Velocity-map ion imaging (VMI) has been used to study the angular distribution of the NO fragment generated in the photodissociation of NO2 at a variety of photolysis wavelengths. Images were recorded for the channels NO 2Π1/2 (v"NO = 0, J"NO= 3/2, 11/2 and 21/2) + O (3P2,1), for excitation energies ranging from the onset (Eavl/hc = 0 cm-1) to Eavl/hc ≅ 900 cm-1. The angular anisotropy parameter β was obtained as a function of available energy. Photofragment multiphoton ionization (PHOMPI) spectra were also recorded in the energy range Eavl/hc = 0-300 cm-1 for each of these channels. Large fluctuations of beta as a function of Eavl were found in all observed dissociation channels. These variations are discussed in terms of the lifetimes of the originally photoexcited overlapping resonances in the Ã 2B2 state of NO2, the dynamics of which are strongly influenced by nonadiabatic coupling with the X̃ 2A1 state. The potential use of this photolysis process for production of cold oxygen atoms is discussed.
|Number of pages||8|
|Journal||Physical Chemistry Chemical Physics|
|Early online date||6 Sept 2007|
|Publication status||Published - 1 Nov 2007|