Channel switching effect in photodissociating N2O+ ion at 312.5 nm

A experimental observation is presented on the N2O+ photodissociation process, which exhibits a complete channel switching effect in a narrow energy range. The N2O+ ions, prepared at the X (2)Pi (000) state by (3+1) multiphoton ionization of neutral N2O molecules at 360.6 nm, were excited to different vibrational levels in the A (2)Sigma(+) state in a wavelength range of 275-328 nm. Based on the estimates of total released kinetic energies from the time-of-flight mass spectrum, it was found that the dissociation pathway of N2O+(A (2)Sigma(+)), NO+(X (1)Sigma(+))+N(S-4) with lower dissociation limit, changes abruptly and completely to NO+(X (1)Sigma(+))+N(D-2) with higher dissociation limit, in a excitation energy range of merely 250 cm-1 at lambdasimilar to312.5 nm. This phenomenon was explained by competition between the two dissociation pathways across the special excitation energy region. (C) 2004 American Institute of Physics.