The rate of nonlinear ionization is strongly enhanced as a molecule is
stretched beyond its equilibrium internuclear separation, reaching a
peak rate that is many orders of magnitude greater than that at either
small or large distances. The enhancement results from nonadiabatic e
lectron localization near the nuclei and its presence is insensitive t
o the laser frequency and intensity. Most intense-field dissociative i
onization experiments are influenced by this effect.