the Institute of Experimental Physics, University of Bialystok
and the Institute of Atomic Energy, Swierk
under the auspices
of the European Crystallographic Association;
Committee of Crystallography, the Polish Academy of Sciences;
and the Polish Neutron Scattering Society
The School is financially supported in part by
the International Union of Crystallography;
the European Crystallographic Association;
the European Office of Aerospace Research & Development;
the Ministry of Science and Information Society Technologies;
the Warsaw University of Technology;
and the University of Bialystok.
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Eric Collet,
France
Topics
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X-ray diffraction is intensely used to solve crystal structures and makes it possible to better understand atomic interactions and the origin of physical properties. Time-resolved x-ray diffraction makes it possible to observe molecular reorganization as photoinduced transformation take place and gives information on the physical process. Very short x-ray pulses (ps or fs) makes it possible to observe phenomena at the time-scale of molecular or atomic motion with an atomic spatial resolution. During this lecture and after some reminder around x-ray diffraction, I will generally discuss the different informations we can probe with x-ray diffraction and especially around photoinduced phase transition, with example performed both with and without time-resolved experiments :
- relation between atomic motions and Bragg peak intensities.
- differences between local excitation and coherent processes.
- 3D ordering or disordering phenomena : symmetry breaking and signatures in diffraction.
- problem of coexistence of stable and photo-induced phases
- processes of the transformation and diffuse x-ray scattering : from the excited molecule to macroscopic transformation.
- An important part of the lecture will be devoted to some photo-active materials with the possibility of tuning their optical, magnetic, conduction or other physical properties by light stimuli.