Frustrated Coulomb explosion of small helium clusters

TL;DR

This paper introduces 'frustrated Coulomb explosion', a process where charge hopping during helium cluster Coulomb explosion produces energetic neutral helium atoms, supported by experimental observation and theoretical evidence.

Contribution

It presents the first observation and theoretical explanation of charge hopping in helium clusters, termed 'frustrated Coulomb explosion', without external fields.

Findings

Observation of energetic neutral helium atoms from cluster explosions

Theoretical support for charge hopping mechanism

Introduction of 'frustrated Coulomb explosion' concept

Abstract

Almost ten years ago, energetic neutral hydrogen atoms were detected after a strong-field double ionization of H$_2$. This process, called 'frustrated tunneling ionization', occurs when an ionized electron is recaptured after being driven back to its parent ion by the electric field of a femtosecond laser. In the present study we demonstrate that a related process naturally occurs in clusters without the need of an external field: we observe a charge hopping that occurs during a Coulomb explosion of a small helium cluster, which leads to an energetic neutral helium atom. This claim is supported by theoretical evidence. As an analog to 'frustrated tunneling ionization', we term this process 'frustrated Coulomb explosion'.