Real-time studies of reversible lattice dynamics by femtosecond X-ray diffraction

Ultrafast X-ray diffraction allows for observing structural dynamics of condensed matter in real-time, in this way directly probing reversible and irreversible geometry changes on atomic length and time scales. This article reports recent progress in this rapidly developing field, focusing on experimental work performed with laser-driven X-ray sources. After an introduction into the state-of-the-art methods for generation and measurement, we discuss coherent lattice motions of ferroelectric nano-layered systems and structural dynamics related to polar dipole solvation in bulk molecular crystals.