LIF measurements of atomic arsenic in hydrogen and methane diffusion flames

Abstract

Laser-induced fluorescence (LIF) was used to detect atomic arsenic in hydrogen and methane diffusion flames. Elemental arsenic was excited at 197.2 nm (4p)3 4S3/2→(4p)2 (5s) 4P1/2 by mixing the fourth harmonic of a YAG laser (266 nm) and a dye laser (760 nm). The fluorescence was detected at 249.3 nm (4p)2 (5s) 4P1/2→(4p)3 2D3/2. In nitrogen-diluted methane flames, arsenic LIF was contaminated by fluorescence from polyaromatic hydrocarbons. Atomic arsenic was mainly found in the low-temperature, fuel-rich region and was quickly oxidized at high temperatures under both fuel-rich and fuel-lean conditions. The results were consistent with equilibrium calculations.