Methodologies Of Coherent X-ray Diffraction Imaging On Ultrafast Nanoscale Dynamics And Its Applications On Nanobeam Dynamic Buckling And Shock Induced Microjets

Due to the small size effect and surface effect,performance of nanostructures is markedly different from bulk materials.Accurate measurements of the responses of micro-nano structures under various loading conditions play a vital role in the model establishment.However,there is still a lack of effective in situ experimental methods to detect the response of micro-nano structures under external loadings,especially dynamic loadings.This work combines large-scale molecular dynamics(MD)simulations and X-ray coherent diffraction(CDI)simulation,to validate the feasibility of investigating ultrafast dynamics of micro-nano structures.Two-dimensional coherent diffraction patterns are simulated via GAPD based on real experimental geometries and atomic configurations obtained from MD simulations.Hybrid Input-Output(HIO)algorithm is used to reconstruct the 2D structures from the diffraction patterns,and reconstructions are compared with input atomic configurations.As two application cases,we first investigate the feasibility of CDI for measuring the deformation field of nanobeams,and then the mass distribution projection of shock induced microjets from metal surfaces.As two application examples,feasibilities of measuring the deformation field of micro-nano structures under different loading conditions,and mass distribution measurements for shock induced microjets are validated.The accurate measurement of the deformation field of micro-nano structures provides feasibility for extracting nano-scale surface characteristics,such as surface Young's modulus and residual surface stress.CDI simulations are performed for different stages of the shock induced microjets,including the initial growth stage,the extension stage,and the fragmentation stage.It is proved that CDI can provide us valuable information about the size,morphology and mass distribution of shock induced microjets,and its underlying physics and mechanisms,and guide the future experiment design and data interpretation.