Backward scattering impact on the photoionization time delay of asymmetric molecules


 The time delays in photoionization of asymmetric diatomic molecules are numerically investigated using the technique of reconstruction of attosecond beating by interference of two-photon transitions (RABBITT). Our results show that two different oscillatory structures appear in the molecular photoionization time delays as the photoelectron energy changes, and the contribution of these two oscillations to the time delays varies with the nuclear distance. By using an analytical interference model, we demonstrate that one oscillation is traced back to the two-center interference and the other originates from the photoelectrons backward scattering. With the increases of internuclear distance, the backward scattering impact on the time delays is gradually distinct in a particular direction of the photoionization. The amplitude of the backward scattering induced oscillation decreases when the photoelectron energy increases. Furthermore, the stereo RABBITT time delays display a distinct downshift as the increases of asymmetry degree of molecules, which is attributed to the increasing depth of the additional Coulomb potential experienced by the ionized electrons.