Photodissociation of H₂⁺ in intense chirped laser fields

Regarding an experimental measurement of proton kinetic energy spectra of H₂⁺ with a chirped pulse [L. J. Frasinski, J. H. Posthumus, J. Plumridge, and K. Colding, Phys. Rev. Lett. 83, 3625 (1999)], we present a nonperturbative, time-dependent calculation for the photodissociation of H₂⁺ in intense laser fields by combining three numerical techniques. The results show a finer kinetic-energy distribution structure of a proton due to the intrapulse pump-dump mechanism between two electronic states as the pulse duration and intensity change. Higher-energy peaks are also suppressed by frequency chirping of the laser field. The dissociation probabilities show that a positively chirped pulse is always more efficient for population inversion than no chirping or negatively chirped pulses, and a slight coordinate shift of the initial state could result in a significant increase of dissociation probability.