Two-dimensional imaging of atomic and nanoparticle components in copper plasma plume produced by ultrafast laser ablation

We report on the spatial and temporal evolution of the plume generated during ultrafast laser ablation of a pure copper target with 800 nm, ≈50 fs, Ti: Sapphire laser pulses. Time-gated imaging was used to record 2-dimensional images of plume populations. The temporal evolution of neutral (Cu*), and ionic (Cu⁺) components of the plume are separately imaged by exploiting bandpass interference filters, while nanoparticles are investigated by collecting their characteristic broadband emission. The ionic component of the plume moves two to three times faster than the neutral component, with a velocity which is almost independent of laser fluence. Plume emission intensity variations at different fluences and delay times are studied for both atomic and nanoparticle components.