Dichography: two-frame ultrafast imaging from a single diffraction pattern

Area of Science:

• * Ultrafast X-ray science
• * Nanomaterial imaging
• * Coherent diffractive imaging

Background:

• * X-ray Free Electron Lasers (XFELs) offer ultrabright and ultrashort pulses for probing matter dynamics.
• * Capturing time-resolved structural dynamics of nanomaterials requires high spatial and temporal resolution.
• * Overlapping diffraction signals from multiple pulses complicate data analysis.

Purpose of the Study:

• * To introduce and validate Dichography, a novel method for separating and reconstructing images from time-delayed X-ray pulses.
• * To achieve high-resolution, time-resolved imaging of nanomaterials using dual-color X-ray pulses.
• * To investigate the timescale of structural damage in nanomaterials under intense X-ray illumination.

Main Methods:

• * Experimental setup utilizing pairs of time-delayed, dual-color X-ray pulses from an X-ray Free Electron Laser.
• * Development of the Dichography algorithm to computationally separate overlapping diffraction patterns.
• * Reconstruction of two distinct images from single diffraction events for structural analysis.

Main Results:

• * Successful reconstruction of two time-delayed images of xenon-doped helium nanodroplets with 20 nm spatial resolution.
• * Observation of structural consistency in nanodroplets up to 750 fs delay, indicating damage occurs at longer timescales.
• * Validation of the method by imaging silver nanoparticles with high fidelity.

Conclusions:

• * Dichography effectively separates diffraction signals, enabling time-resolved imaging with XFELs.
• * The study provides insights into the ultrafast structural dynamics and damage thresholds of nanomaterials.
• * This method opens new avenues for time-resolved studies in physics, chemistry, and materials science.