Thomas Elsaesser

Title

Real-Time Probing of Structural Dynamics in Solids by Femtosecond X-Ray Diffraction

Abstract

Diffraction of X-rays from crystalline materials allows for determining time averaged equilibrium structures with high precision. Function of physical, chemical, and biological systems is frequently connected with nonequilibrium processes, involving ultrafast changes of electronic and/or nuclear structure. X-ray diffraction with a femtosecond time resolution has developed into an important tool to probe such changes most directly and unravel the mechanisms behind them. Recent prototype experiments performed with laser-driven X-ray sources will be presented in this talk. The interplay of coherent lattice motions and transient electric polarizations in nanolayered ferroelectrics is observed in real-time, revealing the coupling mechanisms and making polarization switching on ultrafast time scales possible. The first implementation of femtosecond powder diffraction gives insight into chemical processes and transient charge density maps of molecular materials.