Proton ejection from molecular hydride clusters exposed to strong X-ray pulses

TL;DR

This paper studies how small hydrogen-containing molecular clusters eject protons under intense X-ray pulses, revealing a unique proton segregation mechanism that preserves the cluster's heavy atom structure.

Contribution

It systematically investigates proton ejection and cluster stability across the iso-electronic sequence from methane to neon under strong X-ray irradiation.

Findings

Proton ejection is driven by electron migration within the cluster.

Proton segregation prevents explosion of heavy atoms.

Hydride clusters maintain integrity unlike core-shell systems.

Abstract

Clusters consisting of small molecules containing hydrogen do eject fast protons when illuminated by short X-ray pulses. A suitable overall charging of the cluster controlled by the X-ray intensity induces electron migration from the surface to the bulk leading to efficient segregation of the protons and to a globally hindered explosion of the heavy atoms even outside the screened volume. We investigate this peculiar effect systematically along the iso-electronic sequence of methane over ammonia and water to the atomic limit of neon as a reference. In contrast to core-shell systems where the outer shell is sacrificed to reduce radiation damage, the intricate proton dynamics of hydride clusters allows one to keep the entire backbone of heavy atoms intact.