# Laser-induced transient opacity in helium nanodroplets probed by single-shot coherent diffraction

## TL;DR

This study demonstrates that single-shot coherent diffraction imaging can detect ultrafast, laser-induced electronic structure changes in helium nanodroplets, revealing transient opacity effects with potential applications in ultrafast nanoscale imaging.

## Contribution

It extends CDI to observe transient electronic modifications in nanoparticles caused by laser pulses, enabling real-time tracking of ultrafast electron dynamics.

## Key findings

- Laser pulses increase helium nanodroplets' XUV absorption.
- Diffraction signal decreases due to electronic structure changes.
- Method captures ultrafast electron dynamics in nanosystems.

## Abstract

Single-shot coherent diffractive imaging (CDI) with intense short-wavelength light pulses enables the structural characterization of individual nanoparticles in free flight with high spatial and temporal resolution. Conventional CDI assumes that the target object exhibits a linear scattering response and static electronic properties. Here, we extend this approach to investigate transient laser-driven modifications of the electronic structure in individual nanoparticles, imprinted in their time-resolved diffraction patterns. In the presence of a near-infrared laser pulse, we observe a pronounced reduction in the diffraction signal from helium nanodroplets when probed with ultrashort extreme ultraviolet (XUV) pulses. This effect is attributed to a light-field-induced modification of the electronic structure of the droplets, which substantially increases their XUV absorption. Our results demonstrate that single-particle diffraction can capture ultrafast light-driven electron dynamics in nanoscale systems. This paves the way for the spatiotemporal tracking of reversible changes in the electronic properties of nanoscale structures with potential applications in ultrafast X-ray optics, materials science, and all-optical signal processing.