Abstract
Laser-driven proton acceleration, as produced during the interaction of a high-intensity (I > 1 × 1018 W/cm2), short pulse (<1 ps) laser with a solid target, is a prosperous field of endeavor for manifold applications in different domains, including astrophysics, biomedicine and materials science. These emerging applications benefit from the unique features of the laser-accelerated particles such as short duration, intense flux and energy versatility, which allow obtaining unprecedented temperature and pressure conditions. In this paper, we show that laser-driven protons are perfectly suited for producing, in a single sub-ns laser pulse, metallic nanocrystals with tunable diameter ranging from tens to hundreds of nm and very high precision. Our method relies on the intense and very quick proton energy deposition, which induces in a bulk material an explosive boiling and produces nanocrystals that aggregate in a plasma plume composed by atoms detached from the proton-irradiated surface. The properties of the obtained particles depend on the deposited proton energy and on the duration of the thermodynamical process. Suitably controlling the irradiated dose allows fabricating nanocrystals of a specific size with low polydispersity that can easily be isolated in order to obtain a monodisperse nanocrystal solution. Molecular Dynamics simulations confirm our experimental results.
Highlights
Laser-driven particle acceleration, in particular electron and proton acceleration, as obtained by intense laser irradiation, is a field that has attracted strong interest in the last few decades[1]
The experiments were performed on the TITAN laser of the Jupiter Laser facility (operating in the Lawrence Livermore National Laboratory (LLNL) located in California) and at the ELFIE laser operating in the LULI facility located in Palaiseau (France)
We present a technique for a quick a-priori production of nanoparticles using the recently introduced laser-driven proton-ablation mechanism
Summary
Laser-driven particle acceleration, in particular electron and proton acceleration, as obtained by intense laser irradiation, is a field that has attracted strong interest in the last few decades[1]. There is market need for (quicker) manufacturing www.nature.com/scientificreports techniques able to produce a larger variety of nanoparticles that are more versatile in its utilization[51]: Several nanotechnology centers[52] and government organizations[53] are requesting proposals for the fast production of a large quantity of solvent-free isolated nanoparticles with higher precision (the required dispersion is ≤10%), where examples can be found in the production of ultra-small silica-organic hybrid nanoparticles “that have the potential to dramatically impact the way we diagnose and treat cancer patients based on their favorable physicochemical and imaging properties”[52], or the production of 60 nm gold nanocrystals with very low dispersion for the detection of early tumors in child brains since improving different imaging techniques[54] In both cases, higher production costs are justified since they allow overcoming important technological bottlenecks or might enable the production of yet non-existing nanoparticles (a similar example where high economic effort is justified, is the proton therapy, a very expensive cancer treatment, unique for curing specific tumors (e.g. brain tumors)). Our setup allows generating in the proton-irradiated material bulk (working or plume target/sample) temperature and pressure conditions that are not available in conventional nanomaterial synthesis laboratories even using industrially produced ion beams, due to their short duration[60]. The detached particles are deposited on nearby cold solid surfaces for obtaining nano- and microstructuration
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