Shaper-based photoelectron tomography of free electron wave packets from multiphoton ionization with tailored 3D laser fields

• Applicant: Professor Dr. Matthias Wollenhaupt
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 467215508

In this proposal, we suggest an experimental method for generating fully controlled and tailored three-dimensional (3D) ultrashort laser light fields. The 3D field is created in the focus of two polarization-shaped femtosecond laser beams propagating at an angle in different directions. In recent theoretical studies, these so-called “super-chiral” light fields have been shown provide exceptionally high sensitivity for distinguishing enantiomers. The main goal of our project is to experimentally explore the new possibilities offered by tailored 3D light fields for coherent control of atomic and molecular photoionization dynamics. In the proposed experiment, we investigate the multiphoton ionization (MPI) of atoms and chiral molecules with these fully controlled 3D laser fields by measuring the 3D photoelectron momentum distributions (PMD) of the released free electron wave packets. Because our established waveplate-based photoelectron tomography technique is not applicable to 3D fields, we introduce a novel pulse shaper-based photoelectron tomography method to accurately measure and reconstruct the full 3D PMDs. In our experiments, MPI serves as a model system to analyze the physical mechanisms of coherent control of ultrafast dynamics driven by 3D fields. At the same time, this method is used as a very sensitive nonlinear method for in-situ characterization of these 3D fields. We demonstrate the novelty of our approach by discussing various MPI scenarios and showing the corresponding simulated 3D PMDs which are only accessible by these 3D fields. We validate the simulation method by comparison with our previous experimental results.In the proposed project, we combine our expertise in advanced supercontinuum polarization pulse shaping, high-precision photoelectron tomography, and theoretical modeling of coherent control of atomic and molecular dynamics. Our central goal is the experimental generation and control of unprecedented 3D PMDs using 3D fields. Tailored 3D fields open new prospects for the control of light-induced ultrafast processes, not only in coherent control, but also in many areas of atomic, molecular, and optical physics such as chiral recognition, laser spectroscopy, nonlinear microscopy, laser chemistry, quantum information, and materials processing, to name a few.

• DFG Programme: Research Grants