Laser-induced fluorescence of As, Se and Sb in the inductively coupled plasma

Abstract

Stimulated Raman shifting (SRS) has been used to generate tunable UV radiation at 193.7 nm, 197.2 nm and 196.0 nm for the excitation of laser-induced fluorescence (LIF) of As and Se, respectively, in the ICP. An excited-state, stepwise LIF approach has also been explored for Se using laser excitation at 206.279 nm. LIF of Sb has been accomplished using laser excitation at 206.833 nm and 212.739 nm. Power dependence studies of the LIF signals for As, Se and Sb have been performed. Saturation behavior has been observed for each element and saturation spectral energy densities are reported at 193.696 nm and 197.197 nm for As, at 196.026 nm for Se and at 212.739 nm for Sb. Evaluation of the saturation spectral energy density provides insight into the relative magnitude of the fluorescence quantum efficiency of Se at 196.026 nm in the ICP. Limits of detection of the ICP LIF approaches are 4 ng ml −1, 2 ng ml −1 and 15 ng ml −1 for As, Se and Sb, respectively, and compare favorably with those reported previously by ICP emission and ICP atomic fluorescence spectroscopy approaches. Also reported are the first observations of high-lying excited-state transitions of Se in a flame by a LIF technique.