Split-pulse X-ray photon correlation spectroscopy with seeded X-rays from X-ray laser to study atomic-level dynamics

TL;DR

This paper demonstrates that combining split-and-delay optics with self-seeded X-ray free-electron lasers enables atomic-scale dynamic measurements at picosecond timescales, surpassing previous limitations in pulse energy and delay control.

Contribution

It introduces a novel approach integrating SDO with seeded X-rays to enhance pulse energy for atomic-scale dynamics studies at ultrafast timescales.

Findings

Speckle contrast in water varies with delay-time as predicted.

Enhanced pulse energy allows atomic-scale dynamics observation at picosecond scales.

Method extends capabilities of X-ray photon correlation spectroscopy.

Abstract

With their brilliance and temporal structure, X-ray free-electron laser can unveil atomic-scale details of ultrafast phenomena. Recent progress in split-and-delay optics (SDO), which produces two X-ray pulses with time-delays, offers bright prospects for observing dynamics at the atomic-scale. However, their insufficient pulse energy has limited its application either to phenomena with longer correlation length or to measurement with a fixed delay-time. Here we show that the combination of the SDO and self-seeding of X-rays increases the pulse energy and makes it possible to observe the atomic-scale dynamics in a timescale of picoseconds. We show that the speckle contrast in scattering from water depends on the delay-time as expected. Our results demonstrate the capability of measurement using the SDO with seeded X-rays for resolving the dynamics in temporal and spatial scales that are not accessible by other techniques, opening opportunities for studying the atomic-level dynamics.