Attosecond x-ray science: Probing electron dynamics in molecules and materials*

The emergence of attosecond science has enabled the direct measurement and control of dynamics in molecules and materials on the natural timescale of electrons. I will discuss our efforts to expand the scope of attosecond science to explore ‘complex’ processes in molecules and materials, where dynamical complexity stems from various interactions, including the coupling between the electronic and structural degrees of freedom, electronic correlations, external light fields, or a combination thereof. As an example, I will discuss the electronic processes in atoms and molecules, where light fields or nuclear motion induced couplings play an important role. By extending the ultrafast spectroscopy to novel materials, we have also examined electron-phonon interactions and electronic relaxation mechanisms in two-dimensional heterostructures. I will also discuss our efforts to develop light sources that combine the strengths of attosecond spectroscopy and x-ray science, thereby revolutionizing our ability to map and control elementary processes in molecules, interfaces, and quantum materials.