3D Electron microscopy characterization of Ag mound-like surface structures made by femtosecond laser surface processing

Laser processing of metal surfaces by ultrafast pulse lasers is a developing technology with many potential uses including applications in heat transfer, medical implants, and tribology. Laser processed silver surfaces has several potential applications such as biomedical devices, antibacterial surfaces, and chemical sensors. However, there is a lack of previous research on laser processing of silver is more difficult to process compared with other metals. A newly investigated dual-pulse femtosecond laser surface processing technique was capable of producing self-organized, micro/nanoscale surface features on silver where single-pulse techniques had previously failed. Three-dimensional (3D) scanning electron microscopy (SEM) was used to examine mound-like structures produced by this new method to determine their composition and formation processes. The interior microstructure revealed that the mounds were comprised mostly of resolidified Ag grains with approximately 1% porosity. Hydrodynamically-driven fluid flow was the primary process that forms these surface structures without significant oxidation.