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

Dissociative tunneling ionization of tetrafluoromethane (CF) in circularly polarized ultrashort intense laser fields (35 fs, 0.8 × 10 W cm, 1035 nm), CF → CF + e → CF + 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 (1t), and HOMO-1 (4t), 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.