Generation of gold nanoparticles by laser ablation in liquid using nanosecond pulsed non-diffracting beams

In this study, gold nanoparticles (Au-NPs) were synthesized via pulsed laser ablation in liquid (PLAL) using nanosecond pulses at four discrete wavelengths – 1064 nm, 532 nm, 355 nm, and 266 nm – to investigate the effects of laser wavelength and beam profile on nanoparticle characteristics. Both conventional Gaussian beams and non-diffracting Bessel beams, generated using a 1^∘ axicon, were utilized to irradiate a bulk gold target immersed in deionized water under identical scanning conditions. Characterization of the resulting colloidal AuNPs was carried out through UV–Vis–NIR absorption spectroscopy, scanning electron microscopy, dynamic light scattering, and zeta potential analysis. The results demonstrate that Bessel beams offer distinct advantages in NP generation, including improved ablation yield and reduced average particle size—particularly at longer wavelengths—due to their extended focal depth and quasi-uniform axial intensity profile. The study highlights the potential of beam shaping in PLAL for tunable and efficient nanoparticle production, with implications for applications requiring size-controlled and contaminant-free nanomaterials.