We have used the method of chemical difference to obtain an accurate measure of k,/k, = 0.59 f 0.01. Furthermore, the quantum yield of production of O ( , P ) , either on direct photolysis or on deactivation of O(l0) by N,O, is less than 0.02 and probably zero.

The method of chemical difference was utilized to accurately deterornine the relative importanceoof all the reaction steps in the direct photolysis of NzO at 21 39 A (25" and 250°C) and 1849 A (25" C), as well as in the Hg6('Pl)-sensitized photolysis of Nz0 at 1849 A (25°C). In all cases, the primary process is predominantly, if not exclusively,The ratio kZ/k3 was found to be 0.69 f 0.05 in all cases. When combined with other data from our laboratory, the average value is 0.65 f 0.07. This represents the value for translationally energetic O(lD) atoms. When excess He was added to remove the excess translational ehergy, kz/k3 rose to 0.83 f 0.06, which is in reasonable agreement with the value of 1.01 f 0.06 found in another laboratory. We conclude that for O(lD) atoms with no excess thermal energy, k 2 / k 3 = 0.90 f 0.10.

The room‐temperature photolysis of N2O (10–100 torr) at 2139 Å to produce O(1D) has been studied in the presence of CH4 (10–891 torr). The reactions of O(1D) with CH4 were found to be The method of chemical difference was used to measure the rate constant ratio k4/(k2 + k3), where reactions (2) and (3) are The CH3 radicals produced in reaction (4) react with the O2 and NO produced in reactions (2) and (3). Thus, near the endpoint of the internal titration, ϕ{C2H6} gives an accurate measure of k4/(k2 + k3). For the translationally energetic O(1D) atoms produced in the photolysis, k4/(k2 + k3) = 2.28 ± 0.20. However, if He is added to remove the excess translational energy, then k4/(k2 + k3) drops to 1.35 ± 0.3.

Ozoone was photolyzed at room temperature in the presence of N2O at 2537 A and 2288 A to produce O(lD) atoms. These atoms can react with either 0 3 or N20 viaFrom the quantum yield of Nz, the relative rate constants kga/k6 and kz/kc could be obtained, where k6 = k b a + k6b. The foomer rate constant ratio was found to be 0.37 f 0.03 at 2537 A and 0.33 f 0.03 at 2288 A, in good agreementowith an earlier repprt from our laboratory. The difference in the two numbers, if real, may reflect differences in reactivity due to different amounts of excess translational energy in the O ( ' 0 ) atom at the two wavelengths.The ratio kz/ke was found to be 2.6 at 2537 A, but 4.1 at 2288 A.

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