Charge recombination in soft x-ray laser produced nanoplasmas

Charge recombination in a nanoplasma produced by a short soft x-ray pulse from the FLASH free electron laser has been observed. XeAr core-shell clusters have been used to follow charge migration and fragmentation dynamics. After multiple ionization of the Xe core, the charge is transferred to the outer Ar shells. While the shells explode the inner nanoplasma expands and recombines slowly. This delayed expansion of the core could be of major importance for future imaging experiments at x-ray FELs.