Andrea Cavalleri

Abstract:

Structural dynamics in laser-excited solids were investigated with femtosecond X-ray diffraction. Lattice dynamics in a semi-metal, bismuth was studied. Results of transient changes of diffraction from (111) lattice planes of a 90 nm Bi film for three different laser fluences were shown.

Abstract:

Ultrashort x-ray pulses offer a unique combination of atomic-scale spatial and temporal resolution, which permits direct measurements of structural transients on an ultrafast time scale. Using time-resolved X-ray diffraction with femtosecond, multi-keV X-ray pulses of transient lattice dynamics in optically excited semiconductors and metals were studied. Thus, short bursts of Ti-Kα-radiation at 4.51 keV were produced by focusing 120 fs laser pulses onto the surface of a moving Ti wire.

Abstract:

For a long time the capability to perform measurements with femtosecond time-resolution belonged exclusively to the domain of optics. However, in the last few years laser-driven X-ray sources have been developed which enable femtosecond time-resolution to be extended to the X-ray regime.

Abstract:

We report on the application of femtosecond x-ray scattering to experimental studies of the photo-induced, structural phase transition in VO2. The transition between the two crystalline phases of the material occurs, for sufficiently intense excitation, within 500 fs.