Molecular alignment of fragmenting H₂⁺ and H₂ in strong laser fields

We present time-dependent ab initio calculations of fragmenting H₂⁺ and H₂ molecules in strong laser fields, taking into account all nuclear and electronic degrees of freedom. In particular, very different and apparently contradicting experimental observations on the alignment of fragmenting hydrogen molecules are naturally explained and consistently interpreted. In addition, striking differences in the alignment of fragmenting H₂⁺ and H₂ are predicted. Whereas H₂ fragments show decreasing alignment with increasing laser intensity, the alignment of H₂⁺ fragments is nearly independent of the intensity. This is in contrast to existing intuitive expectations, but in accord with available experimental data.