Imaging electronic structure changes in molecules using tailored laser fields

• Applicant: Dr. Matthias Kübel
• Subject Area: Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: since 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 437321733

The interaction of molecules with light is of vital importance for life on Earth. The absorption of photons by a molecule can induce motion of its electrons and/or nuclei and trigger chemical reactions. Understanding this correlated motion on microscopic time and length scales is a forefront of science, which is of mutual interest for physics, chemistry and biology. However, the complete quantum mechanical treatment of single-molecule reactions surpasses our current computational capabilities. The development of suitable theoretical methods and the advancement of the scientific field, therefore, depend on experiments that are sensitive to both nuclear and electronic dynamics. Such experiments utilize femtosecond laser pulses, which enable slow-motion recordings of nuclear dynamics or manipulation of chemical reactions. In recent years, advancements in laser technology have led to the development of new experimental tools. Using attosecond laser pulses, observations with unprecedented time resolution have become possible. Phase-stable laser pulses in the visible to mid-infrared spectral range enable the switching of strong electric fields within the time scale of electronic and nuclear motion. These capabilities open up new opportunities. The proposed project aims at the development of novel methods for imaging of light-induced electronic and nuclear dynamics. The proposed approach involves a unique combination of ultrashort, phase-stable laser pulses in different spectral regions. Each pulse will be tailored to fulfill a specific role in the experiment. The new approach will enable imaging of the transient electron density within a molecule. In combination with a reaction microscope, time-resolved snapshots of the motion of nuclei and electron densities will be recorded. For example, we will make molecular movies of how the electron density migrates within a molecule following optical excitation or localized tunnel ionization; and how electronic and nuclear motion depends on each other while a molecular bond breaks or rearranges. I expect that our results will provide valuable contributions towards the microscopic understanding of the fastest processes during chemical reactions.

• DFG Programme: Independent Junior Research Groups
• International Connection: Canada
• Major Instrumentation: COLTRIMS ; Optical parametric amplifier (OPA)
• Instrumentation Group: 0390 Sonstige Geräte der Atom- und Kernphysik (außer 020-038 und 610-619) ; 5700 Festkörper-Laser
• Cooperation Partner: Professor Dr. Michael Spanner