A coherent view of Glasses: How coherent x-rays can elucidate the complex dynamics of glasses

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"Glasses are mysterious materials. Fundamental blocks in many natural and technological processes, still, their properties keep puzzling a large community of scientists nowadays. Following different experimental routes, materials as diverse as colloidal suspensions, emulsions and viscous liquids can be driven in an out-of-equilibrium state, where they solidify under conditions that still remain unknown. This process, traditionally called glass transition, leads to many intriguing phenomena as the emergence of multiple relaxations processes, dynamical heterogeneities, crossovers between distinct amorphous states, and uncommon mechanisms of particle motions. Within the large family of disordered systems, structural glasses play a key role being often considered as archetypes of out-of-equilibrium materials. Despite decades of studies, a microscopic theory of glasses is still missing due to the difficulty to probe their atomic motion with experiments and simulations. Few years ago, I used coherent x-rays to perform the first worldwide experiments probing the atomic motion of glasses. My works reported on a surprising glassy dynamic reminiscent of an anomalous stress-driven particle motion observed in some soft systems. Due to severe technical constraints, the studies performed so far were limited to the external, tiny portion of the huge ""iceberg” of dynamical features occurring at the atomic level, whose comprehension would enable substantial advances in the frontiers of knowledge. Thanks to the new possibilities offered by coherent x-rays, now is the right time to unveil the atomic dance of glasses in all its complexity with the CoherentGlasses project. Following four challenging experimental Research Objectives, we will provide a coherent picture of the microscopic dynamic and structural features accounting for the above discussed fascinating phenomena in glass-formers. A successful project keeps the promise to boost our knowledge on out-of-equilibrium material."