Nanostructured target fabrication with metal and semiconductor nanoparticles

The development of ultra-intense high-energy (≫1 J) short (<1 ps) laser pulses in the last decade hasenabled the acceleration of high-energy short-pulse proton beams. A key parameter for enhancing theacceleration regime is the laser-to-target absorption, which heavily depends on the target structureand material. In this work, we present the realization of a nanostructured target with a sub-laserwavelength nano-layer in the front surface as a possible candidate for improving the absorption. Thenanostructuredfilm was realized by a simpler and cheaper method than using conventionallithographic techniques: A colloidal solution of metallic or semiconductor nanoparticles (NPs) wasproduced by laser ablation and, after a heating and sonication process, was spray-dried on the frontsurface of an aluminum target. The obtained nanostructuredfilm with a thickness of 1μm appears, atmorphological and chemical analysis, uniformly nanostructured and distributed on the target surfacewithout the presence of oxides or external contaminants. Finally, the size of the NPs can be tuned fromtens to hundreds of nanometers simply by varying the growth parameters (i.e., irradiation time,fluence, and laser beam energy)