Ultrafast Resonant Rescattering Quantum Interference in Laser-Induced Photoelectron Imaging

In laser-induced strong-field ionization (SFI), ultrafast electron dynamics can be revealed by analyzing the holographic interference structures in photoelectron momentum distributions (PMDs) produced by interfering electron trajectories. Of these interfering trajectories, ones which involve rescattering from the parent ion or molecule probe attosecond dynamics in strongly driven atoms and molecules. In the strong-field approximation (SFA), backwards rescattering trajectories are respectively labeled short or long depending on whether they rescatter before or after the peak of the vector potential of the laser. Rescattering patterns have been extensively studied for the highest rescattering momentum electrons, at which the short and long trajectories are the most similar; however, the lower momentum rescattering regime is largely unexplored. In this regime, we identify rings of enhanced photoelectron yield which appear to be caused by the interference of short and long trajectories with the same final momentum. We simulate coalescing short and long trajectory interference patterns and match them to high fidelity experimental PMDs with reasonable success. We determine that the locations of these rings are independent of laser intensity. Because these trajectories have different launch points in the laser cycle, manipulating the shape of the laser field by adding a second laser frequency will cause these rings to respond, providing attosecond-scale insight into the target. A complete understanding of these interference patterns may prove crucial to our interpretation of SFI dynamics, and allow us to probe attosecond electron-ion interactions after ionization.