Speaker
Description
Improving our understanding of electron dynamics is essential for advancing energy transfer, optoelectronics, light-harvesting systems, and quantum computing. Recent developments in attosecond x-ray sources provide the fundamental possibility of observing these dynamics with atomic-scale spatial resolution. However, connecting a time-resolved signal to the dynamics remains challenging due to the broad bandwidth of an attosecond probe pulse. This makes exploring the capabilities of different attosecond imaging techniques crucial. Here, we propose attosecond momentum-resolved resonant inelastic x-ray scattering (RIXS) as a prominent technique for tracking ultrafast dynamics. We demonstrate that the scattering signal contains information about the instantaneous distribution of charge density across the scattering atoms. To illustrate this, we consider scattering from an $\alpha$-sexithiophene molecule in which coupled electron-hole dynamics are excited.
The prominent advantage of this tech- nique is the resonant enhancement of the signal from moving particles [1,2]. We introduce a method to extract information about the time-dependent charge density from momentum-resolved RIXS signals. Through an in-depth analysis of the signal from a non-stationary electronic system and the transitions involved, and by illustrating the approach with accurate many-body calculations, we identify favorable experimental conditions for linking signal features to charge-density properties [3]. By analyzing the momentum distribution at different scattered photon energies, it becomes possible to identify the sites with a significant hole population and those with substantial populations of both holes and electrons. This technique is particularly useful for studying exciton dynamics and charge separation, as it provides a way to distinguish coupled and decoupled electron-hole dynamics.