Predissociation dynamics of N(2)O(+) at the A (2)Sigma(+) state: Three pathways to form NO(+)((1)Sigma(+)) revealed from ion velocity imaging.

The predissociation dynamics of nitrous oxide ion (N(2)O(+)) at its first excited state A (2)Sigma(+) has been investigated with ion velocity imaging by probing the NO(+) fragments. The parent ion N(2)O(+), prepared at the ground state X (2)Pi(000) through (3+1) resonance-enhanced multiphoton ionization (REMPI) of jet-cooled N(2)O molecules at 360.55 nm, was excited to different vibrational levels of the A (2)Sigma(+) state in a wavelength range of 280-320 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 N(2)O(+), 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)Pi state to form the NO(+)+N((4)S) 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((2)D) 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((2)D) channel, where NO(+) is rotationally cold.