Moving from a Single-Active-Electron Model to an All-Electron Perspective for Strong Field Interactions

Atoms and molecules are the fundamental building blocks of matter. The attractive forces between them arise from electric interactions between positively charged nuclei and negatively charged electrons. High-powered lasers can stimulate and probe these electric forces, offering a controllable environment for studying molecular dynamics. This project seeks to determine how the full, multi-electron structure of matter contributes to electric interactions. The proposed work includes high-intensity laser experiments and state-of-the-art theoretical modeling. The project will provide intensive, hands-on research training for students and researchers at the undergraduate, graduate, and postdoctoral levels, directly supporting STEM workforce development. The project aligns with national priorities by preparing a highly skilled technical workforce in areas such as advanced manufacturing, machine vision, and remote sensing for national defense. In physics, chemistry, and biology, electric fields—rather than gravity or nuclear forces—govern molecular reactions, condensed matter properties, and plasma behavior. Electric fields involved in interactions between two reacting molecules are significantly more complex than those of a single molecule exposed to a laser field. For this reason, we will use tunable laser fields to investigate multielectron dynamics in matter. Field strengths will range from the intensities that barely ionize neutral molecules to ultra-strong fields reaching intensities up to 10,000 petawatts per square centimeter. Experimental measurements will include ion and electron spectroscopy of singly- and multiply-ionized fragments. The electronic states probed will reach beyond bonding orbitals, delving deep into atomic structure. This research addresses a key gap between simplified one-electron models and the collective, multielectron responses that dominate real-world molecular interactions. By advancing our understanding of these complex systems, the project supports U.S. goals in scientific leadership, technological innovation, and strategic workforce development. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.