Interatomic Coulombic decay in helium nanodroplets

TL;DR

This study investigates interatomic Coulombic decay in helium nanodroplets, revealing its occurrence at various locations within the droplets and detailing the resulting ionization dynamics and formation of ion complexes.

Contribution

It provides the first detailed experimental observation of ICD occurring inside helium nanodroplets at different depths, expanding understanding of decay processes in such systems.

Findings

ICD occurs at the surface, inside, and in the interior of helium nanodroplets.

ICD inside droplets results in slow He^+ ions due to Coulomb explosion.

Formation of He_k^+ complexes observed after ICD inside droplets.

Abstract

Interatomic Coulombic decay (ICD) is induced in helium (He) nanodroplets by photoexciting the n=2 excited state of He^+ using XUV synchrotron radiation. By recording multiple coincidence electron and ion images we find that ICD occurs in various locations at the droplet surface, inside the surface region, or in the droplet interior. ICD at the surface gives rise to energetic He^+ ions as previously observed for free He dimers. ICD deeper inside leads to the ejection of slow He^+ ions due to Coulomb explosion delayed by elastic collisions with neighboring He atoms, and to the formation of He_k^+ complexes.