Mechanistic Insights into Nanocluster Formation via Microparticle Laser Fragmentation in Liquids: Unravelling Photothermal and Photomechanical Processes for Controlled NCs Synthesis

• Applicants: Professor Dr. Heinz Paul Huber; Dr. Anna Rosa Ziefuss
• Subject Area: Synthesis and Properties of Functional Materials ; Technical Chemistry
• Term: since 2025
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 562785215

Laser Synthesis and Processing of Colloids (LSPC) is a well-established technique for generating ligand-free nanoparticles (NPs) and nanoclusters (NCs). NCs, with sizes under 3 nm, are attractive due to their high specific surface area, catalytic activity, and photoluminescence, making them valuable for catalysis, biomedicine, advanced materials, and energy conversion applications. The standard method for generating NCs involves a two-step process: Laser Ablation in Liquid (LAL) followed by Nanoparticle Laser Fragmentation in Liquid (NP-LFL). NP production requires two processing setups, precise control, and significant financial investment, challenging scalability and size selectivity. Microparticle Laser Fragmentation in Liquid (MP-LFL) combines the advantages of LAL and NP-LFL into a single process, enabling ligand-free NC generation with scalable productivity and control over particle properties. However, MP-LFL faces NC selectivity and throughput issues, with contradictory findings regarding NC yield. Some studies have shown 100% selective NC yield, while others have noted by-product nanoparticle formation, suggesting the need for a deeper understanding of the mechanisms involved in MP-LFL. This project aims to close this knowledge gap by investigating the mechanisms behind NC formation in MP-LFL. The focus lies on the study of photomechanical and photothermal contributions to the fragmentation process. The project partners - Prof. Huber at HM, who specializes in time-resolved probing of ablation dynamics, and Dr. Ziefuss at UDE, who has expertise in particle suspension dynamics, will collaborate to provide insights into NC formation and fragmentation efficiency. Using gold (Au) and lanthanum hexaboride (LaB6), two materials with similar optical properties but different tensile strengths, the project will explore how laser parameters, such as fluence and pulse duration, affect NC selective yield. Single-particle and particle suspension experiments at HM and UDE will provide a comprehensive view of MP-LFL dynamics. By advancing the understanding of MP-LFL mechanisms, this project aims to maximize NC selective yield, paving the way for scalable and efficient NC production on an industrial scale.

• DFG Programme: Research Grants