ARGON FLUORIDE LASER-EXCITED ATOMIC FLUORESCENCE OF ARSENIC IN A H-2 AIR FLAME AND IN AN AR ICP

Laser-excited atomic fluorescence spectrometry (LEAFS) can be an extre mely sensitive method of trace analysis. However, some elements, such as As, have strong absorption lines only below 200 nm. Dye laser syste ms capable of resonance excitation of As are complicated and very expe nsive. By coincidence, a simple fixed-frequency argon fluoride (ArF) e xcimer laser produces a broad-band output centered at 193.0-193.2 nm o verlapping the As absorption line at 193.7 nm. The use of an ArF excim er laser as a source for LEAFS detection of As in a H-2/air flame and an Ar-ICP has been evaluated. Detection limits of about 20 ng/mL were obtained with both atomizers. The limiting noise was laser-induced sca tter in both cases. Methods of improving the detection powers are disc ussed.