Photodissociation of methyl nitrite in the vacuum ultraviolet. II. Excitation energy dependence of the NO fluorescent fragments

Abstract

The production efficiency of NO excited fragments in A 2Σ+ v′=0,1,2,3, C 2Π v′=0, D 2Σ+ v′=0 states resulting from the photolysis of methyl nitrite in the far UV has been measured as a function of incident wavelength using the synchrotron radiation of the electron storage ring of Orsay as the source of excitation. The experimental energy threshold to produce each NO excited state is in agreement with a bond dissociation energy of CH3O–NO of 1.8 eV. The excitation spectra of electronically excited NO A 2Σ+, C 2Π, D 2Σ+ are discussed in relation with the absorption spectrum of the parent molecule. The vibrational energy distribution in NO A 2Σ+ v′=0,1,2 can be explained by a statistical energy partition between CH3O and NO products provided some restrictions on the activated modes of the CH3O fragment. NO A 2Σ+ v′=3 population shows an anomalous behavior which can be indicative of a half-collision effect due to the interaction of NO C 2Π and D 2Σ+ primary product with CH3O.