Open Access Conference Proceedings

Controlling nanoparticles (NPs) morphology in laser-mediated synthesis remains a significant challenge. This study introduces an innovative approach for synthesizing metal NPs using an Optical Vortex Beam (OVB) instead of the conventional Gaussian Beam (GB) in femtosecond laser ablation in liquids (fs-LAL). The primary objective is to achieve NPs shape modification through an environmentally friendly method, eliminating the need for chemical reagents and producing ligand-free NPs suitable for catalytic and biomedical applications. The transformation from GB to OVB was accomplished using a series of waveplates that first converted the linearly polarized GB to a circularly polarized beam and subsequently to a spiral phase wavefront beam, known as OVB. A key innovation of this study is the design of a 3D-printed ablation cell, which generates a thin liquid layer and ensures continuous liquid flow over the metal target, optimizing the laser-ablation setup. This optimization not only enhances productivity but also significantly reduces operation time. Results indicate that using OVB provides superior control over NPs morphology compared to GB, resulting in NPs with improved optical properties, as confirmed by Scanning Transmission Electron Microscopy (STEM) and UV-Vis spectroscopy. This approach holds potential for nanocatalysis, offering a cleaner and more efficient method for NPs synthesis.

Keywords: Laser-mediated synthesis, metal nanoparticles, optical vortex beam, morphology, set-up optimization

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