Ultraslow Dissociation of the H$_2^+$ Molecular Ion via Two-color Ultrafast Laser Pulses

We demonstrate a new mode of H$_2^+$ photodissociation in an intense two-color laser field. Bond-softening and vibrational-trapping of the hydrogen molecular ion in intense single-color laser fields are processes that are well studied and understood in detail. In the past few years, two-color fields have received increasing attention. Our experiment shows that H$_2^+$ ions experience ultraslow dissociation when bond-softened by the superposition of 800-nm and 400-nm ultrafast laser pulses in a narrow intensity range. By running theoretical simulations and examining two-color field-dressed adiabatic potential energy curves, we support this interpretation of near-zero kinetic energy release. Furthermore, we show that the shift to lower energy of a known bond-softened peak can be explained by the influence of a two-color field induced potential well.