Abstract
An investigation was made of the use of laser light scattering and laser-induced resonance fluorescence, employed in combination with spontaneous emission, as diagnostic probes of the atmospheric-pressure high-voltage spark discharge, to elucidate information on various species. Raman scattering allowed the space- and time-resolved investigation of N2 behavior in the spark channel. Emission profiles of Al(I) and AlO were obtained to establish the temporal regions that were nonemitting for each species. Resonance fluorescence permitted observation of aluminum species in the nonemitting post-discharge torus both spatially and temporally resolved. The channel dynamics studies revealed the interaction of atmospheric nitrogen with the spark channel. Fluorescence studies on aluminum as the analyte species revealed the presence of Al(I) and AlO in the post-discharge torus region, after the discharge current has ceased, and after the Al(I) and AlO emission has ceased. This establishes that analyte material exists in more than one chemical form in the nonemitting regions of the spark discharge, and that excitation decays before all free atoms recombine into small molecules.
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