Search for: All records

Abstract Nanodiamonds (NDs) have been widely explored for applications in drug delivery, optical bioimaging, sensors, quantum computing, and others. Room-temperature nanomanufacturing of NDs in open air using confined laser shock detonation (CLSD) emerges as a novel manufacturing strategy for ND fabrication. However, the fundamental process mechanism remains unclear. This work investigates the underlying mechanisms responsible for nanomanufacturing of NDs during CLSD with a focus on the laser-matter interaction, the role of the confining effect, and the graphite-to-diamond transition. Specifically, a first-principles model is integrated with a molecular dynamics simulation to describe the laser-induced thermo-hydrodynamic phenomena and the graphite-to-diamond phase transition during CLSD. The simulation results elucidate the confining effect in determining the material’s responses to laser irradiation in terms of the temporal and spatial evolutions of temperature, pressure, electron number density, and particle velocity. The integrated model demonstrates the capability of predicting the laser energy threshold for ND synthesis and the efficiency of ND nucleation under varying processing parameters. This research will provide significant insights into CLSD and advance this nanomanufacturing strategy for the fabrication of NDs and other high-temperature-high-pressure synthesized nanomaterials towards extensive applications. 

Laser-matter interaction and plasma dynamic during laser shock processing determine the key parameters such as laser shock wave pressure and evolution during laser shock processing (LSP) process. A first-principle based model is critically important for elucidating the underlying mechanism and process optimization of the LSP process. The current study focuses on developing a theoretical model for the fundamental understanding of laser-matter interaction and plasma dynamics. The key physical parameters, such as electron and ion temperature, plasma density and shockwave pressure are predicted by this model and validated by experimental results. 

Pulsed laser ablation (PLA) under active liquid confinement, also known as chemical etching enhanced pulsed laser ablation (CE-PLA), has emerged as a novel laser processing methodology, which breaks the current major limitation in underwater PLA caused by the breakdown plasma and effectively improves the efficiencies of underwater PLA-based processes, such as laser-assisted nano-/micro-machining and laser shock processing. Despite of experimental efforts, little attention has been paid on CE-PLA process modeling. In this study, an extended two-temperature model is proposed to predict the temporal/spatial evolution of the electron-lattice temperature and the ablation rate in the CE-PLA process. The model is developed with considerations on the temperature-dependent electronic thermal properties and optical properties of the target material. The ablation rate is formulated by incorporating the mutual promotion between ablation and etching processes. The simulation results are validated by the experimental data of CE-PLA of zinc under the liquid confinement of hydrogen peroxide.