Photodissociation of NO2 in the (2)B-2(2) state: A slice imaging study and reinterpretation of previous results

The photodissociation dynamics of nitrogen dioxide have been probed above the second dissociation limit at photolysis wavelengths close to 226 nm. The O(3PJ)+NO(2) product channel has been examined using direct current slice velocity map imaging of the O(3PJ) and NO(2) fragments. Mass-resolved resonantly enhanced multiphoton ionization spectroscopy and velocity map imaging have been used to probe directly the rovibrational population distributions of the NO fragments. We also examine possible interference from the dissociation of N2O4 by investigating the effect of the sample temperature on the O(3PJ) fragment energy distributions. The O(3PJ)+NO(2) dissociation channel has been found to favor the production of vibrationally cold, highly rotationally excited NO(2) products with all three oxygen spin-orbit components. Other minor dissociation channels which produce O(3PJ) atoms have also been identified. We discuss the significance of these dissociation channels and present a reinterpretation of previous studies of NO2 dissociation on excitation to the (2)2B2 state.