Laser-induced double resonance fluorescence of lead with graphite tube atomization

Abstract

A Nd-YAG pumped dual dye laser system was used In comblnatlon wlth electrothermal atomlzatlon to detect ultratrace quantltles of lead atoms In pure aqueous solutlons. Lead atoms were simultaneously exclted by two dye lasers propagating In opposite dlrectlons along the axis of a graphlte tube atomlzer, and tuned at 283.306 and 600.193 nm. Colllslonal coupllng between the level reached by laser excitation and nearby levels resulted In several fluorescence transitions In the ultravlolet region below 280 nm. The fluorescence was collected at 90' wtth a comblnatlon of a plane mlrror, havlng a 2 mm diameter hole In Its center to allow the exltlng of the laser beams, a spherlcal quartz lens, and a double monochromator. By measurement of the fluorescence slgnals at 261.418, 239.379, and 216.999 nm, detectlon llmlts were 0.2, 0.13, and 0.27 pg, respectlvely. Wlth the same system, the direct line fluorescence signal at 405.783 nm followlng slngle-step laser exdtatlon at 283.306 nm gave a detectlon llmlt of 3 fg. The presence of the metastable level at 10 650 cm-' above the ground state allowed a very efflclent excitation/ detectlon scheme In which the two lasers were tuned at 283.306 and 282.320 nm and the dlrect Une fluorescence was measured at 261.418 nm wlth a resultant detectbn llmlt of 0.8 P9.

Ultratrace Determination of Lead in Whole Blood Using Electrothermal Atomization Laser-Excited Atomic Fluorescence Spectrometry

“…This type of laser-excited atomic fluorescence spectrometer has been described in several previous publications. ,, For these experiments, a copper vapor laser (Model CU15-A, Oxford Lasers, Acton, MA) was used to pump a dye laser (Model DLII, Molectron) at a repetition frequency of 9 kHz. Although this laser possesses the capability of operating at frequency repetition rates up to 12 kHz, the optimum pulse power has been found to be at ∼9 kHz.…”