Coherent imaging of nano-objects with ultra-short X-ray pulses

Abstract : The use of X-rays is fundamental to obtain a spatial resolution in the order of the dozen of nanometers. The duration of the flashes of radiation is placed between the dozen of femtoseconds (1 fs =10-15 s) to the hundreds of attoseconds (1as=10-18 s). During this time frame nano-objects are static in time, image wise it translates as a precise image. Exciting these nano-objects with flashes of X-ray beams it is possible to follow its temporal evolution and record a "movie" of the evolution due to excitation. This type of information is extremely important since it can allow the identification of intermediary structural states and therefore attaining a better understanding of their reactional power.This type of studies it is making its debut in the scientific community due to the recent development of ultra-fast and intense X-ray sources needed to perform this type of imaging. The referenced source is a free electron laser (FEL) and there are only tree of them in the world nowadays. One in Germany, one in the USA and one in Japan. The small amount of FELs is mainly due to its elevated costs. From some years the LOA has shown that lasers can also provide an X-ray beam in the femtosecond region and intense enough to produce images of nano-objects with equivalent temporal and spatial resolutions.This present thesis was built in tree phases: realization of an X-ray laser source, circularly polarized; realization of a new improved imaging system and testing of the nano-samples possessing nano-structures. These nano-structures have a velocity of evolution after excitation in the range of 100 fs. These studies have had place at LOA, LCLS, Laboratoire de Chimie-Physique, Matière et Rayonnement (LCPMR), the CEA de Saclay, BESSY-II in Germany. These cooperations have insured a specific training and expertise in the world of nanometric imaging based on the new technique developed during this work.
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Anna Luiza Barszczak Sardinha. Coherent imaging of nano-objects with ultra-short X-ray pulses. Optics [physics.optics]. Université Paris-Saclay; Universidade técnica (Lisboa), 2016. English. ⟨NNT : 2016SACLX006⟩. ⟨tel-01495628⟩

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