Gas-phase oxidation and nanoparticle formation in multi-element laser ablation plumes

Area of Science:

• Materials Science
• Plasma Physics
• Nanotechnology

Background:

• Laser-produced plasmas (LPPs) are crucial for nanoparticle synthesis.
• Understanding gas-phase oxidation and nanoparticle formation in LPPs is essential for controlling material properties.

Purpose of the Study:

• To investigate the evolution of gas-phase oxidation and nanoparticle formation in LPPs from a multi-principal element alloy target in air.
• To characterize the morphology, composition, and structure of the resulting nanoparticles and agglomerates.

Main Methods:

• In situ optical emission spectroscopy (OES) to monitor gas-phase oxidation.
• Custom-built single particle mass spectrometry (SPMS) to analyze nanoparticle size and composition.
• Ex situ transmission electron microscopy (TEM) for detailed nanoscale characterization.

Main Results:

• OES revealed element-specific gas-phase oxidation occurring at different times during plume evolution.
• SPMS showed fractal agglomerates composed of all principal alloying elements and their oxides.
• TEM identified agglomerates containing amorphous nanoparticles, Ti-rich oxide nanoparticles, and base material.

Conclusions:

• The multi-component target composition significantly influences gas-phase molecular formation.
• Nanoparticle and agglomerate morphology, composition, and structure are directly impacted by the target's elemental makeup and oxidation processes.