Andrea Cavalleri

Abstract:

First conjunct optical and x-ray measurements were reported during an optically driven solid-solid phase transition in the correlated oxide Vo2. Optical measurements were performed by combining the pump-probe technique with visible microscopy. Laser pulses of high fluence triggered a subpicosecond structural transition from the low temperature monoclinic phase to the high temperature rutile phase.

Abstract:

Time-resolved x-ray diffraction with ultrashort ( approximately 300 fs), multi-keV x-ray pulses has been used to study the femtosecond laser-induced solid-to-liquid phase transition in a thin crystalline layer of germanium. Nonthermal melting is observed to take place within 300-500 fs. Following ultrafast melting we observe strong acoustic perturbations evolving on a picosecond time scale.

Abstract:

We review the progress we made recently on the generation of a femtosecond thermal X-ray source (line and broadband emissions) using solid-density-plasmas generated by ultrashort laser, in view of applications to molecular dynamic.

Abstract:

Time-resolved x ray diffraction was used to study ultrafast structural transitions in optically excited semiconductors and metals. Non thermal changes in the lattice structure was observed in less than 300 fs. The analysis confirmed the existence of femtosecond non-thermal melting in a covalent semiconductor. The analysis indicated an ultrafast structural transition in a metal.