Evidence of Roaming Dynamics and Multiple Channels for Molecular Elimination in NO₃ Photolysis

We report correlated state distributions arising from NO3 photolysis at 588 nm using velocity map ion imaging. State-selected NO images reveal clear evidence for two dissociation pathways for the NO + O2 channel. Vibrationally excited O2 (3Σg−, ν = 5−10) is formed in coincidence with low rotational states of NO (2Π) in the dominant mechanism. We also observe a small channel consisting of low vibrational levels of O2 (3Σg−, ν = 0−4) coincident with high NO rotational states. We discuss the results in the context of the recent studies of formaldehyde dissociation and postulate the involvement of roaming-type dynamics.