INDUCED BREAKDOWN SPECTROSCOPY; INDUCED ALUMINUM PLASMA; FEMTOSECOND LASER; ISOTOPIC SPECTROMETRY; TEMPORAL EVOLUTION; EMISSION-SPECTRA; ABLATION; ALO; DYNAMICS; CARBON

Measurements with Laser Ablation Molecular Isotopic Spectrometry (LAMIS) are usually performed in atmosphere for rapid isotope analysis, and an understanding of molecule formation via plasma-air chemical reactions is important for quantitative analysis by LAMIS. In this work, the expansion of a plasma plume from ablation of pure aluminum in air is studied with time-and space-resolved monochromatic imaging and emission spectroscopy. The distributions of neutral Al and O atoms and AlO radicals formed through plasma chemical reactions are characterized. The emission spectra of the AlO bands of a B-2 Sigma(+)-X-2 Sigma(+) system are recorded and the rotational-vibrational temperature was obtained through fitting experimental spectra. Inter-molecular vibrational band interference is well reconstructed, and self-absorption of bandheads, especially for the (0-0) band, is corrected. Interpretation of the spatial-temporal evolutions of plasma species and plasma temperature provides insights into the formation mechanism of AlO radicals in laser-induced plasma.