Product Code: ICAL08_M205

Resonance Raman Spectra of the Overcooled Laser-induced Al Plasmas
Authors:
X.K. Shen, University of Nebraska-Lincoln; Lincoln NE USA
H. Ling, University of Nebraska-Lincoln; Lincoln NE USA
Y.F. Lu, University of Nebraska - Lincoln; Lincoln NE USA
Presented at ICALEO 2008

Raman spectra of the overcooled laser-induced Al plasmas have been studied using an optical parametric oscillator (OPO) wavelength-tunable laser (215-2550 nm, 6ns) as the re-exciting source. Q-switched neodymium yttrium-aluminum-garnet (Nd:YAG) laser pulses (532 nm, 6 ns) with a laser fluence of 20 J/cm2 were used to generate plasmas from an Al alloy target. The laser fluence of the OPO wavelength-tunable laser was around 0.5 J/cm2. The Raman spectra of AlO radicals were clearly observed, which showed that the laser-induced Al plasmas interacted with the oxygen in the surrounding air and AlO radicals were produced. The spatial distribution of the Raman emissions was investigated by fast photography. Temporal evolution of the AlO radicals was studied by measuring the Raman spectra of AlO radicals with different time delays between the ablation and the re-exciting lasers. The temperature evolution of the overcooled laser-induced plasmas was investigated. The chemical dynamics of the laser-induced Al plasmas was summarized.