Molecular beam studies of ethyl nitrite photodissociation

Abstract

The photofragment spectrum of C₂H₅ONO at 28 810 cm^–1 has been obtained by crossing a beam of brief pulses of polarized laser light with a beam of C₂H₅ONO in a collision-free environment. The photodissociation products are C₂H₅O and NO. The angular distribution of fragment intensities peaks in a direction orthogonal to E, the electric vector of the light, indicating that the transition moment lies perpendicular to the bond that breaks. The high degree of angular anisotropy shows that the average lifetime in the upper state is short compared to a molecular rotational period, being at most 2 × 10^–13 s. The distribution of fragment translational energies has also been measured, and shows that the most probable total fragment translational energy is 6000 cm^–1, or about 36 % of the energy in excess of that needed to break the O—N bond. The most probable fragment total internal energy is 10 400 cm^–1. The energy distribution can be matched by a simple modified impulsive model for the molecular dynamics of the photodissociation.