Ionization and dissociation of simple molecular ions in intense infrared laser fields: Quantum dynamical simulations for three-dimensional models of HD+ and

The dynamics of multiphoton excitation of HD+ and H 2 + in quasi-resonant infrared intense laser fields (I0 = 1.18 × 1014 W/cm2) is studied by the numerical solution of the time-dependent Schrödinger equations for the systems with explicit treatment of the nuclear vibrations and the electron motion beyond the Born–Oppenheimer approximation. It has been found, in particular, that on the time scale of 400 fs the overall ionization yield is about 40% for HD+, but only about 0.45% for H 2 + while in accordance with the tunnel (or field) ionization mechanism at least comparable ionization yields could be expected for HD+ and H 2 + . The physical reason for this remarkable difference is that the nuclear motion is excited directly by the strong infrared laser field in HD+, but not in H 2 + .