Evolutionary History of Atoms and Molecules in Reactive Laser-Produced Plasmas

The kinetics of atoms and molecules in a laser-produced plasma were investigated 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. The initial physical conditions of the plasma were measured using emission spectroscopy. Gas-phase oxidation/plasma chemistry was initiated by adding partial pressures of O 2 (up to approximately 20 %) in an N 2 ambient environment. 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 O 2 strongly influences spectral features and molecular formation in laser-produced plasmas. Atoms and molecules co-exist in laser-produced plasmas, although with different temporal histories depending on target material due to differences in thermo- and plasma chemical reactions occurring in the plume.