Ultrafast electronic and nuclear dynamics in molecular photoionization studied by RABBITT

• Applicants: Dr. Serguei Patchkovskii; Professor Dr. Giuseppe Sansone
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 546852490

The experimental technique of reconstruction of attosecond beating by two-photon transitions (RABBITT) was first introduced for the temporal characterization of trains of attosecond pulses. It was later shown to be well-suited to observing electronic dynamics on the ultrafast, attosecond time scale. The technique is now undergoing a rapid development in its applications to molecular targets. The existing theories and models of RABBITT are however geared towards small molecules, where fully-coupled treatment is possible. Such theories do not necessarily provide a clear physical picture of the underlying dynamics, and are difficult to apply to larger molecules. The goal of our proposal is to derive a comprehensive physical understanding of the processes involved in photoionization of sizeable molecular systems. To this end, we will disentangle the role of nuclear and electronic dynamics in photoionization. We will combine three teams (Freiburg, Berlin and Prague) equipped with our recently developed cutting edge experimental and theoretical capabilities to accurately study attosecond two-color photoionization RABBITT time-delays in several molecules. In our prior work we have developed unique tools for measurements of angle- and state-resolved RABBITT delays and a breakthrough theory and codes for accurate multi-electron calculations of two-photon molecular matrix elements to calculate the delays without the commonly used approximations. We show that RABBITT delays are uniquely suited to disentangle electronic and nuclear dynamics: dynamics in the neutral state, the ion and in the continuum each leads to contributions to the photoionization delay or RABBITT signal which have not been considered before. By studying the RABBITT delays for different parameters and configurations of the driving light field and in different molecules we will selectivel switch some of the contributing processes (delay components) on and off, and thus disentangle and quantify in experiment the role of electronic and nuclear effects. Concurrently, we will further develop our theory for RABBITT delays in molecular systems by combining state of art electronic and nuclear dynamics simulations that will support and guide our experiments.

• DFG Programme: Research Grants
• International Connection: Czech Republic
• Partner Organisation: Czech Science Foundation
• Cooperation Partner: Privatdozent Jakub Benda, Ph.D.