Laser-generated iron-gold-particles: Particle properties in dependence of synthesis parameters

The pulsed laser ablation in liquid (PLAL) is a simple, green, and cost-effective method for the synthesis of bimetallic nanoparticles. On the basis of this method various material combinations within one particle are made possible, thus creating particles with unique physical and chemical properties. Here, we investigate the influence of different laser pulse durations i.e., short (pico-second) and long (nano-second), on the structure of the Fe-Au particles. Detailed characterisation of the Fe-Au particles prepared with two lasers gave interesting results in terms of yields of four different particles structures, metal compositions, size distributions and magnetic properties. Interestingly, here in this work, the pico-second laser produced particles with a broad monomodal (70 ± 30 nm) size distribution. Contrary, the bimodal size distribution (7 nm and ∼ 1 μm) was produces with the nano-second laser. Since Fe-Au particles were formed in liquid, two additional laser-based processes could take place, that is: pulsed laser melting in liquid (PLML) and pulsed laser fragmenting in liquid (PLFL). Based on these findings, we propose particle formation mechanisms for the pico- and the nano-second laser.