Strong field ionization tomography with two-color circularly polarized femtosecond laser fields

Recent experiments using two-color circularly polarized laser fields have demonstrated that high-harmonic generation (HHG), a versatile tabletop source of extreme ultraviolet (EUV) light, can be now extended to from linear to circular polarization. Here we present the first experiments using these uniquely polarized light fields to study strong field ionization (SFI), which is the complementary process to HHG. Using a velocity map imaging photoelectron spectroscopy and tomographic reconstruction techniques, we identify low-energy structures in the 3D photoelectron angular distributions that correspond to the rescattering of electrons with the ion. The observation of rescattering structures confirms the proposed explanation for HHG under two-color fields and paves the way for next-generation spectroscopies to investigate molecular structure.