Attosecond spectroscopy of size-resolved water clusters

TL;DR

This study introduces attosecond size-resolved spectroscopy to investigate electron dynamics in water clusters, revealing how electron-hole delocalization affects photoionization delays and linking electronic structure to ultrafast electron emission.

Contribution

The paper presents a novel attosecond spectroscopy method for size-resolved water clusters, providing new insights into electron-hole delocalization and photoemission dynamics at the molecular level.

Findings

Photoionization delays increase with cluster size up to 4-5 molecules.

Delays are proportional to the spatial extension of the electron hole.

Large clusters show partial localization due to structural disorder.

Abstract

Electron dynamics in water are of fundamental importance for a broad range of phenomena, but their real-time study faces numerous conceptual and methodological challenges. Here, we introduce attosecond size-resolved cluster spectroscopy and build up a molecular-level understanding of the attosecond electron dynamics in water. We measure the effect that the addition of single water molecules has on the photoionization time delays of water clusters. We find a continuous increase of the delay for clusters containing up to 4-5 molecules and little change towards larger clusters. We show that these delays are proportional to the spatial extension of the created electron hole, which first increases with cluster size and then partially localizes through the onset of structural disorder that is characteristic of large clusters and bulk liquid water. These results establish a previously unknown sensitivity of photoionization delays to electron-hole delocalization and reveal a direct link between electronic structure and attosecond photoemission dynamics. Our results offer novel perspectives for studying electron/hole delocalization and its attosecond dynamics.