Femtosecond x-ray diffraction of short-pulse irradiated semiconductors

Summary form only given. Ultrafast optical-pump, x-ray diffraction probe experiments are providing new ways to study transient processes in physics, chemistry, and biology, including the direct observation of the atomic motion by which many solid-state processes and chemical and biochemical reactions take place. Current table-top-terawatt femtosecond laser systems provide an attractive source of few-hundred femtosecond duration bursts of angstrom-scale x-ray radiation with fluxes comparable to standard rotating-anode sources. Their compact size enables time-resolved structural dynamics to be studied in the small laboratory with temporal resolution better than typical molecular vibrational periods. Ultrafast structural dynamics in crystalline samples are readily studied with such systems and experiments discussed in this talk include ultrafast non-thermal solid-to-liquid transition in thin single-crystal Ge-111 films grown on Si-111 substrates; ultrafast non-thermal solid-to-solid transitions in bulk vanadium dioxide from a low temperature insulating phase to a high temperature metallic phase; and harmonic and anharmonic coherent acoustic dynamics in layered Ge-111 /Si-111 and bulk GaAs-111 samples.