Laser-Excited Atomic-Fluorescence Spectrometery as a Tool for Chemical Analysis

摘要

Laser excitation of atomic fluorescence overcomes several problems encountered when doing trace elemental analysis by atomic fluorescence spectrometry (AFS). One major problem encountered in AFS is light scattering, which may ultimately determine the minimum detectable atomic concentration. An atomic fluorescence spectrometer based on a wavelength-modulated continuous-wave dye laser is shown to diminish the light scattering signal and extend the minimum detectable concentration well beyond that obtained by using a mechanical chopper for the determination of Ba in a premixed flame. A pulsed frequency-doubled dye laser was used to investigate the potential of the inductively coupled plasma (ICP) as an atomic reservoir for AFS. The laser was used to obtain spatial profiles of the AFS signal from iron in the extended tail plume of an ICP. The limit of detection for iron in the ICP is comparable to that obtained in a conventional flame, but the ICP offers the significant advantage of relative freedom from matrix problems. The excitation of atomic fluorescence by lasers that are not in resonance with the atomic transition is also studied for the cases of sodium and nickel. This off-resonant excitation opens the possibility of multielement analysis by laser excited atomic fluorescence spectrometry. (ERA citation 08:012756)