# Tunable Isolated Attosecond X-ray Pulses with Gigawatt Peak Power from a Free-Electron Laser

## TL;DR

This paper reports the creation of high-power, isolated soft X-ray attosecond pulses using a free-electron laser, enabling advanced studies of ultrafast electron dynamics with unprecedented intensity and spectral specificity.

## Contribution

It introduces a method to generate GW-scale, isolated soft X-ray attosecond pulses with significantly higher energy and power than previous sources.

## Key findings

- Generated soft X-ray attosecond pulses with gigawatt peak power.
- Pulse energy is six orders of magnitude larger than previous sources.
- Enables new ultrafast electron dynamics investigations.

## Abstract

The quantum mechanical motion of electrons in molecules and solids occurs on the sub-femtosecond timescale. Consequently, the study of ultrafast electronic phenomena requires the generation of laser pulses shorter than 1 fs and of sufficient intensity to interact with their target with high probability. Probing these dynamics with atomic-site specificity requires the extension of sub-femtosecond pulses to the soft X-ray spectral region. Here we report the generation of isolated GW-scale soft X-ray attosecond pulses with an X-ray free-electron laser. Our source has a pulse energy that is six orders of magnitude larger than any other source of isolated attosecond pulses in the soft X-ray spectral region, with a peak power in the tens of gigawatts. This unique combination of high intensity, high photon energy and short pulse duration enables the investigation of electron dynamics with X-ray non-linear spectroscopy and single-particle imaging.