Synthesis of aluminum nanoparticles using spark discharge for applications in ultraviolet plasmonics

This work demonstrates synthesis Al metal nanoparticles with plasmon resonance in the ultraviolet region by the spark discharge method in an argon atmosphere. The resulting primary particles have an Al metal core and a natural  oxide shell and size in range from 5 to 50 nm. Importantly, these nanoparticle ensembles show wide extinction peaks, with the highest point between 250 and 480 nm wavelength. The position of the peak can be varied by synthesis  parameters. During our research, we employed laser radiation at a wavelength of 355 nm, with pulse energies reaching up to 350 μJ and pulse repetition rates of up to 2000 Hz. We observed that the sintering process of  nanoparticles exhibited a dynamic change in size, which correlated with the energy of the laser pulses. This dependence was illustrated by an S-shaped shrinkage curve. By subjecting the initial agglomerates to a series of impacting  laser pulses, we successfully achieved complete sintering, resulting in the transformation of the agglomerates into spherical nanoparticles.