Ion-pair formation in multiphoton fragmentation

Computational examples and physical considerations suggest that, in the statistical limit, ion-pair formation should be an important mechanism for the appearance of ions in the post-threshold region. This is particularly the case when the threshold energy for ion-pair formation is comparable or even lower than the first ionization potential. As the mean energy absorbed by the molecule increases, the ionization mechanism rapidly increases in importance. Deviations from the statistical limit are expected to favor the ionization pathway.