Kinetics of Laser-Induced Nanowelding of Silver Nanoparticles in Solution

It is of importance and interest to understand the nanowelding process of metallic nanoparticles illuminated by lasers due to its potential for providing convenient and controlled ways for shape-conversion of nanoparticles and fabrication of nanodevices. However, the real-time kinetics of the nanowelding process were rarely reported in the literature. In this work, we applied fluorescence microscopy to directly image the nanowelding process of silver nanoparticles (AgNPs) under the illumination of continuous wave laser at 405 nm, and observed the formation of branched structures or assemblies due to nanowelding. By the sizes of the laser-induced assemblies, we observed that the kinetics of nanowelding followed an exponential law. We developed an analytical model based on simple polymerization predict and understand the measured kinetics, and experimentally verified the model by examining the dependence of the nanowelding kinetics on the laser power and the concentration of AgNPs. Furthermore, we observed that the formed higher-order structures were separated into different photoluminescent domains, showing asynchronous, uncorrelated blinking behaviors.