Electro-Nuclear Dynamics of Single and Double Ionization of H₂ in Ultrafast Intense Laser Pulses

We present an efficient method for modeling the single and double ionization dynamics of the H₂ molecule in ultrashort, intense laser fields. This method is based on a semianalytical approach to calculate the time-dependent single and double molecular ionization rates and on a numerical approach to describe the vibrational motion that takes place in the intermediate molecular ion H₂⁺. This model allows for the prediction of the single and double ionization probabilities of the H₂ molecule to be made over a wide range of frequencies and laser intensities with limited computational time while providing a realistic estimate of the energy of the products of the dissociative ionization and of the Coulomb explosion of the H₂ molecule. The effect of vibrational dynamics on ionization yields and proton kinetic energy release spectra is demonstrated and, in the case of the latter, is discussed in terms of basic strong-field molecular fragmentation mechanisms.