Photodetachment of the negative iodine ions in strong femtosecond laser fields

Single- and double-electron photodetachment (SPD and DPD) of negative iodine ions (I−) in strong femtosecond laser fields are experimentally investigated by employing mass-selective negative-ion source combining with time-of-flight mass spectrometry and velocity map imaging technique. By measuring the laser-intensity-dependent DPD yields and comparing with calculated strong field ionization of atoms, the non-adiabatic effect and the resonance-enhancement structure in DPD of negative ions are indicated. The photoelectron kinetic energy and angular distributions in the above-threshold detachment are analyzed. Partial-wave contributions are extracted and the role of the ponderomotive shift in electron detachment is identified. The study would pave the way to understanding the dynamics of the strong-field photodetachment of negative ions.