LASER-INDUCED FLUORESCENCE OF SE, AS, AND SB IN AN ELECTROTHERMAL ATOMIZER

Trace detection of Se, As, and Sb atoms has been performed by electrot hermal atomization laser-induced fluorescence (ETA-LIF) approaches, Pr oduction of far-UV radiation necessary for excitation of As atoms at 1 93.696 nn and Se atoms at 196.026 nm was accomplished by stimulated Ra man shifting (SRS) of the output of a frequency-doubled dye laser oper ating near 230 mn, Both wavelengths were obtained as second-order anti -Stokes shifts of the dye laser radiation and provided up to 10 mu J/p ulse, which was shown through power dependence studies to be sufficien t for saturation in the ETA. An excited-state direct line fluorescence approach using excitation at 206.279 nm was also investigated for the LIF detection of Se. High-sensitivity LIF of Sb atoms was accomplishe d using 206.833-nm excitation and detection at 259.805 nm. The accurac y of the ETA-LIF approaches was demonstrated by determining the As and Se content of aqueous reference samples, The limits of detection (abs olute mass) were 200 fg by ground-state LIF and 150 fg by excited-stat e direct line fluorescence for Se, 200 fg for As, and 10 fg for Sb; th ese LODs compare favorably with results reported previously in the lit erature for ETA-LIF, GFAAS, and ICP-MS methods.