On the influence of vibrational motion on strong-field ionization rates in molecules

The influence of the vibrational degree of freedom on the strong-field ionization of molecules is investigated. On the basis of numerical simulations it is found that vibrational motion leads to a reduced ionization rate for H-2 and O-2 compared with the rate of an atom with identical ionization potential. In the case of N-2 the vibrational motion has, however, a negligible influence on the ionization rate. While these results are in qualitative agreement with recent experimental findings, the predicted reduction of the ionization rate for H-2 and O-2 is too Small to fully explain the experimental results.