CHARGE-RESONANCE-ENHANCED IONIZATION OF DIATOMIC MOLECULAR-IONS BY INTENSE LASERS

We study the ionization of the H-2(+) molecular ion in intense, short- pulse laser fields by numerically solving the three-dimensional time-d ependent Schrodinger equation as a function of internuclear distance R . Anomalously high ionization for the molecular ion at large internucl ear separations is observed for orientations parallel to the linearly polarized laser field. The ionization rate is found to exhibit maxima at large R, exceeding the atom limit by an order of magnitude. This is attributed to transitions between pairs of charge-resonant states whi ch are strongly coupled by the field in diatomic molecular ions. The e ffect is shown to also occur in higher odd-charge diatomic molecular i ons and can be attributed to field-induced nonadiabatic transitions be tween the charge-resonant states and electron tunneling suppression by the instantaneous Stark field of the laser.