大型放射光施設 SPring-8

日　時: 2009年11月4日(火)　 13:30-15:00

場　所: 普及棟

Speaker: Dr. Klaus-Dieter Liss

Language: English

Affiliate: Australian Nuclear Science and Technology Organisation, Lucas Heights, Australia

Title: From seconds to picoseconds – selected applications of time resolved Xray diffraction in materials science and beyond ...

Abstract:
Time resolved synchrotron X-ray diffraction experiments open new insights into materials and physics, in particular with the ever developing sources and detector systems. This presentation outlines some experiments I have performed, which are most fundamental for the further development in their specific field.
The first part concentrates on the study of processes as they occur during thermo-mechanical processing. Fast, large-area 2D detectors are used to follow the grain statistics of a material in-situ on a sub-second time scale, while it is plastically deformed in a synchrotron beam. The different effects of lattice strain, subgrain formation, grain rotation, texture evolution, grain growth, dynamic recovery and dynamic recrystallization can be distinguished beside the conventional analysis of phase transformations.
On the shorter time scales of micro- and nanoseconds, a stroboscopic experiment to study shock waves is presented. Ultrasonic waves were induced by a laser into a silicon single crystal and lattice strain was probed by a high resolution crystal diffractometer, revealing the time oscillations of the ultrasonic wave field. Probing different positions allowed to determine the speed of a shock front, traveling faster than the linear speed of sound, followed by other converted and conventional waves.
Last, it is reported on an X-ray optical experiment in which hard X-ray photons are stored for several nanoseconds in a crystal cavity. Semi-transparent mirrors allow to enter 100 ps pulses into the cavity and leave them delayed by multiple nanoseconds. Applications of this fundamental device lie in the range of X-ray interferometers, Fabry-Perot etalons, resonators for free electron lasers and delay lines.
It is anticipated, that experiments nowadays accessible on a relatively longer time scale become feasible in the near future on shorter time scales while it is important to prepare the way into this direction.

担当者: 小原　真司
PHS: 3910
E-mail: kohara@spring8.or.jp