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Time-resolved X-ray diffraction - Amélie Jarnac - Mercredi 20 septembre 2017 à 10 h 30

Amélie Jarnac - Laboratoire MAX IV de l’université de Lund en Suède

INSP - UPMC - 4 place Jussieu - 75005 Paris - Barre 22-12, 4e étage, salle 426


Time-resolved X-ray diffraction studies of metallic coated InSb : application for X-ray switch and demonstration of high-pressure crystalline phase transition

X-ray diffraction (XRD) is a tool to determine the structure and atomic arrangement in a material through the reflections allowed by the Bragg law. In time-resolved XRD, one can follow the intensity of the allowed x-ray reflections in time. The variation of intensity reveals the displacement of the atoms from their equilibrium position. The displacement can reflect many mechanisms, from propagation of coherent phonons for low laser pulse intensity up to phase transition with change of physical state or lattice structure for high laser pulse intensity.

In this talk, I will present two time-resolved diffraction studies using metallic coated Indium Antimonide (InSb) samples. In a first part, I will present the study of a gold coated InSb sample, designed for X-ray switch application [1], which can reduce the pulse duration of a 100 ps X-ray pulse to 20 ps with a peak reflectivity of 8%.

In a second part, I will talk about the generation and the characterization of an ultrashort laser-induced high pressure pulse. We generate the pressure pulse by partly melting an Aluminium thin film deposited on a crystal of InSb. The pressure pulse delivers a compression up to 5 GPa during 20 ps only. We demonstrated that this pressure pulse can drive a high-pressure crystalline phase transition [2,3] in InSb.

[1] A. Loether, Y. Gao, Z. Chen, M. F. DeCamp, E. M. Dufresne, D. A. Walko, and H. Wen, Struct Dyn 1, 024301 (2014).

[2] A. A. Kelsey and G. J. Ackland, Journal of Physics : Condensed Matter 12, 7161 (2000).

[3] R. J. Nelmes and M. I. McMahon, Physical Review Letters 77, 663 (1996).