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The current state-of-the-art in nanotip synthesis relies on techniques that utilize elaborate precursor chemicals, catalysts, or vacuum conditions, and any combination thereof. To realize their ultimate potential, synthesized nanotips require simpler fabrication techniques that allow for control over their final nano-morphology. We present a unique, dry, catalyst-free, and ambient condition method for creating densely clustered, flower-like, sodium oxide (Na2O) nanotips with controllable tip widths. Femtosecond laser ablation of a soda-lime glass substrate at a megahertz repetition rate, with nitrogen flow, was employed to generate nanotips with base and head widths as small as 100 and 20 nm respectively, and lengths as long as 10 μm. Control of the nanotip widths was demonstrated via laser dwell time with longer dwell times producing denser clusters of thinner nanotips. Energy dispersive X-ray analysis reveals that nanotip composition is Na2O. A new formation mechanism is proposed, involving an electrostatic effect between ionized nitrogen and polar Na2O. The synthesized nanotips may potentially be used in antibacterial and hydrogen storage applications. PACS: 81 Materials science; 81.07.-b nanoscale materials and structures: fabrication and characterization; 81.16.-c methods of micro- and nanofabrication and processing

We report a single step technique of synthesizing particle-agglomerated, amorphous 3-D nanostructures of Al and Si oxides on powder-fused aluminosilicate ceramic plates and a simple novel method of wafer-foil ablation to fabricate crystalline nanostructures of Al and Si oxides at ambient conditions. We also propose a particle size prediction mechanism to regulate the size of vapor-condensed agglomerated nanoparticles in these structures. Size characterization studies performed on the agglomerated nanoparticles of fabricated 3-D structures showed that the size distributions vary with the fluence-to-threshold ratio. The variation in laser parameters leads to varying plume temperature, pressure, amount of supersaturation, nucleation rate, and the growth rate of particles in the plume. The novel wafer-foil ablation technique could promote the possibilities of fabricating oxide nanostructures with varying Al/Si ratio, and the crystallinity of these structures enhances possible applications. The fabricated nanostructures of Al and Si oxides could have great potentials to be used in the fabrication of low power-consuming complementary metal-oxide-semiconductor circuits and in Mn catalysts to enhance the efficiency of oxidation on ethylbenzene to acetophenone in the super-critical carbon dioxide.