Oxidation in laser-generated metal plumes

• Published in: Physics of plasmas 2022-05, Vol.29 (5)
• Main Authors: Kautz, Elizabeth J., Phillips, Mark C., Zelenyuk, Alla, Harilal, Sivanandan S.
• Format: Article
• Language: English
• Subjects: Aluminum; Chemical reactions; Emission analysis; Emission spectroscopy; Iron; Lasers; Neodymium lasers; Niobium; Optical emission spectroscopy; Oxidation; Partial pressure; Plasma chemistry; Plasma physics; Plasmas (physics); Pollution monitoring; Semiconductor lasers; Titanium; YAG lasers; Zirconium
• ISSN: 1070-664X; 1089-7674
• DOI: 10.1063/5.0090155

The temporal evolution of atoms and molecules in a laser-produced plasma was investigated using optical emission spectroscopy for several metal targets (i.e., Al, Ti, Fe, Zr, Nb, and Ta). Plasmas from metal targets were generated by focusing 1064 nm, 6 ns pulses from an Nd:YAG laser. Gas-phase oxidation/plasma chemistry was initiated by adding O2 (partial pressures up to ≈20%) to an N2 environment where the total background pressure was kept at a constant 1 atmosphere. Temporally resolved emission spectral features were used to track the gas-phase oxidation. The dynamics of atomic and molecular species were monitored using space-resolved time-of-flight emission spectroscopy. Our results highlight that the partial pressure of O2 strongly influences spectral features and molecular formation in laser-produced plasmas. Atoms and molecules co-exist in plasmas, although with different temporal histories depending on the target material due to differences in thermo- and plasma chemical reactions occurring in the plume.