25°C). In all cases, the primary process is predominantly, if not exclusively,\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{*{20}c} {{\rm (1)}} & {{\rm N}_{\rm 2} {\rm O} + hv{\rm or H}_{\rm g} 6(^1 P_1) \to {\rm N}_{\rm 2} + {\rm O(}^{\rm 1} D{\rm)}} \\\end{array}$$\end{document} Experiments with trace amounts of C 3 H 6 added showed a slight, but not significant, difference in product ratios (N 2 and O 2 ). From these experiments the quantum yield of O( 3 P ) from all possible sources was estimated as 0.02 ± 0.02. Experiments with excess N 2 at 1849 Å indicated that O( 1 S ) was not produced in the direct photolysis. The O( 1 S ) yield is probably zero, and certainly <0.05. The O( 1 D ) atom can react with N 2 O via\documentclass{article}\pagestyle{empty}\begin{document}$$\begin{array}{l} \begin{array}{*{20}c} {{\rm (2)}} & {{\rm O(}^{\rm 1} D{\rm)} + {\rm N}_{\rm 2} {\rm O} \to {\rm N}_{\rm 2} + {\rm O}_2 } \\\end{array} \\ \begin{array}{*{20}c} {{\rm (3)}} & {{\rm O(}^{\rm 1} D{\rm)} + {\rm N}_{\rm 2} {\rm O} \to 2{\rm NO}} \\\end{array} \\ \end{array}$$\end{document} The ratio k 2 / k 3 was found to be 0.69 ± 0.05 in all cases. When combined with other data from our laboratory, the average value is 0.65 ± 0.07. This represents the value for translationally energetic O( 1 D ) atoms. When excess He was added to remove the excess translational energy, k 2 / k 3 rose to 0.83 ± 0.06, which is in reasonable agreement with the value of 1.01 ± 0.06 found in another laboratory. We conclude that for O( 1 D ) atoms with no excess thermal energy, k 2 / k 3 = 0.90 ± 0.10.