Plume dynamics in ZnO under ArF laser radiation

We have investigated time evolution of the plume produced during laser ablation of ZnO under ArF-excimer-laser irradiation in He atmosphere. The plume luminescence is mainly due to excited Zn atoms. The plume propagates straightforwardly within 1 μs after ablation, and then it expands and forms an anchor-like shape due to the plasma confinement by the surrounding He gas. After the disappearance of the plume luminescence at high He pressure, a second excitation with a XeCl-excimer-laser causes a luminescence that can be explained in terms of condensation and formation of oxygen molecules and ZnO nanoparticles in the plume.