Quantum chemical theoretical calculations for this reaction have been conducted by several groups. Takayanagi and Wada (2001) showed that the exothermic energy is mainly distributed in the vibrational energy of the newly formed NO and not in the NO in the original N2O, but the latter NO is not a complete spectator but a part of excess energy is also distributed in the old NO. This result of theoretical calculation agrees well with the above experimental results using the oxygen isotopes. According to the trajectory calculation on the potential energy surface by Takayanagi and Akagi (2002), the ratio of reactions (5.15) forming 2NO and (5.14) forming N2+O2 is affected by the collision energy of O(1D) and approaching angle of O(1D) toward N−N−O.