Predissociation dynamics of N2O+ at the A 2Σ+ state: Three pathways to form NO+(1Σ+) revealed from ion velocity imaging

The predissociation dynamics of nitrous oxide ion (N2O+) at its first excited state A (2)Sigma(+) has been investigated with ion velocity imaging by probing the NO+ fragments. The parent ion N2O+, prepared at the ground state X-2 Pi(000) through (3+1) resonance-enhanced multiphoton ionization (REMPI) of jet-cooled N2O molecules at 360.55 nm, was excited to different vibrational levels of the A (2)Sigma(+) state in a wavelength range of 280320 nm, and then predissociated to form NO+ and N fragments. The internal energy distribution of the NO+ fragment was determined from its ion velocity images. With the help of potential energy surfaces (PESs) of N2O+, three dissociation pathways have been proposed to interpret the three kinds of NO+ fragments with different internal state distributions: (1) the A (2)Sigma(+) state couples to a dissociative 1(4)Sigma(-) state via a bound 1 (4)Sigma(-) state to form the NO++N(4S) channel, where NO+ fragment is rotationally hot; (2) the A (2)Sigma(+) state couples to dissociative states (2)Sigma-/(2)Delta via the 1 (4)Pi state to form the NO++N(2D) channel, where NO+ fragment is also rotationally hot; (3) the A (2)Sigma(+) state couples to the high energy region of the ground state X (2)Pi and then dissociates to form the NO++N(2D) channel, where NO+ is rotationally cold. (C) 2010 American Institute of Physics. [doi:10.1063/1.3457945]