Abstract: Ultrashort pulse laser ablation leads to the generation of plasma plumes (consisting of highly energetic species) which expand from the substrate surface and eventually deposit back onto the substrate as debris. This debris is accumulated around the ablated area or directly ejected into a liquid in the case where ablation is done while the target is immersed in a liquid environment. Debris consists of nanoparticles and we demonstrate their formation in the case of femtosecond laser ablation (180 fs, 775 nm, 1kHz) of silicon, a neodymium magnet and nickel in ambient air, helium gas or liquids.