Photodissociation of NO₂ near 225 nm by Velocity Map Imaging

Abstract

Since the pioneering work of Busch and Wilson[1] with the inception of Photofragment Translational Energy Spectroscopy (PTS), NO₂ has been one of the most studied molecules in the field of photodissociation dynamics. Recently experimentalists have been using a variety of elegant techniques to unravel the intricate photodissociation dynamics of this model triatomic molecule[2, 3]. A whole body of work has concentrated around the threshold regime (400 nm) for the O(³P _j ) + NO channel. Photodissociation studies beyond the threshold regime have been sparse. These have focussed on recording the internal state distribution of the nascent NO fragment from photolysis at 248 nm utilizing laser-induced fluorescence (LIF)[4] and resonance enhanced multiphoton ionization (REMPI)[5], and photolysis around 226 nm with detection by REMPI[6]. There have also been two reports[7, 8] on the fine- structure population distributions of the oxygen atom produced by photolysis over a range of UV wavelengths. Miyawaki et al. also reported the kinetic energy of the oxygen fragment to be 0.13 eV from analysis of their Doppler profiles and that the energy release did not vary with the photolysis wavelength (355, 337, 266, and 212 nm). Shafer et al.[9] recorded the Doppler spectra for the excited oxygen atom O(¹ D) at 205.47 nm and derived a translational energy release which was between