Energy Partitioning in Molecular Photodissociation: Methyl Nitrite Photolysis

The photodissociation of methyl nitrite CH 3 ONO in three different electronicallyexcited states has been studied by determining the internal state distribution of oneof the photofragments. The fluorescence of NO A   Σ 2 + produced for excitation ofCH 3 ONO between 1200 and 1650 Å and of CH 3 O 2   A 1 produced at 1930 Å has beeninvestigated. The vibrational distribution in both species can be explained by statisticalconsiderations. The rotational excitation of NO A   Σ 2 + is of Boltzmann type. ForCH 3 ONO excited in the first nπ* excited state at 3550 Å the NO X fragment hasbeen probed by a two photon laser excited fluorescence technique. The nascentNO X υ″ = 0, 1, 2, 3 exhibit a population inversion and a high degree of rotationalexcitation.