"Charge and lattice dynamics in ionic crystals mapped by femtosecond x-ray powder diffraction"

"Charge relocations and atomic motions on ultrashort time scales play a key role for functional processes in condensed matter. X-ray diffraction methods with a femtosecond time resolution allow for spatially resolving transient structures and, in particular, spatial distributions of electrons, both being relevant for the structure-function relationships of crystalline materials. This talk provides an introduction into this exciting new field, combining experimental aspects with recent results on ultrafast electron and lattice motions in ionic crystals. Experiments with the photoexcited prototype material KDP (KH2PO4) reveal the interplay of lattice and charge motions which occur on distinctly different length scales. As a second example, the field-driven transfer of valence electrons between ions in a superposition of quantum states will be addressed for the materials LiBH4 and LiH. This fully reversible transfer mechanism makes a major contribution to the material’s optical polarizability."