Helicity-dependent dissociative tunneling ionization of CF4 in multicycle circularly polarized intense laser fields

Abstract

Dissociative tunneling ionization of tetrafluoromethane (CF₄) in circularly polarized ultrashort intense laser fields (35 fs, 0.8 × 10¹⁴ W cm⁻², 1035 nm), CF₄ → CF₄⁺ + e⁻ → CF₃⁺ + F + e⁻, has been studied by three-dimensional electron–ion coincidence momentum imaging. The photoelectron angular distribution in the recoil frame revealed that the dissociative tunneling ionization occurs efficiently when the laser electric field points from F to C. The obtained results are qualitatively consistent with the theoretical predictions by the weak-field asymptotic theory (WFAT) for tunneling ionization from the highest and next-highest occupied molecular orbitals, HOMO (1t₁), and HOMO−1 (4t₂), respectively. On the other hand, the angular distribution shows clear dependences on the polarization helicity, indicating that the breaking of the C–F bonds is sensitive to the helicity of the multicycle circularly polarized laser fields.