Multi-ionization of the Cl 2 molecule in the near-infrared femtosecond laser field.

The multi-electron ionization and subsequent dissociation of the Cl 2 molecule in a near-infrared femtosecond laser field was investigated via the dc-sliced ion imaging technique. The single charged molecular ions, Cl 2 + , dissociate from two excited states, 2 Π u and 2 Σ g + , with the electrons ionized from the HOMO-1 and HOMO-2 orbital, respectively. For the multi-charged molecular ions, Cl 2 n + ( n = 2-8), our results showed that the stretch of the inter-nuclear distance benefitted the ionization of the electrons to produce highly-charged molecular ions. In addition, compared with the traditional charge resonance enhanced ionization (CREI) model, the critical distance ( R c ) for the Cl 2 molecule in our experiment was a short range that depended on the charge state rather than a single point.