Fragmentation of methyl nitrite by photon excitation and energy transfer from metastable rare gas atoms

Abstract

The flurorescence of electronically excited NO resulting from the fragmentation of CH 3ONO either by photons of energy 8.43 and 10.03 eV (xenon and krypton resonance lines) or by collisional energy transfer from Xe 3P 2 and Kr 3P 0,2 was studied under identical pressure and detection conditions. The electronic branching ratios (NO A)/(NO B) for the two modes of excitation are different. In the photolysis NO(A 2Σ +−X 2Π) emission dominates while NO(B 2Π−X 2Π) bands appear in the presence of added argon. At 10.03 eV NO C 2Π (υ′ = 0) and D 2Σ + (υ′ = 0) are also produced. For the dissociative excitation by metastable rare gas atoms the relative formation of NO B is higher than that observed in the photodissociation. The NO A vibrational populations are similar for both modes of excitation, indicating that the same dissociative state may be involved. For Xe 3P 2 and Kr 2P 0,2 reactive quenching, the NO B vibrational population decreases exponentially with υ′ and is slightly higher than the distribution calculated on the basis of statistical energy partitioning.