DISSOCIATIVE IONIZATION OF H-2(- CHARGE-RESONANCE-ENHANCED IONIZATION, COULOMB EXPLOSION, AND HARMONIC-GENERATION AT 600 NM() IN AN INTENSELASER FIELD )

The time-dependent Schrodinger equation for H-2(+) in a 600-nm, intens e (I greater than or equal to 10(14) W/cm(2)) laser field is solved nu merically for a model which uses the exact three-body Hamiltonian with one-dimensional nuclear motion restricted to the direction of the las er electric field and three-dimensional electronic motion. High ioniza tion rates of H-2(+) are found, exceeding those of neutral atomic hydr ogen. This confirms, by the rigorous, full dynamical calculation, the recently discovered charge-resonance-enhanced ionization (CREI) - all previous demonstrations of CREI were based on the ''frozen nuclei'' mo del. The numerical kinetic-energy spectra of dissociating fragments ar e compared with recent experimental results. They can be interpreted b y a simple bond softening mechanism (or laser-induced avoided crossing in a dressed state representation), in which the binding forces are c ompletely suppressed by the strong electric field and thus the dissoci ating fragments move as free particles with a kinetic energy close to their initial vibrational energy until they reach a critical distance R=R(c) congruent to 8 bohr, where they are rapidly ionized, due to CRE I. The harmonic generation spectra calculated from our non-Born-Oppenh eimer simulations show that the high harmonics are also generated when the nuclei cross this critical distance R=R(c).