Damped Coulomb explosion of a cluster core encapsulated in a He nanodroplet

Abstract The dynamics of an x-ray ionized two-component core-shell nanosystem is experimentally probed using doped helium (He) nanodroplets. First, a soft x-ray pump pulse selectively inner-shell ionizes the core cluster of heavy rare-gas atoms, causing electron migration from the He shell to the highly-charged core. This leads to a strong damping of the core cluster’s spatial expansion. Thus, He droplets act as a tamper that reduces the radiation damage of embedded nanostructures, a property that could be exploited for improving x-ray coherent diffraction images. A near-infrared probe pulse, igniting and then driving the formation of a He nanoplasma, is used to obtain time-resolved information about the tamper effect. As evidenced by molecular dynamics simulations, the tamper effect is manifested by the time constant of the falling edge of the pump-probe signal curve.