Multi-ionization of the Cl2 molecule in the near-infrared femtosecond laser field

Abstract

The multi-electron ionization and subsequent dissociation of the Cl₂ molecule in a near-infrared femtosecond laser field was investigated via the dc-sliced ion imaging technique. The single charged molecular ions, Cl₂⁺, dissociate from two excited states, ²Π_u and ²Σ_g⁺, with the electrons ionized from the HOMO−1 and HOMO−2 orbital, respectively. For the multi-charged molecular ions, Cl₂ⁿ⁺ (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 Cl₂ molecule in our experiment was a short range that depended on the charge state rather than a single point.