Electronic structure and dynamics in strong fields: precision spectra for multi-electron systems

点击翻译按钮获取中文摘要

Strong and precisely controlled electric fields are available in the form of extremely short laser pulses. These fields are used to literally observe how electrons move in atoms and molecules and to control the transformation of electronic structure by such pulses. Electrons and photons reach us as the messengers of these processes by their distribution in energy and emission angles. The precise interpretation and theoretical and computational verification of such distributions is the overall purpose of this project. Our principal guideline is to establish unambiguous theoretical data, and to do so for a set of atomic and molecular systems that are widely used in experiments with strong pulses. The systems include (in increasing complexity) the Helium atom and the Hydrogen molecule, heavier noble gas atoms Ne, Ar, etc., molecules consisting of only two atoms (diatomics), and finally larger molecules with no or strongly reduced symmetry. In our computations, only the electronic dynamics will be investigated, which dominates the processes up to time-scales of about 1 femtosecond. The initial stage of the project is entirely based on mathematical and computational developments by our group that were established during recent years an that, for the first time, allow the precise calculation of such phenomena with manageable computer resources. To progress further in this direction, method development constitutes about 25% of the research time in this project. Our data will be used to answer questions like: what causes the observed time-delays in the emission of electrons? (Not fully explained even for the simplest noble gas atom of Helium). Can we imagine electron detachment as a process involving only a single electron, or does the collective motion of electrons determine emission spectra? The answer to this question is expected to depend on the molecular species. What does the emitted light tell us about the internal structure of the molecule? Do we only see the electronic skin (valence electrons), do we see the core, do we see motion of electrons?