Large-scale surface nanopatterning of a commercial silicon (Si) wafer in the form of regular 1D arrays of high-aspect-ratio vertical nanosheets (NSs) for antifouling and other potential promising optoelectronic, nanophotonic, and sensing applications was performed via multishot picosecond IRlaser ablation under a 5-mm-thick carbon disulfide liquid layer. Specifically, the nanopatterned surface layer demonstrates the broad ultralow mid-IR transmittance and the high content of sulfur, carbon, and even oxygen in the modified submicron-thick top layer, preventing the appearance of a Staphylococcus aureus bacterial biofilm. High-resolution transmission electron microscopy studies exhibit the anticorrelating inner versus outer surface abundance of donor sulfur versus adverse carbon and oxygen components and the amorphous structure of the sulfur-hyperdoped NSs atop their crystalline basements. These NSs indicate their appearance via the interfacial vapor/ plume bubble-mediated codeposition of Si ablation nanoplumes from the regular trenches and sulfur-containing products of carbon disulfide decomposition in the bubble. Numerical modeling indicates the nanoplasmonic origin of the Si NSs, self-limited in both the 100 nm periods and the submicron heights.

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A comprehensive picture of the nanosecond-laser generation of colloidal nanoparticles in liquids is nowadays the demand of their high-throughput industrial fabrication for diverse perspective biomedical, material science, and optoelectronic applications. In this study, using silicon as an example, we present a self-consistent experimental visualization and theoretical description of key transient stages during nanosecond-laser generation of colloidal nanoparticles in liquids: plasma-mediated injection of ablated mass into the liquid and driving the vapor bubble, finalized by the colloid appearance in the liquid. The explored fundamental transient stages envision the basic temporal and spatial scales, as well as laser parameter windows, for the demanded high-throughput nanosecond-laser generation of colloidal nanoparticles in liquids.

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