Laser-Induced Fluorescence of Se, As, and Sb in an Electrothermal Atomizer

Abstract

Trace detection of Se, As, and Sb atoms has been performed by electrothermal atomization laser-induced fluorescence (ETA-LIF) approaches. Production of far-UV radiation necessary for excitation of As atoms at 193.696 nm and Se atoms at 196.026 nm was accomplished by stimulated Raman shifting (SRS) of the output of a frequency-doubled dye laser operating near 230 nm. Both wavelengths were obtained as second-order anti-Stokes shifts of the dye laser radiation and provided up to 10 μJ/pulse, which was shown through power dependence studies to be sufficient 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 accomplished using 206.833-nm excitation and detection at 259.805 nm. The accuracy of the ETA-LIF approaches was demonstrated by determining the As and Se content of aqueous reference samples. The limits of detection (absolute mass) were 200 fg by ground-state LIF and 150 fg by excited-state direct line fluorescence for Se, 200 fg for As, and 10 fg for Sb; these LODs compare favorably with results reported previously in the literature for ETA-LIF, GFAAS, and ICP-MS methods.

Tungsten Coil Devices in Atomic Spectrometry: Absorption, Fluorescence, and Emission

“…Sum frequency generation or stimulated Raman frequency shifting techniques can further extend the UV range down to 187 nm, making the measurements of these elements possible. As, Se and Sb were previously determined by graphite furnace ETA-LEAFS 26 and ICP-LEAFS, 28 and the LODs were 200, 150 and 10 fg for As, Se and Sb by ETA-LEAFS,…”

“…The components used for the instrumentation have been described in detail elsewhere and briefly summarized here. 5,15,16,26,27 In W-Coil AAS, the Cd HCL was powered by a radio frequency power supply (Leeman Labs, Inc., Hudson, NH). The emission beam from the HCL was cut down to 2 mm in diameter after exiting the lamp by using an iris, and focused onto a point 2 mm above the coil with a fused silica lens of 5 cm focal length; after exiting the glass cell, the radiation was focused, with another lens, into the entrance slit of a CCD-based miniature spectrometer (SP2000, Ocean Optics, Dunedin, FL).…”

Far-Ultraviolet Excited Laser-Enhanced Ionization Spectrometry of As, Se, Cu, and Sb in Air/Acetylene and Ar/O2/Acetylene Flames

“…These wavelengths are necessary for As and Se, where the ® rst excited state can be reached only with wavelengths less than 200 nm . Anti-Stokes Raman shifting of 230 nm radiation has been utilized effectively for laser-induced¯uorescence measurem ents of As and Se in the inductively coupled plasma (ICP) 5 and electrotherm al atomizers, 6 but remains to be utilized for LEI m easurements of these elements.…”

Hydride Generation Laser-Induced Fluorescence of Arsenic and Selenium in the Inductively Coupled Plasma and Electrothermal Atomizer

“…The laser instrumentation used in these studies was the same as that employed previously. 15,16 Brie¯y, a XeF excimer laser (L PX 210i, Lambda Physik, Ft. Lauderdale, FL ) operating at 351 nm provides up to 350 mJ per pulse at repetition rates of up to 100 Hz. The output of the excimer was used to pump a dye laser (Scanmate 2, Lambda Physik) operating near 460 nm to produce radiation near 230 ±235 nm by frequency doubling in a BBO I cr ystal.…”

“…The ETA-LIF system was identical to that described previously. 16 In an effort to reduce laser scatter, the quartz windows at the entrance and exit of the furnace housing were mounted at an angle of 568 ( Fig. 2).…”