The dissociation pathways of N₂⁺ in intense femtosecond laser fields

Using a neutral N₂ beam as target, this paper studies the dissociation of N₂⁺ in intense femtosecond laser fields (45 fs, ～1×10¹⁶ W/cm²) at the laser wavelength of 800 nm based on the time-of-flight mass spectra of N⁺ fragment ions. The angular distributions of N⁺ and the laser power dependence of N⁺ yielded from different dissociation pathways show that the dissociation mechanisms mainly proceed through the couplings between the metastable states (A, B and C) and the upper excited states of N₂⁺. A coupling model of light-dressed potential energy curves of N₂⁺ is used to interpret the kinetic energy release of N⁺.