Inhomogeneous charge redistribution in Xe clusters exposed to an intense extreme ultraviolet free electron laser

The emission of highly charged ions from Xe clusters exposed to intense extreme ultraviolet laser pulses (lambda similar to 52 nm) from the free electron laser in Japan was investigated using ion momentum spectroscopy. With increasing average cluster size, we observed multiply charged ions Xez+ up to z = 3. From kinetic energy distributions, we found that multiply charged ions were generated near the cluster surface. Our results suggest that charges are inhomogeneously redistributed in the cluster to lower the total energy stored in the clusters.