Using laser ablation in liquids, also nanoparticles made of materials that are sensitive against oxidation are easily accessible in the colloidal state. The example video is given for copper nanoparticles fabricated by laser ablation in acetone.
For details please see:
Bärsch, N.; Jakobi, J.; Weiler, S.; Barcikowski, S.: Pure colloidal metal and ceramic nanoparticles from high-power picosecond laser ablation in water and acetone. In: Nanotechnology 20 (2009), 445603
Video made by our colleagues from Particular: